sunnuntai 9. joulukuuta 2012

Motor adapter plate

I also made a template for the motor adapter plate from a piece of particle board I found lying around.

If you look closely you may also notice that the transmission has gotten a little cleaner than before. I washed the engine compartment as well as I could given the circumstances. The adapter template should allow me to either make a CAD drawing for a complete part to be manufactured at a shop or perhaps I'll just make a copy of it using a sheet of suitably thick aluminium. We'll see which will come to be.


Here's an interesting product I accidentally came across this morning. It's a little device that's meant to automatically switch between engine and cabin heaters in the winter. First it heats the engine and then switches to cabin heating until the engine cools too much. My idea is to use it to first heat the battery pack and when it's built in heat sensor detects the pack temperature to be at +5 Celsius it will switch on the cabin plug in which I have connected my charger. In essence making sure that charging won't be started unless there's sufficient heat in the battery box. I'm assuming I can safely leave it in all year and once it gets cold enough it just starts doing it's thing.

Their web page is here and you can also buy them here It's compatible with the usual Defa heating system. Simple and convenient. Gotta love it.

keskiviikko 21. marraskuuta 2012

Volvo gets it right first

I wouldn't have thought I'd ever say this, but if I'd have the money and if I'd be buying a new car in the near future it might have to be a Volvo. Why? Here's why.

It's quite probably based on the PSA Peugeot Citroën HYbrid4 system just like the Volvo's 1,6 liter turbo diesel DRIVe is based on the PSA HDi, but they seem to have made just about all the right decisions here. It's a station wagon, the combustion engine is an efficient diesel and the rear wheels are driven by electric. You should be able to go 50 km on pure electric and there's a button for that. I tried to figure out what that plug was and it seemed like nothing I've seen before so it could be Volvo's own. Update: It's a Mennekes connector.

Other than the fact that my long distance driver has to be a 6- or 7-seater and I don't know if you can have the V60 with 7 seats, is that buying a new car these days doesn't feel that tempting. You may find yourself asking why. Cars are better and more economical than ever so why not. It's because of the ultra proprietary black box design they have become. Every new model is made more and more complex and impossible to fiddle with by yourself and I predict eventually everyone but the car maker's own approved mechanics will be able to do anything to them. 3rd party shops will be left fixing whatever old cars still may be around until they rust away.

That's the worst case scenario that may or may not happen, but the direction is clear and I don't like it. It may even be a necessity to make the ecological improvements possible, but the cost may be giving up whatever tiny control you had left in the way you move around. That's why I've pretty much found my perfect car and quite probably a long time keeper in the Peugeot 307sw HDi90 -07, a station wagon with a 1,6 liter turbo diesel engine and possibility of having 7 seats. I currently need six to accomodate for my immediate family and the palce for the seventh seat is free for luggage. The only reason I see switching cars is that I or some friendly fellow man crashes the car completely. Other than that I'm quite  sure I'll just keep fixing it as long as humanly possible.

In other words a plug-in hybrid like the Volvo would be a really cool car, but I believe it comes with way too much complexity and parts that can break. The same thing pretty much goes for any new, rather expensive all electrics. Cheap and simple they would be tempting, but expensive and proprietary, not so much. So what is cheap and simple, but all electric? A DIY conversion car, of course. Or even simpler, a motorcycle. These are the vehicles I like. Simple, popular vehicles with plenty of aftermarket parts available, just converted to electric with the simplest DC motor and Bottom Balanced traction pack. Easy to maintain, yet as comfortable as the donor chassis you get to choose and with a range as long as you like or can afford. Any part can be swapped for a new or improved at will.

Of course if you care about none of these things, need the range, but want to drive electric as much as possible, then the Volvo looks like it really has it all. It'll be interesting to see what the all electric Saab will be. Who knows, maybe Sweden is the new king of electric cars. I kind of wished it would be Finland, but looks we can just build them for others like Think and Fisker. Oh, well.

torstai 8. marraskuuta 2012

No pipes save lives

I've actually had some progress with the actual car as well. In addition to selling the engine for 40% of the cost of the whole vehicle and some lesser parts for some change, I also got around to removing the exhaust pipe. Had to use an angle grinder to get it out. In part because it seemed hard to get it out in one piece and in part because I wasn't that interested in keeping it in one piece anyway. Some of it is actually pretty good condition and later I heard my buddy had just recently paid 100€ for that muffler. Oh well. Such is life. The engine by the way went to a couple of guys who needed it for a Citroën Xantia which has a blown engine so very good recycling happening there as well.

Bottom balancing

Warning! This article is about LiFePO4 cells. Some of it may apply to other chemistries, but YMMV.

Edit: I've also written a short How To Bottom Balance. You should still read this too.

I've talked about this before, but I realised I don't have a single, nice post about the matter that I could refer to when needed. Hence this post. All said only applies to current LiFePO4 cells. Embrace yourself.

Bottom Balancing (BB) is an alternative to Battery Management Systems (BMS). BMS is traditionally a system which includes a little device connected to each individual cell. That little device will monitor the voltage of each cell and also alert the master board, charger or controller if the voltage drops below or exceeds preset values. While charging the device can also shunt the cell effectively forcing it to stay at a preset voltage level while other cells catch up. This is called Top Balancing.

Sounds good, doesn't it? I thought so too. A nice device you can buy, maybe a little expensive, but still solves all battery related problems nice and clean. Keeps good care of your cells, controls charging, protects from over discharge and so on.

Not so.

Turns out Top Balancing and by extension BMS is based on part fantasy and part lead acid heritage. It assumes that you can tell everything just by looking at the current voltage of the cell at any point in time and every state of charge. It also assumes you can get maximum potential out of your cells by boiling them at the highest allowed voltage and even balance them by doing so. Perhaps even refresh them to full capacity.

The truth is far from all these things. The only way to determine state of charge from the cell voltage is to let it sit for a day or two and then measure the voltage down to accuracy of 0.001 volts. Put any load on the cell and you no longer have a realiable reading. Put any charge on the cell and the same thing happens. The cell voltage will sag under load and rise during charge. If you have Top Balanced the cells, which always have different state of charge, will even react by different amount.

What this leads to is that reading cell voltage in these situations is completely useless. If you can't determine your state of charge (SOC) from the reading how could you control your charging or discharging by looking at these values. You just can't.

Even if you assumed that Top Balancing would work and you could even out the differences in cell capacity at the top you would have a problem. The problem would manifest itself when the first cell, the weakest one in your pack, gets near empty. Due to the nature of the LiFePO4 charge and discharge curve, which is very flat for about 90% of the cell charge and very steep at both ends, you end up with that weak cell plummeting in voltage.

If your BMS is fast enough it will disconnect the pack and save the cell. If not, the single cell will keep going down, kill itself and possibly even it's friends nearby by going into reversal or even swelling rapidly. Even worse there's no way to know when this will happen. The exact moment of weakest cell going empty is unpredictable so you end up using such a big safety margin that you're not even using th  pack to it's fullest. Add into account the fact that high load will exaggerate the voltage drop and you end up in a situation where you or your BMS can't know what's really going on. Your vehicle either stops sooner than it should have or it breaks down.

Charging is pretty much the same in reverse. You try to fill up each by thinking that if you get all of them to say 3.65 volts they will be as full as they can be and they don't mind waiting for their buddies. It sort of works, because the cell voltage will start to climb when the cell gets fuller, but trying to top them like this achieves nothing and there is a possibility you might also be hurting your cells if you do this. Charging is less critical because it usually happens much slower than discharging. You can charge at say 20 amps, but you may discharge at 1000 amps. Things happen so much faster at 1000 amps.

Because we know that cell state of charge can be measured when the cell has rested, and especially when it's very near empty, we can try something different. Instead of trying to balance the cells at the top by forcing them to a certain voltage we drain them. We drain them down to about 2.75 volts. That's well in the steep downwards part of the discharge curve. Well enough to be a reliable indication of state of charge, but not too far to be dangerous to the cell.

When draining you need to drain the cells a little below 2.75 V, let them bounce back to a little above 2.75 V and then repeat until the cell doesn't bounce anymore, but stays at about 2.75 V even after a period of rest. Once you have done this on all of your cells and removed any load from them you can be quite sure that they are now all at the same state of charge very near empty. Bottom Balanced, that is. We have taken all the cells, independent of their actualy capacity to the same line and we can now charge them. But not one by one.

In order to charge this Bottom Balanced pack it is vitally important that you connect the cells and only the cells, nothing else, to each other. You cannot put anything else on the cell terminals except the strap or a copper bar that connects it to the next cell. If you do put something else you will ruin the Bottom Balancing and you will either have to start from the beginning or not have balanced pack anymore.

Once you have all the cells connected to each other forming a pack, all cells still at 2.75 volts, undisturbed, you can start charging them. But only as a whole. You can never ever charge or discharge only a part of the pack or you must start over again (and do not pass go). Since we know that the manufacturers recommend that most LiFePO4 cells not be charged over 3.65 volts to prevent damage we leave a little headroom and charge to a total voltage which is 3.5-3.55 volts times cell count.

Now you may think your giving up something when you're not charging to 3.65 volts. And you are correct. But it's not nearly as much as you'd think. The charge curve is mostly almost flat and only starts to rise at the very end. And it does rise fast. So fast even that you're putting very little energy into the cells when it starts to rise above 3.4 V. What that means is that the amount of miles you are losing is insignificant. Instead it gives our pack a little room to breathe and a safety margin which is needed, because the weakest cells will rise in voltage first. Just like they would die first if you were Top Balancing.

So how do we know when to end the charge? It's very easy. You either pick a charger that has a maximum charge voltage of 3.55 times cell count or choose you cell count based on a charger you can get. I prefer the latter and use a 116.8 volt charger for 33 cells and a 87.6 volt charger for 25 cells. Thats 3.54 or 3.50 volts per cell, respectively. While charging each cell will receive exactly as much charge as the next. At the end of the charge the weakest cells will rise in voltage a bit more than the best, but nowhere near enough to damage them. When enough cells reach a higher voltage the charger will cut the charge as the total charge voltage has been reached.

The chargers currently used do a CC/CV charge, which means that the charger charges at full amps until a set voltage is reached and the holds that voltage by lowering the current until the current drops to about 5% of full current. The last CV phase accounts for 10-20% of the charge depending on cell type. There is now talk of dropping the CV phase completely with the latest cells and only doing the CC phase, which would only give us a 90% charge, but it would happen fast and might save the cells even more than is generally believed. Thus keeping that 90% range for a longer time instead of dropping to say 80% over time.

This charging that I've described here is just a procedure. It's a way to charge the cells. Once the charge has been cut and you have let the cells rest you will observe that they dropped in voltage to about 3.4 volts each. This is the voltage of a fully charged cell. We simply used a slightly higher average voltage to get them there and did this in series to make sure they all got the same amount of current.

We haven't reached the best part of Bottom Balancing yet. It's so obvious to me I almost forgot to write about it even though it's the main reason why we do it.

The magic of Bottom Balancing happens when you run out of juice. As we drained all cells in the pack to the same voltage and have only charged them together they will also reach empty at the same time. There are two benefits in this. First, since they do it simultaneously and since we are at the steep end of the curve there will be hardly any energy left in them so eventually the vehicle will not move anymore. You start to feel this in you accelerator pedal or twist grip before it happens because you start losing power so you can drive to the side of the road safely instead of the car stopping completely and unexpectedly as would happen with a BMS.

Secondly, and quite importantly, the cells, in harmony, will protect each other. Since none of them have much energy left in them they don't have the power to kill their buddies either. In the BMS based Top Balancing scenario the weakest cell will be violently attacked by the other cells, which still have a lot of power left, by trying to extract as much energy from that weak cell as they are able to produce themselves.

In order to prevent a careless driver from eventually harming the cells by keeping the pedal pressed to the floor even though the vehicle isn't even moving anymore, we program a low voltage limit into the controller. This can be as low as 2 volts times cell count, but you can define it higher if you wish to leave more margin. I have personally tested a 2 volt setting (25 cells, 50 volt limit) on a motorcycle and the cells suffered no harm although I repeatedly hit that 50 volt limit. In fact they bounced back to safe territory some time after the load had been removed.

So there. Didn't come out very short, but that's my view of Bottom Balancing and why it works. YMMV.

ps. The so-called "Cell Drift" has not been observed at all when Bottom Balancing. Therefore it has been concluded that these cells do not drift by themselves. Any observed drift has been caused by the BMS themselves or cell level monitoring which loads the cells unevenly. There is no reason to fight "Cell Drift" by installing equipment which will in fact cause it, unnecessarily wear out the cells and even cause a fire hazard thanks to a mess of spaghetti wiring.

Disclaimer: All of my battery ramblings are based on my own experience and Jack Rickard's original work on the subject. They are applicable to CALB SE- and CA-series cells. Other cells and chemistries may at least require different voltages. I take no responsibility for any problems or damage caused by anyone.

Rules and regulations

So I was wrong. EC type-approval doesn't seem to be the absolute show stopper for an EV conversion in Finland I thought it would be. The are other hurdles to jump however.

The Big Kahuna is the UNECE R 100. It describes safety features which must be present in an EV and since 2011 a car needs to be built according to it's rules to pass the Conversion Inspection in Finland, regardless of when it was originally manufactured. I'll go through some of the main points that matter in my build.

  • Protection against direct and indirect contact. Basically everything live must be enclosed somehow. All barriers and enclosures must also be connected to vehicle ground (chassis).
  • Service disconnect. A switch for doing this a good idea anyway. Makes working on the vehicle easier.
  • Markings. All enclosures which if opened contain live parts must be marked with a specified warning sticker. The only problem is finding a place to buy the correct ones.
  • Orange cables. Umm, ok, orange cables. Must be used for all visible high voltage wires.
  • Isolation resistance requirements. I guess if I do everything properly this will just happen.
  • RESS (Rechargeable Energy Storage System) must be fused and must not overheat. Obviously.
  • There must be an indication light or sound when the car is in Active Driving Mode or driver attempts to leave the vehicle when it is in such condition. I think I'll just have a simple lighted switch to turn the controller (or main contactor) on and off. That should satisfy both in my opinion. The light will always be on when the controller has power.
  • Earth ground while charging. Earth ground must be connected to vehicle ground (chassis) and kept connected while charging and until after charge voltage has been removed. Thinking about this I realized that the standard AC power plugs in Finland already do this mechanically. The ground pins are always connected before live wires and are also the last to disconnect. Just wire that ground to vehicle chassis and that should theoretically be it.
  • Vehicle must not move by it's own propulsion system while a charging cable is connected. This may or may not be the trickiest of them all. I'll have to figure out a way to tell if the charging cable is connected or not. Remains to be seen what I come up with.
  • Gas and hydrogen emissions are not of concern since we don't use open type batteries or fuel cells. Also the on-board isolation resistance monitoring system is luckily only required for fuel cell vehicles, at least as far as I can tell.
What remains is the EMC question. The R100 says nothing about such things. My guess is that it's not relevant for cars registered prior to late 2002, due to the regulations passed then. Older cars should be fine without. EC type-approved vehicles may however still need parts which are approved or tested for compliance, but I honestly don't know for sure. My car isn't type-approved, so it's not an issue for me.

keskiviikko 31. lokakuuta 2012

Gentlemen, remove your engines!

Finally got the combustion engine out of the Xsara. It didn't come out quite as willingly as I had hoped, but I still managed to remove just the engine without taking out the transmission with it. Taking out the transmission would have meant dismantling the drive shafts and such. A task which I found quite unappealing. In any case, mission accomplished. I already have a buyer for the engine as well. He should be picking it up on Sunday. After taking the pictures I was also able to unbolt the flywheel.

sunnuntai 28. lokakuuta 2012

The cell that keeps giving

Jack has been testing the new CA-series cells from CALB and they just keep giving. In addition to improved cold resistance and a flatter charge/discharge curve, or perhaps thanks to it, the cells seem to be able to take 3C charge with no sweat at all. That means 120 amps into a 40 Ah cell. And not just take some charge, but take over 90% of capacity in 20 minutes. To me that means you could just forget about the usual CC/CV charging, do the fastest CC (Constant Current) you can muster and quit when you reach about 3.55 volts per cell. The cell doesn't even really warm up. Not at least until you try to push that last 3% with an additional CV (Constant Voltage) phase that now seems quite unnecessary with these cells.

On the subject of BMS I'm inclined to not even consider Top Balancing as an option to anyone anymore. Not only does a cell level BMS unbalance your pack it also seems that baking your cells at an artificial top voltage does not lead to a full charge, but instead could even damage the cell. Whatever cell drift or age induced unbalancing they claim is most likely caused by the BMS itself. In other words the very same system they claim you need to combat these issues is the root cause of them. I have also asked proponents of BMS or active live cell balancing to present numbers to back their claims on the superiority of BMS in charging or cell lifetime balance issues, but NONE have given ANY. In my book that just about sums it up. Safety wise I believe a BMS will cause more problems than it will solve.

torstai 18. lokakuuta 2012

Brush and motor gallery

Now I realize this will be for a very limited audience, if anyone, but here's a a bit of brush gallery of my TTL-200C motors. The measurements are obviously metric.

What the heck. Here's a couple more shots of the motors themselves.

They're about 8 inches in diameter and they don't have an internal fan so an electric blower must be added. Perhaps the converted turbocharger thing Jack sells on EVTV store or something like it. As you can see in the background of some of the pictures the motors came with shrouds which had a hole for a blower, but the shrouds were at the wrong end of the motor (not the commutator end as they should be) so they will need a bit of modification to fit the correct end. That's because the commutator end is partially blocked by the plastic box which covers the wiring.

By the way there are four poles in that plastic box with two of them connect by a copper bar. That's all well and understandable for a series motor, but when I got the motors the other one had three wires coming out. One in A1, one on the copper bar connecting A2 and D1 and the third on D2 (I'm trying to remember the markings right). I wonder what the mystery third wire is for if they really are series wound. It does say SERIES MOTOR on the nameplate. I heard that the motors they ended up using in the Elcat EVs were actually compound motors which would have three wires, but why are they here? Could you use the third wire for some sort of regen without hurting the brushes? Let me know if you have an idea. I'll have to take some measurements to make sure these aren't really compound or SepEx motors too, but I doubt it very much at this point. Most likely the third wire is a mistake of some sort.

keskiviikko 17. lokakuuta 2012

Update on engine removal progress

Just a quick update on what has happened so far. I managed to disconnect all remaining wires and tubing from the engine and also after some quite considerable difficulty was able to cut the bolts retaining the exhaust pipe using an angle grinder. The nuts and bolts were so melted together by rust that they could not be separated by conventional methods. Radiator and it's fan were also taken out.

After that I hoisted the engine a little with a cherry picker I was able to loan, supported the transmission from below and removed all the bolts keeping the two together. I then realised the drive shaft was still connected to the engine block from below. I got it somewhat separated, but was unable to remove the engine completely. At this point I ran out of both time and energy, put a few bolts back to keep the engine in place and decided to continue next week.

It seems that there isn't much space to move the engine sideways and I'm a little sceptical whether the clearance allows me to move it enough to make room for the flywheel come out. I'm still a little hesitant to remove the transmission though so I'll give it another go.

maanantai 15. lokakuuta 2012


Some calculations I got to doing somewhere else, but they seem to be worth repeating here.
First a little round-up of power per mass in kW per kg.

GPX750R 750cc..... 0.34
GPX750R electric… 0.14
Aptera 2e………….. 0.10
Xsara 1.8i…………. 0.07
307sw HDi90……… 0.04
Citroën C-Zero……. 0.04

What you can take home from this is that a diesel or an electric car should be fine with 0.04 kW/kg. For the Xsara at about 1200 kg that means about 48 kW is what we want. That comes down to this:

Power... Voltage... Amps
48 kW... 75 V....... 640 A
48 kW... 99 V....... 485 A

Not a huge lot. Almost in the range of a Soliton Jr. with 75 V. With 99 V nominal very much so. With the AXE7245 the theoretical maximum would be 75 V * 450 A ≈ 34 kW. Not quite enough to be a comfortable drive, but perhaps enough to test with. I can't get 450 A from the 40 Ah CALBs though, 300 A might be near comfortable there, which comes down to about 23 kW. I think I'll eventually find out if the car goes anywhere with that little power.

sunnuntai 14. lokakuuta 2012

Holy wirings, Batman! Again!

Just spent better part of three hours removing the engine wiring harness. I did bleed the oil and the coolant as well, but that didn't take too long. The ECU and old 12 V battery tray came out as well. If you turn they key now there's a 30 second beep and a Key light flashing. Probably the electric engine immobiliser is not happy for some reason or another. There might be a way to reset it though.

Get your motor running

Got my motor running, actually. A couple of times even. First with a lazy 12 volt battery and then connected to my motorcycle. Here's a video of the latter.

I was going to remove the batteries and whatnot from the motorcycle first and then bolt everything nicely to a test bench like I did with the motorcycle parts when I first got them, but then I got lazy and decided to just take the motor to the bike.

Next up: jacking up the car and removing liquids. Looking forward to it! Not really. I'll hate it.

lauantai 6. lokakuuta 2012

Got motors!

Just picked the two old Elcat motors from Järvenpää and here they are in the trunk of my diesel car:

The motors are a bit different. The other one has a long shaft with keyhole and the other one a short shaft with teeth. Both have a Subaru motor plate on them and some sort of an adapter which can hopefully be modified to fit the Citroën flywheel. Good times.

Edit: Apparently these motors were not used in any production Elcats. They were just prototypes. I wonder why they weren't chosen? Let me know if you have more information. Continous 60 minutes kW rating seems a little less than in production specs, but on the other hand max rpm is higher at 8000.

perjantai 5. lokakuuta 2012

Elcat motor(s)

I'm going to go look at two old motors from the venerable Finnish electric car Elcat. They're old and the put out only about 22 kW and 73 Nm, but they are quite affordable as well. Plus there's two of them for sale so I can keep the second one as spare parts or put one in now and work on the other to make it all shiny and new again. The motors are Thrige model TTL-200C.

The motors used to power these little vans which originally had a 72 volt system based on lead acid cells. What this means is that I could actually keep to 72 (or 75) volts nominal as with the motorcycle and keep using the chargers and controllers that I've used to. Testing with 96-99 volts nominal would be interesting, but would also require investing in a much more expensive controller. I'm also not sure if raising the voltage would give me any more useful power out of these old motors. Their useful powerband ends after 2000 rpm as you can see from the graph below.

Another aspect of these motors is their size. They're said to be 50-60 cm long which may or may not be a problem. Luckily my car of choice is not too small and the original engine is not very small either. Looking at the pictures I've taken I think I'll be alright. There's one measurement I should have taken that I didn't, but as I'm about 250 km away from the car at the moment I'll just have to wing it.

Component selection

I'm also searching for suitable components for the car. I got a lucrative offer for an AC system from Amotec Oy for around 5000€ including an AC-50 motor, controller and everything else including liquid cooling. On the pro side of things are the obvious benefits of AC propulsion, such as being maintenance free and having regenerative braking, but on the cons is the somewhat steep price to be paid right away.

ICE to be removed

On the DC side of things I could just get the motor first and test everything which the 72 volt system from my motorcycle including batteries, controllers and so on. For the motors there are multiple candidates such as Netgain Warp 9, Kostov 10" and Motenergy ME1002. I used a much smaller ME1003 (get a clue with the naming, please!) in my motorcycle and the ME1002 specs look nice. Price is also tempting. The problem is finding a dealer for these motors without paying through the nose for the shipping. The best offer so far is little less than 2k€ for the Kostov from Rebbl with taxes and shipping. I'm waiting for a quote from PalonenLABS for the same motor.

As for the batteries the new CALB CA-series is the obvious choice. However, considering that I already have 25 of the older SE-series type SE40AHA I might be tempted to recycle them. Add another 8 and I have my first set of 33 for 99 volts nominal or about 110 volts fully charged. Add another 66 and I have 99 for the same voltage, but 120 Ah or about 12-13 kWh of stored energy. That, incidentally, is the size of the battery pack in the i-MiEV, if my memory serves me right. The batteries would then be connected in 3 parallel and 33 series or 3p33s (perhaps 33s3p). There would also be some inherent flexibility in battery placement. I could for example put one series of 33 under the hood and the remaining 66 in the back for a weight distribution of 33% in the front (50kg) and 66% in the back (100kg). I could also purchase one set of 33 at a time. I would however lose the improvements in the CA-series, most notably better performance in cold temperatures. I will heat the battery boxes anyway, so it might not be a problem though.

Battery boxing and heating

Thinking about battery boxes and their heating. What I have in mind at the moment is having one or two battery boxes either in the engine compartment, in the trunk or both. I find myself visualizing the rear battery box in the trunk more than the one in front. Probably because the trunk is a nice flat area which will be easy to work on whereas in the front one has to carefully think about how to secure the battery box in place and also make it safe in the event of a crash.

In both cases I'm thinking of angle iron based chassis with possibly aluminum on the sides and 20mm of Finnfoam insulation laced with self regulating heat cable on the inside. The cable can be had in 10W/m variant ready to be plugged in so I guess the only thing to figure out is how much of it to put in. Probably some overkill is appropriate as always. The way this would work is that the cable would be connected to the same AC power bus inside the car as the charger so that when you plug in the car it would simultaneously start heating the battery boxes and charging.

If one would like to make it a little smarter I guess one could device a system which would not start the charge before the battery boxes reach a certain temperature and perhaps also automatically control the heat cables so that they would only turn on if needed. They might also get turned off when the charging starts. This way I could use a more powerful charger. If I used a 3kW charger I couldn't use the heating at the same time. Especially since I also have to leave some room for a cabin heater which can use from 650W to over a kilowatt of eletricity. The limitations come from 230 VAC sockets usually being behind a 16 A fuse which gives us about 3500 W to play with.

Perhaps it's just easier to go with a 2 kW charger and have the possibility of turning on all the heating and charging at the same time. At 116.8 volts that means a 16 A charging current which is not very much, but still enough to get the car fulle charged overnight or about 10 km of range per hour if topping up on the road. At 3 kW that would be about 15 km per hour.

torstai 27. syyskuuta 2012

Car chosen

Here's my next conversion. It's a 1997 Citroën Xsara. The latest model you can easily convert here in Finland I believe (but I'm not sure). It may not look like much now, but I'm hoping to spruce it up quite a bit. After all it's just a chassis, a base for the conversion. The front might get a big makeover and a new coat of paint is not far fetched at all. Other than that it's a suitable 5 door hatchback with a front wheel drive and it drives suprisingly well.

And yes, it's called the kWsara.

perjantai 21. syyskuuta 2012

In a magazine

There's a story about the bike in the latest WattiViesti, a customer magazine of the local electric company Pori Energia. There is an online version available. You can find the article on page six. It is naturally in Finnish and the online version unfortunately requires Flash as well.

tiistai 18. syyskuuta 2012

Bottom balancing to the rescue

Last night I rode my battery pack half empty and today added the 25th cell that arrived yesterday. I then proceeded to drive the pack completely empty so I could bottom balance the new cell as well. I dropped off some badges my S.O. had made, located a gas station not to fill up but to check tire pressure, picked up two salads from the local market and ran out of juice before getting home. Yes, I thought the pack would have 5 Ah more left, but alas it did not. I kept pushing against the 50 volt limit I had set in the controller, that's only 2 volts per cell, but couldn't get home without pushing for real.

I was more than a little worried that I had incorrectly estimated the state of charge of the new cell and now ruined it straight away, but it was not so. It was happily resting at 3.2 volts while the rest of the pack was around 2.5 volts per cell. I didn't take very long to go from very worried to very happy about how well bottom balancing had protected my precious cells. I hadn't been able to break them even by pushing them down to 2 volts. And I tried. The bike would just stop going as the cells refused to give more than a few amps and floated back from their lower limits with no problems whatsoever. I can therefore testify that bottom balanced cells will protect each other and not let you kill their colleagues.

I then turned my attention to the newcomer and drained it down to about 2.5 volts where the older cells were waiting, connected my 2 kW charger and let it do it's thing. About 40 Ah went in as expected. For the bottom balancing I used the electric motor of the bike itself.

maanantai 17. syyskuuta 2012

Missing cell: Arrived

Finally got my last cell today from It arrived at about 3.276 V. Perhaps a little less than half charged then. I'll now have to drain the main pack before I can add the newcomer into it. It will also need to be drained to 2.7 V initially. I might want to improve upon my earlier bottom balancing on all of the old cells as well. When I did it for the first time I eventually ran out of patience. That's not to say bottom balancing hasn't been working perfectly. It has.

tiistai 11. syyskuuta 2012

If I converted a car

I've been researching my ideal kit for a car conversion. AKL (Finnish Central Organisation for Motor Trades and Repairs) has set some rules for working on electric vehicles. The rules define that working with over 50 VAC or 120 VDC requires you to notify the Finnish Safety and Chemicals Agency (Tukes) and the personnel needs to be formally qualified for the work. These are also the same voltage limits set by law in Finland for electrical work. Therefore I have concluded that to avoid any problems one should stay below 120 VDC in private conversions as well. That way nobody should have a problem with these vehicles and it kind of makes me feel a little bit safer and more confident as well since there are set limits to work with.

120 VDC might not seem like much, but since the arrival of the new grey CA-series CALB cells which seem to sag a lot less than anything seen before (except possibly the A123 pouches which are quite hard to work with) you wouldn't need to oversize your pack to account for the voltage sag. They are capable of over 10 C discharge which means you can get decent performance at below 120 VDC and cell sizes as small as 60 Ah (10 C at 60 Ah cell is 600 amps). At a floating 100 volts and 500 amps you're looking at 50 kW in power which should be quite enough for a small car.

This brings me to my kit. It's not a kit really, but a selection components I'd use if I'd start the project today.


I've been using a couple of KP chargers from for a while now and although both of them have arrived with a broken fan, they are quite affordable and seem to do the actual charging fine. On the smaller one I got first the fan itself was broken and/or mounted the wrong way. The 2kW charger I got later had been slightly damaged in transport which prevented the second fan from spinning. These were easily fixable though. Therefore I'd get the KP-L 3kW 116.8 VDC 22 A charger from

You might think it's a bit silly to start building a kit with the charger, but a good charger is very important and not as easy to come by, especially if you don't want to break the bank. Charge voltage will also determine your pack voltage and number of cells which in turn will define your motor and controller choices. The other option would be to get the biggest charger you can find with charge voltage over 120 VDC and use a relay to cut charging at exactly 120 VDC. You'd only get one more 3.5 volt (charging voltage) cell in though and you'd loose the CV part of the charge. Remember that usually we're first charging with Constant Current (as much as the charger can do) and then we taper the charge by holding the desired voltage (Constant Voltage) while reducing the amps going in until we're at 3.5 volts per cell. The charger will then cut off the charge when a set low current limit is reached.

Alternatively Rebbl sells an Elcon 2500W charger that you can probably program to your needs.

Battery pack

Now that we know our charging voltage which on the KP-L set for 96 volts nominal is 116.8 volts we can calculate that to get about 3.5 V per cell we need 33 CALB cells. It's actually 3.54 V per cell to be exact, but close enough. 34 cells would put us below 3.5 and 32 above 3.6 V, so 33 is the number for us. The reason we are so careful to choose and match our charger with our battery pack is that we will be bottom balancing the pack and just simply charging to full voltage with no BMS. If you were using a BMS you could be a bit more careless, but you'd end up with a mess of wires each a potential fire hazard and we really don't want to go there. Bottom balancing is the way to go and it really does work.

The number of cells is 33 and the rest depends on the size of your car and probably even more on the size of your wallet. I'd say 60 Ah cells are the minimum to get a 40 km range (or 6 kWh and 3000€) and going up to 180 Ah should give you 120 km range in a 200 kg pile of batteries (or 18 kWh and 9000€). If was to order batteries now, I'd order from


This one's easy. Or hard. Depends on if you just go with EVnetics Soliton Jr. or decide to find some other alternative. You can order one from Rebbl. They also ship them EMC certified to fulfill all EU regulations. 600 amps should be plenty and if you like more you can always opt for it's bigger brother, the Soliton 1.


This is going fast. Also from Rebbl, or wherever you want to order, the Kostov 10". According to it's spec sheet 115 volts, 270 amps continous at 4500 rpm should give you around 26.2 kW. We don't quite have 115 volts, but close enough to get a ballpark figure. Around 25 kW is very realistic. For peak throughput with the Soliton Jr. at about 100 volts we are looking at double that at 50 kW. Enough for a compact car I think.


There you have it. The main components of a possible future "kWkasi". Pronounced "koo-vee-kasi" in Finnish. Get it? No? Don't worry. Here's the shopping list with quick specs for each component.

Kostov 10" motor (25kW continuous, 50kW peak in our setup, 69 kg)
Soliton Jr. controller (450-500 A continuous, 600 A peak, up to 340 V, 7 kg)
33pcs CALB CA180FI cells (96 V nominal, about 110 V charged, 19 kWh, 185 kg)
KP-L 3kW charger (22 amps at 116.8 volts for 8 hour recharge from empty, 9 kg)


Please note that although I've mentioned Rebbl webshop quite a few times I have not ordered from them anything yet. Which just means I can't vouch for them. They seem respectable though. and have come through for me just fine on my previous orders.

sunnuntai 9. syyskuuta 2012

Finally shipping

My 25th cell is finally on it's way from Germany. I put the order in at a couple of weeks ago and they were kind enough to fill the order last Thursday after claiming they had done it on Wednesday. Tracking says otherwise. Now I do realise it's just a single SE40AHA cell and they make no money from it whatsoever, but the lack of customer service pretty much guarantees I will not order a big number of CA cells from them either. did their job much better and with no hassle so that's still the place to go for me. Unfortunately they don't even list other than CA180FI size cells, but I'm sure they'll have others by the time I have another project going. Which might as well be never, but I'm hoping otherwise as always.

Other than that I hope the weather stays comfortable to ride for a while longer. Having said that I did end up driving the bike in quite a bit of rain as well. I was at a friend's place helping out with some Linux details and it starter pouring while we were at it. Had to get home so I just decided to give it a go and got home with zero problems. There was quite a bit of water everywhere, but it didn't cause any issues. Actually I think I made my mpg record too. Wet weather makes one gentle on the throttle.

I did get into a talk about swapping my older bike, the Z500 I had planned to convert first, for a VW Beetle, but it sort of dried up. I'd like to get a well restored specimen with a broken down engine. Preferably free as well. Not likely to happen. More likely one of our cars to suffer an engine malfunction. And they're not too likely to be break either. The other one being a Honda VTEC and the other a diesel. Among the list of cars I should have kept for future conversion is a VW Golf that needed to have it's engine replaced. The car I really feel bad about losing though was my first, a 1977 Honda Civic 1200. Now if I could travel back in time to get that beauty back in the condition it was... Oh boy oh boy. It would have made a beautiful electric vehicle.

perjantai 31. elokuuta 2012

New charger among other things

Got my big new charger yesterday. It really is big. However it does fit into my tank bag which makes it small enough to take on the road for a quick top up in about two hours from empty to fully charged. I also installed a LED light strip to function as a daytime running lamp as now permitted in the EU. This way I don't have to turn on the head or tail lights in daytime and thus save my 12 volt system from extra load. The LEDs are always on and take so little power I wasn't able to measure it with my ammeter.

But first here are couple of videos of my friend taking a ride with the kWsaki electric motorcycle. First taking off and coming back and then the actual footage from riding around Finnish countryside.

The first short video was shot with my Sony Xperia Pro phone and the latter with a GoPro on top of the tank. Here are also a couple of shots of the charger, DRL installation and an emergency cut off switch I also added which you can use to disengage the main contactor if there's trouble.

perjantai 24. elokuuta 2012

25th element

No, it's not a Luc Besson movie. I wouldn't mind if it was, they're great, but it's a cell. I now have 24 cells and a 87.6 volt charger. That makes 3.65 volts per cell as the charging voltage. CALB recommends 3.6, but with bottom balancing you want to leave a bit more headroom to protect the cells. With 25 I'd get to 3.5 which is ideal. Hence the 25th element. If I can't find one used I'll have to order. The postage will be one fourth of the whole price, but it cannot be helped.

At 3.5 I will sacrifice some SOC (State of Charge) in order to make the cells last longer and also make them stay better balanced. Right now three of my 24 cells can get up to 4 volts while charging which is way too much. They drop back into line quickly after the charge ends, but it still makes me uncomfortable. The extra cell needs to find a place somewhere, but I'm sure I'll figure it out. I should also see a couple of kilometers more range, which never hurts.

Something I realized about charging. It's just a voltage per cell. It's not a target. It's just means to an end. Sure, it won't be exceeded, but it's really the current that counts. How you should charge these LiFePO4 cells is with constant voltage and a constant current until at the end when the current should gradually drop until the pack is deemed full enough. It's quite possibly the only "BMS" you need. At least for the charging phase. Of course you should make sure you don't charge when it's too cold, or too hot for that matter, and make sure your charger is reliable enough not to exceed the set voltage and also ends the charge when due.

As for protecting the battery when discharging it's really where the magic of bottom balancing happens. If you've carefully drained your cells to the same limit below three volts before using them they should all also return to that same voltage on each and every full discharge. For a bit of additional protection I've set my controller, the AXE7245, to a low voltage limit of 60 volts. That's 2.5 volts per cell. It should be quite improssible to kill any cells this way. At least if a cell dies despite these precautions it really was a bad cell and should be put away anyway. No amount of active BMS could have saved it.

That's all there is to it really. Some human-based BMS logic is needed not to do anything stupid and keeping an eye on the cells for any physical defects, but we're just fine this way. If I was building a car with a larger battery pack, and I'm not saying I wouldn't be, someday, and especially if it was for someone else, I might consider some electronics to keep an eye on the minimum and maximum voltages. Perhaps battery pack temperature as well. Just to be safe and catch a few situations that might occur when you have more voltage and the cells are hidden out of sight. On a motorcycle, there's just no need.

keskiviikko 22. elokuuta 2012

Do want

I took a test drive with Pori Energia's Citroen Z-Cero (same as Peugeot iOn or Mitsubishi i-MiEV) electric car. So it's small, only for four persons, is kind of cheap looking, both inside an outside, and costs over 30.000€, but it's really fun to ride! The continuous, silent torque of the electric motor is just so much fun. We started with 111 km left on the range indicator and the estimate started dropping quite quickly once I hit the highway nearby. When we got off it the meter actually started going upwards as the electricity consumption was re-estimated. In total we drove around for about 50 km and there was over half of the pack capacity left. To be honest I didn't even register what the reading was when were done so there definitely was no range anxiety there.

Obvious reaction is that I'd really like to have one. Problem is it's quite expensive for a small car that could otherwise be had for closer to 10.000 € (Citroen C1 or a Peugeot 107). On the other had if you compare it to a Toyota Yaris, which would be my number one choice for a small car, you'd only end up paying something like 10.000 € more. With electric driving costing about 2 cents on a km and gasoline up to 10 cents per km, you'd only have to drive about 125.000 km to break even. Now that's not too hard to imagine at all. With zero emissions no less! And I have to say the C-Zero felt as nice to drive as a Yaris. Even better actually, because of no shifting and dead silent acceleration. Wind noise was quite loud above 100 km/h, but so it would be in a Yaris as well.

Immediately after that I started thinking about making one myself. You could probably get a running VW Beetle for a couple of thousand euros and a similar electric drivetrain including batteries would be about 15 to 16 thousand. Almost half the price of a C-Zero or an iOn. Of course it wouldn't be a new car, but at least you'd now exactly how it works and how to fix it since you built it yourself. The same couldn't be said of these new electric vehicles. You'd still need to take them to the local dealer for maintenance - no matter how scared the dealers are of electrons destroying that lucrative business.

All in all the car exceeded my expectations in every respect. The Nissan Leaf is usually considered to be a much better car so I wonder how good can it be if the cheap-ish C-Zero was this nice.

perjantai 17. elokuuta 2012

Spring break

New Hagon springs being installed. The forks are almost fully compressed here and that's why the springs are protruding so much. Once the forks are pulled to full length the springs disappear almost completely. I took a quick test ride and the front end seems really good now. They don't bottom and handling is much improved. I also released extra air pressure from the rear shock to make it softer which also contributed to the suspension and stopped the chain from making a noise while hitting the center stand.

As a bonus a picture of charging my Macbook Air from the battery pack which also works like a charm. Now I know where I'll head if the electricity goes out and my beloved laptop is running out of juice.

Springs and problems

It's a day of good news and bad news. The bad news is that the motor I got does not appear to be in perfect condition. The commutator seems to be out of round as you can see the brushes moving in the following video. Not really quite sure how this has come to be. I haven't had a reply from the seller yet. The motor also gets very hot.

Update: I have gotten into touch both with the seller and Motenergy. They don't see a problem in the video so I suppose everything is in order after all. Motor heating might also be within limits. Maybe.

The good news is that my new progressive front springs from Hagon arrived early! I wasn't really expecting them in weeks since they are made to order for this somewhat rare bike. I knew there was a package coming, but I assumed it would be the LED lights for the bike I ordered from

Good looking springs with proper installation instructions included. Hopefully they will also solve my problems with the front fork and it will finally become as nice to ride as it should be.

keskiviikko 15. elokuuta 2012

Faster charger

A new, faster charger is now on it's way from It's a 2 kW model which outputs 20 amps at 87.6 volts. This should allow me to charge my 40 A battery pack in two hours which is very nice indeed. Makes longer trips with planned charging stops possible and also daytime trips to nearby locations such as the family cabin in Luvia. I will still keep my 6 A charger for overnight charging to charge the batteries slower and possibly to a more full charge when time is not of essence. I'm also planning to make a test drive to figure out the 0-100km/h and quarter mile results at 300 amps using GPS and possibly on the same charge get a feel on how far I can go if I don't drive at best speed all the time. Minus the acceleration of course. Or two. Perhaps the hypermiling test will actually need a fresh charge.

Another idea I've been thinking of is should I drain the pack completely, ideally to 2.75 volts per cell, reset the Cycle Analyst and then charge. This would reverse the amp hour counting from the current counting from zero upwards to counting from -40A towards zero. The positive side of this would be that I'd know exactly how much juice I've put into the battery and would immediately notice not only the difference of charging at 6 A and 20 A, but also if the pack loses it's capacity over time. On a negative side I'd lose the cycle counting capability of the Cycle Analyst and also the per trip statistics in favor of total average over time. In this case the cons probably outweight the pros and I won't end up doing so.

lauantai 11. elokuuta 2012

Free charging shot

Posted this on facebook a couple of days ago already, but here it is for the rest of you to gawk at as well. Went to check out the free charging station at the Pori Energia office in, you guessed it, Pori, Finland. All you need to do is send a text message and the station will lift up allowing you to plug in. Press a button on the pole and it will come down preventing your plug from being stolen. Not bad. Four normal 230 V AC plugs inside.

Kind of got me anxious to get a faster charger. At the 6 A pace you need to pretty much stay the night or a whole day to fill up an empty 40 Ah tank, but at 12 A or 16 A you'd only have to wait a couple of hours. Couple of hours are much easier to kill than a working day. 12 A is the recommended charging speed for the 40 Ah CALBs, but I suppose I could get away with 16 A. At least if I'd get that sort of missing 25th cell that would give me the optimal 3.5 V per cell at 87.6 V total. Right now I get 3.65 V per cell and some of the cells end up hitting 4 V when charging.

tiistai 7. elokuuta 2012

Street legal

So I had the bike inspected yesterday. The inspector was mainly interested in the motor and battery mounts and the weight of the bike which we measured on site. The scale tipped at a light 170 kg. 60 kg less than previous curb weight. Not a bad weight loss plan I'd say. The brakes or suspension were not inspected at all which is reasonable since they were stock and weight hadn't increased either.

Parts of the registration form for the Finnish readers. The papers cost 100€.

I also took the bike for a ride. A tankful so to speak. Spent almost everything on a 40 km trip. This did include quite a bit of top speed testing which resulted in 110 km/h. Slightly less than the 130 km/h I had calculated, but it did reach it very nicely so if more was required I think I could get it by changing sprockets. Driving at top speed isn't what the bike is for so I think I'll stick with the quite nice acceleration it now has instead. Driving slower should improve range as well. I'll let you know how many kilometres I get once I drive a tankful that way.

A friend of mine giving the bike a short test ride and the EV impression.
Don't get confused by the ICE bike starting nearby.

Charging the bike in the evening took less than 7 hours. The cells we're within 1% of 3.0 when near empty. Shortly after the charge most cells were around 3.3 volts with a couple nearer to 4 V. This is to be expected and quite normal when using bottom balancing. As you may or may not remember all cells were drained to about 2.75 volts before use which means they are equalized when empty. All cells are not created equal however and when charged the weakest ones will reach the highest voltages while the best cells don't go above 3.4. The charger then simply cuts off the current when 87.6 V total is reached. Even the weakest cells will then come down in voltage reducing the total by a couple of volts.

In other words no fire hazard also known as a BMS is needed. You just have to keep your eye on the amp hour counter and not kill the cells by draining them dead. Just like you wouldn't want to drive your gas tank to empty in the middle of nowhere. As an additional precaution the controller is set not to work below a certain voltage which will also prevent you from killing the cells. 

A slight over voltage when charging at slow speed is not that dangerous. Not at least compared to discharging them below rated voltage at 400 amps. This is why bottom balancing works and BMS does not. If you're using a top balancing BMS you charge all cells to same voltage, but when the pack is near empty you can have most cells above 3 volts while the weakest go way below that near to 2 volts which will cause them to die and you won't notice anything until it's too late. Especially because of how fast things happen at 400 amps.

maanantai 6. elokuuta 2012

Here we go

Having the bike inspected right now. Or actually waiting for the paperwork to finish. Looks like we have a winner!

perjantai 3. elokuuta 2012


It's hard not to be annoyed when the project is delayed due to matters not quite related to the electrification itself. The ESCS front forks have turned out to be quite a show stopper. I've now ordered new progressive springs directly from Hagon which will hopefully make the front shocks behave properly instead of bottoming and thus stop the front wheel from hitting the battery box. I might also try to raise the box a little bit to make some more room for the tire, but there isn't much space left. I may need to switch the connecting battery plates to reverse order as well. That might give me a centimeter more to play with.

torstai 2. elokuuta 2012

The almost finished gallery

Some shots of the bike as it now stands. On the list of things to do are still front chain guard, improving battery box support in front and the extremely soft suspension. After that I think I'm ready for the inspection.