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.