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.

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.

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.

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.

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.

Missing cell: Arrived

Finally got my last cell today from faktor.de. 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.

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.

Charger

I've been using a couple of KP chargers from evassemble.com 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 evassemble.com.

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 ev-power.eu.

Controller

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.

Motor

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.

Conclusion

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)

Disclaimer

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. evassemble.com and ev-power.eu have come through for me just fine on my previous orders.

Finally shipping

My 25th cell is finally on it's way from Germany. I put the order in at faktor.de 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. ev-power.eu 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.