lauantai 5. huhtikuuta 2014

More batteries on the way and moving about

I just put some CALB SE60AHA 60 Ah LiFePO4 cells on order from I would have preferred the new CA-series, but they had none in stock. If I'm lucky, they'll arrive during next week. After I put those cells in I'll have 25 times 40 Ah plus 25 times 60 Ah for a total of 100 Ah capacity, which comes to about 8 kWh of usable juice. I'm hoping that will be enough to move the car around for about 50 kilometers (or 30 miles). It's not much, but should suffice for a city car. Also it will be easily to count amp hours from zero to 100 when driving.

In any case, it will bring the weight of the car to just about where I'd like to have it and once I've registered the car as it is, I can always swap the batteries for better ones later as they improve over time. I will probably need to construct a small battery box in the front as well. I'm thinking of placing the 40 Ah cells (35 kg of them) in the front and the 60 Ah cells (65 kg) in the back. That should give me a pretty nice weight distribution and since I've taken out around 60 kg from the back anyway with the fuel tank, spare tire and exhaust, I might even get lucky and not lose any seats. We'll see.

The two packs will be connected in parallel (25s2p, if you will) and I'm quite confident that they will balance the difference in capacity by themselves, both during charge and discharge. In any case, it will be impossible for them to be at a different voltage. I'm also sure the total voltage will immediately show if there's a problem with any of the cells in either pack, since it will start sucking juice from the other pack. It's not quite as sure shot as with a simple single series pack, but I think it will do for now. These two packs may see a new life later on in two separate motorcycles, if and when the car gets bigger cells.

In other news I solved the issue of pack negative leaking into the car chassis via Alltrax AXE7245 throttle input 2. I did this by taking the pack voltage down to 12 volts using a power supply and from there to 5 volts using a little DC to DC converter. This way I don't have to connect the 5 volts negative to the chassis at any point. For whatever reason my TPS kept on giving 1.2 volts on zero throttle instead of the 0.65V before, but that got solved with a new curve from They came through again in a day or so. Very good service.

With the ground leak problem solved and a new curve in the controller I was able to take the car for a little spin in our yard. Well, not a spin really, since there's no room to spin, but some motion back and forth anyway. Looks like my reverse light wasn't working though. Probably just the reverse detector plug got loose again from the transmission. It's missing the clip to keep in place properly.

Almost forgot. The hissing sound that the car makes comes from a rather loud blower I also installed. I don't expect the motor to heat up too much, but the blower pushing filtered air into the motor should help to keep it clean inside and also blow out any carbon dust from the brushes. I don't think I'll do anything about the noise. It's not a very pleasent one, but I reckon it's not a bad idea for the vehicle to make some noise audible at low speeds to alert pedestrians, which might otherwise be taken by quite a surprise.

2 kommenttia:

  1. Looks great, Jarkko
    Wish I lived in a country where people were allowed to invent and produce such vehicles without getting run over by legislation and rules.

    1. That's funny, because I've been thinking exactly the same... What I've got is pretty much one of the newest model years one can easily convert. Especially if you'd like to work on something made in this millenium things get really hairy. You've got all kinds of EMC requirements and type approval crap to worry about. On the other hand, new cars are much more complicated to work on anyway, due to all the electronics, and older classics you're free to work on, so it's not quite as hopeless as it seems. Still I can't help to feel like being on my toes all the time about what the geniuses at EU and local authorities can come up with when they really put their minds into it. Or more like what the OEMs can lobby them into thinking is good for us the people, when in reality it's just the OEMs protecting their asse(t)s.