torstai 31. heinäkuuta 2014

Bike upgrade

I finally had a chance to install four more cells into the kWsaki electric motorcycle. Actually, take four old cells out and put eight new ones in. Good that I did, because taking out four of the old cells I found two of them slightly bloated and below acceptable voltage. The other one was below two and the other below one volt. Not happy cells.

Both were cells which I had earmarked for observation before, with letters "A" and "X". I also took out cells marked "B" and "D". I've only marked cells which have seemed dubious at some point, either for going high on recharge or low on full discharge. Hopefully I caught all bloated cells and none were left in, since I didn't really go through the rest of them. It's hard to say at which point these got damaged, but I'm hoping they just developed issues while I pushed the pack really low right before doing the swap. At least I didn't notice any issues before.

The other thing that I did was to attach the new 102V 21A charger to the belly of the bike. It looks just about as ghetto as can be and it rather is, but it works and it'll look prettier once I modify the belly pan to fit back on. In any case, the charger works and charged the battery from the new empty voltage of 83.8V, which is just a hair above my previous fully charged voltage, to 102 volts and bit over it. Strangely it wouldn't stop charging even when the Cycle Analyst registered a charge current of less than one amp. The highest voltage I noticed was 102.5 volts. I suppose it would stop at some point. The measurement at such low levels is not very accurate and the little laptop PSU doubling as a DC/DC converter was also running, which may make a difference as well.

When I pulled the plug, 39 amp hours had gone in to the pack. Just one amp less than rated capacity. I think this is a good results, since most of the cells are now over two years old and I'm not charging them fully anyway. The next morning the pack had settled to a total voltage of 97.8 V. I'll have to get used to that number now.

I also got to do a little test drive with the new pack. I have to say that the bike felt better than ever. Even with the added weight of four more cells and the rather big TCCH/Elcon 2.5 kW charger, acceleration was brisk and it just felt very peppy. Especially so on the freeway, where the speed would start to run out at 100 km/h, it now did so around 120 km/h instead. I managed a new top speed record of 128 km/h. Up from the previous 110 km/h or so. In other words just a little faster than you are allowed to drive anywhere in Finland, so I think it'll be plenty.

The Kelly controller I now have in the bike seems to be also doing thing a bit differently from the Alltrax AXE I had in before. Where the AXE would suck amps probably as much as it would put into the motor, the Kelly pulls a lot less. Even with the 600A controller set to 85% output, or 510 amps, it had only taken up to 200 amps from the pack. This was during the test drive I did the new speed record with, so it definitely was putting everything it was allowed to into the motor. In any case, it's much better this way, so I'm not complaining. The batteries can take it a little easier and I still get full power.

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