More Charging

Last weekend when I found out that my charger would not work (see 10/04 post for that resolution) I decided to charge the batteries individually with some of the shops quick chargers. This was good and got me the juice to bring it to work last week, but unfortunately it left my batteries incredibly unbalanced.

The batteries in the pack ranged from 11.8 volts to almost 13 volts. This is not good. In a perfect world all of the batteries would have the same voltage. In the real world they should be very similar, off by maybe a few tenths of a volt.

I spent the morning today with the quick chargers again. One by one I charged each battery to 13 volts. Your pack is only as strong as your weakest battery so it is important they are similar in voltage. It only took a couple of hours but at least I got to catch up on politics and watch the VP debate (insert witty political comment here).

Once I got them all balanced, I hooked them back up in series and charged them all together with my 72volt charger. They actually took a charge pretty well. I gave ’em about 3 hours on the charger and took the pack from 75 volts to about 80 volts (a fully charged 12 volt lead acid battery will read about 14.4 volts). With a decent charge on the pack we decided to take it for a spin. With plenty of juice in the “tank” she moves along pretty well.

We got back to the shop a little later with about 77 volts to the pack. Still a good charge. I put the charger back on the pack and gave it the rest of the afternoon. I came back about 6 hours later and the pack voltage was only at 80 volts. I thought it would have gone higher than that but it was stuck right at 80 volts. Perhaps once I cycle them a few times they will wear in – I’ve heard that a few times in different forums.

That was about it for the day. I did have the opportunity to give it a little bit of throttle and got it up to 42mph. I was in fourth gear (it’s only a 4 speed transmission) and I still had some throttle left. I also had Dylan in the car. I don’t think it will have much problem making it to 50mph, and could even push 60 if I were by myself and had a nice charge on it. The official range and speed tests will hopefully be next weekend.

There are finally some new pictures! No new videos as it was a pretty uneventful weekend. Next weekend should be better as I’ll be working on the charger wiring and the heating system.