Over the weekend I finished the first stage of converting my Electra Townie 21 to electric. It's using a wilderness energy brushed 36 w/ 35 amp controller, which I already owned. And it's using a pack built from modified dewalt batteries. The pack is built out of five of the dewalt batteries.
It's constructed to bypass the BMS unit on discharge. For charging it's built to parallel the BMS units across the five batteries in the pack. I drop one of the batteries into a DeWalt charger and it charges all of them together. I haven't put the pack to use since building it this way.. however I'd used a smaller version of this pack last year.
Yesterday was the first serious use of both this bike and the pack.
I rode my usual commute.. about 7 miles total with no charging during the day. Since the dewalt charger is so large I didn't want to carry it with me.
When I got home the pack was still giving power enough so I could ride w/o pedaling and get decent speed, but the pack voltage had sagged to 26 volts. Eep, given it is 33 volt nominal that's a very deep discharge. I put the pack on the charger and of course it started blinking right away. Desparation time.. and I remembered I have a 36 volt soneil charger, used for my refurbished Vego 600, and got that. I connected it to the discharge connector of the pack and turned it on. It's charging the pack and it has recovered to 31.51 volts with nearly 7 ah of electricity put back into the pack.
Right now if I, disconnect the soneil charger, and then drop the dewalt pack onto the dewalt charger... it goes to two solid lights, and then starts blinking.
I remember reading someone saying the blinking happens when the charger thinks something is wrong -- such as the voltage being out of bounds (too low).