(Here's a question I've been asking most of the engineers and technicians I know. All have been giving me different answers.)
I purchased this eBike used the other day. The guy said the battery pack was "Not lighting green and not getting warm anymore".
Took it home and indeed the light on the battery pack stayed red and the fan motor was not going and as far as I could tell was not charging.
Put the batteries themselves on individual trickle chargers (2amps 12v) and overnight brought them both up to 11volts according to my meter.
I then placed the batteries back in the pack and put them in the bike. The bike lit up and continued to cycle the red, yellow, and green LED's (which, thanks to your help, I now understand means "low battery").
I then decided to leave the batteries inside and try plugging the the battery pack in as it was designed to charge.
The pack lit up green and the fan started running. So i figured it was working fine and left it charging overnight.
The next morning I wake up to very VERY hot battery pack and batteries that have sulfated and had begun to bulge out while still inside the pack. I waited until they had cooled and luckily they did not leak at all (which is amazing). They were very hard to get out though due to their new size.
As far as I can tell there is no visible damage to the charging circuit. No enlarge caps, the fuse didint blow. Nothing melted.
------- WHERE DID THE FAILURE HAPPEN?
Was it the batteries that were partially charged so it thought everything was ok?
Or was it the charger that failed?
I need to figure out a test so I can deem the charger BAD or OK. If it's still ok and the batteries were just screwing it up I would love to use it as a new one costs more money than I have just laying around right now. I definately have plenty of good large SLA batteries an intend to rig a trailer and find some way to either cool the motor better or just buy a newer brushless motor (somehow).
Those batteries were toast to start with. They only reached 11v with the trickle charger. But the evg charger is pretty high amp, and overheated the batteries trying to get them up to full charge. But the dead batteries wouldn't do it, so they kept charging and charging and charging, till they got real hot but still never reached a voltage that would shut off the charger. A good set of batteries should charge in 2-4 hours at most with that charger. New batteries should fix the problem, unless something burnt out in the charger when it ran so long.
When I had an evg, I ran it on 16 ah of nicads, giving my a lot of range and no more weight than sla's. Something to think about when you have some bux.
Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global