Battery pack will power the bike, but not charge

PJungnitsch

Member
I had a misadventure repairing the charger for my Biktrix Juggernaut, it shorted briefly once plugged in, as noted here:

https://electricbikereview.com/forums/threads/connectors-and-the-cycle-satiator.10853/

The battery ran the bike after, and there is full voltage on the output plus the battery indicator shows (a small amount) of charge. But I can't measure voltage on the charging port, and when plugged in the charger will not activate. Got a new charger but it acts the same way, assume it won't go into charge mode without sensing voltage.

Took the case apart, and the fuse looks good, as does all the wiring. The battery pack looks like it was made with care:







Would disconnecting the white connector in the picture have a chance at rebooting the battery management system?
 

harryS

Well-Known Member
Wow, that's a nicely made battery, except for the clumsy design of the output connector. Are there four wires to that round connector or two? In other words does it have a separate pair for charge vs power out? I've not owned a battery that uses the same pins for power/charge unless it's my tool batteries.

If you can carefully disconnect/reconnect the white connector without sparking more stuff, maybe that will reset the BMS. Many of them run off one of the cell groups, and that's likely where they get the power, except that a BMS should rest when powered off. Maybe the charge side never powers off.

On my Luna shrink wrapped battery (which has separate charge and power connectors and also no on/off switch), the little XT60 connector touched something metallic in my battery bag. Zap. Yep. It's also hot and can send current out. Now I keep a dummy plug on that port. Didn't fry anything though.

Good luck.

.
 

PJungnitsch

Member
Only two (out of four) input terminals on the charge connector are used, a + and a -

Output is separate, the tall rectangular thing to the left in the photo. Here there is two (out of five) used.

The positives are Y'd together, the negatives are separate, that goes through two circuit boards on either side of the battery pack, with the BMS in the middle.

Just tried disconnecting the white BMS connector to see if it would reset, no luck

I see there is another fuse deeper down in the construction, can't see if it is blown, but no power to either side of it so likely not the problem
 

JohnT

Active Member
I would think the best source for advice would be Roshan at Biktrix.

I don't know Biktrix, but Pedego batteries have two fuses, one for main power and one for charging. When the charging fuse blows, the bike will run but not charge. You say there's no power to either side of the 2nd fuse, but did you check with the charger plugged in? You seem to know electronics. I'd be checking continuity, starting with the fuse.