Battery stopped charging at four bars

jasond1979

New Member
Hi I've had my Bosch system for about two years now maybe a year and a half. Its been working flawlessly but my 400 battery all of a sudden stopped charging at 4 bars which I can live with. But the problem is now its dead and won't work on the bike. Has anyone else experienced this? Can Bosch repair the battery? Would hate to dish out $500 for another battery. The only thing that has happened to it, is about six months ago it fell off the bike because I didn't have it clicked in, but other than a few scuffs it has worked great.

Anyhow any input would be appreciated.

Best,

Jason
 

Sonoboy

Active Member
First, have you had a recent update to your Bosch firmware? Just thinking that may be the first thing I would look at. Second, do you charge the battery on the bike? Have you tried removing the battery and charging directly to the battery, bypassing the bikes wiring?

The next set of thoughts are blue sky thinking from someone who knows a little about battery management systems but, admittedly, not everything. Especially when it comes to the Bosch system. I have searched for a teardown on the Bosch battery, to no avail (perhaps one of the EBR members has some info). The following is what I've learned about the Tesla battery management system.

Each cell (of approximately 6800 to 8000 cells, depending on model) is supplied with power for charging via a very precise diameter wire that will conduct the necessary current for charging. However, if a particular cells' internal resistance changes, due to physical or chemical damage, this wire will act like a fuse and short, thus decoupling the faulty cell from the rest of that subgroup of cells. The overall battery is degraded, yes, but only by a small amount (especially when you're talking thousands of cells in a power pack).

This leads me to this line of thought: is the Bosch battery similar to that of Tesla? And if the operation is the same, could your battery have been damaged in the fall, causing the permanent (and safe) decoupling of some percentage of the cells?

Again, just tossing it out for discussion.
 

Barzin Daragahi

New Member
Did you try a different charger? It could be as simple as the charger failing. I have a couple of Bosch powered bikes and one of my chargers stopped charging the battery to full. Maybe, take it to your local shop and ask them if they wouldn't mind testing it with one of their chargers.
 

rich c

Well-Known Member
Bad news, I don't think $500 will even get you a new one. I thought a tech can diagnose the motor and/or battery by plugging in to the software.
 

MarinaBill

New Member
Hi I've had my Bosch system for about two years now maybe a year and a half. Its been working flawlessly but my 400 battery all of a sudden stopped charging at 4 bars which I can live with. But the problem is now its dead and won't work on the bike. Has anyone else experienced this? Can Bosch repair the battery? Would hate to dish out $500 for another battery. The only thing that has happened to it, is about six months ago it fell off the bike because I didn't have it clicked in, but other than a few scuffs it has worked great.

Anyhow any input would be appreciated.

Best,

Jason
Hi. My Bosch system just hit 2 1/2 years and the same thing happened, 4 bars charge and dead on bike. What solution did you find? Thanks, Bill
 

Old

New Member
Dont' own a Bosch, but know a bit about Lipo batteries.
First try another charger on your battery. If it works fine then you know it is the charger. get a new one.
If still only 4 bars, it is a failed cell in your battery. One is enough to talke down the voltage so that you see 4 bars only. Another guy had the same problem, kept using the battery, and then eventually had 0 bars, ( when a second cell failed). In this case, try to see if someone can open up the casing, identify and substitute the dead cell. Dont try this yourself. way too dangerous. see youtube videos of "lipo fire" and you will understand why.
 

MarinaBill

New Member
Hi. My Bosch system just hit 2 1/2 years and the same thing happened, 4 bars charge and dead on bike. What solution did you find? Thanks, Bill
Update: Bosch is replacing both battery and drive unit even though the bike is a few months out of warranty. Amazing customer service!
 

batmick1

Active Member
That is good news. I am also having some issues with charging stopping erratically and the system shutting off as I am riding. I traced it down to a bad connector in the female plug on the battery. The contacts for the "+" are oxidized and bent. Still waiting to hear back from Bosch through my LBS.
So far I have been able to fix the issue by cleaning and bending the contacts back when it happens.