WARNING: this is not going to be conventional (and is not without danger)......
Short version/Spoiler:
I connected the charger to the battery output in desperation and got the voltage up to the correct level over a period of about 12 hours....carefully monitoring the battery temperature and voltage. I stopped when the battery pack became too warm for my liking and restarted when it had cooled down.
This recovery depended on some care, much risk and a dose of luck.......and can't really be recommended. It's just my story! The battery now charges normally to just over 41v and the ebike works just as it should do with a range of about 30km.
The battery lifetime may be compromised but who knows?
Background:
I bought a Chinese ebike (Enro ROC.....not the Italian manufacturer). I think the seller had bought up some old stock. The bike and battery looked perfect. I exported the bike still in its packing case and untried (by shipping container) to our overseas apartment. The bike was fine. The battery charged up to 36/37v. When I started to pedal I got about 5 seconds of "boost" and then I was back to raw pedal power.
Clearly there was a problem with the battery. It didn't matter how long I charged the battery, its voltage would not climb above about 37v. Being inquisitive, I tried to take the battery apart. I could get both ends off the case (it was a rear pannier battery). I couldn't get the cells out. There was considerable stiction. The force required to dislodge the cells would have damaged the (good) cells.
OK so my theory was that one group of cells (in series) were not charging properly. That group should have given about 4 volts that would have added to the 37v to give about 41v (about right for a fully charged 36v battery).
I believe the battery management system (BMS) would "protect" the failing group of cells by not allowing them to be charged once they fell below a certain threshold. I was unable to get electrical access to these cells.
Added to this:
a) There were no battery repairers on the island
b) There was only one importer of eBikes...and he certainly wasn't able or willing to help at all.
c) I then found that no-one would ship the battery back for repair/rebuild. Sea freight was effectively quoted at about $1000 each way
d) Passenger planes cannot legally take these high power lithium batteries
e) Most air couriers, although legally allowed to transport such batteries, wouldn't even quote for returning the battery.
f) Only one courier (UPS) was willing to ship the battery ($120 one-way)
At this stage my plan was to cut the battery case longitudinally and ditch the cells. Take the case back to UK and rebuild the battery from scratch.
Against this background, and with only very expensive options, I decided to try charging via the output terminals. This would bypass the BMS. I figured there was a (small?) chance that I might be able to revive the missing block of cells (depending on their state)
And it worked. I slowly got the voltage up to just over 41v.
The ebike now worked as it should.....and has been working well and charging normally ever since.
I have read many forum threads but never found anyone who had succeeded (or even tried) this method.
I have to say this "method" involves substantial risk. You can't just "try" this method by leaving the battery pack charging overnight....it will get too hot. And we are aware of the risk of fire and/or explosion. I was fortunate to have an small empty outside concrete utility room to try this out in. I'm not sure I would have tried it indoors!
I only tell this story just in case it might help someone with a similar problem. It probably won't help if there are two or more blocks of cells failing.
TREAT THIS INFORMATION WITH CARE!
Short version/Spoiler:
I connected the charger to the battery output in desperation and got the voltage up to the correct level over a period of about 12 hours....carefully monitoring the battery temperature and voltage. I stopped when the battery pack became too warm for my liking and restarted when it had cooled down.
This recovery depended on some care, much risk and a dose of luck.......and can't really be recommended. It's just my story! The battery now charges normally to just over 41v and the ebike works just as it should do with a range of about 30km.
The battery lifetime may be compromised but who knows?
Background:
I bought a Chinese ebike (Enro ROC.....not the Italian manufacturer). I think the seller had bought up some old stock. The bike and battery looked perfect. I exported the bike still in its packing case and untried (by shipping container) to our overseas apartment. The bike was fine. The battery charged up to 36/37v. When I started to pedal I got about 5 seconds of "boost" and then I was back to raw pedal power.
Clearly there was a problem with the battery. It didn't matter how long I charged the battery, its voltage would not climb above about 37v. Being inquisitive, I tried to take the battery apart. I could get both ends off the case (it was a rear pannier battery). I couldn't get the cells out. There was considerable stiction. The force required to dislodge the cells would have damaged the (good) cells.
OK so my theory was that one group of cells (in series) were not charging properly. That group should have given about 4 volts that would have added to the 37v to give about 41v (about right for a fully charged 36v battery).
I believe the battery management system (BMS) would "protect" the failing group of cells by not allowing them to be charged once they fell below a certain threshold. I was unable to get electrical access to these cells.
Added to this:
a) There were no battery repairers on the island
b) There was only one importer of eBikes...and he certainly wasn't able or willing to help at all.
c) I then found that no-one would ship the battery back for repair/rebuild. Sea freight was effectively quoted at about $1000 each way
d) Passenger planes cannot legally take these high power lithium batteries
e) Most air couriers, although legally allowed to transport such batteries, wouldn't even quote for returning the battery.
f) Only one courier (UPS) was willing to ship the battery ($120 one-way)
At this stage my plan was to cut the battery case longitudinally and ditch the cells. Take the case back to UK and rebuild the battery from scratch.
Against this background, and with only very expensive options, I decided to try charging via the output terminals. This would bypass the BMS. I figured there was a (small?) chance that I might be able to revive the missing block of cells (depending on their state)
And it worked. I slowly got the voltage up to just over 41v.
The ebike now worked as it should.....and has been working well and charging normally ever since.
I have read many forum threads but never found anyone who had succeeded (or even tried) this method.
I have to say this "method" involves substantial risk. You can't just "try" this method by leaving the battery pack charging overnight....it will get too hot. And we are aware of the risk of fire and/or explosion. I was fortunate to have an small empty outside concrete utility room to try this out in. I'm not sure I would have tried it indoors!
I only tell this story just in case it might help someone with a similar problem. It probably won't help if there are two or more blocks of cells failing.
TREAT THIS INFORMATION WITH CARE!
