New Member

[FinstP]

Hi, Thanks for letting me join. I have two Kalkhoff e-bikes (one was bought for my wife, but she rarely uses it, so it's usually on loan to other family members) and a non-e Budnitz road bike. I mainly cycle for fun on the fairly extensive cycle path network in the Glasgow area. I do cycle into work occasionally and I would do it more but I am usually carrying too much stuff.
I have had none of the problems with the Kalkhoffs mentioned in other threads (in three years of moderate use) but I do have a recent problem with the 36v 17Ah battery (made by BMZ apparently). This started with all of the red power indicator LEDs staying on all the time. It remained useable and I was able to recharge the battery once when the power ran out. However last week it lost all power and won't charge. It shows one flashing LED no matter how long or how often I try to restart charging.
So I took the pack apart. The batteries have a chance of being OK, each of the 10s 5p packs reading the same 0.94V. The problem would seem to be with the BMZ BMS module, which also contains the 5 power indicator LEDs. So, finally, does anyone know where to get hold of a new one of this particular BMS module so I can attempt a recovery? Or do you have any other suggestions?

 

[Deleted member 4366]

0.94v means a scrap battery. The cells mustn't go below 2.5v. Normally the BMS would switch off at about 3v. After that, the further they go down the greater the damage.

Are you sure your voltmeter is correct? Test it on an AA cell, which should be about 1.5v.

If the 0.94v is correct, you might be able to recover some capacity if you charge them very soon. You need to get each cell-group over 3.0v. You should charge them very slowly - maybe 100mA, and do it somewhere where if the pack catches fire, it won't burn your house down.

Recovery will not be a good long-term solution. The cells will probably be very saggy, so don't invest any money in it. use it as a learning exercise.

German Ebay is about the best source for new replacement batteries. there's Chinese rip-offs there, which are reported to be quite good.