northbourne nick

Hi all The BMS in my 700 watt Wisper battery has packed up. There are plenty of BMS's on Amazon with the best getting average ratings. My question is has anybody replaced a BMS in a Wisper battery and could recommend a particular brand? many thanks in advance Nick

The problem was in the controller unit. A resistor need replacing. David from Wisper replied to this thread and asked me to send the controller unit to him. Wisper fixed it free of charge. Excellent service from Wisper. I Don’t think they make that controller anymore so I would have been stuck without their help.

Hi Richard Since I started this thread David from Wisper (see thread) has asked me to send my controller in to be looked at. At the same time I emailed Wisper directly and got a reply from their tech department. Both alluded to a resistor inside the controller that may need replacing. My bike was out of warranty so removed the controller (front of battery box) to see if I could buy a replacement. These are no longer available so hopefully when I hear from David he was able to find the problem and repair it. Failing that it's going to become an expensive piece of wall art! I'll update you when I hear back from Wisper Regards Nick

Thanks David I'll pop it in the post first thing. Regards Nick

Hello David Thank you for replying. What is the address to send it to? Regards Nick

I have taken some more diagnostic tests. My bike has a torque sensor and when the power drops off it feels the same as when I stop pedalling, except it surges about every second. Ive swapped over batteries (my wife's bike) and tried it again, still the same. So its unlikely the battery, connectors all seem snug. By trial end error I disconnected a plug from the controller one at a time and found when the orange 3 pin plug is disconnected the bike works fine. So as I don't have to completely unwire the bike to find what it connects to does anybody know what this plug connects into? Many thanks in advance Nick

No idea what caused the problem. hasn't been dropped or any of the other reasons you mentioned. It did come from nowhere.

Hello Yes it has a throttle but makes no difference when the power drops. Cheers Nick

I have owned a 905 Torque from new and all of a sudden it will lose most of its power when cycling. The battery level shows full but it feels like there's virtually no pedal assist. This happens on flat ground and I am not loaded up with shopping or anything heavy. I initially thought it may be the battery but the power indicator on the battery and the bike say otherwise. I have tried turning off and back on again (IT Crowd) but this doesn't cure the problem. Any tips greatly appreciated Nick