Arctan

All sorted now with a cheap e-scooter charger and a couple of silicon diodes. Cut charge at 41.5, and battery slowly dropped back to 41. Settling or balancing perhaps? I'll add a voltage and current lcd module later, in place of DMM. Battery University has comprehensive info on voltage vs number of charges vs stored energy, very informative. In time I'll examine the three wires, additional to the main charging pair. Because I won't be traveling far, even 40 volts might do, with monitoring. Took it out for a short spin, great fun. Curious about mid frame motors, coming from RWD Volvos, and met a man with a TSDZ2B 36V 250W Torque Sensor Tongsheng Mid Drive Motor which I can dream about adding to my lovely Schwinn hybrid bike, at a later stage...

OK, yes, I thought the 4.08 was a bit on the low side. Hopefully I can revive the Giant charger . I can connect a 4 .2 volt charger in the short term to perhaps charge individual parallel packs, just so they don't discharge further? I don't want to let them rot. And Giant using cantus is both interesting and further complicates my plan! I appreciate that signalling SOC and temperature and stuff to the charger is useful. Today I'll pick up the Torx security bits and open the charger. Is the canbus stuff just for the charger, or is it also for the bike connection please? Many thanks for the clues!

Just measured the individual parallel packs. 10 of 4.08 volt. If I'm lucky, that means balancing operates, and cells might or might not be ok?

Hello to all fellow members. I didn't use my bike for about four months. It uses a 36v 8ah battery. I gave the battery a top up charge after two months or so. When I decided to give it a top up recently, it looked like the battery had died, when I pressed the test button. The five led column wouldn't light, and. after further presses, lit up two LEDs in the middle. The test button has aways been a bit mechanically uncertain, although I now have an idea that multiple presses or a long press may toggle the display over in to a diagnostic mode! I Put the battery on charge, fingers crossed. Charger was showing it's red light for a few hours, then green. But still the odd central pair of LEDs on the battery pack. Then the led went out on the charger. Panicking, I watched some youtuube videos, imagining I had an ugly low resistance or shorted battery, and that internal inspection was needed. After getting the casing open, an accidental press of the button gave me a full LED column. I thought 'just the charger then'!. A quick measure across the outer pins of battery gave 40 or so volts, and I thought 'this battery hasn't died'. A more specific look reveals 40.8 volt across battery pack terminals 1 and 4, and 37 volt across pins 1 and 2. 1)So, with all LEDs showing, is this a healthy battery? 40.8 suggests partial discharge. (I can measure the individual clusters of parallel cells, now that the box is open). 2} What are the two different voltages on offer across different pins? How does that relate to the motor, display electronics etc? I should say that I think I just about understand the purpose and behaviour of a BMS! There is a huge PCB in the battery, with 'balance wires'. (Speaking of pins above, I mean the battery connector where it connects to the bike) Then there is the defunct charger. I see lots of low cost 42 volt 2 amp offerings on amazon etc. But both the male and female XLR 's of the Giant bike charging system have all pins going somewhere, wires attached that is. I'd be delighted if a simple cheap two wire item could replace the un affordable Giant replacement charger. I've yet to open the charger, looking for an obvious fail. But waiting on Torx security bits. I understand more traditional PSU's (Analogue, regulated), but I appreciate that switched mode is much harder, and so a replacement might be easier! Regards to all, John.