Hoverboard wont charge

Hi,

My hoverboard (see pictures) will not charge the battery - the charger LED stays green. The battery is almost new, and charges fine when the charger is directly attached to it (the yellow connector). I ran the hoverboard untill battery voltage was around 39.5V, but it still wont charge. I have battery voltage at the mainboard where the battery connects, and charger voltage (41V) at the connector on the mainboard coming from the charger inlet. Somehow the voltage is not let through the mainboard to the battery. There are no error blinks on the mainboard (only nine when turned upside down) and the howerboard works just fine when riding it. It will not power up with only charger attached (battery disconnected). WIth battery and charger disconnected I have about 15V where the battery connects to the mainboard (and at the yellow battery connector towards the mainboard). When shorting the on/off switch this voltage drops slowly and rises again when the short is removed. Guess it is some of the capacitors holding charge. I have tried recalibrating without any change.

Any ideas on what causes this error? Any suspect mainboard components? I would really appreciate some advice!

could it be the same problem as last time?
https://endless-sphere.com/forums/viewtopic.php?f=14&t=99936

I dont think so. The old battery would not charge connected to -C and +B (the yellow connector) however shorting -B and -C started the charging (bypassing bms). The new battery charges when the charger is directly connected to the yellow connector=-C/+B (bypassing the hoverboard logicboard). I cant see any other possibility than some failing component(s) on the logicboard, not forwarding the charger input voltage on the logicboard to the battery?

yeah, that sounds like a problem on the board between the charger and the battery.

the most common problem is a connection failure, where either a solder joint (at a connector on the pcb) is cracked, or the actual pins on the connector are worn, spread, etc.

there could also be a failed component, that's usually a fuse. it might be glass tube with silver ends, or an smd part, typically white with silver ends.

could also be that whatever the hoverboard has for a "brain" chip is detecting or has detected a condition that it's programmed to lock out the charger for, to prevent a fire. if the battery voltage ever got way too low, or too high, it might be setup to do this. or potentially if it took way too long to charge at a higher current rate. neither is likely, but possible if the designers thought of them.

there could be some other part failed, like if the main board has a fet or other control device in the charge path, that has failed rather than being disabled.

if you can trace the charge path with a multimeter on continuity, with all power disconnected from the board, no charger and no battery, you can at least locate which parts are involved in it. you might also be lucky and simply see where the problem is, unlikely as that might be.

Is your 1st picture showing the battery with its cover removed? Looks like 11 screw terminals holding down tabs, possibly the balance connector terminals. BTW, looks they really stepped up the design of the battery BMS, if that is what it is. Probably got temperature sensors in it,

If it were me, I would walk a voltmeter around these screws. If they're the balance signals, betcha you find a bad cell like you did in the other thread.

Any particular reason that connector on the lower right is disconnected?

Hi,
Sorry for not replying, notifications from the forum went straight to the junkmail folder.
It was an embarrassing error , I had put the connector from power inlet to mainboard the wrong way. As seen in picture one, there is no socket on the mainboard, just four pins, so it is possible to connect the cable two ways. Turned it around and now it works. Positive is the two pins to the left in the picture, closest to the big black thing (diode?).

Thanks a lot for helping!

Edit: the disconnected wire in the lower right is for a bluetooth module not fitted to my board I think.

Good deal. Thanks for posting the solution. Lucky nothing burned up when the plug was backwards.