Is my battery goosed?

[Nosweat]

I hadn't used my bike for the past five weeks for various reasons. When I came to turn it on the other day nothing happened - no lights on the battery, nothing on the LCD display.
I tried charging it (battery in bike) but the charger was constantly showing green.
I swapped displays over to my partner's bike as she has the exact same setup - both displays are working fine for her bike.
I took the battery out and when I pushed the on button all the lights came on and went off again.
I plugged into the charger and the charger LED went red. A few hours later it turned green, making me think it must just have been a flat battery (though a month of not cycling seemed quite short for it to go totally flat).
When I reinserted it into the bike battery holder there was a big flash and a smell of burning! So I took it out immediately and looked at the terminals. On the battery pack the two positive springs appear charred and the two positive spikes on the battery park holder have actually partly melted!
I used a multimeter to measure the voltage between either of the battery's positive and negative terminals - in each case it's 41.2 volts.
So I currently have a paperweight of a heavy bike with a motor but no power or battery, and a battery that looks like it won't even fit into the holder as the prongs have melted.

Admittedly the battery is five years old, but I have not used the bike as often as I expected to and would have thought there was still a reasonable amount of life left in the battery cells. Is it possible to replace the prongs on both battery and holder terminals? Or do I need a new battery and holder (in which case I hope compatible ones are still available?) It's a 36V 17AH downtube for front wheel (XF07) motor.

 

[saneagle]

The battery in your voltmeter is flat, so it's giving a false reading. Measure anything else of known voltage to confirm.

The problem with your bike is most likely a short circuit. When your battery was on the bike, the BMS's over-current would trip and switch off the battery. When you tried to connect the battery, the full current would flow through the terminals until the BMS tripped, which is what burnt them.

The question is where is the short circuit? Typically, it's blown MOSFETs in the controller, but then it wouldn't have been working at the time you laid up your bike. You need to think back to what might have happened to it.

 

[Nosweat]

Above post amended as I evidently misread the multimeter, it's 41.2 volts. I only recently changed the multimeter battery and other things around the house are reading fine.

I have no idea what could have happened as the bike has been untouched and in storage for the past few weeks and was working fine right up until the last time I used it. Where does that take me? At present both battery and cradle appear unusable. If they can be repaired, or if good cells can be reused in a new battery where can I take it for that repair? Or do I need a new battery and charger?

Incidentally where is the controller in the circuit? The components on the bike, obviously besides wires, are an LCD control on the handlebars, a pedal sensor, a motor, a battery cradle and a detachable battery.

 

[saneagle]

Above post amended as I evidently misread the multimeter, it's 41.2 volts. I only recently changed the multimeter battery and other things around the house are reading fine.

I have no idea what could have happened as the bike has been untouched and in storage for the past few weeks and was working fine right up until the last time I used it. Where does that take me? At present both battery and cradle appear unusable. If they can be repaired, or if good cells can be reused in a new battery where can I take it for that repair? Or do I need a new battery and charger?

Incidentally where is the controller in the circuit? The components on the bike, obviously besides wires, are an LCD control on the handlebars, a pedal sensor, a motor, a battery cradle and a detachable battery.

There's nothing wrong with your battery. You have to find the reason for the short in the battery receiver or the controller. I can't help you beyond that because you haven't shown us which bike you have, nor which battery, nor anything at all about what you have.

 

[Nosweat]

Posting in the Woosh clinic as it's a Woosh kit. 17AH 36V downtube battery, XF07 front hub motor, torque sensor/controller in crank and KD58C display. Where would I begin to look for the cause of the short, and can the battery and its holder be repaired? I don't want to sink £300 on a new battery only to find the same thing happen but am mystified how something like this could have occurred when I haven't been using the bike for a few weeks.

 

[Woosh]

Did you get in touch with support@wooshbikes.co.uk?

 

[saneagle]

Posting in the Woosh clinic as it's a Woosh kit. 17AH 36V downtube battery, XF07 front hub motor, torque sensor/controller in crank and KD58C display. Where would I begin to look for the cause of the short, and can the battery and its holder be repaired? I don't want to sink £300 on a new battery only to find the same thing happen but am mystified how something like this could have occurred when I haven't been using the bike for a few weeks.

Blown MOSFET happen when you put the motor under huge load, like riding too slow up a hill or holding the wheel still when you operate the throttle. It's very easy to check if that's the problem as long as you have a multi-meter.