Battery submerged in water - safe to recharge?

[canard]

Does anyone know if it is safe to recharge an electric bike battery that has been completely submerged in water? Long story short - yesterday I managed to ride into a very deep puddle of water during a torrential rainstorm in which the entire motor unit and battery of my BH Emotion Max 700 got submerged in water. Now I'm afraid something dangerous will happen with the battery if I try to recharge it - does anyone know if this would be safe?

Any advice would be greatly appreciated!

 

[Deleted member 4366]

It's probably OK. Check the battery terminals with a meter. If you have voltage around 24v or more, it's OK. If there's no voltage, it might be recoverable, but you'll have to open it up. If it were mine, I'd do that anyway just to make sure that there's no water in it.

 

[canard]

I see, thank you. I forgot to mention it's a 36 V battery, so I'm assuming a voltmeter would have to show approx. 36 V for it to be undamaged, or would 24 V be OK?

 

[Deleted member 4366]

Between 31v and 42v is the correct range. When you charge it up, it should be close to 42v. If it doesn't go past 41.5v, you need to investigate why.

 

[canard]

Got it, thanks.

It's actually the act of charging that concerns me the most - do you know if there's a risk of fire/explosion or poisonous gases etc if attempting to charge a (potentially) water-damaged battery?

 

[Deleted member 4366]

I would say that risk of fire or explosion is very close to zero.

 

[canard]

Ok, I recharged the battery and measured the voltage at 41.6 V. Pretty close... I guess this means it's OK?

 

[Deleted member 4366]

That's pretty normal, so no cells were drained by water. In most batteries, all the connections apart from the output are at the top, so it should survive quite a lot of water coming in. Fresh water is not particularly conductive, so as long as it's not in there too long, it wouldn't do any harm. Most upright batteries have holes in the bottom to let any water out. If You had been through salt-water, it would have been a terminal case.

 

[canard]

Good to hear, thanks. I doubt there was much salt in the water I rode through but I'm sure it was filthy enough, courtesy of over-flooded storm drains.