why did my battries explode?
 

hi guys,

yes another battery gone down . i use a x-15 computerized charger and nimh much more 4800 mah 7.2v saddlepack batteries and like usual i charged it up today and then i hear a big bang, i go up the plastic container has a whole in it (fire proof) and the cap of one of my cells has fallen off or exploded off, i hear a humming noise in the battery.

my settings for charging is usually 5.0 amps and has been for the past 2 months however i thought i saw on the charger "8.62v" and i thought that was quite strange, so is that my problem?

sorry it sounds abrupt.


Edd

8.62 is voltage, not current.

You haven't stated what cell type it is, just the matcher (much more).

It may have been previously damaged and shorting, it may not have been equalised and so that cell over charged and BANG. Lots of possibilities.

I am glad you are not hurt tho

nimh much more 4800 mah 7.2v saddlepack

chris wake up m8

thankyou for your consideration.

but is'nt 8.62 volts too high for a 7.2v battery? i don't really understand. and do you think that the rest of the cells will be ok?

8.62v is fine, its like saying a 12v car battery is always 12v, run a volt meter across you car battery and it'll come back nearer 14v, 13.5v at least.

ok but i mean wouldnt the charger have noticed this and stopped when the temperature started rising?

Mine hit 9v+ whilst charging, but settle when it's finished, so i wouldnt worry about the voltage.
Chargers will only auto cut off if they have temp cutoff.

Can you tell me a bit more about this X-15 charger? I have never heard of it.

8.62 is not an unusual voltage under charge, NiMH's will generally peak at over 9V.

Assuming no charger fault there are two main reasons why NiMH cells fail under charge. One is dodgy soldering and assembly which has blocked the vent holes. The other is that one of the cells has self-discharged more than the others, so gets overcharged and fails. This is why it is good practice to equalise cells before charging, at the very least check each one with a voltmeter to see that they are all about the same.