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I watched a guy turn on a two "C" cell Pelican light in Cayman one day.
You should have seen the detonation! It took his ass off the wall he was
sitting on and when we picked him up we spent 5 minutes picking the
shrapnel out of his face! (Damn good thing he had his mask on!)
Cheers,
JD Selser
On Thu, 29 May 1997 07:06:06 -0400 "G. Irvine" <gmirvine@sa*.ne*>
writes:
>I know you guys know this already, but these gell cells lead acids
>will offgas severely when charging, discharging , sitting still, or
>whenever they feel like it. I did discover one really nasty mode of
>offgass that we can easily prevent. 
>
>     Bottom line, let the batteries sit for minumum ten minutes, and
>more like an hour before sealing the scooter or light - don't seal
>unless ready to dive.
>
>     Here is what I did. I was testing different batteries last night,
>and I came across two seemingly identical batteries which had a volt
>difference in voltage with a trickle charge attached. I threw a
>non-automatic charge on the low battery, and imersed it in water, now
>being suspicious of both batteries - it was bubbing hydrogen from the
>relief plate. 
>
>     I took it off charge, and it continued to do this for ten 
>minutes.
>I put a load on it and it stopped. I then tested both batteries, and 
>the
>one which had had the highest charge failed 30 minutes short of where 
>it
>should have burned, and the other ( the offgasser) was fine.
>
>     I tried the offgass thing a few times - it takes several minutes
>for it to calm back down after you apply a higher voltage to it than 
>its
>fully charged state. The correct fully charged state for these twelve
>volters appears to be 13.33 volt. The other was at almost 15 - no 
>good,
>and higher than 13.33 applied to the fully charged battery produced 
>gas.
>
>     Closing up a battery like this turns your scooter into a bomb if
>the hydrogen gets into the motor compartment. Let them rest open for a
>while , and do not ever leave them closed until ready to go in the
>water. Most of these chargers are not exactly precise instruments, and
>you want to be carefull with this. Also, the batteries can do this
>without being overcharged.
>
>     Be carefull with these things - when they explode it is extremely
>powerful. - G
>
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