[mark christopher]

Originally Posted by strobe

Received this e-mail of Paul Worsley earlier on.


Hi Mark,

Just been reading the posts regarding your cell going 'bang'.

Quite simply, you were charging them outside the manufacturers recommendations.
The data sheet supplied by Intellect clearly states :- Maximum charge rate 1C
That means that you should never charge at more than 4.2 amps.

The recommendations from any of the 'matchers' is always dubious, as they did not produce the cell.

The correct rate of charge for cells is ambiguous in many cases.
Example :- GP 4300 cells clearly state on the cell that they should be charged at 0.41 amp (410 ma.) and should not be soldered.
However their data sheet states that the cell can be charged up to 6 amps.
So if one goes bang when charging at 6 amps, would it be recognised that they have been misused ??
My guess is that in a court of law, the instructions on the cell would be the ruling factor.

Intellect do not state any charging recommendations on the actual cell.
I have advised them several times that this is not good practice and they could be liable for any claims, as their product does not state how it should be used.

I think that common sense dictates that cells should never be charged at more than 1C (4.2 Amps)
I would be concerned at anything over 5 Amps. The cells should never be 're-peaked'.

A further consideration is the nature of NiMH cells. MiMh cells 'self discharge' at varying amounts.
The gives the situation :-
If cells have been stored in a charged condition and unused for a period of time, the capacity remaining in the cells can vary greatly. When the cells are then charged, the charger cannot always accommodate this variation and some cells can be greatly over-charged.

Touring Car drivers often charge at 7, 8 and even higher amps, and as a result they have more cells go 'bang' than Off-Road drivers.

Hope this helps,

Paul Worsley. (Cell homologation officer)

Hope this ok to post Jimmy and Paul.

good info Paul!