Dave Plowman wrote:
In article ,
Matthew Ames wrote:
Just put an amp meter inline with the battery and it appears to be
charging at about 100ma

Right. Sub C cells are usually between about 1500 and 2500 mAh
capacity, and the safe basic charge rate is 1/10th of the capacity
for 14 hours. So 100mA sounds rather low - unless the system is old
when batteries *may* have had a lower capacity than today. Also, you
said earlier the charger was marked as 0.6 amp which seems a bit
generous if it's only charging at 100mA.

However, if things aren't overheating etc, I'd leave it on overnight
and check the current again in the morning.

I'd be willing to bet though that it's simply the battery that's
knackered.

I would too. Some of the cells will have grown internal whiskers that will
have shorted them out.
This often happens with NiCads that are left for months discharged.
Sometimes I've fixed them by blasting a current into each cell from a
controlled power supply, but you have to get at each cell to do this..