In message
,
Pete C writes
On May 18, 5:38*pm, Tim Lamb wrote:
How many cells have gone? (measure cell voltage under load)

er... OK. Thinking how to load the batteries and have access to the
connections. I'll get back.

Battery was flat and accessing terminals plugged into the drill not
easy. What I have done is to look at the individual cell voltage on
charge. Lowest 1.37V (4 cells), highest 1.52V (1 cell) mostly around
1.4V

The cells are by Huanyu type GNY 1.2V and 1300mAh

Right, what I meant was the cell voltage while the drill is being run
rather than charged. The duff cells should soon drop to zero while the
others stay around 1.2.

I know what you meant:-) Next time I have three hands, I'll try.

If only a one or two cells are gone I'd just cut them out (dremel
across the 'strap' where spot welded to duff battery) and solder thick
wire in there to bypass them

Yes. Having noted the prices for *C* cells I'm not so happy about
replacing a full set of 20.

Might be worth using the charger on a timer from then on too

Ummm... is there any easy way of finding out how the existing charger
operates?

In the meantime an unwanted cordless drill/vacuum might turn up on
Freecycle or Ebay locally and some sub C's could be had from that.

If you want a project how about getting a LiPo RC charger and re-cell
with '20C' or '25C' LiPo packs

This is rather deep water for my wellingtons:-)

regards
--
Tim Lamb