On 02/07/2012 13:48, whisky-dave wrote:
On Monday, July 2, 2012 12:39:06 PM UTC+1, Jim K wrote:
Mate's Dell Laptop (oldish) has flat batt and won;t boot.

Plug in to mains charger - won;t charge - batt light on lappy "winks"
once per insertion of the jack, then nought.

Lappy won't boot either when plugged in to the charger...?

Had batt out & makes no difference except the batt light "wink"
disappears when you shove the jack in.

Got charger here now, plugged in, green LED on tranny box is lit,
multimeter on the DC jack end - measuring 0.01V - it's rated on the
tranny label at 19.5v 3.3A....

Seems something not right - but :-

do laptop chargers "sense" and adjust their output somehow?? meaning I
can't actually say 100% it's the charger that's shagged & just acquire
a new one...?

All help appreciated

Cheers
Jim K

I've heard that Apple batteries can sense when they are 'dead' and won't charge. If the Dell battery is behaving the same then maybe the battery is dead and has set itself not to be chargable, or it could be a cell or two is damged and that's why it won;t charge.
Is there anything else you could connect to the charge that's about 20V maybe 2 X 12V bulbs in series see if you can get any current out of the charger.

All lithium-ion batteries should have a self protection suicide circuit
in them. They tend to catch fire spectacularly otherwise if they fail
short circuit a thermal runaway becomes inevitable. Not nice.

http://www.electronicsweekly.com/blo...mion-ba-1.html

ISTR Sony and Nokia had a bit of bother with it not all that long ago.

--
Regards,
Martin Brown