Hi Tim,
T i m Inscribed thus:

Update:

A replacement primary battery came today for daughters Latitude D520
and when I fitted it the BIOS Battery Info screen when from 'not
installed' (empty bay or with the old battery fitted) to 'Discharging'
with the new battery so that was something. ;-)

Sounds like the protection circuits in the battery killed the feed to
charge it. If you decide to investigate you will probably find that
one or more cells has died.

Then I found a faulty 90W Dell adaptor I had kicking about and when I
powered it up it made a noise like it was trying but didn't light the
LED nor put any voltage on the output plug. With both daughters and
this charger disconnected from the mains and after insuring there was
no output voltage I measured the output resistance on both and found
the 'dead' one to be shorted (good one about 200 ohms).

That sounds right for a good adaptor.

With nothing to lose I carefully cut it open the duff adaptor and
after a bit of experimenting concluded the short was in the cable as
it exits the power brick. With a decent iron and de soldering pump I
removed the iffy output lead, trimmed it a few inches shorter and re
heat-shrunk and connected the cables. I put it back in it's case,
taped it up and powered it up, LED on and 19V on the output. ;-)

Sounds good ! I bet you've done this before... ;-)

Plugged it into the D520, "AC Adaptor = 90W' and the primary battery
status changed to 'Charging'. ;-)

So the D520 looked like it had two faults, a dead primary battery and
faulty ID function (I'll check that one out tomorrow). It also seems
the modular bay battery isn't so fussy about the PSU and has been
charging and working ok.

Yea, a result !

We then tried the same 'test' PSU in daughters b/fs not-charging
Inspiron 1545 and it also now detects the charger but didn't seem to
want to start to charge. He says the battery had about 2hrs life
before it stopped charging. A mate has a 1545 so we will try his
battery in this one before doing anything further.

I'll provide another update as / when we know anything on that.

Thanks for this update ! Its nice to know.

As the round plug from the D520 adaptor fits the octagonal socket on
the 1545 I may get a pair of genuine Dell 90W adaptors with round
plugs as they can both use either.

Thanks again to all those who have offered help / feedback on this so
far.

Cheers, T i m

--
Best Regards:
Baron.