To the person looking for info about Thinkpad 500 batteries earlier this
month: I have one (a TP-500) and I rebuilt the battery for it. A precis:
The original designed battery for the TP-500 was a lead-acid unit. It proved
dangerously unreliable in service and was replaced by the Ni-MH unit. Inside
the battery case is a charge controller circuit and a Duracell DR19 battery
pack. These packs are still available, they were used in several Compaq
models for example. A crucial difference is that in the TP500 battery, the
connector straps from the charge controller have been spot welded to the
contacts on the DR19 unit. If you are in DIY mode, you can easily fabricate
suitable contect springs (nickel plated coil springs out of an old
transistor radio etc) to make contact with the "standard" DR19 contacts. If
you aren't DIY minded, any competent battery rebuilder should be able to do
the job for you. Just tell them it uses a DR19 pack and they'll need to spot
weld or carefully solder the connections. The connection pads on the DR19
are not actually part of the cells so should be able to withstand careful
soldering heat.
I did mine the hard way. DR19 cells aren't readily available here, so I used
individual 4/5 A size cells with solder tabs. The result works fine.
Incidentally, the charge controller is there to convert the lead-acid
"constant voltage" lead-acid charge supplied by the TP-500 internal charger
to the "thermal limited" charge required by Ni-MH cells.
--
Don Hills (dmhills at attglobaldotnet) Wellington, New Zealand
It's ironic that people who are too smart to engage in politics
are governed by people who are not as smart.
Received on Thu Jul 29 2004 - 05:04:01 BST