Thinkpad 500 batteries

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.