Sealed lead acid batteries in old PBooks?

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DrBunsen's picture
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Joined: Dec 20 2003
Posts: 946

I'm wondering about using 6 and/or 12V sealed lead acid burglar alarm batteries in old 'books, like the 180, Duos, 520/540 series. There are some small ones available that would suit the 520s especially, say a pair of 6V in each side in series.

I understand that the charge curves would all wrong for the onboard controller, and that I'd need to match/ limit voltages. Would I be able to take a line straight from the 24V in to a small charge control circuit, and then from the battery to the lappy via a regulator.

Any opinions? Am I likely to find/make a charger board small enough to fit, say under the trackball/between the two front battery bays?

How can I find out the battery voltage for each laptop type, bearing in mind that their existing batteries are all dead?

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eeun's picture
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Joined: Dec 19 2003
Posts: 1891
Battery voltages

Google around for replacement batteries for each 'book you're looking to modify.
Most resale places will list the battery's voltage and amperage.

The 520 book comes up as:
Chemistry: NiMh
mah: 2100
Volts: 9.6

And for the 180 (third party extra capacity):
Chemistry: NiCd
mah: 3200
Volts: 6

If you don't already have the lead-acid batteries, it would be better to re-cell the existing batteries with the correct type of cell. You can find batteries on ebay that come with soldering tabs attached.

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DrBunsen's picture
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Joined: Dec 20 2003
Posts: 946
Better, yes...

... but cheaper, perhaps not. I'll look into the prices of the correct batteries. I might be able to pick up some RC car battery packs and dismantle them.

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