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First post, by rick12373

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I have a Compaq Presario 9232 where the CMOS battery is dead. It is not an CR2032 but a smaller battery which seems difficult to remove. I know you can get a CMOS battery that is wired like this:

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The motherboard has a 4-pin connector named "Ext Batt" (well actually there are only 3 pins with a gap). If I can find a new wired battery that has a connector like this could I plug it in to the 4-pin connector on the MB and leave the old one where it is?

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I would rather buy something than have to wire something myself. I can find lots of them online but none with the connector that matches the MB.

486 DX4-100 (overdrive)
16MB 72-pin SIMM RAM (2x8MB)
1MB Diamond Speedstar Pro VLB video card
SB 16 Value CT2770
AOpen VI15G Socket 3 Motherboard
HDD/FDD VLB controller card

Reply 1 of 2, by wiretap

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I have the Compaq Presario 9232 as well. I replaced the motherboard battery with a direct replacement. It is a Panasonic BR-1632A/GAN. They are $2 at Digikey. https://www.digikey.com/en/products/detail/pa … 632A-GAN/447502
I bought the computer new in 1996, and the original motherboard battery lasted until 2008 or so before it died. So replacing it with this $2 battery today should get you to the year 2034.

As for the EXT_BATT header, the manual states 4.5VDC input. It is just a standard 1x04 2.54mm pitch dupont pin header. The two pins next to each other are ground, and the one by itself is the positive voltage connection. The quickest/easiest way is to just use a 3xAA or 3xAAA battery holder and wire it to the pins with dupont connectors. This motherboard doesn't have the charging circuit to the pin header, so no need to worry about charge circuit protection.

If you're adventurous, I also have a few plug in module PCB designs on my Github that provide coin cell options for the EXT_BATT header. They can be mounted in various ways.

My Github
Circuit Board Repair Manuals

Reply 2 of 2, by rick12373

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Thanks. Looks like getting the original from DigiKey is the best option. Not sure how to remove the old one though.

This machine was given to me quite a while ago. It is very clean. The original hard drive still works as well, which impressed me.

486 DX4-100 (overdrive)
16MB 72-pin SIMM RAM (2x8MB)
1MB Diamond Speedstar Pro VLB video card
SB 16 Value CT2770
AOpen VI15G Socket 3 Motherboard
HDD/FDD VLB controller card