486 motherboard battery replacement question \ VOGONS

486 motherboard battery replacement question

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First post, by appiah4

Posted on 2018-04-18, 16:21

appiah4 Offline

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Recently bought a 486 motherboard with a leaking Varta barrel battery so I removed it and cleaned up the mess. My original plan was to use the BATT_EXT header with a triple AA holder and three NiMH rechargeables. However while brushing it with vinegar I noticed it has solder holes for two other types of batteries, one being a coin battery holder.

So the question is if I solder one to this board what battery do I use? Can I assume recharging is disabled for the coin battery holder solder points and a CR2032 would be safe or should I use a rechargeable like the LR2032?

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Reply 1 of 3, by keropi

Posted on 2018-04-18, 16:55

keropi Offline

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No you can't assume that the coin-cell battery place is safe to use - unless you verify it won't charge the battery.
There is a strong chance that depending the battery used they made changes to the nearby resistors/diodes/components... I would just use the EXT BATTERY connector or solder a new rechargeable battery, they are not as bad as the old ones when it comes to leaking

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Reply 2 of 3, by scroeffie

Posted on 2019-10-17, 20:32

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does the battery need to be rechargeble ?

Reply 3 of 3, by quicknick

Posted on 2019-10-17, 21:03

quicknick Offline

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EXT_BATT is always the safest bet, but the CR2032 holder is more elegant. Check with a multimeter, you should have close to zero volts on the solder pads with the board powered on; if it's close to 5V then you need to break the charging circuit. In most cases it's a diode in series with a resistor, I recommend removing the diode because it's much simpler to restore the circuit at a later time (just solder back a 1N4148 instead of an unknown value resistor).

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