1. you need to remove the old battery, clean/repair the damage
2. You can't replace a rechargeable battery with a non rechargeable battery unless there is a external battery header you are connecting it to

treeman wrote on 2020-03-03, 21:34:

1. you need to remove the old battery, clean/repair the damage
2. You can't replace a rechargeable battery with a non rechargeable battery unless there is a external battery header you are connecting it to

My MB has an external battery header

in that case find some connectors, usually i cut off the front panel cables from old cases (not retro cases) and reuse those connectors to connect the above battery holder to your external battery pins.

get rid of the barrell battery asap and clean all the acid otherwise it will keep damaging things.

metrox wrote on 2020-03-03, 22:39:

treeman wrote on 2020-03-03, 21:34:

1. you need to remove the old battery, clean/repair the damage
2. You can't replace a rechargeable battery with a non rechargeable battery unless there is a external battery header you are connecting it to

My MB has an external battery header

If you're going to use an external battery box, do yourself a favor and get a 4xAA one, fill it with energizer lithium AAs, and never have to touch it again. It will last forever

maxtherabbit wrote on 2020-03-03, 23:19:

If you're going to use an external battery box, do yourself a favor and get a 4xAA one, fill it with energizer lithium AAs, and never have to touch it again. It will last forever

I just saw some new Energizer Lithium AA and they were rated 1.8v not typical 1.5v. Are you sure you did not mean 3 x AA ???
Using 3 x 1.8v gives 5.4v, using 4 would gives 7.2v which could and probably will damage the cmos over time. In my stock of dead old original ext. bats they are all 4.5v, only one is 6v and not one is above that. Just my observation and can post pics of a few of the original ext batts if you need proof. Of course there could be exceptions but would not risk applying 7.2v to an old board if the Lithiums you use are 1.8v. What happened to to 1.2v Liths ?

1.8V with no load maybe...
Any manufacturer selling AAs that output more than 1.5V would be setting themselves up for trouble.

treeman wrote on 2020-03-03, 22:55:

in that case find some connectors, usually i cut off the front panel cables from old cases (not retro cases) and reuse those connectors to connect the above battery holder to your external battery pins.

get rid of the barrell battery asap and clean all the acid otherwise it will keep damaging things.

My soldering iron is on its way, what a pain in the ass to remove this battery.

jmarsh wrote on 2020-03-04, 03:39:

1.8V with no load maybe...
Any manufacturer selling AAs that output more than 1.5V would be setting themselves up for trouble.

That is the problem, most modern devices draw a lot of current when on so the Volts would drop due to current draw and internal resistance of the battery . Most CMOS chips, including the old ones draw very little, most less than 100uA, newer ones as little as 10uA. One of my 286 mobo's uses a HD146818P as the clock/cmos. Max input and supply is 7.0v, recommended supply is 5v (4.5min- 5.25max). Under Battery backup supply is 2.7v min, 4.5v max. Current draw is 30 to 50uA typical depending on whether Xtal or other external timing source (all from the datasheet). About same as putting a 90k to 150k resister across the battery. Not much draw.

metrox wrote on 2020-03-04, 04:05:

treeman wrote on 2020-03-03, 22:55:

in that case find some connectors, usually i cut off the front panel cables from old cases (not retro cases) and reuse those connectors to connect the above battery holder to your external battery pins.

get rid of the barrell battery asap and clean all the acid otherwise it will keep damaging things.

My soldering iron is on its way, what a pain in the ass to remove this battery.

just clip it off with some wire cutters

back in the day the standard for the lithium primary batteries that were used for external RTC batteries was 6v

I have several of them that still work actually

IIRC the current passes through a diode before it gets to the IC, so that would drop it back down under 7v even if the "loaded" voltage of the energizers was actually 1.8v

If the motherboard manual doesn't specify a voltage for the external battery, a bit of trial and error is required. I've encountered boards that refused to start when supplied by 4xAA(A) batteries but worked as a charm with only 3 pieces. Diodes in series drop far less than you'd expect, due to the extremely low current; 0.2 volts is typical in these circuits.

I know at one point I tried only using 2 of the lithium AAs, and the clock did not run while my 286 machine was powered off

Yeah, in any case, 3, 4.5 and 6 volts are the values to try. I think the board that refused to start with 6 volts was the ATC-1415.