Before it dies, I would like to say that a diode can also safe the motherboard.
If the battery shorts internally due to what ever reason, a small glass diode (1N4148 or similar) can prevent a short circuit.
Because, in the unlikely case the battery is shorted, and the diode successfully prevents the PSU from charging the battery, the diode acts as a fuse.
It's not a proper fuse by any means, but it's a weak part that can fail under such circumstances (good thing).

Edit: Small edit.

Good evening all.

I have almost no knowledge of electronics whatsoever, so could please someone explain to me in simple terms how to use a multimeter to check if an external battery connector is charging the battery?

I already bought some double cr2032 sockets with batteries and I'd like to confirm it's safe to use them with the external connection.

Thanks!

Set your meter to the DC voltage setting and then take the two probes and put the red probe on the positive (+) pin of the battery connector and then place the black probe on the negative (-) connector on the ext battery connector. If you have voltage present then it's designed to charge an external battery. If no voltage is present then your all set. If voltage is present you'll need a blocking diode inline with your new battery to prevent it from charging and causing problems.

chrismeyer6 wrote on 2021-06-16, 22:43:

Set your meter to the DC voltage setting and then take the two probes and put the red probe on the positive (+) pin of the battery connector and then place the black probe on the negative (-) connector on the ext battery connector. If you have voltage present then it's designed to charge an external battery. If no voltage is present then your all set. If voltage is present you'll need a blocking diode inline with your new battery to prevent it from charging and causing problems.

Thank you, that seems simple enough - from a previous post I was under the impression that I needed to measure amps with the battery present.

About the diode, if needed, do I place it between the + connector and the battery? And what about the diode polarity? And what kind of diode?

Thanks again.

You can put the diode on the positive side and you want it so it let's power flow out of the battery to the motherboard. They usually have an arrow that shows it's directionally and you'd want it facing the motherboard so it blocks power flowing into the battery. You just need a blocking style diode nothing special or fancy.

I have never seen an external header for a rechargeable in any type of clone system. Perhaps there were some OEM builds that worked this way, but it's not a common thing by any means

It still doesn't hurt to check cause you just never know.

Chrismeyer6, I posted a diagram in this thread How to modyfy SOYO SY-4SAW2 to take Lithium Cell, instead of Nickel rechargeable. Bios upgrading.
It should be the case for many motherboards as I was able to validate.

Maxtherabbit, I have a few motherboards that are not OEM that have headers for external batteries. I have attached CR2032 batteries and they still work so I guess they don't have the recharging function in the headers.

The motherboard should have a circuit like the one below, you just need to look at the components near the battery and take some continuity measurements to figure it out. You need to cut the line somewhere between the yellow mark, either by removing the diode, the resistor or just cutting the trace anywhere between them. The +5v line comes directly from the +5v pins of the power connector so it's easy to find.

pixel_workbench wrote on 2021-06-10, 13:58:

That's a terrible idea. You can learn about the details of different batteries here: […]
Show full quote

tonata wrote on 2021-06-10, 08:02:

Can you please comment on my solution on using a 18650 lithium ion rechargeable battery. Can these batteries be safely recharged by a 386 motherboard while in use?

Here is a 18650 https://fr.aliexpress.com/item/1005002420574151.html charger if a comparison can be made. Or maybe I should put a diode to be on the safe side reducing to it 3.3 V ?

That's a terrible idea. You can learn about the details of different batteries here:

https://batteryuniversity.com/learn/article/c … based_batteries

https://batteryuniversity.com/learn/article/c … m_ion_batteries

It's a pity these links no longer work as I'm sure they were an interesting read.

I use a LIR2032 in a button cell holder soldered directly to the motherboard in place of the OEM unit. Saves all the mucking about. Never had an issue.

Dusko wrote on 2021-06-27, 02:37:

Chrismeyer6, I posted a diagram in this thread How to modyfy SOYO SY-4SAW2 to take Lithium Cell, instead of Nickel rechargeable. Bios upgrading.
It should be the case for many motherboards as I was able to validate.

Maxtherabbit, I have a few motherboards that are not OEM that have headers for external batteries. I have attached CR2032 batteries and they still work so I guess they don't have the recharging function in the headers.

So we are saying the same thing. I was saying the headers do not recharge, not that they do not exist

maxtherabbit wrote on 2021-06-27, 15:07:

So we are saying the same thing. I was saying the headers do not recharge, not that they do not exist

Right! I misread your message, sorry.

MotoPete wrote on 2021-06-27, 03:57:

It's a pity these links no longer work as I'm sure they were an interesting read.

I use a LIR2032 in a button cell holder soldered directly to the motherboard in place of the OEM unit. Saves all the mucking about. Never had an issue.

Strange. You can go to the main site and navigate to the articles, if the direct links are not working. Worth a read.