Laptop battery takes days to charge

[Roland Perry]

In message <Edp* [e-mail]>, at 19:21:34 on Thu,

18 Jan 2024, Theo <theom+ [e-mail]> remarked:

If it has such a battery, but I don't recall seeing one for decades.

My latest laptop is a bit posh, and has hot-swappable main batteries, plus a tiny built-in rechargeable battery to keep it going while you do the swap (and also to keep the machine's setup when it's gone to sleep).

Desktops tended to go for an RTC/set-up-RAM powered by an embedded 10yr battery, rather than exchangeable coin-cells. Which is great until the desktop is more than 10yrs old, but they didn't really care.

[Theo]

They are common, eg:

Some of them have a rechargeable NiMH cell on a wire plugged into the board: which the laptop theoretically trickle charges. That can go flat, and it can be worth a try to charge it outside the laptop and re-connect it:

I'd guess there must be a separate settings battery, since those batteries that run the system would be easy to run flat?

I've not seen them with a primary 10yr cell, are you sure they aren't NiMH cells like the laptops?

There were some RTCs with a lithium primary cell integrated into the chip module (eg Dallas Semiconductor, latterly Maxim), but those were in the

286/386/486 era.

Theo

[Roland Perry]

In message <+eA* [e-mail]>, at 21:47:54 on Thu,

18 Jan 2024, Theo <theom+ [e-mail]> remarked:

That's a scrap motherboard from an extremely low-end laptop. Apologies for not having seen one myself.

The battery settings are for the hot-swappable ones. The built-in battery powers it for about two minutes (full functionality, screen on etc) according to the test I did just now, which is vastly in excess of the time it takes to change the swappable one.

Reasonably so, yes.

And your theory is they reverted to a combination of unpowered RTC and button cell?

[Pamela]

Is the OP's battery NiMH or lithium-ion?

[Theo]

The battery that's not charging is lithium ion, but a reason for it not charging can be flatness of a small settings battery, which can be either primary lithium (CR2032 usually) or NiMH rechargeable.

Theo