I´m afraid replacing the battery alone will not do the trick. Some of the corroded traces / vias might be interrupted. After removing the old battery and carefully cleaning the whole area, you should check all the corroded traces for continuity.

I did, used ipa than a fiber pen and cleaned it with citrus juice. Looks not to bad. I also check the bottom side of the board but there is anything ok.
I will also check the traces with a multimeter, this was first aid.

But i read i cant replace a ni-cd with a ni-mh .

The question is can a use a Li-Ion Battery (LIR2032) for the ni-cd one. I read that is possible but im not totaly sure, anyone did before?

Jackhead wrote on 2022-07-11, 17:56:

But i read i cant replace a ni-cd with a ni-mh .

Hi! Was it a generic article about NiCad/NiMH, by any chance ?
If so, then yes, generally, that's right. You can't charge, for example, an AA NiMH rechargeable battery with an old NiCd charger.
The technology is so different. Old NiCd accus could be charged by comparably primitive charging circuits.
NiMH rechargeables began to need a real charger, so to say.
One that's semi-intelligent, at least.

However, coin cell batteries aren't as dangerous.
They won't explode or catch fire. They "plop" open, then a tiny amount of acid will come out. That's all.
If charging is no requirement, just add a small diode in series as a flow control, the RTC is modest. It will prevent charging.
Germanium or Schottky diode are ok, they have a voltage drop of 0,2v. Say, OA91 or 1N4148.
Normal silicon diodes have 0,7v that's too high.

Isn´t 1N4148 a standard Si-Diode?

majestyk wrote on 2022-07-11, 19:08:

Isn´t 1N4148 a standard Si-Diode?

Correct. My bad. I meant BAT48.. 🙂

Jo22 wrote on 2022-07-11, 19:03:

Hi! Was it a generic article about NiCad/NiMH, by any chance ?

Here it is Ni-cd to Li-Ion :

https://www.large.net/news/8hu43nj.html