Battery voltage ?

That's two 1.2V NiMH cells, probably AAA size 650mAh going by the markings.

Theo

Thanks for confirming.

Each of those cells will be a standard 1.2v because that is what NiMh technology produces.

Nick

Yup, what they said: AAA tagged NiMh cells - 1.2V 650mAh

ss brought next idea :

Those are two NiMH 650mA either AA or AAA. To be sure of the size, compare to an ordinary AA or AAA. You can buy much higher capacity versions now, but buy from a reputable seller because many have a faked capacity. You need a type fitted with solder tags, but there is a work around if you are used to soldering.

You cannot solder to batteries with electronic type mulit-core solder. You can manage to solder to them using a dab of plumbers flux, which is much more aggressive. Soldering to batteries has to be done in as short a time as possible, to avoid damage.

No, but they clearly say NiMh

So they are tagged AA NiMh cells

I will go for the tagged batteries, be a safer bet for me.

They are a lot easier.

You can solder chrome plated end plates if you rough the chrome up, And you don't need special flux, but you need a helluva hot iron.

Back in the day you could get massive 'hammerhead' bits and a little channel into which you popped your cells, and with the bit between two cells melt the solder on each one, remove the bit and sling them together to solder them end to end.

The Natural Philosopher explained on 02/06/2020 :

I had to find some way to connect to an untagged Li-ion AA last week. In anticipation, I tried to make a small spot welder, using a car battery, heavy cable, connector and 2.5mm, relay and push-button. It failed miserably, the relay's contact resistance was too high. I ended up using my plumber's flux soldering trick. I managed well enough with my old 20w iron - the trick to avoid damaging the cells, is speed.

Really? News to me. ;-)

When I replace the dead ones I will give the flux soldering a go on the dead ones, and see what happens.

You need a reasonably large bit and a hot iron. Obviously clean things first. Then ordinary leaded multicore will work just fine. You need to do it as quickly as possible.

Yep, the end of a battery is a big thermal sink you need a lot of heat from somewhere to get it hot enough for the solder to take. A tiddly littel bit designed for fine PCB work isn't going to have enough heat in it to heat the end of a battery suffciently or quickly.

I`ll give it a go I have some leaded multi core and some flux, be a bit of practice for the future. Nothing to lose as will be binning the old ones.