I'm trying to identify these batteries within an alarm unit that I need to replace since they are no longer holding a charge.
I've had a look online and cannot find anything with the same numbers as shown on the side.
Does anyone know if these are a standard type of flat battery i.e. in the same as AA, D have designations that I just don't know the name for regardless of the serial numbers etc. on the side? They measure roughly 38mm*38mm*5mm.
Thanks
Random nos could just be a factory line no and date code. The 3 wire thing may be your hardest part - you will need to know what is in the battery end to keep the bit on the PCB happy. The simplest are a temperature dependent resistance to the negative terminal, but some are more complex.
Can you get clearer photos of the wiring and where it goes. It looks like 2 cells strapped in parallel,
If so you can probably replace with a similar capacity, in a single cell of that is easier to get hold of. From the size you give I'd expect 500 - 800 mA Hrs per cell. so 1 to 1.6AH for the pair.
Also they do look like unprotected cells Far more common is like this example below - where under the tape on a thin PCB is the low volt lock-off and charge limiting circuits, that prevent the cell being deep discharged or over charged (much below 2.5 V per cell internal shorts develop, and attempts to recharge can occasionally be explosive, and much above 4.2 per cell there is a risk of out-gassing - bad in a sealed cell ! ) There is also normally a fuse or the equivaent is performed in electronics. I assume these protective functions are elsewhere in the unit in your case.
Assuming it takes some charge you can confirm the end of charge voltage with a meter by charging it open as you have it and putting a meter on the terminals. You may wish to tape/protect other parts while you do this.
Knowing the full and empty charge voltages helps identify the chemistry the charger is expecting - quite often the rated voltage of the cell relates so some odd average state between charged and flat and is the one voltage it never is.
Mike.
40*40*50
Random nos could just be a factory line no and date code. The 3 wire thing may be your hardest part - you will need to know what is in the battery end to keep the bit on the PCB happy. The simplest are a temperature dependent resistance to the negative terminal, but some are more complex.
Can you get clearer photos of the wiring and where it goes. It looks like 2 cells strapped in parallel,
If so you can probably replace with a similar capacity, in a single cell of that is easier to get hold of. From the size you give I'd expect 500 - 800 mA Hrs per cell. so 1 to 1.6AH for the pair.
Also they do look like unprotected cells Far more common is like this example below - where under the tape on a thin PCB is the low volt lock-off and charge limiting circuits, that prevent the cell being deep discharged or over charged (much below 2.5 V per cell internal shorts develop, and attempts to recharge can occasionally be explosive, and much above 4.2 per cell there is a risk of out-gassing - bad in a sealed cell ! ) There is also normally a fuse or the equivaent is performed in electronics. I assume these protective functions are elsewhere in the unit in your case.
Assuming it takes some charge you can confirm the end of charge voltage with a meter by charging it open as you have it and putting a meter on the terminals. You may wish to tape/protect other parts while you do this.
Knowing the full and empty charge voltages helps identify the chemistry the charger is expecting - quite often the rated voltage of the cell relates so some odd average state between charged and flat and is the one voltage it never is.
Mike.
40*40*50
