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Identifying a lithium battery

Rubia30

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

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  • 0

    There are three wires and one does go to the PCB at the rear of the unit as what seems to be thermal protection. Unfortunately I have no documentation regarding the batteries so do not know what the capacity is. I will be replacing all three of the batteries at the same time. From what I can see online most of these are 3.7v not 3.8v. As far as I can determine the numbers do not match the dimensions in any way. They obviously mean something to the mystery manufacturer. 

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  • 0

    There are three wires and one does go to the PCB at the rear of the unit as what seems to be thermal protection. Unfortunately I have no documentation regarding the batteries so do not know what the capacity is. I will be replacing all three of the batteries at the same time. From what I can see online most of these are 3.7v not 3.8v. As far as I can determine the numbers do not match the dimensions in any way. They obviously mean something to the mystery manufacturer. 

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  • 0 in reply to Rubia30

    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

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