Potterton EP2002 controller back up battery

[billge]

Hi
Can anyone please help me with a question regarding the back up battery inside a Potterton EP 2002 controller which is 5 years old. The controller works fine but I lose all the settings whenever the mains electricity goes off. As we live in a country area this can happen 2 or 3 times a week sometimes. I get fed up having to reprogramme the controller with our own settings.
I assume that the back up battery inside the controller has died, The back up battery inside the controller is marked "Minamoto NiMH, MH-12 x 3. 3.6v, 18mAh".
It is a small round green coloured battery (it looks like 3 small round disc type batteries piled one on top of another) and it about 10mm in diameter and approx 10mm tall. It seems to be a fairly ordinary back up battery with 18mAh capacity ?? Is that correct ? However I cannot find a similar 3.6v battery of that capacity and size whereas I can find a Varta of 15mAh for £2.99. Is there any problem with using a new 15mAh battery instead of the original ?
If so, has anyone had experience of resoldering in a new battery ? Is it fairly straightforward please ?
Any input very gratefully received.
Many thanks.

 

[denso13]

The Varta one is advertised as a replacement so should be fine. Fitting is relatively straightforward, depending on your soldering skills

https://www.watchbattery.co.uk/shop/products/BRVR-3V150H2P.shtml

 

[billge]

Thanks very much for the reply Denso13. However I think that the particular Varta battery in your link fits into a different type of Potterton controller - although I suspect that the principles must be the same. I think that the battery in the link below is the correct shape etc but is 15mAh instead of 18 mAh.

http://www.ebay.co.uk/itm/VARTA-MEM...BACK-UP-BATTERY-2-PIN-X1-fd1c4-/401034746031?