"Piers Finlayson" wrote in message
.. .
I cracked open an el cheapo cordless power tool set at the weekend. I put
an uncharged battery into the charger an after a few seconds the charger
indicated charging was complete. The battery was still uncharged. I then
tried with the other battery and got the same problem.

Assuming the batteries are also near freezing, they will appear to charge
but depending on type need need to be at least 5-10 deg C.