[NJT]

Mine gives a low batt warning if I leave in my dive bag in the cold. Once it warms up it is OK.

BTW I am getting battery kit, WITH 'O' RING, before the weekend.

Dead easy to change.
Take the strap off.
Rotate the cover on the battery compartment .
Check it is all clean and dry in the battery compartment
Replace the battery, right way up.
Replace the o ring, regardless of what state it is in.
Close cover and lock
Replace strap
Take it for a pootle dive
If it floods all is not lost.
The battery compartment is separate from the main computer.

Regards
Nick