John Schmitt wrote:

The other day, without warning, the battery in my mobile died. It still
appeared to have about 80% charge in it at lunchtime, in the afternoon
when I next looked at it, it wouldn't even switch on. I had left it on,
I normally do because I get a good week's use on one charge. A couple
of people I have talked to say that this has happened to them. I only
have had a couple of this type of battery, so my sample size is too
small to be meaningful. There must be some of you out there who have
much larger experience of NiMH. How often does this sort of total
failure occur relative to gradual?

John Schmitt

Its all too familar.

Lithium ions are better at that sort of thing - they tend to die more
gradually.

NiMh has pretty horrible self discahrge anyway, and it ends its life by
discharging itself in a day rather than the usual 6 weeks ...

Strongly advise updating to lithium, - check tghe net - loads of
aftermarket lithium batteries from specialist companies.