rarely used htc spare battery full charge yet phone dies

[kC_]

Hi, Ive had a spare battery for my n1 which i keep in my coat pocket in case I need it and not near anything I can charge the phone with.
Its an original htc battery and probably not used in 6 months or so, and now ive come to use it, the phone randomly switches off, even though the battery is reporting plenty of charge left in it.

maybe a few full discharge/charge cycles will fix it, but if i lllllleave it alone (even idle with screen off) ill sometimes try to wake it, and it wiill be powered off.
and kind of annoying as its my primary phone so ideally dont want to miss calls etc.
is there any way I can discharge it other than being in the phone? maybe wire up a small bulb or something to its contacts, has anyone seen any guides on how to do it? or do you think the battery is just nailed (due to zero use)

cheers

 

[scaots]

When you start back up is the battery drained (even 30% or so as old batteries can be odd) or was it just off with a good charge still? If so try cleaning the contacts with some steel wool or something. They might just be dirty.

I got a generic new battery that isn't much better than my old one but the old one is about done for at 20%, while the new one drains fast from about 70-33 then last third lasts forever. Old batteries can have a pretty flakey power curve probably depending on use.

 

[kC_]

Hi, thanks. When I switch the phone back on again the battery is near enough full power.
Ive left it charge for a few hours.. and the contacts look clean (have cleaned them with switch cleaner)