help - gps / pda battery replacement

[jaky cakes]

Hiya folks - not surf related - but in urgent need of some advice from any electronic minded persons...
I have bought a high capacity (1800mAh) replacement battery for my pda (navman pin 300 mio168)
the battery arrived fully charged - but once flat - it will not hold a charge for maore than a few seconds.
DODGEY BATTERY YOU MAY WELL THINK.
So I bought another battery from a different seller (ebay) and still same problems. the pda goes through the motions of being charged - bar graph scrolling - amber to green led status, - but once unplugged from charger the unit dies with low battery warning.
both house and car charger do the same - yet work fine with original navman battery.
Is there anything i'm not seeing here?? any tests / checks?
I really needed this unit working before my hols next week - which is why i bought the battery afew weeks ago to test - but once again the whole world is set against me. everyone thinks I'm paranoid!!!!
cheers folks

[pirate-storm]

is the charger working properly? could be a loose wire somewhere.

[jaky cakes]

is the charger working properly? could be a loose wire somewhere.

Charger works fine with original battery - and shows to be charging when connected to navman.

[nero279]

won't help you i know, but i had a very similar thing with ebay replacement batteries for an O2 XDA exec. just doesn't like the replacement batteries at all.

[Antshiel]

Will a standard charger charge a hi power battery, have a look at the power ratings on the charger. If your trying to charge a battery of higher power than the charger can put out then some chargers go into shutdown so as not to destroy the battery.

[jaky cakes]

Will a standard charger charge a hi power battery, have a look at the power ratings on the charger. If your trying to charge a battery of higher power than the charger can put out then some chargers go into shutdown so as not to destroy the battery.

I think the battery is the same power output - just a larger capacity to last longer - 1800mAh as opposed to 1300 mAh standard.