Have a look through this short checklist:
1) Your phone originally came fitted with a NiCd (Nicad) or Nokia BMC-3 NiMH (Nickel-Metal-Hydride) battery (like the one being offered / reviewed here).
2) The original battery wore out (maybe more than once) and you eventually bought a Nokia BLC-2 Li-Ion battery to replace it.
3) The BLC-2 doesn't seem to charge properly - it only charges for about an hour at the most before shutting off, and if you are lucky, it may last 2 days in standby before you have to recharge it.
Does this all sound familiar to you?
Although the new Li-Ion batteries are an exact physical fit for the phone, some phones are so old that they don't know how to charge a Li-Ion battery, hence the poor performance even with a brand new, genuine, original Nokia BLC-2.
This battery, the older NiMH (Nickel Metal Hydride) version, is the CORRECT version for your phone. Since buying this and running it through a few charge/discharge cycles I'm now getting around 5-6 days and nights of standby from my Nokia 3330 again, the same performance it had when it was new in 2001.
My battery (A genuine BMC-3) was originally supplied to me by Fonem8, but the supplier Amazon directs you to for this item will have changed many times over since this review was written. If you have the problems described above when using a BLC-2 Li-Ion battery in your old phone, be sure to check that the battery you are buying from the current supplier is a NiMH (Nickel-Metal-Hydride) BMC-3 as advertised, and NOT a BLC-2 Li-Ion 'Equivalent'.