I have a question about rechargable Ni-MH batteries.?

If I use the battery for the first time in my digital camera, without charging it up first is is true that I wil never be able to completely charge it up? Please let me know. Thanks.

The camera I bought lasted about 20 minutes initially before running out of power. Then I placed it in the recharger for 12 hours (which I was told by the seller was the amount of time needed). The unit lasted about 20 minutes again. Did I do it wrong?

it depends on the number of snaps you take and not on the time in digital cameras.
For normal digital cameras minimum required current rating is more than 1500 mah(AA size cells).
If it uses a differnet cell, than the manufacturer would have special designing only the same specification will suit which is approx 3.3-7.0 v and 1000-1800 mah.

But usually any camera normally should work for atleast 50- 80 snaps with or without flash.because the flash consumes most current in digital cameras atleast with flash it should work minimum 30 flashes.

you go through the camera manual for further clarifications.

as far as charging batteries minimum it should be charged 8- 16 hrs for full charging initially.

Never tried it before, but I suggest you dont try it, just incase it is true, who knows?

No, it's not true. Unlike NiCad batteries, NiMH batteries are very forgiving. Just be careful NOT to over-charge it. Hopefully the charger you are using will sence the "full" condition and automatically shutoff to prevent over-charging.

After few charge/discharge cycles, it should charge to full capacity.