Imitation canon batteries

[quocvuong154]

Hi all,
Im in the process of making a custom 12,000mah battery pack for the 50d since my 50d came with imitation canon batteries which last for about 3 min of recording before dying.  I was wondering those that have original 50d batteries, how much recording time do you get more or less on a full charge in raw non crop.
Thanks

[BuckSkin]

I have found aftermarket batteries to outperform the originals; the quick discharge you are experiencing is common for batteries that are at the end of their life.
Also, Lithium batteries don't hold up well to long dis-use; leave them in the drawer for too long and they won't take a full charge or many times any charge at all.

Most camera batteries are 7.4 volts; two 3.7 volt 18650 Lithium cells in series equal 7.4 volts (or two pairs or triples or so forth)
I, myself, have thought of building an exterior battery pack; the problem with that being, many of the imported 18650 cells are claimed to have ridiculous MAh ratings when usually 400- to 500-MAh is about tops for most of them.
To get genuine 3.7 volt lithium 18650 cells with decent MAh ratings can push the price upwards of $40 per pair, which makes such a project get quite expensive in a hurry.