unique battery issues - one works other don't

[gotonenow]

Hi, I have a blackberry pearl 8120.. from ebay china lol..

Well here it is, I am in areas with low signal and I have one battery that works fine, it will connect to edge.. but barely lasts a day so trying to get a second.

I have ordered a bunch of different batteries off ebay for it.

I have two different replacement batteries that will start the phone fine, it will find the gsm network barely but not the edge networks.. its weird..

So my question is why would one battery seem to work fine, but another work but not have enough energy for a good signal ? Is this something someone has seen before I can't find any information about it...

I am kind of wondering if the battery that came with it, probably a fake from china as the other thing were bull (reall bb though) could have a higher voltage or something and really it is working better to find the signal than orignal blackberry batteries ? is this possible.

Or do bad ebay batteries sometimes just make the phone not as strong a signal..

confused in Canada

Thanks and merrry xmas everyone !