Is a Li-Ion battery dead when it displays 0V?

I saw a link on how to repair your laptop battery on engadget and I saw as the guys checked the voltages of the batteries, they displayed 0V. I think i remember reading somewhere here that when it displays this that the battery actually isn't dead and needs like a jump start or something. And something similiar but not the same, where would I be able to find used lithium ion batteries? I know they're in laptop batteries but what else are they also in so that I can pry them out and use them?

if it is just the CELL, then it is likly that it is dead.
BUT
if it is a "protected" cell with a protection curcuit, then it can read 0V untill it is recharged (your jump start).

if your repairing a laptop battery, you will likley have to replace ALL the batteries in the pack, as replacing any single one with a "new" cell will result in a lack of balance, and further loss of cells till they are all replaced anyways.

if your trying to repair a PACK, you would not want used cells unless you get the used cells all from the same pack thing, and they are all of the same relative age, and use.
"surplus" electronics stores sell tons of batteries in packs that the pack was not designed right, or the product never made it.

Oh I was just asking about the laptop thing, my current laptop battery is fine but I have other friends whose laptops are not in the best shape. I also wonder if it is possible to upgrade my current pack as its only a 6 cell battery and wonder if I can upgrade it to like a 9 cell one by just adding 3 more cells. I asked about the used cells because I was wondering if there was a source for really cheap or free lithium-ion batteries for like flashlights or something. I currently only use NiMh AA batteries and have some AAA but if I could get my hands on some free Li-ions why not.

you could potentially "improve" a Li-Ion 6 cell pack by parelleling 6 more cells properly to the 6 cells that are in there. but you would never add a few cells to a series set.

there are tons of discarded PACKS that have within them perfectally good batteries, you can scrounge them out of all kinds of stuff. you still would want to learn a LOT, or put protection curcuits on them to use them.

Johnny, be careful with what you are thinking of doing. First, in many laptop batteries, they have a circuit board that is specific to the number of cells, and the configuration they are in. So you need to take into account the voltage being put out by your pack, make sure it doesn't have a protection circuit trying to manage the 6 cells, etc.

Also make sure you learn about the fire/explosion risks of using Lithium batteries and how to charge them if you don't already know.

For example, this battery pack has 3 parallel sets of 4 Li-Ion's in series.

LuxLuthor said:

Johnny, be careful with what you are thinking of doing. First, in many laptop batteries, they have a circuit board that is specific to the number of cells, and the configuration they are in. So you need to take into account the voltage being put out by your pack, make sure it doesn't have a protection circuit trying to manage the 6 cells, etc.

Also make sure you learn about the fire/explosion risks of using Lithium batteries and how to charge them if you don't already know.

For example, this battery pack has 3 parallel sets of 4 Li-Ion's in series.

Click to expand...

I am only thinking about it ... lol. I have read that you can even make them explode if you take too long to solder the batteries on. From all these stories, I am actually afraid to mess with my current battery pack for my laptop. However, I was planning on looking for some cells inside whatever I can find and buying a proper charger for it. Does anyone have some advice on some types of battery packs that would contain cells that people throw out or don't know about? Thanks. This flashlight thing just hit me like a month ago and have been crazy about them. But I don't want to be throwing too much money into this as this is more of a hobby and I need every last bit of my money for college right now. I've only bought a few cheap cheap chinese LED flashlights and are actually impressed by their output. LOL. I am waiting for my first Cree light from DX for $10.