Connecting Multiple LiPo Batteries Together

[OVNI]

Hi,
Can someone explain why it is not recommended to hook up 2 or more Lithium Polymer batteries in series (or parallel) when each have protection circuitry, i.e. PCB/PCM, already built in? The explanations I read are that one battery could charge another but why would that be undesirable if protection is present?

Or in other words, why is protection for the battery as a pack a must?

Thanks.

 

[Isaac Clarke]

different capacity due to different brand, age, varies protection circuit.... Protection circuit only prevent battery from discharge below certain threshold...( won't protect from reverse charge ( where the battery with higher mah dump energy into a depleted cell.),reverse voltage,short circuit,....

lithium ions- have + ions(possitive (Li+) charge due to lack of electrons means it want electrons.) in the cathode while in the anode there áre - ions (Li-) which means the lithium there have too many electron and want to get it of it... during use excess electron from - go to + and the process reverse during recharges.... no protection circuit.. All the electrons will move to + and turns to elemental Lithium(Li2) no charge = no volt= dead battery... correct me if i'm wrong lolz.

 

[Cyparagon]

If they're the same capacity and you balance charge them (or charge in parallel), I don't see any reason you can't have lithium in series.