A123 cells in series Balance?

[noelex]

Is it safe to charge a 2 or 3 cell pack of a123 cells in series (thinking of a pack with the smaller 1100mHr) without balancing during charging?
Is it safe but likely to shorten the life of the pack considerably?
I understand this is not safe for Li-ion (although most SLR camera batteries are a 2 cell LI-ion and the simple camera charges don't balance. How is this safe?)
Thanks John

 

[bretti_kivi]

how do you know there's no balancer PCB tucked into the DSLR pack?

What does the source of the pack have to say about charging it?

Bret

 

[noelex]

Thanks for your reply Bret, but I think you may be confusing a protection PCB with balanced charging.
To answer your question the DSLR batteries, that I have seen, don't used balanced charging because the number of connection pins are too low.
Balanced charging involves reading the voltage of each cell in a pack and charging them so the voltages are identical.

 

[bretti_kivi]

yep, there are only two pins on my pentax packs. However, that doesn't mean that there's no internal regulation, but if there's only two cells, why complicate with extra pins? There could easily be voltage comparison on a board, even if it's not complete balancing.

The A123 sources I've seen claim that balancing is not necessary. They are, however, for the RC community.

Bret

 

[ICUDoc]

I balance my A123s when I recharge them fast (3 amps plus) but they rarely get out of balance if I just whack them on the "dumb" charger. Many other RC users have also stopped using the balance taps, so I would consider it safe if you are going low-flow. Are they definitely A123s or just LiFe from another source? I really trust the A123 brand-they seem VERY tough.

 

[mdocod]

to ensure a complete charge in a multi-cell series charged A123 pack, just plan on charging to a total of 3.8V per cell for the pack, this should pretty well and balance them all close enough, wouldn't hurt to have balance taps on hand so you can check the condition of each cell on occasion for diagnostic purposes, but there doesn't seem to be a really strong case for balancing the LiFePO4 chemistry, as it's less "voltage sensitive" compared with LiMn, LiCo and LiPo.

Eric