A123 Lithium cell use

[leorcc]

A123 Lithium cell use

You could always balance first with a new pack before you start charging. Ive found that once the packs have charged and discharged a couple of times the pack keeps pretty level all the way through. Then I can charge and balance on 8A at once.

Apart from that, is it a decent charger for A123 John? How much A can it supply on a 10 cell pack?

[terrorhurtz]

A123 Lithium cell use

Note that you shouldnt try to balance a half-charged pack. That may actually make the balance at peak worse. On a new pack it shouldnt be a problem, but even then its a waste of time - its only the balance at peak we are interested in and tiny differences at half charge can turn into large differences at peak.

Leaving it charging at 0.5 amp will be much more successful.

Yes, it is a very nice charger, they have clearly put a lot of work into it. The only nice-to-have on it would be the ablity to set the cut-off voltage (fixed at 3.7 per cell for LiFe).

The problem with using average voltage is common to a lot of the chargers I suspect. One that might do it better is the FMA CellPro 10s, because it was designed as an all-in-one solution. But the CellPro only has a small text screen and I think being able to graphically see the balance is much more important.

[m2xt]

A123 Lithium cell use

John, What is your view on balancing by discharging each individual cell in a pack to a common target voltage?

[terrorhurtz]

A123 Lithium cell use

That might be OK, as long as the target is above 3.55 Volts i.e. the cells are over 90% charged.

It would still take a while, a) because of the voltage drop acrioss the cell at any significant currents, but mainly because b) the cell voltage seems to exhibit a considerable amount of hysteresis, particularly at higher currents. In other words, after a change in state-of-charge, it takes a while for the cell voltage to settle to its true value.

[leorcc]

A123 Lithium cell use

Well RMP does not supply balancing leads with their A123 packs.

From the Australian forum:
quote:

Got some premade A123 packs from RMP, a bit disappointed with them . Ill have to pull the heatshrink off them to balance them as their are no balance connectors