DURALITE - how can it be discharged?

[I3DM]

Hello guys.
i have a Duralite Li-Ion 4000 Mah pack that has been recognized by the factory as it has a faulty cell, and i should be getting a replacement.
either way, Jack from Duralite told me i can try to discharge \ recharge it to see if that takes care of the problem - but i dont have a Li-Ion specific discharger, and was wondering how i can discharge it.

i have a Robbe power peak ultimate charger that has 3 discharging modes - Nicd, Nimh and PB (flight box batteries), as far as i can think of discharging is mearly a resistor effect and i can probably discharge it in Nicd mode, as long as i keep the discharging current to a certain amount.

with this charger you have to specify a number of cells and it discharges each cell to 1.0V i belive, and this is a 7.2V pack, so i should probably set the charger for "Nicd" and 6 cells (7.2V) and have it discharged then...

if some of you know that this might be dangerous \ unsafe in any way, please advise what you know.

if you have another way to discharge the pack - i would gladly listen to that too. i know Li-Ion packs have their own charger (i use the original Duralite unit) but as far as i can think of, the discharging stays the same, after all - the discharge procedure in flight (through the Rx and servos) is the same with all kinds of packs...

thanks for your help.

[DavidH]

The Duralite Li-Ion cells do NOT need to be discharged below 2.75 volts per cell. The pack should NOT be discharged below 5.5 volts.

David

[I3DM]

David i know that thanks, but can i sue my discharger on Nicd or Nimh mode or could that be of any problem ?

i could just set the discharger for 6 cells, that will discharge it to a 6V total - above the 5.5V limit...

thanks.

PS - sent you PM.

[DavidH]

Most nicad and nimh dischargers discharge the battery to 1.1 volt per cell. I am only guessing that a nicad discharger set to a 6 volt would work. That should discharge it to 5.5 volts. I would keep a close eye on it.
The problem with the pack with the bad cell. Is that cell will not let the rest of the cells charge fully. When the packs are built the cells are matched to there fully charged voltage.

David

[I3DM]

So do you suggest just running it on Nicd mode but to make sure in the instructions whatever number of cells is needed for a 5.5V - 6V discharge ?
thanks !

[I3DM]

Oh and one more thing, at what current is it OK to discharge these Duralite Lithiums ?
thanks.

[I3DM]

Ok guys, the questionable pack was replaced by the factory - no problem.

but right now another Duralite (newer 4000 Mah pack) that i have been using for about 3 weeks, after about 3-4 hours charge, i come back and find the light on the charger going on and off every 30 seconds or so, like the faulty pack started to do. the voltage after the charge was 8.30V unloaded and 7.54V with a 1 amp load.

does anyone have any idea about this on\off light thing ???
thanks.

[Lee Taylor]

From the little bit that I know and have been told about Li-Ion cells, you don't need to discharge them. Li-Ion cells DO NOT develope a memory like Ni-Cd or Ni-Mh cells. And also, like like the man said up above, you want to keep the pack above 5.5V...because if they you don't, the cells basically fry themselves. Just wanted to help out...someone correct me if my info is inaccurate.