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View Full Version : more discharger info...


builthatch
2006.12.04, 09:17 PM
So i spent some time talking to whomever is the battery guru over at ****** and he was telling me that nimh like to be discharged down to 0 volts, kept there for a few minutes, then removed and pop back to 1.2 volts nominal voltage. It's at this point that they are best for storage or recharge. He said this is the proper way to equalize and cycle the cells. He did not have much if any experience with the smaller intellects like the ones we use, however he said this is typically what is good for nimh.

I see PN's discharger, which didn't work to well for me, has a 'cutoff' of .7. the trinity tray i use cuts off at .9 for sub c.

what knowledge do you all have about this? ****** said the real info about this stuff, many times, is withheld by those who really know as they do not want to share their secrets. He said a limited amount of people really know what the batteries like, hence so much internet fodder about batteries by those on forums and the like....

what do you guys think? I have returned my PN piece i bought last week and ordered and INDI booster 3 in it's place...

machine
2006.12.07, 03:16 PM
interesting.

I look at my AAA batteries as a comsumable item. I charge them at 1amp, and discharge them on my PN discharge after every race. Before the start of a new season i toss out the old batteries and buy new ones. After all they are only AAA. Where as my Sub C matched packs i treat them quite a bit differently.

builthatch
2006.12.07, 05:31 PM
So i spent some time talking to whomever is the battery guru over at ****** and he was telling me that nimh like to be discharged down to 0 volts, kept there for a few minutes, then removed and pop back to 1.2 volts nominal voltage. It's at this point that they are best for storage or recharge. He said this is the proper way to equalize and cycle the cells. He did not have much if any experience with the smaller intellects like the ones we use, however he said this is typically what is good for nimh.

I see PN's discharger, which didn't work to well for me, has a 'cutoff' of .7. the trinity tray i use cuts off at .9 for sub c.

what knowledge do you all have about this? ****** said the real info about this stuff, many times, is withheld by those who really know as they do not want to share their secrets. He said a limited amount of people really know what the batteries like, hence so much internet fodder about batteries by those on forums and the like....

what do you guys think? I have returned my PN piece i bought last week and ordered and INDI booster 3 in it's place...

1ntegy is what the asterisks are all about.

i got my booster 3 today so we will see how she does!

ph2t
2006.12.11, 07:04 PM
From batteryuniversity, a great source on batts.

http://www.batteryuniversity.com/partone-16.htm

a small quote:

Depth of discharge

The typical end-of-discharge voltage for nickel-based batteries is 1V/cell. At that voltage level, roughly 99% of the energy is spent and the voltage starts to drop rapidly if the discharge continued. Discharging beyond the cut-off voltage must be avoided, especially under heavy load.

Since the cells in a battery pack cannot be perfectly matched, a negative voltage potential, also known as cell reversal, will occur across a weaker cell if the discharge is allowed to continue uncontrolled. The more cells that are connected in series, the greater the likelihood of cell reversal occurring.


I discharge on my ICE charge to 0.8v - 0.9V a cell depending on the discharge rate. (usually around 1 - 1.5A ).

I've found doing many cycles (5 - 10) at the following rates are good for my batts. (pn racing 800mAh and duracell 850mAh AAA's).

Charge = 0.7A
dv/dt = 8mV/cell

Discharge = (1.5A)
v/cell = 0.9V

cycle = 10 times
cycle pause = 2 mins

With this I set it and let it go. The ICE charger shows me the values of each cycle at the end. It always shows that after each cycle I progressively get more current into the batts.

First cycle (the dirty one, lol) I'll get about 650 - 700mA
By the last cycle I'm near peak of (approx) 790mA

So I can see the results for myself and I can see that 0.9V per cell discharge works just fine.

ph2t.