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Old Oct 23, 2006, 12:37 PM
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Same capacity from all 4 packs (I purchased 4 of them, initially charged at 0.2 amps). It took a while. And I was doing as much capacity testing that I could without coming anywhere close to dropping below 3.0 volts per cell under load. And as I mentioned above, one cell did have a resting voltage of just under 3.6 volts. Somewhat of a necessity when I started hearing bellyaching about 'do a full discharge, we don't like partial voltage discharges, all cells are different, wahhh!'. Oh, and MAX drain was 10.6 amps (well under the 15 amps the cells are rated for continuous). Temperature for that 9-10 amp continuous case was well within 'hold it in your hand for as long as you want'.

After my initial rants about these batteries being too heavy, I thought I'd check them out to see if they were worth it. TrueRC had already offered a refund, but I'd been rating for these packs, and curiosity got the better of me.
Net result, they're heavier than expected, don't have the capacity as expected, BUT, hold voltage very well under load. I have a slowstick AP plane that could REALLY use a battery that keeps it's voltage when I kick the throttle because the wind shifted direction. These batteries may fit that bill. It's the odd case where the TP prolites (which also hold voltage under load very well) aren't heavy enough to maintain my CG where I want it. [go figure]. And the desire to occasionally kick the throttle with my foamie pusher jets to make then stand on their prop.

So, these cells won't do what they were originally planned for, BUT, they did solidify my desire to get cells that keep voltage under load. [my 8C Common Sense batteries and 'old style' maxamps batteries have served me well, but time to move on, oh, and to get out the wallet].
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Old Oct 23, 2006, 01:18 PM
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The ICE charger does –NOT- give an accurate indication of capacity added.
My ICE does give very accurate discharge information, but charging is a different story.
The capacity added is wrong, and in addition to that, the ICE counter stops adding at 100ma even though the charger continues to a lower cutoff point.

Charge the lipo at 0.5C and discharge it at 1C, then you’ll know for sure.
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Old Oct 23, 2006, 02:15 PM
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Quote:
Originally Posted by IA-Flyer
The ICE charger does –NOT- give an accurate indication of capacity added.
My ICE does give very accurate discharge information, but charging is a different story.
The capacity added is wrong, and in addition to that, the ICE counter stops adding at 100ma even though the charger continues to a lower cutoff point.

Charge the lipo at 0.5C and discharge it at 1C, then you’ll know for sure.

That's a new twist, I'll Try again using 0.5C and discharge at 1C. One concern I have for dicharging at such a low amperage is the low voltage cut off for the ice charger. I can't set the low voltage charge 'high enough' to ensure that it will stop such that the open circuit voltage isn't below 3.6 volts. So I'll have to guess the cut off time with a discharge current that low.

Be forewarned, though, some of the packs I charged were 'filled up' at 0.6 amps after the initial 200 mah was added at 0.2 amps. I wanted to make certain that in case I was close to the 'overdrained' part of the pack, I wouldn't shock the battery.

I don't believe you're going to find an additional 200 mah by charging the whole thing at 0.75 amps. I'll do it anyway, but I don't believe it'll be there.
It really doesn't matter, because I've measured the output current using a watt meter. And we're all really concerned with what is possible to get OUT of the pack, not what goes into it.
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Old Oct 23, 2006, 11:18 PM
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It’s been forever since I’ve done this stuff. Guess if I was having any battery problems I’d still be here.

If you do a 1C discharge, using a 3.6v per cell cutoff (the ICE allows 2.5v-3.7v per cell). Depending on the temperature (72F) and strength (10-15C) of the pack, you’ll discharge about 85-90% of the (manufacturer rated) total capacity.
The resting voltage of the pack, 5-minutes after the 1C 3.6v discharge will be about 3.7v per cell.
I avoid discharging my cells below 3.7v in a normal flight, so this test gives me the “usable flight capacity” I’m interested in.

PS. Be sure to scroll down and make a note of the “IR” after you do the discharge. It’s a good indicator of pack strength, and it will change as the pack ages.

Jim
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Old Oct 24, 2006, 12:33 AM
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Many charge through balancers will cut a discharge when one cell gets down to 3.0V, giving you the possibility to do a max discharge without risking any cells. The bad thing is that they draw current from the balancing tap during the discharge and this might affect your results.

Fred
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Old Oct 24, 2006, 05:57 AM
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Already done. .163 mohms. I was using it to make estimates to what voltage I could discharge the pack underload to make certain it's open circuit voltage would be > 3.6 volts.


Quote:
Originally Posted by IA-Flyer
It’s been forever since I’ve done this stuff. Guess if I was having any battery problems I’d still be here.

If you do a 1C discharge, using a 3.6v per cell cutoff (the ICE allows 2.5v-3.7v per cell). Depending on the temperature (72F) and strength (10-15C) of the pack, you’ll discharge about 85-90% of the (manufacturer rated) total capacity.
The resting voltage of the pack, 5-minutes after the 1C 3.6v discharge will be about 3.7v per cell.
I avoid discharging my cells below 3.7v in a normal flight, so this test gives me the “usable flight capacity” I’m interested in.

PS. Be sure to scroll down and make a note of the “IR” after you do the discharge. It’s a good indicator of pack strength, and it will change as the pack ages.

Jim
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Old Oct 24, 2006, 01:27 PM
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Quote:
Originally Posted by Nethole
Already done. .163 mohms. I was using it to make estimates to what voltage I could discharge the pack underload to make certain it's open circuit voltage would be > 3.6 volts.
If that was a 1C discharge at 72F.
Not as strong as a 1320 PL, but stronger than a 1320 G2 (after 19, 20+ minute flights).
1320 G2 = 272
1320 PL = 118

PS, you may need to reduce your cutoff voltage to 3.5vps to discharge 85-90% @ 1C.
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Last edited by IA-Flyer; Oct 24, 2006 at 01:32 PM.
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