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Short flight times with Li-Poly battery

613 Views 6 Replies 6 Participants Last post by  basmntdweller
Just curious if anyone had a suggestion for my problem? I have a 1200mah Great Planes Li-Po battery and only get maybe a six minute flight out of the battery. It's on a foamy with a Himax 2015-4100 with 6.6 to 1 gear. The plane is on a Apc 11x7 prop and weighs 13.8 oz. RTF.
After 6 minutes of flying it barely has enough power to hover. I recharge the batery and it only takes 600mah to be fully recharged after flight. I have cycled the battery on my new Hobbico Accu-Cycle Elite battery and it takes 1096mah to recharge from discharging down to 3 volt per cell. Also have a Phoenix 25amp speed control with soft start and shut down set at 7.2 volts. Why is my flight time so limited, or is this just normal.
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sounds like your just pulling a lot of amps for that pack particular pack. I'm not sure what the GP lipos are good for. You could try switching to an 11x7 GWS HD or APC TE prop if you are using a SF prop now, or just drop down a prop size all together.
Or even a GWS 11X4.7 or 12X6. Those APC SF props are amp hogs.
I don't know who makes those cells but there are several different 1200 packs available. The undesirable ones are only rated about 5C. If that is what you have, then pushing it as hard as your setup does, it will not perform well at all.
I'm not positive, but I think your 7.2V cutoff might have damaged your battery pack. For a 3 cell Lipo pack, it's my understanding that you should use the cutoff formula of 3V/cell x # of cells, or 9V for a 3 cell pack. Someone please correct me if that's wrong.

Do yourself a favor and get one of the E-Tec 1200HP packs from B-P-P or one of the other battery suppliers. We've had great luck with them. I'm averaging 25-30 minutes flying time on my Yak which is configured almost like your plane.

ProBro #222
I think you might be right.

I have 6v set for my 2 cell packs....but according to the speed control instructions, 5v is what they recommend for a 2cell LiPoly. So their 2.5 would be worst case scenario (7.5v) I rarely go below 7 though because it doesn't seem to be much fun anyways.

I heard that once they are damaged though...they won't take a charge at all.
The 7.2 setting for a three cell pack allows for voltage drop under load as does the 5 volt setting for two cell packs. As soon as the load is removed the voltage is back over the 3V per cell minimum. I have had a three cell pack of the old Kokam 1020s (3C max) drop to under 4 volts and it came back, after putting it on a standard futaba wall wart on the tx side. I monitored the voltage till it rose up to about 11 volts then put it on my Lipo charger. I continued to use the pack for the rest of that indoor season. I only quit using the pack because I trashed my IFO mk3.
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