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Old May 31, 2005, 02:25 PM
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El Cajon, CA, USA
Joined Feb 2001
793 Posts
Question...lipolys and the bottom line.

Ok. I've flown and read a fair amount about Lipolys for the past 2 years. I've looked at graphs and think I've got a handle on things but I am curious.

If I follow the steps below is it safe to assume I am not "hard" on my Lipoly's?

1. Put your motor/batt on a whatt meter and ensure you arn't exceeding the rated amp draw for the pack.

2. Set your speed controller to cut off at 3.3 volts/cell.

Is it that simple or am I missing something?

Thanks

Daniel
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Old May 31, 2005, 02:28 PM
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vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,687 Posts
I'd say 3v per cell is OK, and run at 75% of manufacturers continuous as your 'peak' rating..
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Old May 31, 2005, 02:38 PM
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orlando fl
Joined Oct 2000
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have good cooling for them. like vintage says avoid the max peak recommended, and continous operation is hard even then. I like to avg a 10 min flight and put back about 75% of the rated capacity during the recharge. Thats around 4.5C. This will provide a decent life cycle and avoid a lot of problems. The AVG is important. I like the newer cells as they can withstand higher discharges, like 10-12c, but I only do this is very short burst, again I look for an AVG discharge rate of 4.5 (75% cap/10min flight).
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Old May 31, 2005, 02:40 PM
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Ontario, Canada
Joined Nov 2002
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Yup, 3.0V per cell is a good starting point, albeit a hair on the conservative side.

I have found that 2.8V-2.9V allows you to overcome the initial sag you get until the Li-Po self-heats a little, and the voltage recovers. (only really relevant for EDF's and other high-load 'planes which need 100% power for the first 30s of flight)

Keep in mind that 2.7V is a universally accepted cut-off voltage published by Panasonic, Sony, etc.

Also, if you fly at say, 5C or higher, you will have substantial reserve capacity at lower power settings as the Li-Po voltage is proportional to load. (for example, a 10C cut-off at 3.0V/cell has nowhere near depleted the cell...)


Fun!
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Old May 31, 2005, 03:06 PM
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Haralson County GA. USA
Joined Oct 2004
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Quote:
Originally Posted by meteor
Yup, 3.0V per cell is a good starting point, albeit a hair on the conservative side.

I have found that 2.8V-2.9V allows you to overcome the initial sag you get until the Li-Po self-heats a little, and the voltage recovers. (only really relevant for EDF's and other high-load 'planes which need 100% power for the first 30s of flight)

Keep in mind that 2.7V is a universally accepted cut-off voltage published by Panasonic, Sony, etc.

Also, if you fly at say, 5C or higher, you will have substantial reserve capacity at lower power settings as the Li-Po voltage is proportional to load. (for example, a 10C cut-off at 3.0V/cell has nowhere near depleted the cell...)
Fun!

That depends on the LiPoly cells in question.
Have a look in the Battery Graph Valut at the TP ProLites. They will deliver high voltage and near maximum capacity even at 13C loads which will deplete the packs even at 3 v LVC to the point there is very little bounch back.
The newer generation cells from TP,Apogee,Tanic,Etec, and PolyQuest all carry a minimum 3.0V LVC recomendation for good reasons.


Charles
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