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Old Oct 18, 2011, 12:57 PM
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BryanEW710's Avatar
United States, OH, Cincinnati
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Question
Motor Cuts Out at WOT at Flight End

All,

I've noticed with some of my older lipos that, while they will fly around at 60-80% throttle quite happily for the duration of my flights, pushing them to WOT causes the motor to cut out temporarily. Is this just a sign that the pack is aging, or that I need to get rid of it? Once the plane is on the ground, I can slowly throttle it to about 90-95% of the stick's travel, but that last little bit causes the motor again to cut out.

For reference, I'm dealing with 160mAh 1S lipos that are about a year or two old being flown in a PZ Su-26XP. My standard flight envelope is scale, sport, and aerobatics at no more than 80% or so throttle. Flights are 6min and generally consist of flying for 5min and starting a landing approach at the 1min (remaining) mark. When I check the cells (with a DVM) later, I find that they are above 3.7V, so it does not appear that I'm doing any damage (as far as I know). Perhaps I need to check them fresh off the plane?

Admittedly, I'm quite new to the inner workings of LiPO batteries, so there is certainly some ignorance here.

Thank you for your time
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Old Oct 18, 2011, 12:59 PM
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Joined Aug 2011
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I am going to guess that your hitting the low voltage cut off of the ESC. Or possibly the ESC has gone flakey on you.

As it is with any battery the more currrent you draw the faster the voltage falls off it may be falling off to LVC at high current draws.
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Old Oct 18, 2011, 01:01 PM
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United States, OH, Cincinnati
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Quote:
Originally Posted by UlteriorModem View Post
I am going to guess that your hitting the low voltage cut off of the ESC. Or possibly the ESC has gone flakey on you.

As it is with any battery the more currrent you draw the faster the voltage falls off it may be falling off to LVC at high current draws.
That makes sense. I'm going to go with the battery having too high a voltage drop because this does not happen with my newer lipos.

Given that, should I treat this as a sign that these are getting close to retirement age?
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Old Oct 18, 2011, 01:06 PM
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A pretty rough indicator but yes over time lipos loose some of the 'delivery' capacity as you have witnessed. It will probably still deliver close to the original Mah rating, but it just cant do it quite as fast.

That doesent mean they have reached the end of their usefull life but I wouldent commit them to 'important' applications.
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