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Old 09-22-2008, 10:04 PM
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kyleservicetech's Avatar
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 8,952

I've had that same exact question on my two models, powered by Hacker A50-12S and A50-16S with 6S2P A123 cells. Over the past year or two, I've put together a Microchip (Picchip) on board metering system that records total flying time, total AmpHours for the flying season, as well as the AmpHours and Amperes for the current flight. Recently added, it records the current pulled by the motor every 5 seconds for play back without requiring a PC computer. (I wrote the RCReport article last year on an "RCHourmeter")

The results were somewhat surprising. The motor current does drop off somewhat after the model reaches flying speed, but what was not expected was how much this same current varied, depending on whether the model is flying level, or climbing or diving. And it did not take much of a dive to cut the motor current by 50% or more.

The A123 cells in my models have each passed 10 hours of actual flying time, pulling 57 Amps out of the 6S2P cells. Total AmpHours to date is 175 Ampere Hours on each battery pack. The A123 cells have not lost ANY RPM on the motor during this flying season.

Also note, the Hacker A50-12S with 14X10 APC prop turns 7950 RPM fresh off the charger, and 7840 RPM after flying 60% of the battery capacity.
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