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Other › Voltage limit on 3S 2200 Lipo
11-28-2005 08:22 AM  12 years agoPost 1
efliernz

rrVeteran

Hamilton, New Zealand

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I've searched everywhere in the forums and can not find - "how low do you take your 3S pack?"

I'm building a low-volt alarm and the limit is adjustable. I know the 4.2v max / 2.7v minimum stuff, but with the quick fall-off of pack voltage, how low do you go???

Lets face it, is it worth going below 10V for 2 minutes flying?

Comments please - thanks.

Pete, Trex500, Trex600E, Streched 600, DSX9, DX7, Low-volt alarms - check the gallery for my alarms

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11-28-2005 12:23 PM  12 years agoPost 2
Daniel Wee

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Singapore

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If you're going to make an alarm, you should have it go off around 9.7V or so.At about 9.45V (roughly, depending on cell type) the curve has a "knee" where the voltage drops off quickly. Once this happens, it's time to stop or the temperature will go up very quickly and basically you will damage your cell. As such, having an alarm go off at 2.7V is way too low.

Also remember that different packs go over the "knee" at different rates, depending on their capacity. There will also be times when the voltage drops below the trigger level due to sudden current draws. Make sure your hysteresis isn't too much so it will reset itself once the voltage recovers.

Daniel

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11-28-2005 12:53 PM  12 years agoPost 3
AnnihilaT

rrKey Veteran

The Netherlands

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Also resting voltage after a flight should be 11.1 volts or 3.7v per cell. If its not you have taken the pack too low and continued use of it in this way will shorten its life / lessen its capacity.

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11-28-2005 01:11 PM  12 years agoPost 4
tnorris

rrApprentice

Hico, Texas

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Your right efliernz.. It is not worth going below 10V for just a few more minutes of flying. If you have your alarm set for 9.5V to 10V, that should be good.

Travis

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11-28-2005 03:08 PM  12 years agoPost 5
TRex888

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Monmouth, UK

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I use one of these and have it set to 9.6V http://www.customidea.com/hrpolyx.php

Sounder is a bit weak, but LED is fairly bright.

Damn nose in hover

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