Old 05-27-2014, 07:46 PM
  #9  
jester_s1
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The "LiFe hurts your servos" story is about the closest thing we have in RC to an urban myth. I put it right there with fretting over what kind of oil your commercial glow fuel manufacturer uses and Spektrum being a manufacturer of quality products.

But there was a time when I wondered myself too, so I spent a few minutes with a Fluke multimeter and got some answers. A good NiCd hot off the charger plugged straight into my meter gave me 7.1v. Hooked up into the system ready to fly it dropped to 7v, but that could have also been from the little bit of time between the two measurements. It could have also been a difference in how I plugged it in for all I know, but I don't fret about 1/10 of a volt. So 7v is what the system sees and is designed to work with. And, of course, manufacturers build some headroom into that because if you want an electronic component to last you don't design it to run right at the ragged edge of burning up. I went ahead and put a little load on the system by putting moderate pressure on a servo, much like one would see in a big loop. That dropped me to 6.8v which returned to 7v when I released the pressure.
So then I did the same tests with a hot off the charger LiFe. It was Hyperion brand for those who want details. The battery gave me 7.2v plugged straight in, and still 7.2v in the airplane. the loaded test drew it to 7.1v and change.
So the worst case scenario is that your system will see 3/10 of a volt more power than it should under load. This 3/10 of a volt is still less than the system was designed to see from a hot off the charger NiCd. For the mathematically disinclined, 3/10 of a volt is about a 4% difference. It doesn't matter. The only time the system sees more voltage than it was designed for is at rest, when the difference drops to a tick under 3%. That doesn't matter either. If your servos and receiver can handle a 6v NiCd, they can handle a 2 cell LiFe.
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