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max voltage a Rx and servos can take

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Old 06-28-2017, 04:33 PM
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RCer22
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Smile max voltage a Rx and servos can take

Hi folks. I was hoping there would be some help here.
I want to use a LiFe 6.6 volt battery to power a Rx and an ignition for an engine at the same time. A fully charged LiFe battery will show a 6 plus voltage reading and I'm not sure whether or not it will harm the Hitec Rx and and Futaba 148 servos in my plane. Has anyone had any experience with this type of thing? The sellers of the battery say there shouldn't be a problem doing this but it's not their plane that will be flying. I know some servos can handle upwards of 6 volts but I don't have any experience with these things yet.
Thanks for any help.
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Old 06-29-2017, 05:53 AM
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The 6.6 volt battery will not be a problem.
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Old 06-29-2017, 10:22 AM
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Rx and servos won't have a problem, some engine ignitions will not like it e.g. the older ZDZ ignitions say "6.0" volts max right on the control unit and they mean it. Put unregulated 5 cell NiMH/NiCD or two cell LiFe batteries on it and you'll be buying another ignition.
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Old 06-29-2017, 11:37 AM
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RCer, you better check with the manufacturer of the equipment before you ruin it. Dan.
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Old 06-29-2017, 12:14 PM
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The good old Futaba S148 servos were rated for 5 cell (6V) operation. A 5 cell Nimh charges to 7.25V. A fully charged 2S Life is about the same, but drops off very quickly when off the charger, much more so than the Nimh. People get hung up over differences in nominal voltages, what matters is the battery chemistry's fully charged voltage. The Life nominal voltage is higher than 5 cell Nimh, not because the voltage is actually higher, but because you can not run the 2S Life as low as the 5 cell Nimh.
All RC receivers have an internal regulator, usually 3.3V that drops the battery voltage down for the receivers internal circuitry, though not the servos.
I've never seen, nor heard of a receiver,especially modern 2.4gHz receivers that are not rated for at least 5 cell operation.
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Old 06-29-2017, 12:17 PM
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Which Hitec receiver?
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Old 06-29-2017, 01:48 PM
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Quote:
Originally Posted by Zeeb View Post
Rx and servos won't have a problem, some engine ignitions will not like it e.g. the older ZDZ ignitions say "6.0" volts max right on the control unit and they mean it. Put unregulated 5 cell NiMH/NiCD or two cell LiFe batteries on it and you'll be buying another ignition.
The battery voltage required is between 4.8V (4-cell Ni-MH pack) and 8.4V (2S Li-Po battery) and no voltage regulators are needed with any of these batteries. We recommend a 2S Li-Fe or Li-Po battery with a capacity of at least 800mAh.

I'm using the 10GX2 Evolution Gas Engine and that is what it says in the PDF file for battery power.

My concern is the radio gear. A fully charged battery floats at about 6.6 volts. Hopefully it doesn't stay there for long. I do have an ESC w/BEC that I can use if I have to and it drops the voltage to around 4.9 to 5 volts. Any more input is appreciated.

Thanks
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Old 06-29-2017, 01:58 PM
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Quote:
Originally Posted by Xpress View Post
Which Hitec receiver?
Hitec Minima 6E

From what I can see on the package it will handle the voltage.

So all that remains in question is the servos.
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Old 06-30-2017, 04:48 AM
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What Zeeb said. Most receivers and servos will handle a 2 cell LiFe or 5 cell Nixx but many ignitions systems will not.
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Old 07-05-2017, 07:29 AM
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Quote:
Originally Posted by RCer22 View Post
Hitec Minima 6E

From what I can see on the package it will handle the voltage.

So all that remains in question is the servos.
The Minima 6E will handle direct 2s LiPo voltage but please be advised that this receiver is not designed to work with any type of internal combustion engine. It is strictly for use with electric parkflyer models, there is a very good chance you will experience a receiver failure in those high vibration environments.

Last edited by Xpress; 07-06-2017 at 02:58 PM.
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Old 07-05-2017, 12:34 PM
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What Rx do you recommend ?
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Old 07-06-2017, 02:59 PM
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Quote:
Originally Posted by RCer22 View Post
What Rx do you recommend ?
Either the Optima 9, or the Maxima 9 (if you have a Hitec Flash 7/8 or Aurora 9X and digital servos).
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Old 07-06-2017, 03:22 PM
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Are you saying those receivers only work with digital servos?
Whats wrong with my Futaba 148s?
What about the optima 7 Rx

Last edited by RCer22; 07-06-2017 at 03:27 PM.
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Old 07-07-2017, 07:36 AM
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Quote:
Originally Posted by RCer22 View Post
Are you saying those receivers only work with digital servos?
Whats wrong with my Futaba 148s?
What about the optima 7 Rx
Only the Maxima 9 requires digital servos, the Optima 9 works with all servos. I do not recommend receivers with single antennas for use with a gasoline engine, always use a dual antenna receiver for better signal redundancy.
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