Receiver power - RC Groups
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Sep 23, 2017, 06:34 PM
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david.ingham's Avatar
Question

Receiver power


The FlySky FS-iA6 description says "Input Power :4.0-6 .5 V DC". Will that work directly from 2s Li-Po, up to 8.4 V? Or what do people do?
(My present RC airplane is electric and takes the Rx power from the motor controller. Now I am planning an 0.20 powered RC converted Pushup, replacing the one I lost a decade ago.)
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Sep 23, 2017, 08:56 PM
Rough Landing
rainyday101's Avatar
Quote:
Originally Posted by 049flyer
Thanks for showing those links. I suppose the Life pack is better than the NiMh? How much flight time do you get before they are done?
Sep 23, 2017, 09:25 PM
Registered User
Bit more involved than that I'm afraid.
Most Modern Servos have voltage limits.
Unlike earlier servos which were intended for 4 x 1.5v dry cell power (6 v).
Many servos will burn out at ..anything... over 5 volts. Read! their specs carefully.
So 2S is not a viable solution as a direct Rx/servo power source.. Need an esc with an inbuilt bec OR a standalone BEC... to adjust that voltage down to 5 v.
Also..Many Rx s can accept down to 3.3 v happily.
HLG guys use a 1S battery.. And 1s specific servos where lightness is a criteria.
Sep 23, 2017, 09:30 PM
Registered User
Amp Abuser's Avatar
LiFe packs hold their charge very well. You will not have to top off your batteries
prior to flying like you do with nimh cells up to 15-20% drain over the course of a week.
LiFe cells can puff, and at risk in a crash like lipo. I have had two packs puff no apparent
reason other then possible heat as the summers here get up to 106F

I use 1S with my Nano II with 1S servos
4x80mah nimh with Nano I and 4.8v servos
Sep 23, 2017, 11:43 PM
Registered User
The Life packs have a bit less voltage than the Lipo packs enabling you to use them without a regulator.. I have run a variety of servos on Life packs without problems. Most servos these days can handle 6 volts without problems, our old nicad packs measured 6 volts fresh off the charger.
Sep 24, 2017, 02:42 AM
Registered User
4 Nicads metered at 6v hot off the charger and only for brief moments of use.
Not that it mattered as servos of that era were designed for 6 v. .. but ran fine on 4.8v.
Although their perf specs were always quoted at 6 v levels.. which they rarely saw
One always got better speed and torque when on 4 dry cells (6v) rather than nicads' 4.8v.
Again; Many of the smaller Moderne servos have specific Voltage requirements. Buy with eyes open.
Old servos, if you've still got 'em, Are less picky about voltage.
Last edited by Bare; Sep 24, 2017 at 02:48 AM.
Sep 24, 2017, 02:28 PM
Registered User
david.ingham's Avatar
Thanks everyone.
Since there is nowhere near me to fly with combustion engines, this may not get a lot of flight time, so I am thinking 2 x CR2 or 2 x CR123a non-rechargeable might be a good solution. I don't have a charger for LiFe or for 4 x NiMH.
Or maybe I will use a light cheap motor controller or a bec and 2 x LiPo.
Sep 24, 2017, 10:27 PM
Registered User
david.ingham's Avatar
This looks light and is cheap: https://www.banggood.com/DC-DC-Conve...mds=mywishlist. That way I can use my regular LiPo charger, which has a 1/2 A setting.
Sep 27, 2017, 11:22 AM
Rough Landing
rainyday101's Avatar
Another option:

https://alofthobbies.com/4-8-v-480-m...ck-square.html
Sep 27, 2017, 05:14 PM
Registered User
Quote:
Originally Posted by rainyday101
Thanks for showing those links. I suppose the Life pack is better than the NiMh? How much flight time do you get before they are done?
Most of my 1/2A planes are 2 channel pylon racers. I get over an hour of hard pylon racing "on" time, so at 5 min per flight, I would probably fly about 10 flights or so. I also have a FrSky Taranis radio with telemetry as standard so I know to a tenth of a volt what my receiver battery is delivering. Plus I have set voice alerts to warn me when the battery is getting low.

In a glider, I just turn the rx on and shoot it up on the high start or motor up on the Cox .049, flight after flight. As I am not wiggling the servos like I do with my racers, I just leave the Rx in the glider "on" continuously for about 2 hours before my radio warns me the Rx battery is low.
Sep 28, 2017, 05:13 AM
Hey, watch this!
Raymond-leflyr's Avatar
Here's one I used on a 1/2A plane a few years back. Did just fine.

https://hobbyking.com/en_us/turnigy-...___store=en_us
Sep 29, 2017, 11:15 AM
Registered User
I got a couple of those but have not tested them. The reviews seem to say 1 amp can be used up quickly with normal servos, so it seems ideal for 1/2 A 1/4A flying. You can use up a good cell from an old puffed up LiPo pack or whatever. For .049 to .10 planes I just use dollar store AAA nicads or nimh . A lot of them are 600 mah now which is better than the AAs of years ago. There are 2/3AAA now and many other choices.
Sep 29, 2017, 01:05 PM
Rough Landing
rainyday101's Avatar
Right now this is all I am using and they work fine.

http://www3.towerhobbies.com/cgi-bin...&I=LXPYL6&P=ML

Weight is 1.9 oz., but still lighter than the 4 AA alkaline packs we used in the past.
Sep 29, 2017, 06:48 PM
1977 kawasaki kd100-m
smallengines1284's Avatar
I used to just use an eflite 1S 150MAH with a servo plug and just put it on the throttle channel, but that was for MAX 3 flights maybe 4 without recharging it and it was unreliable. now I just do the same with a 280mah 2s for my .020 powered eflite clipped wing cub 250. the 2s I found was a LOT more reliable and was light enough for a .020 powered ARF


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