Flight Batteries

Nicad, NiMH, Lithium, A123? If it's transmitter or receiver batteries you want to talk about, do it in this forum.

Flight Batteries

Postby Clinker » Tue Mar 22, 2011 3:31 am

Hi all,

This is my first post here. I am interested in this site since there seems to be alot of info on 2.4 ghz systems.
For over 10 years now my radio has been a Futaba 8UAF on 72 mhz. The radio is still going strong.
I have made a few electronic gadgets for it like a lost plane and low battery alarm and a campac memory module.
I have also made various sized flight packs depending on the plane. NiCad and NiMh.
I still don't have a Lipo charger
Generally my planes are smaller and use mostly micro servos. Ie; Hitec, HS-81 or Futaba 3101,
Hand launch and 2 meter gliders, though I also fly a 4 servo flying wing.

Recently i ordered this system from Hobby King:
FrSky DF 2.4Ghz Combo Pack for Futaba w/ Module & RX (V2)
My question is ; are my 4.8 volt NiCad and NiMH flight packs going to be alright with this new receiver?
I know that the FrSky modules are capable of handling higher voltage packs but are they necessary?

I am also interested in the telemetry capabilities of this setup but I will save those questions for another post.

Thanks for the advice.
Chris
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Re: Flight Batteries

Postby jeffie8696 » Tue Mar 22, 2011 6:26 am

From what I understand your small servo/plane setups will work fine. It is only when you go to larger planes , digital servos, etc that really tax the battery output that problems may occur. Also the uber high capacity packs may not be up to the task of delivering enough voltage and in fact a smaller/standard capacity 4.8 battery could do a better job .
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Re: Flight Batteries

Postby RCModelReviews » Wed Mar 23, 2011 7:35 am

I always recommend that if people are going to use a NiMH or NiCd pack that they use a 5-cell one for 2.4GHz.

Alternatively a 2S A123 pack is the best option.

Having said that, I fly my little coreflute biplane with a 4-channel FrSky receiver using a 1S 350mAH lipo (3.7V) -- but it's tough and if I crash because of a brownout it is unlikely to be damaged
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Re: Flight Batteries

Postby Clinker » Thu Mar 24, 2011 2:43 am

So I do see that the FrSky receiver has the following specs;

FrSky Receiver Specification:
Operating voltage: 4.0~7.2V
Power consumption: 30mA

My Futaba FP-R148 Receiver Spec:
4.8V @ 14 mA

So, the FrSky receiver is about 2X the current draw.

My flight pack is:
4.8V @ 2300 mAH NiMH, AA Batt. size
I just measured the voltage of the fully charged pack and saw 5.11V.

Now my 1/2AA 4.8V NiCad pack is probably only 300 mAH.

You say that your FrSky receiver will operate marginally at 3.7V.
If, I assume that my high capacity, NiMh pack won't be used below 1.0 V/cell or 4.0 V and even with the higher draw of the FrSky receiver, I feel alright with that for now.
On the other hand, my 1/2AA pack for my handlaunch, seems a little light. It just doesn't seem like enough capacity before the voltage drops.
I like your idea about the A123 Lipo pack because it is still small enough to fit my handlaunch glider fuse. That's something I will have to work on.
Are the generic cells called "LiFePo4" the same as the A123 cells?

I do see, in the future, a need to charge a high capacity, 3cell, Lipo pack for a brushless motor as well as the 2 cell pack above.
Do you have any recommendations as to a good, but not too fancy, Lipo charger.

Thanks,
Chris
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Re: Flight Batteries

Postby aussie_flyer » Sun Jun 26, 2011 11:07 am

RCModelReviews wrote:I always recommend that if people are going to use a NiMH or NiCd pack that they use a 5-cell one for 2.4GHz.

Alternatively a 2S A123 pack is the best option.

Having said that, I fly my little coreflute biplane with a 4-channel FrSky receiver using a 1S 350mAH lipo (3.7V) -- but it's tough and if I crash because of a brownout it is unlikely to be damaged


How to check your A123 batteries at the FLight line?
I am coming form the old school of always checking my batteries with a tester, as I have alway sonly used NiMh or NiCD's.
But I wan to go to A123's especially as I am putting together a 50 cc petrol model.
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