tcraftpo

My Feedback: (7)

I have my first gas powered model (Dynaflite PT-19) with a G38 (NOT electronic ignition) in the cowl. Currently I am running a 4.8V, 2700mAh NiMh receiver battery. In all my glow powered planes, an average of 40 to 60 size, I use a 4.8V receiver battery. I was wondering if I should be using a 6 volt receiver battery for the bigger servos? Thanks for any help!

Pat

Texastbird

Most servos have a lot better speed and more power running off of 6 volts. Check out the specs on your servos and see the difference an extra cell will make.

krayzc-RCU

My Feedback: (31)

got to lov the difference that 6 volts will do to your brid[8D]

Charlie P.

What are the servos? I am currently putting a 6v (my first) 2000mAh pack in a Giant Super Sportster because I "cheaped out" and went with Futaba S9001 throughout instead of the S3151 or S3152 I use in my other gassers (on 4.8V - one with a BattShare & two 1450 mAh packs). The 6v gained me 18 oz-in (or about 33%) with that servo, so it seemed well worth it to me. I'm also curious as I've always run 4.8v packs up 'till now.

phantomdriver

Put 6 volt to reciever & servos and the 4.8 to ignition and be happy.

beepee

His engine is magneto powered, no bats there.

I hear all these 6V recommendations, but I offer an alternative view. It very much depends on the style of flight expected. If for general sport flying about, 4.8V is my choice. I don't need the extra torque and speed (assuming I have the right servos to start with), and I like the lower mAmp load on the batteries. For the same capacity, five cell packs will be consumed faster than four cell packs.

Bedford

TomCrump

I concur with BP. This is a PT-19, not some flip flop 3D machine. 4.8 will power the servos well.

Dr1Driver

4.8 will power the servos and RX, but 6.0 gives an easy 20% increase in torque - just for insurance.

Zippi

My Feedback: (10)

tcraftpo,

I always run 6 volt on my on board equipment. Something else you may want to think about. If your running a 2.4 system you will want to run 6 volts because of all the low voltage issues that cause brown outs, lock outs, etc. It's better to be safe plus you get the benifit of more torque output on the servos.

Texastbird

4.8 will work just fine, but if you try a 6v pack, you will see the improvement in control authority and the way the plane handles. It doesn't matter if it is a Cub or an Extra. We tried this experiment with my flying buddy's Super Cub that has a G26 and he could appreciate the difference the 6V battery made. He is 78 years young and flies very conservatively, but his turns were smoother and he said it felt like he had better control of the plane overall. Give it a try and see for yourself if you can "feel" the difference.

Edwin

My Feedback: (2)

I run 4.8v. I'm sport and warbirds. But I also run a split power bus in my bigger gassers. 4.8v - 1400ma to the receiver, 4.8v - 2700 to 3600ma to the servos. Servo city sells a nice little power bus spliter for about $18 in the servo cables section. Its just extra insurance since I fly spektrum. On my Yak I ran 4.8v 1400ma rec, 6v 3600ma servos (5 HS5955TG), 4.8v - 2000 ignition.
Edwin

tcraftpo

My Feedback: (7)

Thanks for all the info. guys. I will install a 6v battery, especially for the 2.4 "insurance"...and I guess a little performance enhancement lol.

Pat

jooNorway

Remember to run short cables and good switches if you are afraid of brownouts.

When it comes to battery for ignition the choice depends on which motor you have. Have seen my DLE`s needs 6V to work properly, other brands have other needs. (Yes I know your is a magneto, but just had to say) Love my MVVSs which run on 2S LiPo without regulator

Texastbird

Yeah, if you are flying 2.4, that's enough reason. Good luck with your PT. I have flown the Great Planes and the Hangar 9 ARFs, and they are a lot of fun.

alfredbmor

I have read about this issue before, but I just don't get at 100%.

Why a higher Volt battery with the same capacity, let's say 1500 mamp will drain faster than a 4.8 with the same 1500 maH capacity?

With a higher Volt battery, the electronic equipment will automatically drain faster the batteries?

If anyone could explain this issue I will be very happy and will put any effort to understand it.

On some other way to see this issue, is: Why most big gas bird users are prone to use big lipo packs with electric voltage reducers?

pilotpete2

Going from a 4 cell to a 5 cell, or 2S A123 will increase the average current drain by no more than 5%, not worth worrying about.
2S A123 packs without a regulator is arguably a more stable power source than lipos and even the very expensive regulators. Large, instantaneous current demands can result in voltage instability with regulators, A123 cells hold voltage under load better than most regulators. As far as safety goes, no contest[8D]
Pete

alfredbmor

Thanks Pete.

I have not used yet the A123 batteries, I believe that they behave just like lipos, as per the drain that you mention, but safer, isn't it?

My question is really oriented on an .50 size helicopter with four digital servos, and I have been wondering about the battery that I should use, I feel like a bit limitated, because one of the digital servos is the futaba S9254 which is advertised that will not work with more than 6V.
" use only with a 4.8V battery. (if you use it with a
higher voltage battery it needs to be regulated to 6V)"

Thanks again.

Eganwp

My Feedback: (1)

On RX side I've used NiMh, NiCd, LiPo, and A123. I can tell you that A123 so far and above the others. LiPo is okay, but I prefer to fully charge a pack in 10 minutes (at 10 amps) SAFELY, while still in the plane. They discharge curve is much flatter than lipo as well. No need for regulators is also a plus and one less failure point. Gotta love em!

beepee

alfredbmor,

It is kinda like a garden sprinkler, more water pressure equals more water flow. OK, that analogy is good for another complete arguement of its own. The point being that a 5-cell pack exerts more potential against the servos, increasing the drive action. This pulls more amperage out of the batteries. Over simplified, but that is my level. As for the 2.4SS point and low voltage problems - I believe that is specific to JR and maybe Spectrum, but on that I can be wrong. Well, on most anything I can be wrong.

Bedford

Charlie P.

If you're comparing a 4 cell battery of 4.8 volts and 1500mAh rating against a 5 cell battery of 6.0 volts and 1500mAh rating, you will see added strength to your servos - say 20% more torque - but the downside is that you will get 20% less flying time before the battery is drained of that same 1500mAh. So, if you fly a 1500mAh 4.8v pack, switch to a 1800mAh 6.0v pack for more servo strength and the same flight times.

There is a "bucket" analogy: If you have a gallon pail full of water (the capacity, as in 1500mAh for yur question) and you put four holes in it you get less water out over a given time than if you put five holes in it; the latter gives you more water in a given moment but for less overall time. Same with 4.8 v vs. 6.0 v on a similar rated pack.

ec121

My Feedback: (2)

Ohm's law says that Voltage = Current x Resistance. If we assume that resistance stays the same, then current(battery drain) will go up and down with the voltage. There has to be an assumption for a resistance constant, because flight loads are more dynamic and will vary the actual resistance.

Red B.

The higher current draw when operating the Rx and servos on 6V instead of 4.8 V is of little concequence. It is true that the current draw increases, but on the other hand the servos spend less time moving from one position to another. This to some extent compensates for the higher current while the servos are operating.

Much more important is the safety aspect. As far as I know, the most common failure mode of NimH and NiCd batteries is that they expereince an internal short circuit, leaving a cell conducting current, but not producing any voltage. If this happens to a 4.8 V battery, the voltage drops to 3*1.2 = 3.6 V, which may be too low low for some receivers and also for some servos on long leads. If the same thing happens to a 6 V pack the voltage drops to 4.8 V which is a still a safe value.

For this reason alone, I always use 6V batteies to power my Rx and servos.