cruzomatic

My Feedback: (17)

I've been flying now for just over 6 years and just learned my flying buddy is flying with 6.0v rx battery packs. Am I missing something? I usually fly with 4.8v 1100mah Nicad or greater packs, sometimes 1400mah, especially for my retract planes. I've always been satisfied with my rx battery and servo performance.

Just wondering what you all use? Should I change over and why? I'm assuming the additional torque power and speed maybe?

fadi

6V gives you more power and faster servos. When you buy a servo, look at the pack the specs for each voltage is written on it.
This way you can get more torque from your standard sero instead of jumping to a high model...

I usually fly with a 4.8V, don't care much for the difference in performance is small.

bruce88123

I believe most "sport" fliers still fly 4.8 battery packs. Yes, 6v will get you more speed and torque from a given servo IF that servo can handle the voltage. Fortunately most can these days. OK, now for the down side. The servos draw more current at 6v too for the same operation. If you have a 4.8v 1400 mah pack and a 6.0v 1400 mah pack, the 6v pack will be flat sooner and require charging or you will need to buy a higher capacity pack. You will also need to buy a new charger if you have not already done so for the 6v pack.

If you are happy, why change?

checkmate91

I have a 6v 1700mah pack in my trainer simply because I needed a new battery and wanted to see if 6v made any difference. It doesn't to me although I'm sure the plane appreciates it lol. I've deluded myself into thinking I can detect an increased urgency in the movement of the servos on the ground, but not in the air, it's a trainer after all.

Andy

agexpert

My Feedback: (1)

Running 6V is noticable in larger planes. Some of the higher-end servos are designed to run only on 6v, but they will run just fine on 4.8v, as far as I can tell.

I run 7.4V Li-ion packs in all my planes with regulators set to 6V. This gives me up to 4800 MAH of capacity with about one-third less weight, including the reg. I can fly for days before a re-charge is needed, even with 8611a's.

I wish I had done this from the beginning. Now I have a bunch of unused packs...and servos for that matter...wait...planes and glow engines too...does anyone know how to list stuff on e-bay?

BarracudaHockey

My Feedback: (11)

Thats less of a problem in practice than most people seem to think, the actual increase in consumption is on the order of 5 to 7 percent. (Please dont quote Ohms law as a servo isnt a constant load)

bruce88123

How about the Theory of Relativity? They do pull a Relatively higher current.

rrragmanliam

My Feedback: (1)

Am I missing somthing here Bruce? I don't think this is true.

Darren

bruce88123

For a 6v pack the wall-wart definitely would not work, For a LARGE 4.8v pack the standard wall-wart would take a VERY long time to charge and may have difficulty achieving a complete charge.
But if you want to wait for 2 days or so for a flat battery to charge you are welcome to it. I'd rather fly.

horace315

My Feedback: (15)

for the every day flyer in most 40 size planes you really don’t need 6 volt batterys.if you do go to a 6 volt pack just make sure it is a larger mah rating is all. the battery drain isn’t noticeable in the larger capacity batteries run 6 volt packs and haven’t had any problems with battery packs not lasting. you will as said here need a better than stock charger to handle the higher capacity batteries but they aren’t that expensive.

ChuckW

Are you sure about that? In every other application I am familiar with, higher voltage is always better, resulting is less current drain to do the same work. Basically, power (to do work) is a function of voltage times current. A higher voltage can do the same work with less current. I've seen this in practice in fork lift trucks. An 80V truck will run considerably longer and perform better than a 48V truck, even with a similar Amp/hour battery. The cabeling used is often smaller too because it is required to carry less current. Automotive manufacturers are also looking at higher voltage electrical systems so that they can power more devices at lower currents. This means smaller, lighter wiring. I know both examples are on a lot larger scale than RC servos but the basic electrical principals are the same. I'm not doubting you though, maybe there is something about servos that I am missing? If there is, I'd be interested in finding out.

I've thought about using 6V packs myself. My concern though was weight. Is the slight amount of added weight justified for the type or aircraft I fly and performance increase I'd get? At this point, probably not. In another application though, 6V will probably be the way to go.

ChuckW

I've found alot of information online saying that 6V won't last as long as 4.8V at the same mAh rating. Kinda makes me think even more that I'm missing something. Maybe it is a characteristic of NiCads or NiMH? Maybe it has something to do with the internal resistance?

Getting back to the original question of this thread and it's intent, it looks like the concensus is that 4.8V is more than adequate for general sport flying.

flyingJ

Part of the reason for the lager Mah rating when up gradeing from 4.8 to 6.0, is the servo motor is nonregulated. Increase voltage, increase rpm{hence speed}. Now you have changed 2 paramiters in the OHM's law, not one. Think what the reaction speed and torque would be at 9.6, but the servo life would be very short lived because its windings and pots can't take that for long.

benfisherone

If the servos you are using are old stay with the 4.8 pack. I had old JR servos in my quarter scale and they locked up with the increased voltage. Most newer servos will handle 6 volt, and with a sport plane you will notice the diff. Most of my bigger planes will be changed to 6 volt because I am running digatal servos. They use more voltage. A better charger would be good too. Most of the smaller planes do just fine with a 4.8 pack.

da Rock

As for the discussion of theory about which pack will run down the fastest..................

Someone recently did a magazine article comparing 4.8v packs versus 6v packs and the focus was on how long they lasted in the guy's model. That's what we're worried about, right?

It was a very good article. The guy trotted out all the theory and explained it as well as he could in just a couple of pages. And he explained his test setup and it was sensible and accurate.

Turns out that in spite of all the theory to the contrary, his 6v packs lasted about the same as the 4.8v ones. He offered some guesses about why that was, since it wasn't in keeping with what theory would suggest. But he drew a very wise conclusion at the end of the article.

With our model airplanes, in practice, the theory ain't worth arguing. He concluded that they work about the same and screw theory. It works the same, so don't sweat the theory.

(an excellent quote I saw somewhere: In theory, theory and practice are the same; in practice they are not.)

BarracudaHockey

My Feedback: (11)

It was in RC Report.

Also if voltage rises and resistence stays the same current will also rise but as I said, servos arent a constant load (resistence)

ChuckW

Makes sense. I wasn't considering the fact that the servos were now pulling the same load, only faster. I've only really completerly drained my reciever pack once or twice. Normally, after I get done lookign at everyone elses planes, watching other flights, and so on, I get in 3-4 flight and that's it. I check the voltage between each flight and they've never been dead yet.

backfire

One important variable that seems to be left out here is that the total battery energy available equals volts X amps X time. The extra cell of the 6V pack makes available 25% more total energy (work). So, even though the servos work harder (faster & stronger), the 6V and 4.8V systems can have similar run times, as you point out.

D-LOCO

Since a servo is a "motor load" it draws the current it needs to produce the torque on the shaft - regardless of voltage.

As has already been mentioned, at a given torque, the motor will draw LESS current at a higher voltage.

That's why "under voltage" on a motor will make it run hot - its drawing more current and that's where the heat comes from assuming the mechanical load stays the same.

Motors 101.

Dave
AMA 847123

P-40 DRIVER

For non performance applications, a 4.8 volt Nicad pack charged at 10% rate is the most reliable and cheapest way to go. Everything else only needs tobe done for performance or weight savings which in most sport applications is a waste of money. The one thing I see in this hobby all the time is people spending money constantly with very little return on investment. The stuff that comes with your average 6 channel radio will fly 90% of whats out there.