6.0 vs 4.8 volts

I have used 6V. applications for years in certain models. I have use a number of different equipment servos and receivers, namely Airtronics, Futaba, Hitec and JR.

None of these are for use on the Duralites so just don't go for broke there. I have been flying a Duaralite battery model with a Hitec RCD Rcvr, JR and Hitec servos using a duralite (7+ Volts) and NO voltage regulator. No radio problems have ever surfaced in many years of flying whatever I put together.

Good Luck

The extra voltage means extra current, which means the pack will drain faster. If you always have plenty of pack left then it might not be an issue.

Not all servos can handle the extra voltage from what I can tell, so look up the specs on your servos if you can.

I have seen some radios that for some inexplicable reason suffer from servo flutter. Both of those were JR's which is also surprising. Once the batteries were changed back to 4.8V, the flutter went away.

Jim W

Due to discharge curves of NiCd and NiMh, using a 6.0 volts battery pack with a 4.8 volts failsafed Rx system can be very marginal about safety. When the threshold for a 4.8v system is reached by a 6v pack this one is almost completely depleted. Daniel.

Servo speed vs. life of servo. I belive that Hitec can take up to 10v. Why not just call them up on their 800# or email them?

" belive that Hitec can take up to 10v" NIL - especially digital servos which must be kept at max 6V with use of voltage limiting device of some kind or you will surely end up with melt down. Local 1/8 scale gas buggies started running 2 cell lipols and very quickly had digital servos heat and melt holes right through the cases before dying. Have seen a number of dead digital servos of all leading brands ruined because of a 5 cell battery pack straight off the charger (more so with a rapid/field charger) have a float voltage above 7V and this will kill servos, especially digitals, even first day or a slow death over a period. This especially if the overvoltage 5 cell battery is connected and turned on straight away without allowing at least ten minutes off the charger for the "float charge" to dissipate. NB Hitec feather HS50 has a maximum rating of 4.8V. Overvoltage is a prime cause of glitching and erratic behavior.

For longevity and less problems with any brand of servo, far better to run at 4.8V with a larger capacity battery than use 6V. A standard 600 mAh battery cannot supply the current required by a .60 size models are loaded up with 7 - 8 servos. (If a small city car has a flat battery, then it is easily jump started from the battery of a truck parked alongside. Reverse the scenario and try to start the truck battery from the little city car and it will not work - the wires will simply heat up as not enough grunt.)

regards Alan T. Alan's Hobby, Model & RC Web Links

Pros: Faster servo response Higher servo output torque

Cons: Potentially shorter servo life SOME servos are not rated for 6v Shorter battery runtime Increased weight

As you increase voltage in a circuit with a fixed resistance, the current draw goes up. This higher current produces more torque and better speed on the servos, but in adding the extra cell, you have not increased the battery's capacity... only it's voltage, so that 600mah pack will drain 20% faster.

Not a big deal if you have a field charger and check your battery level prior to every flight. Cermark makes a nice power panel with a

Of course, the runtime issue can be offset by switching to NiMH, giving you 1400mah in the same AA pack that would only be 600mah in NiCd.

Increased weight is not that big of a deal, especially if you are already balancing with lead... may as well make some of the weight functional.

--- Rich

| As you increase voltage in a circuit with a fixed resistance, the | current draw goes up. This higher current produces more torque and | better speed on the servos, but in adding the extra cell, you have not | increased the battery's capacity... only it's voltage, so that 600mah | pack will drain 20% faster.

You were doing good until you tried to explain it :)

Alas, a receiver and a bunch of servos do not have a fixed resistance. The resistance of the receiver and the electronics in the servos is probably fixed, or pretty close to it, but the motors in the servos definately do not have a fixed resistance, and they're only given power when the servo is moving anyways.

With the electronics part, yes, increasing the voltage by 20% will probably increase the current draw by 20% (unless there's a voltage regulator in there, but there usually isn't.) But in normal use, the majority of the power is used by the servo motors, and in that case, yes, more voltage will mean it draws more current, but since it's going faster, it should draw that current for less time. In fact, assuming that it requires X joules of energy to move the servo from point A to point B, with more cells it would draw less current to do so, though by doing it faster it's probably less efficient, so that assumption would fall appart.

In any event, it's generally seen that turning your 4 cell receiver pack into a 5 cell receiver pack does decrease the amount of flying time you get before it needs a recharge, but I suspect that the true difference is a good deal less than 20%.

A similar situation occurs when you increase the number of cells for an electric plane power pack. You increase voltage, total energy stored and weight. Generally it's said that adding a cell will give you shorter flights but more power, and this is true, but the flights are generally shorter only because you use the extra power. If you fly in exactly the same way as you did with the smaller pack (using a lower throttle position to give you the same amount of power, though you'll need a bit more power for the added weight) then your flight ought to last even longer than before. But where's the fun in that? :)

I wasn't trying to be exact :)

--- Rich

The higher voltage drives the servomotor faster, but the higher RPM also increases the inductive resistance of the motor and helps to limit current flow. Raising voltage 20% won't raise current flow 20% on a motor as it will on any purely resistive load.

Dan