Gentlemen,



I'm wanting to use a 2150 mAh 7.4 volt Li-ion battery for
my 40 size plane with a OS 70 4 stroke.

What's the difference in a 5.1 volt regulator and the 5.6
volt reg. ??

Thanks,

Bob

Bob,
The higher the voltage the faster the servo.
The higher the voltage the higher the current draw and the faster the battery drains.
Not sure the plane but since it is a 40 size I'm guessing servo speed is not a requirement.
I would use the 5.1 volt setting to get more flights in the day.

What regulator are you using?
I am thinking of going this route.

Good Luck,
KW_Counter

I question wether Higher voltage will cause higer amperage (current). Normally higher potential  (voltage) requires less current to do the same amount of work (watts).  w=I x V.

Will it? Yes. It's been proven. The test was conducted between a 4 cell and 5 cell pack which is a much higher difference, and the actual consumption was increased by around 5 percent. In other words, a non-issue.

The practical answer is, the difference in performance on that plane, and the difference in consumption, would be so negligable as not to be noticed.

Pick one and go with it.

I couldn't get that principal out of my head either for along time. When it comes to variable loads on the system doing actual work it is absolutely correct. What I wasn't taking into account though was fixed resistance in the various circuits of the receiver, servos and even things like the wiring, connectors and switch. If you apply Ohms law to a 4.8V battery going through a 2 Ohm fixed resistance, you come up with 2.4 Amps. Make that a 6V battery and you end up with 3 amps. (I just made those numbers up because the math was easy)


I run 6V, 2000mAh packs in the majority of my stuff though and it has been plenty.

Huck,
Your formula is correct, but you're using the wrong formula. You should be using I=E/R. Higher voltage will indeed increase the current draw and thus reduce battery life a little.
Paul

I have some electronic training sets here at work that allow you to build circuits and use different voltages to power them. I tested 4.5V and 6V since these are fairly close to what we use in RC. I applied these voltages to fixed resistors, relay coils and DC motors. In every case, there was more current flowing when hooked to 6V than when hooked to 4.5V. The 6V circuits clearly used more power. The measured numbers were identical to what I calculated they should be using Ohm's law.

Of course the 6V circuits were clearly more powerful. This is good if you need the servo torque, speed, etc.

When you're done picking the pepper out of the fly poop, it's back to what I said. At the flying field you won't notice a difference.

Thanks guys,


I almost feel like an E.E.



Here's a link to the Regulator and Li Ion pac.

http://www.chiefaircraft.com/cgi-bin...ARCH=Search%21

Bob

Yep, that pretty much sums it up.