I would like to replace the NiMH battery here
http://www3.towerhobbies.com/cgi-bin...4&I=LXGBM7&P=K

with one of these lipos for longer battery life per charge. Can any of these safely replace the NiMH?

A) http://www3.towerhobbies.com/cgi-bin...4&I=LXMDN2&P=K
B) http://www3.towerhobbies.com/cgi-bin...?&I=LXMDN0&P=K
C) http://www3.towerhobbies.com/cgi-bin...?&I=LXMDM8&P=K

The NiMH battery is a 8.4V and the lipos are 7.4V. Is that a big enough difference to matter?

It will be powering a 550 size inboard motor in a Vista EP ARF Sailplane.

In your shoes I'd be going the other way... up to an 11v lipo for more power.

However all of this depends upon the ESC you are using.

Most motors will tolerate higher voltages as long as you keep the overall wattage input within the same range.

The ESC ends up being the determining factor.

Will the one you have tolerate LiPo's, and how many cells or volts will it handle?

How many servos do you have and are you using the ESC's own BEC to power your RX and servos?

Better yet post the link to the ESC.

Also I would look at different lipos, maybe Thunderpower or Flightpower. I bought some electrifly lipos one time, and they were about twice the size, and heavier than my Thunderpowers. I had to send them back as they would not fit in my plane.

Doesn't say much about it but here is the link to the ESC which was supplied with the sailplane.
http://www3.towerhobbies.com/cgi-bin...?&I=LXBNC5&P=V

It has a Deans female adapter attached.

Using two standard Futaba S3004 servos and I am using the ESC's own BEC to power your RX and servos?


Vista booklet: Motor run time and flight time can be extended by using batteries with higher capacity, but do not use batteries with a higher voltage (more cells) as they will not fit in the model.

You are in LUCK!

That ESC ( I have one of these too ) is LiPo compatible and it will accept 11v input.

Look closely at it.

There should be a jumper. It may or may not be labeled.

Put a mark next to how it is now, then move the Jumper to the other two pins.

After doing that it will be able to handle LiPo batteries.

It's the same ESC used in several different brushed planes.

The warning about the number of cells sort of does not apply here as you will be installing a smaller battery with higher capacity and voltage.

I have no idea what the jumper would be, but everything is soldered in place and it wouldn't be worth it to me to undo the solder and redo it. Is there a battery that would give more flying time that could be put in without redoing the ESC?

Photo 1) Complete ESC setup as done by manufacturer
Photo 2) Top circuit view
Photo 3) Circuit view
Photo 4) Front and bottom view
Photo 5) Front view of front connections

I don't see it in those pictures. But that is one of the ESC's that I've received from GP that purports to be LiPo compatible.

On the one I have which looks identical to that, there is a jumper on the one side you did not photograph... the side closest to the battery.

The jumper controls the cutoff point to make it compatible with LiPos.

If there is no jumper, you could try running 11v through it, but to be safe run a smaller prop. Step down a size to avoid overheating the ESC.

To play it really safe you could always replace the ESC, but in your shoes I'd just try it, run it up on the ground to full throttle for about 10-15 seconds and check the condition of the ESC.

It should be warm to hot, but not so hot that the covering appears to melt off.

A smaller prop will prevent overdrawing the ESC.