sputnikxxx

I got a 18 amp esc, e flite 370 inrunner brushless, 3700rpm running through a gear box with a 11x4.7 prop, I want to use a 3cell lipo, I am looking at a 10c but im not sure if it will be able to handle the discharge rate.... or should I go with a 15c, only thing is then im worried about my esc getting fried... ? suggestions?

PatternPilot

My Feedback: (58)

Hello,

Always go with the higher "C" rated battery, It will work better and generate less internal heat and give you a higher discharge.
EX: 1500mah at 15C = 22.5 amps max 1500 at 10C= 15 amps
As far as the speed controller it is only rated for 18 amps and if you keep drawing over that then you will have a issue.

Scott Anderson
Team Tanicpacks.com
Team Castle Creations

jdetray

The "C" rating of the battery has very little to do with how much current the ESC will see. The 15C pack might weigh more, but it won't add any stress to the ESC.

- Jeff

sputnikxxx

ok thanks for clearing that up, someone told me it did... but basically the higher the c rating the higer the capable discharge rate?.. if im thinkin correctly which mean, a cooler more stable battery, main thing is I want to make sure my power being sucked from the battery is not more than it can handle, and the esc I have can handle the amps produced... its all so clear now

jdetray

You are correct -- a battery with a higher "C" rating will run cooler and be operating more conservatively. Under load, its voltage will be a little higher than a battery with a lower "C" rating.

The component with the biggest influence on the current required by your power system is the prop. If everything else (motor, battery) stays the same, a small prop will make your system draw a smaller amount of current. A larger prop will make the system draw more current.

If the prop is too large, it could draw enough current to make the motor, ESC, or battery (or all three) overheat. That's where your wattmeter is really valuable -- to be sure your motor, ESC, and battery are all operating within their limits.

Another poiint is that it is always a good idea to not operate your components right at the edge of their capabilities. For example, if I had a power system that draws 18A, I would not use a 18A ESC. I'd choose maybe a 25A ESC.

- Jeff

Trogdor the Burninator

What capacity battery are you considering? All the worry about the battery might be better directed at that motor. With the 3700kv model you really aren't going to be able to be past 10 amps ever. Well, I guess you could prop there but you're not going to be able to run it continuously there for long without overheating. I have both of the higher kv eflite 370 motors (4200 and 5100 or whatever the #s are) and while they're pretty good, they can't run at 10amps+ for but a few seconds before getting hot and your lower kv motors handles less amps.

So, the ESC is probably overkill.. I use 10 amp controllers. A decent 10-12C 1320 3s pack should probably be fine. I've used 10C 900 packs for awhile (also 1320s) although I do think I pushed those a bit but they were earlier technology packs from a couple years ago. You would only need the 15C kinda pack if you really wanted to go small like 700mah range.

Do you know what gearing you'll be using on this motor? That will affect how much amps you draw from the battery with your 11x4.7 prop. I'm guessing 6.6:1 or the GWS D equivalent would be good, maybe a little lower ratio would be acceptable but I'm not sure.

JoshGordon

Have you been able to hook your set up into a Watt meter? This will help you determine your needs.

--
Joshua Gordon
Common Sense RC
www.CommonSenseRC.com
Toll Free 866-405-8811