A question about motors: If I have a motor rated for 10A is it okay to hook it up to a system tha...

[G+_Michael Heinz]

A question about motors: If I have a motor rated for 10A is it okay to hook it up to a system that can't provide the full 10A? 

 

In other words, if I build a quad with four 10A motors do I have to use a battery that can provide at least 40A?

[G+_Eddie Foy]

At what point?  The battery under rated or the ESCs under rated?  ESCs would be a bad move. (might create SEDs, Smoke Emitting Diodes )  Battery less so, in operation, but will still cause problems. Could over heat the battery causing damage/fire. You might be able to scale the sticks, and/or the flight controller to not go full power.  But you are typically about 50% power just hovering in place.

 

If I get the chance I want to do some current tests on the systems.  I don't think the current ratings are true.  But could be wrong.

[G+_Michael Heinz]

Well, what I'm thinking of is I have to replace the motors on my quad, but the motors the kit came with have been out of stock for 6 weeks now, so I'm looking at some Turnigy "baby beast" motors. These motors weigh less than the original motors, but they're rated for 10A rather than 4.5A.

 

The kit ESCs are rated for 12A, so they're fine, but the batteries I have are rated for 20A/30A.

 

Total weight of the quad will be the same or lower than it was before, so I don't expect the motors to need to work at full power.

 

My intention is to upgrade to larger batteries eventually, but I'd like to get as much use out of these batteries as I can - as long as it's safe to do so.

[G+_Taylor Graham]

Power usage varies based on what prop you're running as well. My motors are rated at 15a, but at full throttle they can pull 21a with the props im running. Batteries usually have a sustained C rating as well as a "Burst" rating. The burst rating is good for spikes of power of ~15 seconds or so.

 

Are you sure the batteries are rated at 20a, not 20c? 20a is pretty low. 

You should probably keep your actual usage under the batteries burst rating. If you run the battery to hard, it will get hot, then puffed, and eventually i believe it will smoke, and finally catch fire :D.

[G+_Michael Heinz]

Sorry, I thought "A" and "C" were interchangeable - yes, they're rated for 20C.

 

I'm afraid my understanding of voltage and current stopped at the "Picture a waterfall" stage - but between you and Eddie I think I've grokked the idea that I should keep the ratings of the motors below the ratings of the batteries. 

 

Thanks.

[G+_Taylor Graham]

What capacity are the batteries? Multiply your capacity in mAh by 20 to get your max sustained current draw.

[G+_Michael Heinz]

Conveniently enough... they're 1000mah batteries, which is probably how I made the correlation.