Chuppster
Well-known member
I just used made up figures to make it easier for me to explain, it would have been better to say a matched set up but wouldn't have been as easy to explain without some numbers. To be fair I did say they were just made up to make the example.
Yes you can have short circuits, prop stalls, the wrong prop and all number of things in any plane but you can't always have a backup or enough headroom for every possible instance (I don't actually know what being submerged in water or a power line strike does to a power system current or voltage wise for example).
With the wrong battery choice and a forced prop stall even a 30a esc potentially can be popped everything we're discussing has to presume a normal flight plan executed without mishap. There's so many variables that can change and cause issues in any part of a power circuit a mean difference must be presumed.
My example was just to demonstrate what I'm trying to explain.
Maybe we possibly shouldn't use a battery that can put out more power than your esc can handle but i dont know if the answer is as easy as that and without going into a specific system and working out the specific specs of each component it isn't easy to guess any weak spot. Most people throw stuff together based on what they've read others do and then find things are running hot only to be told it's ok theirs does as well which we both know shouldn't actually be the right way of doing things but we all do it nonetheless.
Not particulary related as such but a little boring story for you, over 35 years ago now I used to successfully race cars and once I started working and had disposable money (ahh disposable money, them were the days) i started getting the more expensive gear, the better cars, the more powerful motors etc but soon started going through escs in such a rate it ended up on a weekly basis, I went through pretty much every brand and every top end model often each time getting a bigger power one thinking it wont blow if its even bigger but I still kept blowing them. I didn't particularly know what I was doing of course and just kept banging different stuff in that various magazines reviewed or what the local model shop had in (or perhaps to be truthful just the latest greatest thing on the market that week so I could get pit wall envy) until I had the biggest motors, biggest batteries and the biggest escs but still regularly blew the escs, had poor run times, problems with charging and rather than battling at the top of the winners list i was dropping further down.
In the end I spoke with a development guy from an esc manufacturer at a show who recommended I change the way I was doing things so i changed the entire system going back to a cooler motor, smaller batteries and a quality speed controller that was a fraction of the power rating of some escs i had popped but that guy was either a very good salesman or he genuinely wanted to help either way I followed his suggestion . From then I went back to being the one to beat as it were. That system stayed with me for the rest of my electric car days until I moved to fuel.
Yes I understand they were nicads, the motors were brushed and most of the escs had massive fets stuck out the top of the units but I thought I would tell the story anyway.
Incidentally the esc I ended up with back then was a tekin and it's sat on the shelf next to me now back in it's original box. It's one of those things that brings back such great memories it will stay there forever.
And yes I've had a little drink so you get to read a boring story ha.
Hmm, while being slightly off topic your story does intrigue me. I'm wondering if the ESC's would burn up due to the current spikes from accelerating off the line, or perhaps from the back-EMF coming from the motor. Brushed ESC's are so much simpler than brushless ones. At least you found someone who could help you out!
My basic rules for setting up a power system are this: Pick a motor that can deliver enough power. Pick a cell count. Ensure that the battery is rated for the current you are drawing (C-rating x capacity), preferably 1.5x what you're drawing. Use an ESC rated for at least as much current as the motor that can support all your cells. Then pick a prop that pulls about as much current as the motor is rated for, sitting on the ground. Larger diameter prop for more thrust, higher pitch for more speed. Following those rules I've never burned anything up. When I ignore one or more of those, I usually fry something.