25 Jan 2003 earlwb   » (Master)

I can't beleive it is so hard to get two identical speed controls.

I wanted to get two ESC's for a firefighting robot I am trying to build. So I ordered two ESC's from a nice supplier. They both arrived, except one was DOA. So I sent that one back to the manufacturer for warranty repair/replacement (that's what the instructions say to do). So they send me a even better one that the one I sent them (heck what do you do?, they did really good on the warranty DOA). Big difference too, a 140 amp (.012 ohm) ESC replaced with a 162 amp ESC (.004 ohm). Doesn't exactly allow for a robot to track straight. Anyway, I order another 140 amp ESC from the supplier and they accidentally send me the wrong one a 65amp one. I ordered two of a different model ESC from a different dealer, and I wind up with them accidentally only shipping one instead of two.

I've called them all and they are all correcting the orders and sending the stuff out. So everyone is bending over backwards to correct the problems. But it's just the bad karma of it all. Jeeshhh. Only four weeks trying to get two matching ESC's. Besides all the time lost waiting. I have to sort of squish everything into the robot and build up on top of that in the robot, so there isn't a lot of room to go trying to disassemble everything.

I should have known better and just built the stupid things myself. But I haven't been able to get the 140-160 amp motor controllers that small yet. Mine are too big.

But before anyone says anything. A set of motors needs maybe 20 amps max to work. But a 140 amp motor controller doesn't need neat sinks as the transistors have such low on resistance (PWMing them) that they don't even get warm. Thus you can cram them into a small, tight, low to little air circulation place, and they don't get hot.

Definitely going to be hard to build a firefighting robot at this rate. Maybe for next year's firefighting contest, I'll be ready. Don't know about this year.

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