I've made a larger sized quad, and put larger motors on it, and larger ESC's.
I learned at great cost about some ESC's. I'm hoping to save you money should you be looking for ESC's for APM diydrone products. Here's my saga for those interested:
HobbyKing Red Brick 50A ESC"
Wow, only $10 for a 50 amp ESC! Wow, let me get that! The HobbyKing Red Brick!
I should have looked at the reviews. I tested one by itself, it seemed to work fine. Next, I installed them on my quad, and paralleled all of the BEC's together, powered up, and not a peep from them. I think paralleling the BEC's wrecks them. All four of them are completely dead.
Darn, I was planning to go quad fishing, and now I'm dead in the water.
Swift 35 amp ESC:
Since I was in a hurry to go fishing, I went to a local hobby shop, and purchased 5 Swift 35Amp ESC's. I tested one, and I got only 1.6 lbs of thrust from my 1500 kv motor, and a 3 cell lipo, using an 11" DIYDrones propeller. I had 2.4 lbs with the Red Brick. But that's ok, I can still go fishing.
I was configuring them, exactly like the manual, to disable the low voltage cutout. Out of the 5 ESC's, two of them failed during the configuration process, at exactly the same place. I'm sure the drive electronics were still fine, something in the micro, probably a bug in the firmware caused this. I'm down to 3, so I go back to the hobby store, and purchased one more (and they gave me one), so now I have 5 of them again (one spare). I configured them at the hobby shop, just in case the bug happened again. It didn't so now I can proceed.
Bummer, these are NOT compatible with the APM2. They work, but they BEEP Continuously if you're not actually spinning the propellers. Very annoying, especially for FISHING! You'll simply scare the fish away, and all the other fisherpeople will be mad at you! I was able to change version 2.7.3 and make it so it didn't beep when disabled. This got me through my fishing adventure (another story, yet to finish, although if you're clever, you'd be able to find the quad copter fishing video my significant other made).
It turns out that the reason they beeped, is they are too "smart", they have an "Auto Zero" feature that works fine when you connect directly to the receiver, but the APM2 puts out a couple of levels, so the "at rest" PWM value is lower than the lowest it put out during the initialization process, well, I think it's something to do with that.
Turnigy Trust 55A SBEC ESC:
When I returned from camping, I had my new ESC's, yeah! They were the Turnigy Trust 55A SBEC. I did check the reviews and they seemed ok.
I tested one alone, seemed to work fine. It only had 2.2 lbs of thrust with the same setup as the Red Brick (it was a bit lower than the Red Brick). But that's ok, no problem. However, alas, it also isn't compatible with APM2. It's maximum PWM frequency is 433Hz. It won't take 444Hz, it only beeps at you. Even if you set the frequency of the APM2 to 120 Hz using mission planner, it STILL doesn't work, because the APM2 must be sending out the 490 Hz before reading the configuration and changing to 120 Hz. So, no matter what, these ESC's ONLY Beeped! But when I added a line of code in 2.7.3 that made the maximum frequency be 433 Hz, this worked. Ok, problem solved, right? WRONG!
I tried to program these ESC's to disable the low voltage shutoff. I thought I had done that, but the configuration only "took" on one of the ESC's, the other 3 were still going to shut off on low voltage as I found out too late. This resulted in a crash, my battery was getting low, and I knew it (I was using telemetry), and I was about to land it, but a motor cut out, and the copter crashed. Patches was taking an aerial video at the time, here it is:
I'd been thinking of a name for this quad, and now I found one: "Patches".
Here's a picture:
Ok, so I'm going to test out the low voltage function, so I didn't charge my battery so I could test the low voltage cutout parameter. Well, what I found out (short story) is that if the battery voltage goes too low, then one BEC 5 volts will backfeed into another, and SMOKE an ESC. Basically, I smoked 3 of them! POOH. And when I say SMOKE, I mean SMOKE!
I found out it was this part that smoked:
At this point, I don't have my quadcopter again, I'm waiting on parts again!
I'm planning on replacing that smoked part, and see if the ESC's work, but I haven't done that yet.
Hobbywing 60Amp ESC's:
So now I wised up. My original quad had HobbyWing FlyFun 30 Amp ESC's, and I've never had ANY trouble with ANY of them. So I ordered some 60 amp ESC's.
I finally received my HobbyWing ESC's last Friday. As a safety precaution, I used 3 schottky diodes in series with the 5 volts coming from 3 of the 4 ESC's. One ESC does NOT have the diode, but the other three do. This allows full voltage for the APM2 coming from one of the ESC's (the one without the diode), but there's a safety net from the other 3, and it's now impossible to feedback the BEC 5 volts from from one ESC to another with the full 5 volts. I really doubt if I would have had to do that with these ESC's, but considering the luck I've had, I wanted to be sure. Worst case, it would only wreck the one without the diode, but I didn't want to loose another 0.3 volts for the APM2.
Anyway, at this point, I am going to be sticking with the HobbyWing ESC's, they are working GREAT!