Bench testing P3A brushless motor?

[ggoosen]

So i crashed my P3A due to a stupid error on my part this weekend.

Long story short, while fishing with my drone it went into the sea. Luckily enough the error that caused it to go into the sea (line wrapped around the propeller motor) was what allowed me to fish it back out again.

None the less, i stripped it all, cleaned it with fresh water and then baked it in the over for 24 hours on 50deg (low heat) to dry everything out.

After that, i cleaned the boards with isopro. I stripped the motors and cleaned them as well and then put them back together (they had sea sand in all of them)

After putting everything together, i turned it all back on, everything comes up but i get an ESC error.

After researching i have found this could be due to a faulty motor, busted esc or faulty cable to the motor.

So what i want to do is bench test each motor. Now i know i cant just hook it up to a battery direct, but is it possible to go and get an ESC, hook it up to the motor and test the motor works? That way i can illuminate the motors for being the cause. As i understand if the ESC is done then i have to replace the main board.

 

[N017RW]

Yes you should be able to test a motor by using a known good ESC of adequate rating.

But there’s very little to go wrong electrically with a motor except, in this case, corrosion of the coils causing a short within a coil or to a neighboring coil.

Mechanically it would be a bearing failure which is easily tested by hand spinning.

It would seem more likely your problem is not a motor just based on the susceptibility of all the other components involved.

 

[ggoosen]

agreed, much higher chance the motors got jammed and burnt the esc out?

Any idea what type of ESC i should be looking for?

 

[N017RW]

If you don’t have other r/c ‘stuff’ at-hand it’s going to be bothersome. You’ll need to wire up the esc to power and a way to drive the esc. It would likely be cheaper to buy 4 motors.

 

[ggoosen]

If you don’t have other r/c ‘stuff’ at-hand it’s going to be bothersome. You’ll need to wire up the esc to power and a way to drive the esc. It would likely be cheaper to buy 4 motors.

Ive got some stuff from my RC cards (they were all nitro). But i have controller, receiver and batteries.

I think all i need is an esc (that can be used with the DJI motors) and a battery maybe?

 

[N017RW]

Ok. You can find escs on-line from numerous sellers or a local shop.

‘Castle’ is one brand I have used.

A 15 amp rating should be sufficient for your testing. It will have documents for hooking up the radio, batt, and motors.

 

[MotorCycle-Man]

That was a "keeper" for sure.....what pound line was used to be strong enough to pull that water logged drone back to dry land......I hope that you get it all sorted out and fixed asap.......The best of good luck to you....and did any one see you pull it out of the water that did not know your lost it and Thought you hooked on a drone......my eyes would have popped out IF i seen that .smiles.

 

[ggoosen]

Ha ha yeh, we were fishing for Jewish so had 50lb braid.

At least we caught some fish before it swam.

 

[MotorCycle-Man]

WOW..........you sure did ! and i enjoyed the keepers too !

 

[solentlife]

Sorry to say this - but if your AC went into Seawater ... even if it works today - I would not give it much hope of long life. The instant a powered up item goes into SW - it immediately starts corrosion and damage. You can rinse in FW and dry as much as you like - but I know from own bitter experience ... its a lot of effort for little reward. It usually requires a non solvent spirit such as Vodka or just plain spirit to wash and clean out the salt / water residues. Even common Tap Water has additions that mean its not true FW.
I have lost various Rx's and airborne setups after being dunked in Rivers, Harbours etc.
My P3S went into the river near my house ... that water is basically drinkable ... still caused total loss of my P3S boards / camera ... but motors were fine !

But assuming I am wrong and you have managed to save it and corrosion has been stopped ... then any BRUSHLESS ESC of 10A or more will do the job ... a cheapo of eBay will do.

I test BL motors with common cheap ESC with BEC ... and a Servo Tester ... with a small LiPo to power the ESC / BEC ....
The servo tester acts as the throttle of a radio ... and you can get these for about $5 ...

Nigel

 

[ggoosen]

Sorry to say this - but if your AC went into Seawater ... even if it works today - I would not give it much hope of long life. The instant a powered up item goes into SW - it immediately starts corrosion and damage. You can rinse in FW and dry as much as you like - but I know from own bitter experience ... its a lot of effort for little reward. It usually requires a non solvent spirit such as Vodka or just plain spirit to wash and clean out the salt / water residues. Even common Tap Water has additions that mean its not true FW.

But assuming I am wrong and you have managed to save it and corrosion has been stopped ... then any BRUSHLESS ESC of 10A or more will do the job ... a cheapo of eBay will do.

I test BL motors with common cheap ESC with BEC ... and a Servo Tester ... with a small LiPo to power the ESC / BEC ....
The servo tester acts as the throttle of a radio ... and you can get these for about $5 ...

Nigel

Thanks Nigel.

I've found someone with a main board plus motors for sale. So I am picking that up.

 

[ggoosen]

Anyone know which parts form the esc?

 

[solentlife]

The ESC are built into the main board ... the three wires from each motor are soldered direct to each ESC on board.

Nigel

 

[ggoosen]

Ok. You can find escs on-line from numerous sellers or a local shop.

‘Castle’ is one brand I have used.

A 15 amp rating should be sufficient for your testing. It will have documents for hooking up the radio, batt, and motors.

Not sure if im allowed to post links here.

Found the following. Let me know if yout hink they are ok?

ESC with BEC
RC Afro 30A Race Spec Mini ESC w/BEC | eBay

2S lipo
2S 7.4V 30C 4000mAh LiPo Battery Deans for RC Car Helicopter Airplane Truck AU | eBay

Servo Tester (Controller)
Multi Servo Tester 3CH ECS Consistency Speed Controler Power Channels CCPM S1 813184923948 | eBay

 

[solentlife]

Blimey !!!!

1. A simple 10 - 15A ESC is enough
2. No need for 4000mAh size ... you only need a small pack ... but the question is - how are you going to charge the battery ? Your DJI charger cannot do a normal LiPo.
3. Servo tester is fine

Why not ask around - there should be an RC flyer around near you with gear that can test this for you ? Model flying club / RC Shop ?
Why buy items that only use once ?

Nigel

 

[Jrs 2069]

Love the fish one ? What kind of fish are Jewish and I’m not being an *** just curious from your post , I’ve caught a Goliath grouper aka Jew fish off ft myers Florida

 

[ggoosen]

Love the fish one ? What kind of fish are Jewish and I’m not being an *** just curious from your post , I’ve caught a Goliath grouper aka Jew fish off ft myers Florida

In australia we call them Mulloway or Jewfish, aka as Kob is South Africa.

Argyrosomus japonicus - Wikipedia

 

[jiminyfixit]

So i crashed my P3A due to a stupid error on my part this weekend.

Long story short, while fishing with my drone it went into the sea. Luckily enough the error that caused it to go into the sea (line wrapped around the propeller motor) was what allowed me to fish it back out again.

None the less, i stripped it all, cleaned it with fresh water and then baked it in the over for 24 hours on 50deg (low heat) to dry everything out.

After that, i cleaned the boards with isopro. I stripped the motors and cleaned them as well and then put them back together (they had sea sand in all of them)

After putting everything together, i turned it all back on, everything comes up but i get an ESC error.

After researching i have found this could be due to a faulty motor, busted esc or faulty cable to the motor.

So what i want to do is bench test each motor. Now i know i cant just hook it up to a battery direct, but is it possible to go and get an ESC, hook it up to the motor and test the motor works? That way i can illuminate the motors for being the cause. As i understand if the ESC is done then i have to replace the main board.

I feel your pain. I started out repairing water crashes 7 years ago and have determined that an ESC will not usually survive the AMP loading when a motor tries to fight water density, instead of air. Unlike the P2V class of DJI drones that had individual ESC's for each motor, (could easily be replaced), DJI decided to put the ESC's in the main mother board of the P3 class drones. More cost to the DIYer and more trouble to replace. You're on the right track if you can find a perfect working main board WITH motors. Good luck and have fun.
Jim