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I keep burning out electronics! What's my deal?!

#1
So I got a 1.2m EFlite Mustang for Christmas and I plugged it all up with a 4s 2200mah battery. After a few sessions of setting things up on my Taranis, the receiver stopped working and only showed a dim little flashing light. I got out another ESC and servo and the receiver still didn't work. I got out an Ar610 receiver and the Mustang's ESC didn't work, either; I got a low-voltage warning on the 610. So I replaced the ESC with an Aerostar RV 60amp ESC from Hobbyking, and I popped in an FrSky V8FR-II receiver, as well as picked up some 3s 200mah batteries. I think I wrecked this system with 4s batteries when I was supposed to use 3s batteries. Voltage or something... Lesson learned

Fast forward to now, I've been fiddling with FT planes and have shelved the big, beautiful Mustang until I am certain the electronics won't die mid-flight and leave me with a sad pile of foam.

I was using that same Ar610 module mentioned above in the FT Mighty Mini Corsair and FT MM Mustang (I wrecked the Mustang lol, high-speed cartwheel through waist-high prairie grass) with great success. Everything else was FT stock, with the BL Heli ESC and some 3s 1000mah batteries. After maybe two dozen flights, the receiver now flickers rapidly and won't bind. The ESC seems to be okay, the batteries check out, but that receiver is toast.

I don't really get all the amps and C-ratings and angry pixies. I came to realize that I had been assuming the motor only draws what it needs, so I get the proper voltage with either the recommended mAh and/or C-rating, or slightly more mAh and/or C-rating. I had been led to believe that mAh was roughly defined as how long the battery lasted, and C was how much power could be drained without explodifying the battery. Is this incorrect?
 

rockyboy

Skill Collector
Mentor
#2
You're on the right path now! :D

Voltage is something to never exceed - those are a measure of how angry the pixies are. :p
mAh on batteries is how much juice is in the tank which leads to how long it will last.
The motor will only draw mAh as quickly as the load demands (propeller & air resistance) but it will try to spin as fast as the incoming voltage will allow up to the kV rating of the motor and the ESC throttle setting.
Battery C rating is how quickly the battery can dump out the mAh without overheating and getting all explody or if it survives and cools down, becoming an inert lump of polymer that won't hold a charge.

That receiver could have been still reeling from the earlier encounter with an ESC hooked up to too much voltage - or the knocking around in the prairie could have started jiggling components loose in the chips or on the board. It's had a rough life :p
 

PsyBorg

Wake up! Time to fly!
#3
How are you powering the receiver and servos? Are you pulling off the ESC's built in BEc? or are you powering direct from the battery?

Built in BEC's (battery elimination circuits) are only rated to produce a set amount of current. If you are exceeding that limit powering the receiver and too many servos that could cause stability issues with brown outs and such.

If you are pulling directly off the battery that is more then most of those parts can handle voltage wise and you will toast them. Look up your parts and add up current draws. Then see what the esc's bec you use is rated for. You may have to run an external BEC.


DANG Rockboy was faster on the draw.
 
#4
A voltage stabilizer will smooth out power surges. Sometimes even the shortest power surge will fry a Rx. It simply plugs into a channel port in your Rx and will help protect against brown-outs. Hope that helps! :)
 

rockyboy

Skill Collector
Mentor
#5
DANG Rockboy was faster on the draw.
:p

A voltage stabilizer will smooth out power surges. Sometimes even the shortest power surge will fry a Rx. It simply plugs into a channel port in your Rx and will help protect against brown-outs. Hope that helps! :)
Good point - here's a good overview of using those to prevent noise in the FPV feed - they do have a another effect of preventing very short voltage sags from impacting equipment by discharging the stored pixes back into the line which should also help prevent receiver brown outs

 
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PsyBorg

Wake up! Time to fly!
#7
hahaha I love it.. a plain old capacitor is now labeled as a "Voltage protector" and being sold at 500%+ mark up above normal pricing. They are common values and common voltage ratings. You can go to discount electronics warehouses and get them for less then 3 to 5 cents each if you buy em in bulk.
 
#8
My BLHeli ESC has a 1a BEC, shouldn't that be enough? All I can find are these expensive BECs ($15 and up) that handle like 5a or 20a or more.

If I solder in a capacitor, where should I do it on the Ar610 using all PWM inputs?

Thanks you guys! I started this hobby with no help but the internet, and it's people like you three that provide me with what I need!
 

Hai-Lee

Old and Bold RC PILOT
#9
The simplest place/method to solder the capacitor is to an old servo or "Y" harness lead, (red and black wires only required).
With the lead you can plug it onto any spare channel or even the bind plug location and with enough lead length so that you can mount it in a convenient location, (secure and out of the way).

If you know how to remove and refit the pins on a bind plug you could even re-purpose a spare bind plug to connect the capacitor, (with an suitable lead length of course).

Have fun!
 

PsyBorg

Wake up! Time to fly!
#10
Simple search for 5a bec on Amazon comes up with tons of choices most under 10 dollars. repeat that search and choose what suits your needs. there are also 3 amp becs that come up in that search as well that are even cheaper. typical rull of thumb from a quick search of another forum nets the advise for 5a bec for up to 6 servos on airplanes.
 
#11
Thanks Psyborg, I've been really busy and I was lazy about my search.

Thanks Hai-Lee, I'm assuming the bind plug still works with the capacitor Y-harness plugged in? I suppose it's not a huge deal to unplug-replug-unplug-replug when I want to bind...

I've ordered a handful of BECs and I'll grab some capacitors after I've finished moving house.

So voltage is a hard limit for all the electronics, and I need to add up the amps drawn by electronics so as not to burn out the receiver & ESC. I knew about voltage, but for some reason the amps rule was explained away as "Oh, ESCs have BECs on them nowadays", which could have been a painful lesson to learn. I knew about all this in a tentative, layman's sort of way, but I thought BECs were really just for quads with high current draws. I'm still so ignorant! 😭

You guys have saved me lots of money and time!! Thank you!
 

Bricks

Well-known member
#12
Me personally every thing said above is correct but with our small foamies BEC should not be a problem I think you hit the nail when you plugged in the 4S battery. Most receivers will not handle a full 5 amp draw that is why on the large plane you will see BEC`s. My 30CC 3D gasser runs a plain receiver off of LIFE 2S battery running 7 digital servos with out ever a hiccup.
 

Namactual

Well-known member
#13
What Bricks said.

The linear BEC’s that are usually onboard the ESC’s are rated @ 6volts. The way they step down voltage is transforming the extra watts to heat. So if your going from 2s 8.4 volts to 5 volts you will be able to pull more amps than a 3s 12.6 volts before burn out. @ 4s 16.8 volts I would not trust any linear BEC’s unless it’s specifically rated for the application. Honestly, I still wouldn't.

I would just use and external switching BEC. Just make sure you don't mount the BEC and Rx next to each other. Also use the ferrite ring if it comes with one.
 
#14
There are 2 different receivers in my story. The one that took the 4s is toast for sure, I saw where the pixies escaped and left their dust on the board. Even the ESC was acting all wobbly-kneed and he's been permanently retired.

The other receiver was on the FT MM Corsair, and I'm surprised it's dead. The Power Pack F should come with a BEC, unless the Ar610 receiver is just especially weak. Edit: I've now moved to FrSky modules, specifically the V8FR-II. JSYK.
 

Namactual

Well-known member
#16
It does not say if those are linear or switching.:unsure: I would not imagine they would be linear, but I have no idea.

I used these with good luck...
Amazon
Cheap electronics they are though. No guarantees. I have bought four and used two regularly. The other two were for backups which are still new in the plastic bags.

For really expensive kits I would go with a better brand. Castle Creations come to mind.
 
#17
Okay I grabbed some of those.

I read somewhere that you have to disable integrated BECs on the ESC?? Is that true?

And where do I solder the BEC? I'm assuming the plug side goes into the throttle port and I solder the pigtails in place of the ESC's output plug?

Maybe pictures would help, if someone can provide! Thanks again, guys!
 

Hai-Lee

Old and Bold RC PILOT
#18
You do not need to disable the BEC on the ESC but disconnect it from the Rx by removing the red wire from the plug that connects the ESC to the throttle channel.
The UBEC can plug into any spare port on the Rx to power the Rx and servos.

Have fun!