Overheating esc.

[Chrruss1]

I'm having an issue with my escs overheating. I have 2- 850kv, 210 watt motors that run fine on 2 separate 40amp escs and 2,3s batteries but when i try to run them on 1 large 4s battery, the 2 escs overheat.

My question is, what are the hows and why's to running 2 motors on 1 battery without overheating the escs?

 

[Mr NCT]

The nominal voltages for 3 and 4 cell lipo batteries are:
11.1V battery = 3 cells x 3.7V= 3S battery
14.8V battery = 4 cells x 3.7V= 4S battery

So by going from a 3s to 4 s battery you up the voltage and so up the amps and up the heat. A watt meter like this one will help you see where you're at as you mix and match batteries, motors and props.

https://www.amazon.com/gp/product/B06XPVKY13/?tag=lstir-20

 

[quorneng]

Chrruss1
Basically if an ESC is getting too hot to touch then it is likely its being over loaded i.e. it is passing more than 40A to the motor.
Going from 3s to 4s with the same motor and prop is likely to nearly double the amps.
You were lucky the over load did not destroy the ESCs.

As Mr NCT says using a Watt meter is the only safe way is to find out the actual full power amps. It is a real time meter so if you see the amps are rising towards the maximum of any part of the system you simply stop before anything gets damaged or destroyed.

 

[skymaster]

are both esc's and motor's the the same brand?

 

[joelspangler]

When you up the battery cell size (and the thus the voltage), it'll try to spin the props faster. If you don't downsize your props, you're likely to eventually run into a situation where you are pulling more amps than the ESC can provide. If you want to fly on 4s, you'll likely need to downsize your prop. I personally bought a cheap amp meter with xt60 connectors on it so I can see how much power I'm pulling when I'm not sure what size prop to use.

 

[Merv]

I agree with the above, on 4S you are drawing more amps. If the motor is also over heating, try a prop that is 1 inch small. If the motor is OK, try a larger ESC

 

[LitterBug]

If it is an old analog BEC on th ESC, that will generate more heat just going from 3S to 4S. Does it gt hot even before you start to fly?

 

[Chrruss1]

If it is an old analog BEC on th ESC, that will generate more heat just going from 3S to 4S. Does it gt hot even before you start to fly?

It's a scratch build that hasn't flown yet. Still working out the motor, battery. propeller. I just burned up 2 escs revving it up. the motors are smaller than i'll probably end up going with. Would small motors on big battery cause the escs overheat? i'd like to figure out what i'm doing wrong so i understand what's going on.

 

[quorneng]

Chrruss1
It is the motor, how it is loaded (the size and pitch of the prop) and the voltage (number of cells) that determines how many amps it will draw through the ESC and out of the battery. The capacity (mAh) of the battery determines how long it can provide those amps.
What is important is the maximum amps drawn by the motor must not exceed the rated capabilities of the ESC or it fails
The motor also has a maximum amp rating. Continuous running beyond that figure will cause the motor to overheat and eventually fail.
Even the battery can be permanently damaged if its rated max amps are exceeded.

In a plane the motor. ESC and battery have to be highly stressed simply to provide enough power to fly hence if these components are mismatched either a failure will occur or the plane just won't fly.

If you have burnt out two ESCs then the most likely cause is the motor is over loaded with too big a prop.
The only other possibility is the ESC are rated for 3s LiPo (it will be marked) and you have used a 4s. In this case it is the over voltage that will kill the ESC rather than the amps.
You really do need to know what amps your motor is drawing at full power to make a viable decision on what to do next.

 

[LitterBug]

Perhaps if you can provide a few pictures of your motors and ESCs we can have a better understanding of how you have things wired and what components you are using.

 

[Chrruss1]

Chrruss1
It is the motor, how it is loaded (the size and pitch of the prop) and the voltage (number of cells) that determines how many amps it will draw through the ESC and out of the battery. The capacity (mAh) of the battery determines how long it can provide those amps.
What is important is the maximum amps drawn by the motor must not exceed the rated capabilities of the ESC or it fails
The motor also has a maximum amp rating. Continuous running beyond that figure will cause the motor to overheat and eventually fail.
Even the battery can be permanently damaged if its rated max amps are exceeded.

In a plane the motor. ESC and battery have to be highly stressed simply to provide enough power to fly hence if these components are mismatched either a failure will occur or the plane just won't fly.

If you have burnt out two ESCs then the most likely cause is the motor is over loaded with too big a prop.
The only other possibility is the ESC are rated for 3s LiPo (it will be marked) and you have used a 4s. In this case it is the over voltage that will kill the ESC rather than the amps.
You really do need to know what amps your motor is drawing at full power to make a viable decision on what to do next.

Thank you!

 

[DaveM]

The nominal voltages for 3 and 4 cell lipo batteries are:
11.1V battery = 3 cells x 3.7V= 3S battery
14.8V battery = 4 cells x 3.7V= 4S battery

So by going from a 3s to 4 s battery you up the voltage and so up the amps and up the heat. A watt meter like this one will help you see where you're at as you mix and match batteries, motors and props.

https://www.amazon.com/gp/product/B06XPVKY13/?tag=lstir-20

YES! I consider a Whatt meter (first introduced by AstroFlight in the late 1970’s) a critical tool For electric flight.

 

[Shurik-1960]

If you are engaged in aircraft modeling for a long time , then you definitely need to have : 1.Wattmeter ,2. Balancer for propellers ,3 . A good charger. And the models will grow by themselves ...)))

 

[Merv]

... And the models will grow by themselves ...

I keep planting them but none of them grow. Maybe I'm not getting them deep enough.