# Efficiency of Afro ESC 30 Amp speed controller

(Miguel Lazaro) #1

Hi all!

I can´t find in the datasheet how efficient the speed controles are. Does anyone know? We want to do a heat sink for our robot so we need to know how much heat will the controllers generate.

Thanks,

(Rusty) #2

Hi Miguel, that’s a tough question that will depend on a lot of factors. There is heat in a lot of different components and areas on the ESC.

I can point you towards some of the main sources if you’re interested.

(Miguel Lazaro) #3

Hi Rusty, if you can give us an estimate of the main sources it will help us. Nowadays we have no information about it, so any information provided to us will be welcome.

(Rusty) #4

Miguel,

A lot of the heat comes from the FETs. On the Basic ESC, the type of FETs vary between batches, but they are usually SiR158DP. Per the datasheet, those have a resistance of about 0.0018 ohms. If we assume that each one is switching about 15 amps, then that’s I^2R = 15^20.0018 = 0.4 W of heat each.

Another important component for heat is the linear regulator for the BEC. Recently, the Basic ESCs no longer include the BEC, but if you have an older one and you’re using it to power anything, it will create quite a bit of heat. The BEC drops the voltage to 5V by burning off the rest as heat. For example, if you’re using the BEC to provide 250mA, then the power loss to heat will be V*I = (vbat-5)*0.250. For a 4s battery, that’s (16.8-5)*0.250 = 2.95 W, which is a huge amount of power for a linear regulator to dissipate.

You also get heating in the copper traces, the diodes, and some of the resistors, but those are less than these components.

Let me know if you have any other questions.

-Rusty

(Miguel Lazaro) #5

Rusty, thank you very much for the information. As first aproach it could be enough.

Thank you again.

(Philip Krug) #6

Rusty,

The Basic 30A ESC (w/ forward/reverse firmware) page, under specifications, indicates the ESC has a BEC.

Am I missing something or are the specs out of date?

Thanks
Phil

(TCIII) #7

Based on Rusty’s quote from above, I would say that the store webpage specs are possibly out of date.
Regards,
TCIII AVD