mamba max brushed

[BrianG]

You might be able to. It also depends on the servo load. If you are running one lower power/speed servo, you should be ok.

However, I always recommend a UBEC over 3s or 8 cells. The ESC will just heat up more because of the BEC and that's the last thing you need. Think of it this way, running 4s on the built-in BEC with a 1A load will force the ESC to dissipate over 9 watts. That's really a lot.

[jollyjumper]

ok, thank brian.
i will be running servo's of the digital kind with 8kg of torque or even better.
so i'll need the bec then.
i tested a motor of my truck(stocker) and on 7.2volt it only did 15k rpm.
so i'll be runnig 4s lipo or or 12 cells NI-MH anyway.
then it will do about 40~45kph.
thats good for me.

[BrianG]

Your ESC will thank you. ESC temps will be lower too and that's a good thing! :027:

[jollyjumper]

well something's off.
maybe its the bec.
the steering suddenly lost lots of torque.
my servo was a little warm.
will try other servo tomorrow.
will see then. hope its not the MM.

[BrianG]

Originally Posted by jollyjumper

well something's off.
maybe its the bec.
the steering suddenly lost lots of torque.
my servo was a little warm.
will try other servo tomorrow.
will see then. hope its not the MM.

Sounds like the servo isn't getting the power it needs. The built-in BEC in most ESCs are linear ICs. They usually have some type of thermal and overload cut-off to pretect themselves. Measure the voltage on the BEC (use a servo Y adaptor) while working the servo and see what the voltage looks like. It could be driving the BEC into overload (from the hi-power servo) and cutting back the voltage.

[jollyjumper]

could all this start all of the sudden?

[BrianG]

I suppose it's possible. The internal BEC is supposed to have protection, but if it was pushed too far too often/long, it might be permanently damaged, which would explain the suddenness. Again, measure the voltage while the servo is moving and see what the voltage does.