Exposing the heatsink on your MMM?

Originally Posted by primus95

Without a fan? What's your gearing?

He means that he runs 6S which is going to produce alot more heat and a higher chance of the of the ESC reaching critical temp hence why having the fan is a good backup plan

[sikeston34m]

Originally Posted by primus95

I see no real need for a fan on 4S if geared correctly, so I agree with you there. But I would also like to keep the ESC as cool as possible , hence chopping the top.

On 5s however, IMO a fan or open case is a must, the heat generated in the ESC & motor so much greater. My motor temp goes up 20C running 5S over 4S

You're seeing such an increase in temps because you're using the same gearing.

I put together a 6S setup on an Emaxx using a heli 8 pole outrunner geared for 32mph. I was SHOCKED at how cool everything ran. This was with a MMPro btw. A good indication that amp draw was relatively low.

Motor temps and Esc temps both relate to efficiency losses. These losses stack up and create more heat as amp draw increases.

To increase the voltage and drop the amp load on the motor means more power with less heat. You must gear down to see this.

[RBMike]

You guys have it wrong. Everything is cooler on 6S if your geared & motored properly. I run 6S with 1400 to 1700Kv motors, I take the fan out & forget about it. Always cool.

Power= Voltage X Current

As Voltage goes up, current goes down. Current thru the system is what causes heat not voltage.

If your stuff gets hotter on 5 or 6 S then you have the wrong motor or gearing at least.

With 6S/1400Kv, I use 950 to 1000mA in a 5 minute qualifier with a 2 minute warm up at a fairly large track (NorCal).

[coolhandcountry]

I have only ran a fan on one setup.
I was pushing that though.
I think exposed heat sink is not a bad idea.
As long as not to much foreign materials went into ESC.

Originally Posted by Pdelcast

In the wurx!

You have perked my interest dear sir!

[shaunjohnson]

i'm only geared for 40mph, 17/65 on an e-maxx tranny in a revo.

my peak amp spikes are only 70A and i can barely get that much power to the ground regardless.

it's all about the Watts required!

25.4v from a 6s peak voltage x 70A for 40mph = 1778W
16.8v from 4s peak voltage to attain same speed still requires 1778W of power to get that kind of acceleration to that speed.

so 1778W / 16.8v = 105.8A in theroy.

all in all, more amps = more heat

hence higher voltage is better for temps, wanna run 60mph but getting too hot?
try running 12s, same principle.

if you need your fan to be on all the time then if it fails then you are fecked!! no backup plan or anything, least if my fan were to be broken, i'd still be able to finish the race and hopefully find the dead fan before it was needed by the ESC.

[webracer]

I have been thinking of removing my MMM case altogether, and submersing the ESC in a bath of silicone fluid. I haven't done it yet as I cannot find a clear plastic sealable box in a suitable size for the ESC. This will keep it cool (and I could add another heatsink to the outside of the box), and make it waterproof.
Has anyone done this? I want the clear box so that I can see the lights on the ESC.