A question on getting ESC temps down

[sleebus.jones]

So in my current setup of 12 cells NiMH, 15/46 with a MM ESC and Feigao 10L, my ESC is getting hotter than I'd like it to. I read this a while back:

Although not always true, a rule of thumb is:
Hot motor, cool controller, cool batteries = undergeared
Cool motor, hot controller, hot batteries = overgeared
Warm motor, warm controller, warm batteries = happy components

It appears that I fit into the overgeared category. I was wondering, if I switched to a 7XL from the 10L, would that help the ESC heating, or not make any difference? The motor is fine, it gets maybe 120.

Sleeb

[MetalMan]

I don't think the 7XL would make it run any cooler. My guess is it would make the MM ESC run hotter. Do you have a fan over the MM? For my Revo a 40mm 5v fan made a huge difference in ESC temps.

[t-maxxracer32]

i too am having a problem with it so i tink im going to go to radio shak and pick up that 5 dollar 12v fan... if it would work. not sure. i will see later today thogh

[sleebus.jones]

Nope, no fan on the ESC. I'm trying to see what I can do with passive cooling before I do active. I figure building an air duct out of some 1/8" plexi should be simple, and also a bit of air management with the body will help too. I'll let you folks know how it goes

[Sylvester]

Too bad we cant just easily take off the original heatsink and put on a larger one.

That 10L isn't a hot motor and is about equivalent to the 7XL, although the 7XL has more torque. I only played around with the 10L for a little bit and the lack of torque (well, not as much as the 7XL) was really the only difference that I noticed.

If your MM is getting too hot, try going with a smaller pinion. What gearing are you running?

[sleebus.jones]

I'm running 15/46, so yeah, it's geared pretty tall. 13/46 was no problem, and still pretty spunky. I may try 14/46 as a happy medium. My thinking was that if I was overgeared at 15/46 for a "L" can, that 15/46 on a "XL" can might not be overgeared, which would (theoretically) reduce my ESC temps.

You noticed a lack of torque with the L? Holy smokes dude, I thought that bugger was pretty torquey. The 7XL must be a beast. I'd be tempted to try it, only that metalman said he thought it might make the ESC hotter, and I definitely don't want to go in that direction. What gearing/cells/etc are you running on yours and how are your temps?

Sleeb

[riceman]

I've found that my fan makes a huge difference. I'm running a 25mm 5V fan mounted directly to the cooling fins. No problem running my Neu 1515 with 5S. Temps are around 125 F under race conditions.

sleebus,

Remember, I'm running my setup in a buggy, not a truck. For some reason, I'm thinking that you are running this in a truck.

I'm running 14/46 in my buggy and the temps on the motor and esc never got hot enough to compel me to take a temp. I got pretty good at judging motor temps by touch when I was running nitro, and if I had to guess, I'm not getting anything over 140 on the track. I do, however, run fans on both the esc and motor, as an insurance policy.

As for the 7XL being torquey, it is a beast in an 8lb buggy. I can clear our big jump with only a 6 foot running start. The nitro guys have to hit the turn before the jump just right to get enough of a start to clear it. The only downside is that my Crimefighters seem to be wearing out more quickly, even though I only run them on the track. I'm running 10,000 in my center diff, 7000 in the front, and 1000 cut with shock oil in the back with no rear sway bar (our track tends to get lots of ruts) and my buggy hooks up really well.

[suicideneil]

Hey sleeb, hows it going over there? Quiet without me, Im enjoying my exile overhere. I've been thinking about your cooling problem too- would it bother you to put a couple small holes in your body; if not then I have a nice solution. What body you got on the BL buggy- drill two holes where the head lights would go, and then run some nice wide tubing from there to the esc, that way when your driving along the air is drawn in through the holes, down the pipes, and onto the esc, kinda like a ram scoop real cars use in place of a head light. If the body is the wrong shape then just mount the tube in the window say, and direct it right down onto the esc, but not touching obviously. I reckon something like that would work great, if not then it would have to be a small fan on the esc. Good luck at any rate and tell SOD I said hi!

EDIT: I just watched the vid, wow that things fast & I see the shell now. Hmm, my idea wont work- instead what about a scoop either side of the nose (symetry+better airflow) that goes in under/through the sides of the shell then direct them onto the esc, and hold in place with....voodoo magic?

[BrianG]

There are a couple things to consider when making cooling mods involving the body and piping; 1) When you replace the body, you have to move the mod as well. 2) If you land on the lid, the pipe may be smashed against whatever it is near (of course if you don't crash, you don't have to worry about this. :)). 3) Routing the pipe around all the other parts.

If at all possible, I alwys see if I can add another/more heatsink rather than going with a more exotic cooling solution. Keeps it simple too.

Just my $0.02...

[sleebus.jones]

aangel: I'm running this in a Hyper 7, so not a truck. :) I forget offhand, but are you running a MM ESC? If so, I'm guessing the temps are fine then?

Neil: howdy there. The body already has holes in it, so I don't have any problems making them bigger. I may just open up the top of the front "window" and see how that works. right now it just has some holes drilled in it. Hoses and all that are way more than I want to get into...and won't flow enough air anyway I don't think.

BrianG: Yeah, I thought about crashworthyness too. I was thinking a plexi "funnel" to aim incoming air at the esc, and wanted to keep it far enough away from the body to keep it from getting cracked up. BTW, how is the gasket working on the center diff? I'm still bleeding diff oil, so I'm going to need a solution or maybe a 777 diff. :)

Sleeb

[BrianG]

Originally Posted by sleebus.jones

... BTW, how is the gasket working on the center diff? I'm still bleeding diff oil, so I'm going to need a solution or maybe a 777 diff.

I really don't know. I ordered the paper-ish gaskets from Tower and installed them just in case. They seem to be holding up (used 2) but then again, I haven't run my buggy yet either (was waiting for metals to finish it up). :dft001: Seems to hold up with the buggy on my workstand though. :)