MM 5700kv motor cooling XXXT

[DrKnow65]

Ok, I've looked and looked for a solution for cooling the Mamba Max motor I'm puting into a losi XXXT. The motor runs too tight to the laydown style transmission to allow for most clamp style heatsinks.

I had to open up the motor to replace the bearings (5x11x5mm for those who want to know). In the process it occured to me that I could possibly replace the bell/end cap (not sure what's correct term on a brushless) with a internally and externally finned unit. Mabey somthing I could have prototyped? I think it would be cool to have mounts for a fan also. Everything would have to come directly out the back of the can to fit the XXXT.

I also found that there is a 6mm tall plastic bushing on the 5mm shaft at the back of the rotor that perhapse could be replaced with a "turbo" fan like the one in my ofna .21 turbo nitro motor? To help circulate the air inside the motor...

The stipulation is that the whole thing needs to be less expensive than the motor it's going on ($80+/-).

[BrianG]

You have any pics of the motor in the vehicle? Maybe you could cut part of a clip-on heatsink to fit and then thermal epoxy it in place. The coils are on the can part so the best cooling will be done if the heatink is there. For the heat to get to the endcap, it has to travel along a fairly thin-walled aluminum can. It will help, but not as much as having the HS on where the coils are...

how come you needed to replace the bearings it was my understanding that castle use very good quality ones.

The problem with the mamba motors is that there not as efficient under partial load as some of the german motors.

I know that with a xxxt its a pain to get a heatsink on the motor but with my plett extreme without a heatsink and just a fan the temperatures are quite good.

I know that a lot of these feigao motors that companies like Orion, mtroniks, trinity etc etc are selling have built in fans but to be honest the efficiency of feigao motors offset that cooling advantage.

[DrKnow65]

I will post pic's shortly, have to figure how to do it... laymen

[DrKnow65]

http://imageevent.com/drknow65/rccarstuff Hope that will take you to the photo's. I don't realy know how to insert them properly so they just show up in the post, yet :)

[DrKnow65]

Here -rejoycing in my triumph not much room for a heat sink, and the gap changes front to back with pinion sizes.

[DrKnow65]

Chilledoutuk, I apologise, I didn't see your post till just now.

Castle does say their beating are sealed but you should have seen the abuse on this system befor I got it... lots if cleaning.
The bearings were noisy and I could even feel axial slop in them (more in the back, front wasn't as bad). The motor does work, I just don't like to have failures. An ounce of prevention is worth a pound of cure, that kind of thing.

Do the other motors with internal fans have 5mm shafts? Perhapse I could salvage one from a dead motor, should I get the opportunity.

Your opinion- what motor has near the same performance of the 5700kvMM but has better efficiency? cost?

[squeeforever]

I would get a Neu 1509.

[DrKnow65]

Ouch, for that cost I could make quite a few mods to the setup I have now. Are they around in reasonable used condition??? and are they that ($$$) much more efficient?
Sooner or later the best advise comes with a grain of salt... thanks guys.
Would still like to persue the end cap heat sink and see how that goes.

well the neu motor is a good motor but it has a 5mm shaft which will mean you need 48dp 5mm pinions which are quite rare indeed.

Well the way i see it is you have two choices go for a feigao based rebuildable motor with the built in fan or go for a more expensive high quality motor that has just a higher efficiency to begin with.

I have had a hacker c40 8s for some time now and its without doubt the best built motor i have ever had and the fins are excellent at dissipating heat when assisted with a fan.

You have to be careful with some of the HQ motors as some of them have very short output shafts which makes them impossible to use in some rc cars.

notably the kontronik twist and the plettenberg 1/10th motors have very short shafts which is ok in setups like the xxxt and other 2wd transmissions but in some 4wd cars there impossible to use.

If you are prepared however to use higher voltage such as 3s lipo you could pickup a velineon motor and use that with your mamba max and 3s lipo.

[DrKnow65]

Has anyone tried using a venom temp failsafe to monitor/protect engine temp on an electric car? I've read some about how the magnets get week after getting too hot.

[BP-Revo]

Well, your entire goal is to eliminate heat. Heat is really just a product of inefficiency. So, in other words, you are just trying to mask the inefficiency of the motor with more cooling. You aren't fixing the problem, just lessening the symptom.

To fix the problem, you need to go with a more efficient motor, i.e., a Neu.

Thats really my opinion. As for the fan idea, I personally think the wires would get in the way (so the fan would end up being a bit small) and there isn't much air in there, or areas for air to flow around (clearance between wires and rotor is very small) so I don't think it will have too much of an effect.

[DrKnow65]

I believe the combo I will be running soon shouldn't have too much of a problem with heat to begin with (losi xxxt, MM 5700kv, 8000hv 2s lipo). What I would like to accomplish is simply reliability with the option to push the package without failure (say to 3s or 4s at some point). As I am building on a budget now and will only be able to put more money in incrementally I would rather spend $25-40 protecting the $130 MM setup I got used and spend some money on shocks and tires or broken parts than to spend $230 on a motor I don't really need now and not be able to keep the car running due to lack of funds for other stuff.

I am looking for a good ole' hot rod ideal of making something less/more for as little as possible, over build and under use... ferrari's and bmw's are neat and fun but how much do you really get to enjoy one if you can't afford the tires or insurance. Now a cheap 86 5.0l mustang with bad paint and a cheap 350 horse motor is better than the ferrari when you get to drive it fast all the time with what your resources are.

I would love a neu motor, truely I would. If or when I find one in the $120 range I'm sure I could work out picking it up (there is a hacker c-40 I've got my eye on right now and if it dosn't exceed my price range I just might get that).

Point taken on the internal flow... I wasn't thinking of actually circulating the air inside the can as much as helping the heat transfer from a finned endbell to the exposed coil windings at the back of the can (copper is one of the best heat conductors) and the fan would also act as a bit of a heatsink itself to cool down the rotor?

Note: external 5vdc fan=$11.42
5mm "turbo" impeller off a broken nitro motor I alread have=free
Machined aluminum end bell with internal and external fins...Mmm mabey not so cheap? but could I do it all for $40, possible.
If it cost me $70 I'd be at the cost of the neu including the esc that runs the motor.