Motor Temps

Squares · #1 24-09-2012

Hi Gents,

I have done some searching but havent found an answer yet. With regards to motor temps, I understand that anything over 200 deg F is considered too hot, is this at any part of the motor?

I have just about got my Hyper 7e reliable, and on Sat I did a whole battery on a short figure of 8, so lots of intense throttle/braking. After I checked the temps and got the following:

Pinion/motor mount end 75 deg F
Midway along the motor around 120-140 deg F
End Can where the wires are, as high as 200 deg F.
Battery and ESC were both cool at around 85 deg F.

Is this cause for concern? The use was fairly intense without much air flow, a high-ish ambient temp and lots of braking.

It is a Castle Creations 1800kv 1512 1.5Y running on 4s. Standard Hyper "Spur" with a 19t pinion.

Is there any harm/point in putting on a heat sink for the motor to help with temps?

thanks for any advice.

Rich.

jasonwipf · #2 24-09-2012

Always go with highest temp at the end of the cam. If the mid side of the can was 140, your inside motor/rotor temp is likely to be 50-80 deg higher. If your motor end was 200 your inside motor can inside might be 200-220. The resins used inside the motors begin to loose integrity at about 200-225 depending on the model. You were with in parameters but just barely. Keep the end bell below 200 and the mid can below 180.

To cool things down try (one at a time, try these in descending order):
1. Driving habits. This is the Biggest contributor of heat and mileage. Drive on the track you race, not in figure 8s or in parking lots when testing your car. Herky Jerky 100% acceleration and 100% braking will wear your tires faster, lose mileage and increase temps dramatically. My best lap times on tracks were by shear surprise as I was taking it easy, carrying my weight thru turns, not braking hard and not gunning it like a crazy man.
A good analogy might be: Imagine you were on a dry dirt road in the countryside with a real 500HP sports car. Would you get better acceleration slamming the gas 0-100% instantaneously and spinning out the wheels in one place for 3 seconds before you gradually accelerated OR gradually building up speed from 0-100% throttle over 2-3 seconds? Of course gradual as we would maintain traction better and get better acceleration. While it may seem hard to see on an R/C track, the same physics apply. It takes me .25-.50 a second for me to full out accelerate from a turn with my throttle finger, but I always overtake those guys that gun it 100% instantly and spin their tires into low traction saw blades or spin out sideways and crash when they exit turns.
2. Adding holes in body for air flow. Depending on track you will have 13-22mph avg. car speed and that is great air flow thru your car.
3. Going up or down on the pinion gears. I suspect your pinion is a tad high. I used to run hypers at 16-17t, but then again I was on small American tracks.
4. Battery weight. If you are running at over 600g you might be too heavy. Batt. Weight matters. Try running a mile with a back pack full of text books and you'll know. I've seen dropping 150g make a 15-20deg difference.
5. Seized bearing(s). This is like driving your car with the parking brakes on. BAD heat and electric stress.
6. Heat sinks. Work well but can be expensive and unnecessary if you check other things.
7. Electric fans. Electric fans brake alot and are only rated at 7-12mph wind flow over the motor. If you have no air flow inside car shell, you are just recirculating hot air. It is better to have holes in the body in front of the motor than a fan ANY day.

My personal opinion is you car is fine. running in fig 8, hot acc. and braking was causing your heat issues but keep the 1-7 tips in mind for next time.

Squares · #3 24-09-2012

Hi Jason,

Thank you so much for your very detailed reply.

As I was just bashing, I was flat out kicking up dust and larking about.

I will take all of your advice into consideration for the future.

Thanks again,

Richard.

jasonwipf · #4 29-10-2012

Cool, I find when bash I can get my temps even higher than in racing due to long high rpm runs. You should be fine just watch that end bell temp. Cheers.