Active Motor Cooling

[bronsonj]

Hello all,

Once a year I pull a float in the Christmas parade. The motor got quite hot last year and I am trying to avoid that again this year.

My latest idea was to add some cooling fins and fans to the motor that are powered off the 12v source and connect them with a thermal switch.

At 75 C the fans would turn on and at 95 C a buzzer will sound. Around 15C cooler and the switches will turn off.

My hope is to use these switches zip tied to the motor.
https://www.ebay.com/itm/KSD301-250V...r=521953257105
The switches are rated for 10 amps. The fans use 0.15 amps and the buzzer uses 0.02 amps.

The fans will be mounted above tiny cooling fins to help a little more. I plan to drill the cooling fins and mount them like ScottyB mounted his temp sensor on the bolt in the side of the motor. I was wanting to mount two fins and a fan on the front side of the motor and two more fins and a fan on the back side.

Here are the fans, fins, buzzer:
https://www.bgmicro.com/FAN1128.aspx
https://www.bgmicro.com/to-220-heat-...uge-0-020.aspx
https://www.bgmicro.com/piezo-alarm-by-murato.aspx

This is bolts where I'd mount the fins and fans. Two sets on opposite sides of the motor:


Thoughts? Is this merely a fools errand?

[scottyb]

Have you considered getting a different motor for the parade?
Some motors have a vented brush (end) cap to let heat out.

[yurtle]

Back when I was feeding my stock series motor 48 volts and set for 500 amps (which it never achieved), I was considering fabbing up a rectangular hopper from HDPE, which I happened to have lying around. The hopper would have a towel leaving end edge, wrapping around my motor once, then returning to the other edge of the hopper. My plan was to carry a cooler if ice, and feed it as it melted. Just for 4th of July buggy parade. Never got around to it. I planned on using distilled water, just because it's a better insulator than tap water with chlorine, fluoride, and other dissolved solids.

[yurtle]

If you go the cooling fan route, I'd get a WAY bigger fan. Maybe several.

[JohnnieB]

I suspect it will take a lot more than the fins and fans you've listed to keep a sepex motor cool at parade speeds.

First, are we talking about the TXT48 with stock motor, tall tires and a Lithium battery pack you posted the Data Log files for?

If so, it'll take something more like wrapping a towel around it with water constantly dripping on the towel (evaporative cooling) to get rid of the heat being generated at walking speeds.

Based on the "Beet Run" data log, your motor has an average energy consumption of about 1700W from 2MPH to 4MPH, and at the low RPM the motor is turning in that speed range, it is probably only about 65% efficient (if that much), so abut 600W is being converted to heat. Basically, you will be trying to get rid of the heat generated by a half dozen 100W incandescent light-bulbs.

If possible, do a data log for a few minutes at parade speed over terrain similar to the parade route and I can crunch the numbers to get a better guesstimate.

(I've got the tire height a bit over 23" tall, is that right?)

[JohnnieB]

I knew the red neck motor cooler had been mentioned here, I just couldn't remember who I was discussing it with.

[yurtle]

That be me.

[yurtle]

Could you borrow or buy cheap stock wheels/tires? I have a whole set under my house, that I inherited when a neighbor upgraded.

Funny story. My neighbor asked if wanted them, and I said yeah, if they're bigger than mine. We rolled one next to mine, and sure enough, they were one inch higher. Fast forward a few minutes later, and now the old ones were an inch higher. DOH! loaded tires aren't round anymore.

If you feel like driving 8 hours, they're yours.

[bronsonj]

ScottyB: I haven't considered a different motor for the parade. I didn't really want to spend $600 or so for the one day. That may be a better option as it could prevent other problems, but I just don't see that being doable at this point.

Yurtle: I did get two fans, planning on putting each on their own thermal switch, but thinking back those fans put out 20 CFM each and that's probably not going to be enough.

JohnnieB: Yes it's the same cart. I was worried as the parade route is going to be longer so I ordered another set of Volt packs to double my capacity. But that is the same cart. The parade doesn't have any walkers, so it's faster than 4mph, but certainly less than 12mph. I'm not a good estimator of slow speeds but I would say the speeds fluctuate mainly between a jog to a mild run with occasional stops. So heat dissipation may be 5 x 100w bulbs instead of 6x. Regardless those fans are not going to be enough...

[bronsonj]

Yurtle, thanks for the offer but I think 8 hours and 3 tanks of diesel are a bit more than I want to spend for stock wheels! I can ask around though as we have a fairly active golf cart community here even though area hasn't been designated as 'golf cart friendly' (at least, not yet).