Alltrax heat

[kojo]

In a recent post I read about the Alltrax controller getting too warm and going into thermal shutdown. What does the case temp. have to be up to, to go into that? Also, how will it react, will it go but not fast? Mine done this yesterday, when I stopped and started back on the pedal I noticed it didn't take off as fast and would slowly get a little faster but wouldn't go quite wide open. I stopped again a little down the road for a min. and it seemed to act a little better but then again it still didn't have the get-up and go it had. I measured case temp. when I got home and it was 146 f., is that too hot or could it be the ITS. Thanks for any help guys.

[JohnnieB]

Connect a laptop to it and generate a log of the monitored data.

The column labeled "Throttle Position" is actually the Duty cycle % and the one labeled "Diode Temperature" is the temperature of the buss bar the MOSFETs are attached to (M-).

The Duty Cycle % lags the throttle position depending of the throttle curve selected and the throttle up rate selected, but will go to 100% if your foot is on the floor for more than a few seconds no matter how they are set.

The cutoff is 95°C (203°F), but that is the buss bar temperature rather than case temperature, so I'm not sure what you would measure on the case at thermal cutoff, but it would probably be less than what it is at the buss bar.

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When you installed your Alltrax controller (DCX?), did you remove the stock thermal pad that was between the stock controller and heatsink?

I took the heatsink out of the cart and used a wire brush on a bench grinder to get it off. I brushed it until was a bright aluminum color with a slightly rough texture. (Smooth and level, but Matte finish rather than Glossy.) When I installed the controller on the heatsink, I coated the backside with a generous layer of thermal grease.

The highest buss bar temperature I've ever recorded with it is 41.3°C (103.3°F) and that was when I was driving the cart as hard as I could.

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Give Alltarx a call. They can tell you more.

[scottyb]

Good info JB

[kojo]

No, I didn't remove anything, I kept it as it was but, sounds like I might need to. Thanks for the help JohnnieB.

[JohnnieB]

Originally Posted by kojo

No, I didn't remove anything, I kept it as it was but, sounds like I might need to. Thanks for the help JohnnieB.

There are better thermal pads today than there were when most of our carts were built, but any thermal compound is still better than most thermal pads. Thermal compounds are messy to use, so they are not well suited for mass production and thermal pads are typically used on production lines.

As long as the product will survive the warranty period, the bean counters are happy. Actually, if the cost of replacing failed items during the warranty period does not exceed the cost to use better produces and practices, the bean counters are happy.

Also, thermal pads are typically a one use item. Whenever a controller (or any other heatsink mounted component or device) is detached from the heatsink, a new pad or fresh thermal compound needs to be used when it is reattached.

BTW: When I said I used a generous coating of thermal compound, I meant I used a thicker layer than I use on shiny and/or machined surfaces. I smoothed it to a thin layer with a putty knife rather than the single edge razor blade I use when applying thermal compounds to power transistors and CPU chips. The object is to fill the tiny low spots in the surfaces, while still allowing metal to metal contacts at the high spots.

[kojo]

I've never used thermal compound but one or two times, but I'm glad you guided me on how much to use. I probably would've plastered it on thicker than you've described, thinking with the ole' adage "the more the merrier". Thanks again buddy.

[kojo]

When the Alltrax controller's go into thermal shutdown, does the cart stop altogether or does it reduce the amps and cause the cart to slow down drastically.

[radioman]

I wonder if a small fan to help cool the heat fins on controller mount would help reduce thermal shut down problems?

[kojo]

Radioman, that's crossed my mind.

[cgtech]

Ezgo 2five has fan from the factory. I have done that (2 computer fans added) with HS geared RXVs that get driven hard, the controller can be forced into "reduced output" pretty quickly on a RXV with gears. It worked well. This is not exactly the same, but pretty close. Has anyone else on here ever checked the flatness of their alltrax controller, i can tell you, they're not very flat by "heatsink standards".