weird fan prob..well not really a prob - RC-Monster Forums

jokerjustin · **weird fan prob..well not really a prob -** 12.20.2009, 11:31 PM

today at the local track i was just messing around getting the hang of the jumps.. after about 20 mins i brang the truck in and notice the fans on.. i quickly temp it and its at 115?
figured it was higher than 150 but the fan stayed on a while so it shot the temp down...
so i take off again for about 3 mins and it comes on again this time as soon as it started i temped it and it was at 125... i really dont mind as its not a big deal but i thought the fans only turn on at 150?

BrianG · 12.21.2009, 12:08 AM

Is that 150*F figure heatsink temperature or device temperature? The temps at the FETs (or the surrounding traces) can be substantially higher than the heatsink temp, especially if it's cold outside. Also, depending on what kind of temp probe you have, they can be inaccurate if you don't calibrate it. I'm talking mainly IR types here where you have to set the emissivity based on the material and color you are taking the measurements off of.

jokerjustin · 12.21.2009, 12:26 AM

im actually temping thru the cooling fins in the case trying to get to the heatsink. its the only way ive figured out to get a heatsink temp. its been decently cold 67F the past few days.

i bout a chepo hobbykind ir temp gun... i knew it wouldnt be the best but it would give me a ballpark figure.. and on this one theres so settings that can be changed.

bdebde · 12.21.2009, 02:04 AM

The 150 temp for the MMM fan is measured at the FETs, someplace you can not get to to take temp with a normal temp gun. I find about 125 on the heatsink is where the fan comes on (150 FET temp), so no problem there. If the fan is always on and/or you get over 150 temps on the heatsink, then you may be pushing it too hard. Oh, and 67 degrees is decently cold?!?!WTF

jokerjustin · 12.21.2009, 05:31 PM

lol im as far south of texas as it gets.. brownsville.... our average temps are 90s for the year...with really high humidity..

the temps usually hover around 118 for the most part but if i drive for extended periods 15-20 mins with no rest breaks it will turn on.

its in a revo running
4s
geared 16-38 locked in 2nd std gear

guess its alright then i just dont wanna risk blowing this thing

bdebde · 12.22.2009, 01:15 AM

Sounds just fine, have fun with!

I am about as far north in Washington as you can get... 67 is decently WARM!