Thermal sensor for a 12vdc fan?

[lazarus2405]

I'd like to rig a small fan inside my (future) controller and have it turn on at, oh, 40-50C or so. How would this most easily be accomplished? Some sort of thermal switch in series with the fan, I'd figure. Could anyone tell me the keywords of what I'm looking for, or better yet, a digikey number?

And while I'm posting... does anyone know how to increase the current limit on a v2 clyte controller without modifying the Rshunt? Necessary resistor values, solder points, etc?

 

[deardancer3]

I'd like to rig a small fan inside my (future) controller and have it turn on at, oh, 40-50C or so. How would this most easily be accomplished? Some sort of thermal switch in series with the fan, I'd figure. Could anyone tell me the keywords of what I'm looking for, ?

You want Single pole (SPST), thermal switch, Normally Open (NO) rated at probably at least 100 millamps, and the F thermal rating ; 100F to 115F, unless you are in Phoenix.

35C: 317-1092-ND or 40C: 317-1093-ND digikey might work, as might some others.
http://dkc3.digikey.com/PDF/T073/P1824.pdf

I can check the local electronic surplus house, but could be a week or so.

dick

 

[lazarus2405]

Thank you very much. That was exactly what I was looking for, and that second one should be perfect.

No need to check any local suppliers. I'm placing a digikey order this weekend for hall sensors, and was wondering what parts I should get, while I'm at it.

 

[fechter]

And while I'm posting... does anyone know how to increase the current limit on a v2 clyte controller without modifying the Rshunt? Necessary resistor values, solder points, etc?

I don't think that one has been reverse engineered yet. It might be nearly the same as the old one, there should be some way to change the gain of the amp that's looking at the shunt.

One problem is if you jack the limit up too much, the shunt might overheat and desolder itself.
That's why I usually beef up the shunt, then use the amp circuit to lower it.

 

[lazarus2405]

One problem is if you jack the limit up too much, the shunt might overheat and desolder itself.
That's why I usually beef up the shunt, then use the amp circuit to lower it

Then I have to remeasure the shunt resistance. Not a big deal, I suppose.

What would be the best way to keep things cool, in the 60-100A range, while we're at it? I was thinking a 4cm fan inside the case and a full CPU heatsink/fan mounted on the outside, using a thermal switch, powered off a 12v dc/dc converter.

 

[fechter]

I'd go for extra fins on the outside with a fan there so you can keep the controller box sealed against rain. If you're using good FETs with low on resistance, the controller should not get hot enough to need a fan, but at 60-100 amps for any length of time, I think things could get hot.

 

[lazarus2405]

I'm not concerned about the FETs, but rather everytthing else. I'll add some copper to the busses, which should help. I don't know what else I'd need to keep cool. I just don't want something to desolder itself at 50mph.

While you're reading, fechter, what do you consider the chances of blown hall sensors from a phase wire short that blew the low voltage components on the controller? After Bob let me know that the unit had failed in such a way, I thought about it and decided it was an almost certainty. Checked the sensors and couldn't get a reading above background (using 5.8v). Looks like they were exposed to full battery voltage.

So, anything I should add to my digikey while I'm at it?

 

[fechter]

Digi-Key Part Number 480-1998-ND
Hall sensor.

If they took full battery voltage, they're toast for sure. No fun to replace either.