Powering a motor cooling fan

[stuey]

Hi guys, quick question. I want to add a motor cooling fan to a TC, I was going to use a spare ESC fan I have. Usually the fan would be powered by the ESC, but does it power it directly from the main battery, or from the BEC which feeds the radio? The speedo does not have a power feed for a fan, as it does not have that option.
Cheers

[beale]

Any spare RX channels? That's what most use. You could double up on the ESC fan connections or just run it off the main battery, will run at ludicrous speed off main batt but plenty of cooling!

[stuey]

I was thinking of that, I guess it doesn't pull too much current. I'm not sure how good the bec is in the Hobbywing 1060 Speedo.

[dlr]

I have one of the wtf/yokomo fans which can take 8.4v quite happily and I had this wired straight to the battery leads. When I changed my chassis, to start with I had it in my receiver, only a cheap Hitec thing, had a couple of brown outs which was interesting/annoying to say the least with the car spearing off at full throttle for a second or so!

Back on the battery leads and no issue since. I expect better recievers will be fine but off the battery the fan spins quicker anyway due to the higher voltage. Most fans are 6v so might burn out a bit quicker direct off the battery so bear that in mind or just get one like mine

[stuey]

The brown outs were what I was concerned about. The little extra power drain from the receiver could put it on the edge. I have an old schotty diode in the box, I might put that in line to the fan feed to knock a bit of voltage off it and power it from the battery pack.
Thanks for the feedback guys

[andrewc]

Stuey;

I've recently added a fan to my motor in my 4WD buggy; I butchered up the separate AA battery holder (receiver power supply) that most people have lying around to make to necessary leads.

Been running it off my sanwa receiver on a spare channel with zero issues for a couple of months. Was also amazed that it dropped motor temps by more than 30C!!

[Northy]

First of all, the speedo supplies the BEC power, not the receiver, so the receiver shouldn't make a difference.

Second, a schottky diode will only drop ~0.2V, so not much at all.

G

[Chris Larner]

Andrewc did you fit the fan to the motor or mount it so it was blowing at the sensor end of the motor or side of the can?

[stuey]

Originally Posted by Northy

First of all, the speedo supplies the BEC power, not the receiver, so the receiver shouldn't make a difference.

Second, a schottky diode will only drop ~0.2V, so not much at all.

G

I think some confusion has set in here. I know the BEC supplies the RX power, if you plug a fan into the RX for a power feed it is adding to the load on the BEC, albeit only a small amount I would guess. I am a flyer too and I always consider the RX supply, as a few seconds of signal loss can be the end!!
Thanks for the heads up re the Diode, I thought some of them knock about 0.7v off which would help a bit.

[Northy]

That's ok, yes a standard diode does, 4001 or something.

G

[andrewc]

Chris

Like this; at rear end of can but as close to chassis edge as I could get to blow down side.

Staggered at the difference in temps!

I put it far enough back that I can remove motor without 'unsticking' the fan.

[stuey]

I powered the fan from the rx in the end and seemed ok. Motor was still mega hot though!