wiring a fan to a MM?

[ClodMaxx]

i have an old novak esc fan that i want to wire above my MM to help cool it. my question is where would i solder it? i can't add it to my batt leads, as it'll be getting the full 16.5v when i run at 5s. is there a way to solder it to the caps? i'd rather not have to add a 9v battery just for the fan, as that's one more thing to add weight (and another PITA to have to deal with in general).

any insight would be appreciated.

[BrianG]

This might help...

[JB3231]

I soldered mine to the leads for the receiver where they meet the board. I wouldn't do it again though. I would just solder to the wires next time.

[suicideneil]

I like that write up Brian, its one of the simpler little projects that even I could manage (probably).

Anyway, since ClodMaxx already has the novak fan I would say do the following:

1. If you have a spare slot on the rx, then just extend the wires (if need be) so that it can plug into the rx- it only draws a tiny amount of current so wont hurt anything.

2. If there isnt a spare slot, make one by using a short Y-splitter on either the throttle or servo channel so that the fan can plug in and the esc/servo rx plug can too.

There should be a spare slot though for a bec or rx batt to plug in so use that one, but sometimes this is doubled up as the channel 1 slot. Makes no odds though, just plug the fan into the rx and its good to go.

[BrianG]

Thanks. I was bored that day and thought it might be useful to someone. For some reason, people seem to like running fans.

Although, I was under the impression it was a 12v fan? A moderate-speed 12v fan will have very little airflow at 5/6v, but might be enough.

[ClodMaxx]

Originally Posted by BrianG

For some reason, people seem to like running fans.

well, i'm not one of them...

Originally Posted by ClodMaxx

if it gets too hot, i'll gear down... i think fans are band aids.

but i don't think i have a choice with the MM, LMT motor and 5s a123 packs. the novak fan i have is 5v but the only slot open on my rx is the second channel. i guess i could configure the spektrum to switch the fan on with a button...unless maybe it just automatically turns on when plugged in. (the battery slot is taken by a rx pack)

[BrianG]

Originally Posted by ClodMaxx

the novak fan i have is 5v but the only slot open on my rx is the second channel. i guess i could configure the spektrum to switch the fan on with a button...unless maybe it just automatically turns on when plugged in. (the battery slot is taken by a rx pack)

All receiver slots have power (middle connection) and ground (spot usually nearest the outside of the rx module). If the battery slot is filled, use the CH3 slot. The fan will come on right away. You could also use a servo Y adaptor cable, or make your own. Either way works.

Hmm, seems to me like an electronic-modding (PS modding, etc) specialty-adaptor-cable (Y charging/balancing adaptors, servo wire adaptors, etc) division of Mike's site would be popular...

[ClodMaxx]

yep, i realized after i made the post that it would get power as soon as i plugged it in. i have a light system i wanted to control with my tx for my crawler, and had to buy a r/c relay switch from dimension engineering to do be able to turn it on and off from the tx. as soon as i plugged the light system in without the pico switch, the light system turned on.

so, that's what i'll do - thanks neil and brian (notice the spelling) .

you're right - a specialty adapter section would be a nice touch to the Monster store!

[ClodMaxx]

hmmm... seems i can't find the 5v novak fan. but i did find a brushless 12v fan that i hooked up to the maxx at one time. i might just hook that up to the battery leads and have it blow on the MM and LMT at the full 16.5 volts. if it blows, it blows - but it certainly created some air current when i had it hooked to 14 cells.... bwahahahahaha...

[BrianG]

That's actually what that write-up I made is for....

[ClodMaxx]

right, but it'll be minus your fancy-schmancy voltage regulator. it's a great write up, but i'm an artist - wrong side of the brain. i have a hard enough time remembering what oil weight my 1:1 car takes when it needs to be changed.

the 12v fan i have is huge, and i like that my maxx looks rather clean without it at the moment. it'll be tough to leave it in there. if anything, i'll try it and see how far it drops the temps. if it doesn't drop it more than 10 degrees or so, i'll pull it back out.

[dadgummit]

Hey Brian, that is an awesome write up!!! I have just one question though. What is the minimum voltage for that regulator? Will it boost a 7.2v pack up to 12v? Thanks!!

[BrianG]

Thanks!

A linear regulator will not boost voltage, only reduce. And you need about 1-1.5v higher than the regulator voltage to work (this is called the drop-out voltage). So, a 12v regulator needs at least 13v to run right.

To boost voltage, you'd need a different type of switching BEC. All the UBECs that we use are actually bucking regulators.

[Arct1k]

Try ebay i got 25mm 5v brushless fans for about 4$ - I'll dig out the link later if you need it

[ClodMaxx]

this isn't bad for the price. 8 CFM should keep it cool too.

the same guy has a 4.5 CFM version in a 5v fan for $3.50.