# I need a key-off activated 2-5 min timer circuit



## GizmoEV (Nov 28, 2009)

I have a cooling blower attached to my motor which is controlled by a 12V relay hooked up to a NO thermal switch on my motor. Right now the blower shuts off when the key is turned off. What I want is a timer which will run the blower for a couple of minutes when the key is switched off. I'm hoping I can build something simple from RS parts. Any suggestions?

Thanks,


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## DIYguy (Sep 18, 2008)

GizmoEV said:


> I have a cooling blower attached to my motor which is controlled by a 12V relay hooked up to a NO thermal switch on my motor. Right now the blower shuts off when the key is turned off. What I want is a timer which will run the blower for a couple of minutes when the key is switched off. I'm hoping I can build something simple from RS parts. Any suggestions?
> 
> Thanks,


There's one on my build thread. Just looked it up. Start at post #394
http://www.diyelectriccar.com/forums/showthread.php/good-ohmn-here-we-go-23492p40.html


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## major (Apr 4, 2008)

GizmoEV said:


> I have a cooling blower attached to my motor which is controlled by a 12V relay hooked up to a NO thermal switch on my motor. Right now the blower shuts off when the key is turned off. What I want is a timer which will run the blower for a couple of minutes when the key is switched off. I'm hoping I can build something simple from RS parts. Any suggestions?
> 
> Thanks,


I think a time delay relay would work.

http://www.suntekstore.com/goods.php?id=14002896&utm_source=gbus


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## O'Zeeke (Mar 9, 2008)

major said:


> I think a time delay relay would work.
> 
> http://www.suntekstore.com/goods.php?id=14002896&utm_source=gbus



Thanks for the link major, great site


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## Roy Von Rogers (Mar 21, 2009)

Get a temp sensor and fix to motor, wire it so it will run til motor cools off.

There are some simple thermodisks that would work...and its KISS.

Roy


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## GizmoEV (Nov 28, 2009)

Roy Von Rogers said:


> Get a temp sensor and fix to motor, wire it so it will run til motor cools off.
> 
> There are some simple thermodisks that would work...and its KISS.


I could do this with the existing NO thermal switch but I'm not sure it is necessary for it to run that long. Basically I want it to run long enough that if the brushes are really hot they won't heat soak the comm to a temp hotter than it would ordinarily be or locally heat just the parts under the brushes to more than the parts between the brushes. Maybe this is overkill but I don't want to have happen what happened to my last motor, a couple of comm bars lifted even though I stayed below the safe rpm limit of 6000rpm. D&D said that they lifted due to the overheating it experienced early in its life before re-gearing and forced air cooling.

I don't know what temp the the thermal switch D&D is installing will turn off at but if it is sufficiently high then the fan might not run exceptionally long. The thermal switch I used on my old motor wouldn't turn off until ~96°F or so, so the fan would run a long time to cool to such a low temperature. I also figured if I set it up right that the fan could automatically come on after the key was switched off even if the thermal switch hadn't turned the fan on. I have a relatively steep hill climb just before getting home so it is entirely possible that the comm and brushes will be hot from 2-3 minutes of conducting 400A and the thermal switch won't detect it.


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## GizmoEV (Nov 28, 2009)

DIYguy said:


> There's one on my build thread. Just looked it up. Start at post #394
> http://www.diyelectriccar.com/forums/showthread.php/good-ohmn-here-we-go-23492p40.html


Thanks, between that schematic and major's link I should be able to come up with something that will work just fine.


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## evjunky (Mar 5, 2012)

Roy Von Rogers said:


> Get a temp sensor and fix to motor, wire it so it will run til motor cools off.
> 
> There are some simple thermodisks that would work...and its KISS.
> 
> Roy


i agree just get one with the right temp they are only a couple of bucks or even a secondhand turbo timer


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## Nathan219 (May 18, 2010)

This should work and for $25 free shipping.

http://www.ebay.com/itm/APEXI-TURBO...Parts_Accessories&hash=item3cc1c2bdf8&vxp=mtr


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## evjunky (Mar 5, 2012)

Nathan219 said:


> This should work and for $25 free shipping.
> 
> http://www.ebay.com/itm/APEXI-TURBO...Parts_Accessories&hash=item3cc1c2bdf8&vxp=mtr


lol it will work just dont expect it to be genuine lol how much is freight from hong kong?


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## GizmoEV (Nov 28, 2009)

Nathan219 said:


> This should work and for $25 free shipping.
> 
> http://www.ebay.com/itm/APEXI-TURBO...Parts_Accessories&hash=item3cc1c2bdf8&vxp=mtr


Thanks for the idea. A little overkill, however.



evjunky said:


> lol it will work just dont expect it to be genuine lol how much is freight from hong kong?


Especially the fact that it displays "A/F Value, O2 Sensor Voltage, Battery Voltage and Countdown Time display in Blue LED"

Except don't sparks create O3? Maybe I can see how much ozone I'm creating while driving.


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## DIYguy (Sep 18, 2008)

I kinda like the timer Major suggested. It's cheap, available and adjustable.. and u dont have to build it.


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