Cooling Fan Amp Draw
Thread Starter
Melting Slicks
Joined: May 1999
Posts: 2,037
Likes: 0
From: Sarasota FL
Cooling Fan Amp Draw
Well, I finally got my wiring sorted and late starter in. I replaced the fusible link feeding the fans with blad fuse holders (the old one was eaten up by battery acid). I found an old post stating the main fan drew 20 amps. Plus, the fusible link was marked 20. So, I used a 20 amp fuse, which immediately blew when the fan kicked on. I then tried a 25 - it worked but I'm afraid of burning up the fine wire left over from the old wiring.
What should I do. Could the 20 amp fuse have blown at 18 or 19? Is the fan drawing too much?
What should I do. Could the 20 amp fuse have blown at 18 or 19? Is the fan drawing too much?
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by Aaron's 87
Well, I finally got my wiring sorted and late starter in. I replaced the fusible link feeding the fans with blad fuse holders (the old one was eaten up by battery acid). I found an old post stating the main fan drew 20 amps. Plus, the fusible link was marked 20. So, I used a 20 amp fuse, which immediately blew when the fan kicked on. I then tried a 25 - it worked but I'm afraid of burning up the fine wire left over from the old wiring.
What should I do. Could the 20 amp fuse have blown at 18 or 19? Is the fan drawing too much?
What should I do. Could the 20 amp fuse have blown at 18 or 19? Is the fan drawing too much?
Try a 20 amp "slow-blow" (I can hear the comments now) fuse -- this type of fuse doesn't blow on a temporary surge.
Tom Piper
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by Tom Piper
Most electric motors draw much more current for a moment when starting than when they are running (some motors draw 13 times the run current when starting).
Try a 20 amp "slow-blow" (I can hear the comments now) fuse -- this type of fuse doesn't blow on a temporary surge.
Tom Piper
Try a 20 amp "slow-blow" (I can hear the comments now) fuse -- this type of fuse doesn't blow on a temporary surge.
Tom Piper
When the fan motor get kicked on, and is free to run. I takes about 10-11 amps @ 13.5 volts... 
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by Aaron's 87
So...
Stick with the 25 if it works or go down to a 20 slow blow fuse?
Stick with the 25 if it works or go down to a 20 slow blow fuse?
Tom Piper
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by jfb
My 87 fan motor draws 14 amps. Rule of thumb is 2.5 times the running current for the start up current.
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by Tom Piper
Most electric motors draw much more current for a moment when starting than when they are running (some motors draw 13 times the run current when starting).
Try a 20 amp "slow-blow" (I can hear the comments now) fuse -- this type of fuse doesn't blow on a temporary surge.
Tom Piper
Try a 20 amp "slow-blow" (I can hear the comments now) fuse -- this type of fuse doesn't blow on a temporary surge.
Tom Piper
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Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by Steel Breeze
Tom, This cooling fan unit I am building. If it were to start up on high speed. It would draw 130 amps for about 1 millisecond, then work it's way down quickly. However, it will not be starting on high. When it switches to high, it will be instantanious. Therefore the fan will be turning at an already high rate of speed. I anticipate the current bump to be around 70 amps, for less than 1 millisecond...
Tom Piper
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by Tom Piper
The resistance of the wiring, and such, will limit the current to something lower than that during that short time duration.
Tom Piper
Tom Piper
Burning Brakes
Joined: May 2006
Posts: 1,097
Likes: 2
From: Richfield Utah
Originally Posted by Aaron's 87
I know I'm a wiring dumba**, but can I get blade type slow blow fuses to fit in the holders I have?
