Who's Running an Electric Fan - Alternator Upgrade?

[Detroit Iron]

I installed an electric fan which draws 23.5 amps. Not to my surprise, my alternator isn't happy. It's almost maxing output according to the gauge. I'm considering a Powermaster alternator which claims to have an output of 75 amps. Considering where my gauge needle is, I don't feel 75 amps is enough.

I'm curious to know what you guys running electric fans have done to boost alternator amperage. Thanks for the input.

 

[moparryder]

First, I gotta ask what size/brand fan you using that pulls over 20 amps?! I run a 14" 1600cfm speed daddy fan and averages low 7 amps. I also have a spare secondary fan that pulls 6 amps when extra cooling is needed. I went a odd route but works. I installed a 100 amp gm one wire, re-wired main harness and deleted my ammeter. I would suggest either new efficient fan(s) or re-wire and by-pass your ammeter as I personally don't like running a heavy load through the factory ammeter. I would take power from battery(fused and 40amp relay) to bypass the ammeter if you want to keep all that you have with 20+ amps. I'm sure someone else will chime in with more experience soon.

 

[old_skool]

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

 

[67 B-body]

Yaaa,,, you probably shouldn't be drawing that kind of power through the factory amp meter.....
I just posted a link to this "old thread" in another location regarding fuel pump wiring,,, but it could serve you in this as well....
Coming directly from a battery post, or a buss bar fed from direct battery +12V is the way to go...
Good luck!
http://www.forbbodiesonly.com/mopar...Clean-SAFE-wiring&highlight=clean+safe+wiring

Side note: My twin 10" fan arrangement does not use that kind of amperage.....

 

[Detroit Iron]

Thank you for the input. I will dig into the info you all have given me.

This fan is actually in my '64 Barracuda. These cars came with a 19" radiator. The core support is limited to a 19". I have a healthy 340 in this car. It's hard to see in the next photo, but the fan isn't positioned directly in front of the radiators in these cars. It sits off to the side, so with that and the small radiator, I have issues. My core is a three row, so that's good, but not enough. The car really gets hot sitting in traffic.

The electric fan I chose is a Derale 19" with aluminum shroud. It fits the radiator perfectly. It cools the car perfectly, but the amp draw is an issue.

Thanks for the info, and I will get to re-configuring this thing.

 

[67 coronet]

ya,those 19" metal electric fans work nice,but pull a ton of amps.jump your factory amp meter and install an aftermarket volt meter.factory amp guages can catch on fire when you pull that much power through them.make sure you set the fan up on a 40 amp relay and find a bigger alt(like the power master)if you are gonna keep that set up.

 

[bigmanjbmopar]

I run a 14" pusher fan in the front on a relay / stat set to around 210° so when the radiator upper portion gets hot the fan kicks on and an extra push of air used mainly for traffic situations so at least the radiator gets some air moving through it. 18" flex fan on the engine side with a half shroud.

Your set up looks like no air can get through? does it work good? I also have a 100 amp tuff stuff alternator to more than enough to handle any load.

 

[383man]

I also run a pusher fan in front of my radiator and I have it on a toggle switch. But it does not draw anywhere near what yours is. Heck I have an electric fuel pump and the fan and I still use a stock 60 amp alt that more then handles mine. Ron

 

[slepr1]

100 amp alternator and fan relay. I like to trickle charge my battery when I take short runs or after test and tune, my alternator thanks me.

 

[Reveye]

Derale is a good product. I am running 2 - 10inch electric fans, coming in just around 20 amp draw, 40 amp relay with 30 amp circuit breaker protection. Works perfect. Never goes over 195 degrees now even in traffic. I have a Tuff Stuff, one wire, 100 amp alternator. Works great even at idle.

 

[ilm65]

100 amp alternator and fan relay. I like to trickle charge my battery when I take short runs or after test and tune, my alternator thanks me.

These are Spal fans in a Be Cool set-up and they draw 17 amps each and in addition, I have an electric fuel pump. My PowerMaster 75 amp wasn't supplying enough to keep everything running and provide ample charge through #2 welding cable to the trunk mounted battery--eventually ruined an Optima Red Top. Went with a Tuff Stuff 100 amp alternator (must upgrade the charging wire (and be sure to use a fusible link)), disconnected the AMP gauge per Mad Electric's recommendation, installed a 900 CCA Optima Yellow Top and absolutely NO PROBLEMS! Oh yes, be sure to use a trickle charger during storage season.

 

[Detroit Iron]

The Tuff Stuff alternator seems to be the solution. I'm also going to take the amp gauge out of the loop. I will post an update once I get this thing all situated. Thanks for all the input.

 

[bigmanjbmopar]

Awesome! Hope it all works out for you. put up pics when you have it all done.

 

[Jeremiah]

The Tuff Stuff alternator seems to be the solution. I'm also going to take the amp gauge out of the loop. I will post an update once I get this thing all situated. Thanks for all the input.

I have ran the Tuff Stuff 100A alternators in several cars from the our street/strip car to a all weather daily driver and they never missed a beat. IMO an excellent value.

 

[SwedCharger67]

I think cooling fans is a difficult topic. If you have a fan that is badly designed you'll need a lot of amperes to move any air (you need brute force), while a correctly designed fan will move lots of air with less Amperes. The shape of the wings is very important.

I have noticed in other non-automotive fields that there are a lot of fans out there which are designed without any consideration to air flow and efficiency, they just want to sell stuff.

For example, bathroom ventilation fans, my latest quality fan: I can hear when starting the fan that the shape of the wings doesn't work at low speed, but when the fan reaches operating rpm the sound changes and suddenly the shape of the wings is correct and it starts moving lots of air!

I'm heating my house with a modern wood burner, it uses a fan for air flow through the burner. The fan itself is badly designed, I can see how the soot deposits on the wings. It's clear that the air flow is bad, and the fan is just manufactured, it's not designed for efficiency in any way. The burner is just using brute electrical force to move air, and probably uses 3x more electrical power than necessary for the amount of air.

Some data stating air volume moved per Ampere would be a great help comparing fans.

Considering the shape of the wings, I think submarine propellers and wind turbines show the way to go.

- - - Updated - - -

Some electrical comments...the amp gauge is not so picky about the size of the current. The needle is just moving in a magnetic field and cannot burn. The current inside the amp gauge is moving in a thick bar (no thin copper wire) and will not burn easily (other things will burn before this bar). The critical stuff is the screw terminal connections (need to be clean and tight) and the size of the wires.

Upgrading the alternator and corresponding wires is probably a must when starting adding electrical cooling fans, electrical water pumps, electronic engine management. Just my engine management is consuming 15 Amps at idle (injectors+coils+electronics) so already with a mechanical cooling fan and water pump, adding some more powerful headlight bulbs and the original alternator is already working hard...