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View Full Version : Alternator probs after electric fan install



cwm
06-27-2005, 03:17 PM
Got my 2 speed fan installed and took it out wheeling yesterday it was about 100 deg and it kept my motor nice and cool however if I run my AC my alt gage drops to about 9 Volts.
If I shut the AC off it goes up to 12 Volts.
Also does that if I run the head lights with the fan.
Do I need a higher amp alt or is my stock alt just shot????

gsh
06-27-2005, 10:33 PM
Um, what year is yours? I think my '93 is 90 A stock. Newer units were more, some 136 A. I think I remember hearing that the Dodge unit is cheaper for the same part, some places. Then you could get one of those $$$$$ aftermarket uber amp suckers. Mine will drop that low too at times, headlights, wipers, defrosters, brake lights, blinker all on at a stop light in cruddy weather.

Kraqa
06-27-2005, 10:38 PM
Before you go blaming the alt. Lets start with the basics.

How did you wire your fan?

cwm
06-27-2005, 10:47 PM
Quote
"How did you wire your fan?"
Not that it matters but i used 2 70 amp relays wired to a 3 position swich that run directly off the batt.

Swamp boy
06-28-2005, 10:35 AM
YOu just need a 136 amp alt.. My taurus fan draws almost 100 amps at start up and I believe 50 continuous... (on high) thats alot if your alt is only putting out 90 to begin with..

I got my 136 amp alt. From a 98 ZJ limited in the bone yard for $15..
It has been on my rig for 2 years.. :smt003

If you are going to look in the bone yard Look for Dodge Trucks and grand Cherokees with alt.. Number 56027913

and these are the vehicles it came in...
* 1997-1998 Dodge B.Series Van
* 1997-1998 Dodge Dakota
* 1998 Dodge Durango
* 1997-1998 Dodge Ram Pickup
* 1997-1998 Jeep Grand Cherokee

Not all of them but its a good place to start..

nate
06-28-2005, 01:21 PM
Taurus fan is ~75-100 amps at startup, and just over 30amps after.

90amp can't handle it.

OverkillZJ
06-28-2005, 01:54 PM
Taurus fan is ~75-100 amps at startup, and just over 30amps after.

90amp can't handle it.

The battery would handle the overload draw at startup. Just like using a winch (400ish amps, not coming from the alt!)

nate
06-28-2005, 06:25 PM
Not really startup. Sustained amperage the alt can barely keep up. Remember that 90amps is with alt spinning quick... idle is probably 30amps.

Jim311
06-28-2005, 07:53 PM
That's one of the things I don't like about electric fans. Too much power consumption. You might loose some HP from a mechanical fan, but you certainly don't have to worry about issues like that, and they're much more reliable and cheaper to replace than electric fans! Pulls more air, too.

:mrgreen:

cwm
06-28-2005, 08:04 PM
I put the alt off my builder motor it says its 120 Amp .Does a little better at Idle still not enough to make me happy so I think I will try and find a little smaller pully and try that.
It charges 14 volts going down the hwy its just at Idle or slow crawling that it drops down below 10 Volts.
Of course this is looking at the factory Alt gage and of course for some reason I cant find my Multi metter!

As far as the factory fan pulling more air maybe at hwy speeds but not for crawling!
With the factory fan all new cooling system including a Flow Cool water pump crawling with the air on it would get a little over 220 . with the Electric fan crawling with the Air on it never got to 210.

Jim311
06-28-2005, 08:55 PM
Never had problems with my mechanical fan... never saw more than 210 even crawling in deep sand on a 100+ degree day.

cwm
06-28-2005, 09:37 PM
Never had problems with my mechanical fan... never saw more than 210 even crawling in deep sand on a 100+ degree day.

Good for you! Didnt work for me!

Here in the desert if it says it is 100 degrease out it can easly be 110 to 120 a couple of feet off the ground.
But hey if yours is working and your happy thats all that matters!![/quote]

Swamp boy
06-29-2005, 08:51 PM
Never had problems with my mechanical fan... never saw more than 210 even crawling in deep sand on a 100+ degree day.

Good for you! Didnt work for me!

Here in the desert if it says it is 100 degrease out it can easly be 110 to 120 a couple of feet off the ground.
But hey if yours is working and your happy thats all that matters!!

You suck at the quoting... :mrgreen:


Anyway.. I have the 136 amp alt and I can run my fan on high and it will idle at 13.5 volts (as per my test meter) and I rarely use the high speed on the fan the low works good enough and believe me I know about the heat.. 110* is average summer day here in South Louisiana..(Of couse that is actually including the 110% humidity we get to which makes it feel like about 600*)

I know deserts get hot but when I was in Desert storm it felt nice compared to a late summer day here.. :smt003

Carl

Kraqa
06-29-2005, 08:52 PM
Pulls more air, too.

:mrgreen:



check again.



the tarus fan pulls alot more then stock.

doyll
07-28-2005, 03:02 PM
There's a big difference in how 110* "South Lousiana" heat will cool something vs how 110* desert heat will. The reason is your HUMIDITY!! It will make you FEEL hotter, but it obsorbs a lot more heat then dry desert air will. Dry air is just that... DRY!! humidity absorbs heat. Radiator/temp guage feels the humidity absorbing it's heat. You feel the evaporation cooling you in desert vs Lousiana humidity. Different feels for different deals. :partyman:

Swamp boy
07-29-2005, 09:23 PM
:smt003 Damn Skippy .... Its hot here... I know that shit...

I wake up in the morning at 7AM and break a sweat between my Front door and my Truck door... That sucks shit...
Its 87* at 7am... :rolleyes:



On a side note and completely off topic I was in Best Buy today and saw a laptop with a scratch pad kinda screen ...You could just write on it...

So I wrote...

"BestBuy sucks my nuts " and stood back and watched people read it and bust out laughing... :smt003 :smt003


Soooooooooooo...That was my fun for the day... :snakeman:

doyll
07-29-2005, 10:05 PM
At least your nuts were cool at Bust Bey !!

nate
07-31-2005, 09:10 AM
haha. If it hit 87* here people would start dying. It was barely pushing 60* today with it raining and all.