tbryanh
Full Access Member
I am thinking about upgrading to an electric cooling fan. Will I need a higher amperage alternator if I do the upgrade?
Does Electric Fan Upgrade Require Alternator Upgrade?
- Thread starter tbryanh
- Start date
dyoung14
Is getting worn out
I just rebuild a alternator for a member here i turned it into a 240 amp 3g instead of the 130amp stock that the 3g is
Any time an increase in demand on the electrical system is made, like Electric fans USED ONLY WHEN HOT...means your ALT is hot it stresses the system at a greater rate/load than what it may be designed for.
I would suggest the upgrade as a good 160 Amp 3G can produce a good amount of current at lower RPM, helping to negate a problem with keeping everything alive.
One thing to remember is that most alternators are rated cold amps....not hot...so loading a 70 or 95 amp alt with AC electric fan stereo etc in heat of summer puts a tremendous load at or near it's peak output or worse over it peak output. Better to have some headroom with 160 amp alt and draw 100 than have a 95 am alt and draw 100 amps...MAKE sense...
When Good enough isnt....OVER KILL is!
And I'm the fool Dyoung just beefed up the alternator for, cant wait for it to get here. Big dummy me, it was running fine in cooler weather but when the heat wave hit and everything had to run near constant pulling a load, I wound up dead in the water
Gee lets do things like calculate load draw..... at what is already WAY over a total of 130 amps if everything is running full tilt 
New alt should take care of the charging problem, and also actually make the fans cool at their optimum ability since they were not receiving full juice before ( although I did manage to pull over a better than grade 14 % a couple times in better than 100 deg heat grossing over 18k even with the fans not getting enough juice, without any problems, so I think, they are working at least
flareside_thun
Reviving The General Tao
A larger output alternator is definitely recommended since electric fans can draw A LOT. Even the fans from the older t-birds draw 30 amps. I've always wondered how they "turn-up" alternators.
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smokinpipes
Navistar Nut
On my '86, I have dual electric fans; and I've replaced the stock 65Amp alternator with a CS-144 Delco Remy 140Amp alternator... when those puppies kick on it drops the system volts right down to 12 unless you are diving down the road.
So if you have no additional load other than stock, and 99% of your fan usage will be during the day, a 105Amp stock alternator would be fine, but turn on anything else, and you can kiss the diodes inside goodbye.
Or you could go to AutoZone, and buy a lifetime alternator, save money, and who cares if you overload it.. when it fries, return, and replace.
So if you have no additional load other than stock, and 99% of your fan usage will be during the day, a 105Amp stock alternator would be fine, but turn on anything else, and you can kiss the diodes inside goodbye.
Or you could go to AutoZone, and buy a lifetime alternator, save money, and who cares if you overload it.. when it fries, return, and replace.
icanfixall
Official GMM hand model
Just to add something to this alternater draw. An alternater is designed to do two things... First off its there to put back into the batteries what the starter just pulled out of them. Once thats satisfied then it supplys power to all the other running electrical equiptment. The battery packs are nothing in the chargeing system. The batterys are not there to supply anything as your running the engine. So in closeing I would tell you to upgrade the alternater so it can handle the new power draw. As Robert has found out. A well chargeing system can run down the batteries if the draw is more than the alternater can handle.... BTW these injection pumps we have require just around 7 volts to hold the fuel shutoff solenoid so we can stay running. If we could run a manual fuel shutoff valve in the injection pump all you need is a bump start standard trans rig and your running down the road... The true dooms day rig if you ask me... Saddly a C6 or E4OD wont bump start....
firehawk
Full Access Member
You need to consider how you use your truck. Idle often? Then you need an alternator to run everything at idle. Your fans should come with the a/c regardless of coolant temp. If not, you can overpressure the a/c system. I would want an alt that can run everything at night while idling. Not sure of your load and don't want to do the math? Use a good meter with amp clamp and measure at the alt, battery, fans, and any place you can reach.
nice little read here:
http://fullsizebronco.com/forum/showthread.php?t=26658
fyi;
mid year of '92 the 7.3l idi diesel received a serpentine belt along with the 130a 3g alt from the factory.
http://fullsizebronco.com/forum/showthread.php?t=26658
fyi;
mid year of '92 the 7.3l idi diesel received a serpentine belt along with the 130a 3g alt from the factory.
Silver Burner
Burnin' Oil&Rubber
I will say this about diesels. They draw a whole lot less current running by themselves than any gas engine ever. If you're in a pinch (like when my belts all let go one day...) you can turn everything off and about the only thing that will draw any reasonable power is the ecu in the automatic. With good batteries and daylight you should be able to run until dark without the alternator...
justinray
Contributor
I agree with SilverBurner, I've done it, sadly.
CurtIDI94turbo
Curtis
AMPS I get that part. But what is 3G ?
justinray
Contributor
Internally Regulated, self cooling alternator. I believe the G is just 'generation'
Id be willing to bet that a good pump shop would have a manual fuel shutoff valve for these pumps for agricultural or mining applications etc . I remember some of the early big trucks I used to drive had manual shutoffs. Used to have a big knob with a cable in the floor or dash you pull out to kill the thing then push back in to have ready for next start, just like my tractor, and its not that old, its only an 84 IH 284 diesel
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