Alternator hot...normal?
#1
Alternator hot...normal?
I just did my 3g upgrade a couple days ago. I already have some custom audio installed, but I figured adding an e-fan would have been pushing it. Besides...I might want to upgrade the lighting at some point.
Everything appears to be working properly. Fan kicks on and off, alternator is putting out just over 14v. I ran an 8 gauge wire soldered into some copper lugs to connect the charging side. Wiring is not getting hot at all. But after just a few minutes of the truck idling, I noticed the alternator was getting pretty hot. To be honest, I don't think I ever checked the old alternator (it was less than a year old, btw). So I don't know if that one heated up as bad as the new one.
My question is, how hot should it get? Is it normal for a 130a alternator to run hotter than the factory 75-95a models? I did some reading online and it seems like some people say it's normal and some say it's not.
Everything appears to be working properly. Fan kicks on and off, alternator is putting out just over 14v. I ran an 8 gauge wire soldered into some copper lugs to connect the charging side. Wiring is not getting hot at all. But after just a few minutes of the truck idling, I noticed the alternator was getting pretty hot. To be honest, I don't think I ever checked the old alternator (it was less than a year old, btw). So I don't know if that one heated up as bad as the new one.
My question is, how hot should it get? Is it normal for a 130a alternator to run hotter than the factory 75-95a models? I did some reading online and it seems like some people say it's normal and some say it's not.
#2
1994 F150 XLT 5.8L 2wd
8ga is on the small side for 130amps, 8 is rated for 73 amps maximum for chassis wiring, 4ga is rated 135 amps max for chassis wiring. I used a 6ft length (cut to fit) of battery cable that was 4ga with a 150amp breaker, total cost was like $22 (ebay for breaker and AZ for the battery cable). I also took the old charging line and used it to beef up the battery neg>chassis ground. My 130 gets warm but def. not hot, at least I don't think it does. I may go for a drive and report back a little later.
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broncojunkie (04-13-2015)
#3
8ga is on the small side for 130amps, 8 is rated for 73 amps maximum for chassis wiring, 4ga is rated 135 amps max for chassis wiring. I used a 6ft length (cut to fit) of battery cable that was 4ga with a 150amp breaker, total cost was like $22 (ebay for breaker and AZ for the battery cable). I also took the old charging line and used it to beef up the battery neg>chassis ground. My 130 gets warm but def. not hot, at least I don't think it does. I may go for a drive and report back a little later.
And I don't currently have a fuse/breaker installed in the charging wire, but I do have a 150a fuse and holder ordered. Should be in tomorrow.
I do see what you're saying about the wire being too small to carry the load my alternator is putting out, though. I would like to go with 4ga wire, but I'm not sure how. Even if I can get the smaller lug to fit the bigger wire, wouldn't that "chain is only as strong as it's weakest link" deal come into effect? In other words, the terminal itself, which is a small threaded bolt/nut on the back of the case, is smaller than the 8ga wire.
Oh, and I also have some 1ga welding cable and all the hardware to beef up my cables on order, too. Might be here tomorrow or Monday.
#4
1994 F150 XLT 5.8L 2wd
I picked up a lug from az when I got the cable, it was just a hair wider that what the plastic insert in the terminal was, I used a razor and removed the insert then just bolted it in.
As for the small nut/bolt being the weakest link, solid metal conducts better than stranded metal. I also think that since it's only a single contact point and not carried over a length, that it's resistance doesn't really factor in as much as say 3 feet of wire. Kind of makes you wonder though, because on an amplifier you need a low gauge wire but once you attach it to the amp then the computer board is now handling all of that load that you needed a sizable wire to carry.
My thought on why it may be getting hot was that the smaller wire wasn't transferring enough power and it was being left behind in the alternator, for lack of a better phrase. I don't pretend to know everything about electricity, I just know what I've read in research and learned from those who know more about it than me. I'm taking the truck across town here shortly so I'll verify my first post when I get back.
As for the small nut/bolt being the weakest link, solid metal conducts better than stranded metal. I also think that since it's only a single contact point and not carried over a length, that it's resistance doesn't really factor in as much as say 3 feet of wire. Kind of makes you wonder though, because on an amplifier you need a low gauge wire but once you attach it to the amp then the computer board is now handling all of that load that you needed a sizable wire to carry.
My thought on why it may be getting hot was that the smaller wire wasn't transferring enough power and it was being left behind in the alternator, for lack of a better phrase. I don't pretend to know everything about electricity, I just know what I've read in research and learned from those who know more about it than me. I'm taking the truck across town here shortly so I'll verify my first post when I get back.
Last edited by fltdriver; 04-11-2015 at 08:38 AM.
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broncojunkie (04-13-2015)
#6
Yep. That's what I figured. Mine will burn you if you leave your hand on it for more than a couple seconds. Anyway, I just went out and messed with it some more. I adjusted the fan controller so it wouldn't kick on, then I let the truck run till the thermostat opened. Temp gauge stayed below half way mark, even with the fan off. The alternator stayed cool. Turned the fan controller up and I could feel the alternator getting warm the longer the fan was running. I think my problem was that the fan was just running too much, which put a strain on the alternator. I adjusted the controller to not come on as much and the alternator stayed warm, but not hot.
Now, for that charge wire. I'll have to figure something out there! The more I think about it, the more I think that could possibly cause the alternator to work harder. If it could carry more amps, the alternator wouldn't have to run as long...at least is my way of thinking.
Thanks for checking yours out and letting me know! Gave me a good reference point, since I didn't know how hot it should be!
Now, for that charge wire. I'll have to figure something out there! The more I think about it, the more I think that could possibly cause the alternator to work harder. If it could carry more amps, the alternator wouldn't have to run as long...at least is my way of thinking.
Thanks for checking yours out and letting me know! Gave me a good reference point, since I didn't know how hot it should be!
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broncojunkie (04-13-2015)
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#8
Yes, I suppose that would work. I put my 150a fuse/holder inline today...with the 8ga wire. I purchased the holder and fuse together as a package deal I found on ebay. It will only fit up to 8ga wire, so I'd have to get another one. I wonder why they sell the 150a fuse for 8ga wire if it won't handle it? I did some reading and found that you guys are correct, though. It should be 4ga.
#9
1994 F150 XLT 5.8L 2wd
I got a really nice 3 in 2 out that will hold 0-4 gauge (1) 2-8 gauge (2) for the in and 2-8 gauge (2) for the out. It was around ten bucks with your choice of fuses. It's going in the convertible so I can run 2 amps and add 3-10's in my backseat in addition to the 2-12's in the trunk.
Something like this would work for you:
http://www.ebay.com/itm/us-seller-1-IN-2-OUT-BIG-AGU-FUSE-DISTRIBUTION-POWER-BLOCK-4-GAUGE-8-AWG-12-VOLT-/281200759003?pt=LH_DefaultDomain_0&hash=item4178df10db&vxp=mtr
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broncojunkie (04-13-2015)
#10
1994 F150 XLT 5.8L 2wd
Actually scratch that, if you bring two sources each with a 150 amp fuse you could fry your electronics, and if you just put 75amp fuses for each line (to add up to 150 which is your failsafe) then you may be blowing fuses left and right, literally. If you want to use 2-8awg lines you will have to splice into a 4awg then mount the 150amp inline fuse in the 4awg, making sure to stay within 18" total of the alternator. Or... Use a single 150 amp fuse and run both 8's to that, then either 4awg or two 8's again to the solenoid, again fuse within 18" of alternator.
I'm tired so if this doesn't make sense it's probably me.
I'm tired so if this doesn't make sense it's probably me.
Last edited by fltdriver; 04-11-2015 at 09:22 PM.
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broncojunkie (04-13-2015)