Alternator question for electrical guru's
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Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Alternator question for electrical guru's
My battery light came on today so I pulled out the multi meter and discovered my alternator was on it's way out. I replaced it last June with one from Autozone cuz I was in a hurry. I decided to look online to see if the local store had one in stock, then call to verify (I'm sometimes ****) and noticed online that the alternator was listed at 110 amps. I looked in my manual and noticed the Ford one is 130 amps.
I never thought to check this before since I assumed the store would sell me the correct part. Luckily I've spent lot's of time on FTE and am now smart enough to think of these things.
So the question is: How important are those extra 20 amps? The daughter's on her way right now to swap mine out for a new one. She'll have it bench tested before she brings it home, but do the lower amps lead to a shorter life of the alternator or batteries? Should I start looking for a 130 amp alternator to run and keep my 110 replacement as a back up?
Any feedback is appreciated. I have a stock stereo system. The only additional electrical load would be a CB with small foot warmer, cell phone charger, & occasionally an inverter plugged in to run my laptop.
I never thought to check this before since I assumed the store would sell me the correct part. Luckily I've spent lot's of time on FTE and am now smart enough to think of these things.
So the question is: How important are those extra 20 amps? The daughter's on her way right now to swap mine out for a new one. She'll have it bench tested before she brings it home, but do the lower amps lead to a shorter life of the alternator or batteries? Should I start looking for a 130 amp alternator to run and keep my 110 replacement as a back up?
Any feedback is appreciated. I have a stock stereo system. The only additional electrical load would be a CB with small foot warmer, cell phone charger, & occasionally an inverter plugged in to run my laptop.
Senior User
Joined: Feb 2008
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From: Irmo, SC
I think you would be ok with a 110amp alternator. That's what I replaced mine with and it hasn't given me any problems. I don't have any extra loads on the factory electrical with the exception of the boat trailer's lights....and that's only from time to time.
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Post Fiend
Joined: Mar 2007
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From: Texas
Thanks Steve. I tow the occasional trailer too. Forgot to mention that. The factory alternator was replaced on 6/3/07 so it did last just over a year (barely), but not nearly as long as the factory one did. I never thought to compare amperage before, and don't know enough about it, to know if it makes a difference or not.
FTE Remembers
Joined: Nov 2007
Posts: 9,549
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From: Payson, AZ
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Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Thanks for the link Robin. I actually ran across that today while searching for something other than a 110 amp version. I'm just trying to understand why more amps or less amps would be good or bad. I've noticed the replacement alternators never seem to last as long as the originals. I was just wondering if this had something to do with it. I guess I'd also like to know is there an alternator with too many amps that will cause problems too.
Elder User
Joined: Sep 2007
Posts: 624
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From: Kalamazoo, MI
well, here's what you have to remember...
Eagle (voltage)
over
the Indian (amperage) and the River (resistance)
you have two batteries to charge..
that consumes your I and provides most of your R...
so your E has to be able to overcome it...
seeing as how your E is a constant...
your "I" better be able to overcome your R,
to charge your batteries and run your chit...
I'd tell you that has a 130amp on it for a reason...
E
------
I \ R
if you need to find E, multiply I x R
if you need to find R, divide E by I
Eagle
-----
Indian / River
Eagle (voltage)
over
the Indian (amperage) and the River (resistance)
you have two batteries to charge..
that consumes your I and provides most of your R...
so your E has to be able to overcome it...
seeing as how your E is a constant...
your "I" better be able to overcome your R,
to charge your batteries and run your chit...
I'd tell you that has a 130amp on it for a reason...
E
------
I \ R
if you need to find E, multiply I x R
if you need to find R, divide E by I
Eagle
-----
Indian / River
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Post Fiend
Joined: Mar 2007
Posts: 26,966
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From: Texas
Thanks JL. It's been a long day, but it sounds like you're telling me my Indian is too small. Since I have no idea what kind of River I've got, if I went with Robin's link would I get too big an Indian?
Better yet just tell me what amp alternator I should get. I've got an unspecified amount of time to order one now since Autozone gave me a new alternator tonight.
Better yet just tell me what amp alternator I should get. I've got an unspecified amount of time to order one now since Autozone gave me a new alternator tonight.
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Post Fiend
Joined: Feb 2007
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From: Blairsville,Ga
my little indian had started up the river with a skinny paddle,I ordered one of these
FORD F TRUCK 7.3L 135 AMP ALTERNATOR 98 99 00 01 7796: 7796-135 AMP REGULAR OUTPUT DB Electrical Starter-Alternator
if I catch the eagle I 'll just try to squease him a little
FORD F TRUCK 7.3L 135 AMP ALTERNATOR 98 99 00 01 7796: 7796-135 AMP REGULAR OUTPUT DB Electrical Starter-Alternator
if I catch the eagle I 'll just try to squease him a little
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Post Fiend
Joined: Sep 2006
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From: Millbrook Alabama
Now you got me paranoind Chris, I actually got up out of my recliner and went outside and popped the hood to discover that my Advanced auto alternator is also a 110A. Now for the bad news, i have had to replace the alternator about every 14-18 months. I have a little larger stereo, and also a CB and foot warmer. The only good thing I can say is I have NEVER had a problem getting the alternator warrantied. I keep the reciept in the truck, along with a 13mm socket and a 1/2 breakerbar and can change it in their parking lot in 10mins at first flicker of the batt light.
1/8 mile Oval Track
Joined: Dec 2007
Posts: 1,300
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From: Newport,Tennessee
I am they same way Brandon , I just replaced mine again(4th) time since I got my truck, and turns out,the part # they sold me 4 years ago,isn't even the correct one for it. I now have the right one,so I hope this one lasts just a little longer. If not, I have several links saved...
Now you got me paranoind Chris, I actually got up out of my recliner and went outside and popped the hood to discover that my Advanced auto alternator is also a 110A. Now for the bad news, i have had to replace the alternator about every 14-18 months. I have a little larger stereo, and also a CB and foot warmer. The only good thing I can say is I have NEVER had a problem getting the alternator warrantied. I keep the reciept in the truck, along with a 13mm socket and a 1/2 breakerbar and can change it in their parking lot in 10mins at first flicker of the batt light.
Senior User
Joined: Feb 2008
Posts: 108
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From: Irmo, SC
Twinkle Twinkle little star, "V" is equal to "IR"
V=I*R
Voltage=Current*Resistance
Just another way to say ohm's law. My DC circuits professor said that the first day of class....we thought it was stupid as hell, but I'll never forget it.
V=I*R
Voltage=Current*Resistance
Just another way to say ohm's law. My DC circuits professor said that the first day of class....we thought it was stupid as hell, but I'll never forget it.
Hotshot
Joined: Jan 2008
Posts: 13,144
Likes: 11
From: Rochdale MA
Chris you should for the most part be ok with the smaller alternator, yes it's life will be shorter do to the fact that it will work harder to charge the 2 batteries that are in our truck. The alternator does most of it's work when the battery voltage is low. Here in New England the cold zaps strength from the batteries so when we start the engine,the alternator has to "work harder" to supply the "lost power from the batteries. My only concern from where you live is the heat, the alternator works harder, and hotter, and add that to the Texas heat will shorten the life of it.