alternator is not charging when fan is on
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
alternator is not charging when fan is on Hi,
i have an issue with my voltage dropping to 12.8 or even below when my fan is on and it keep killing my battery, the alternator is from 19370821 i think, its wired with one wire from the engine harness, the fan is from ford taurus which pulls 30-40 amp.
this voltage drop causing all kind of issues and its bothering me,
i dont think its the alternator as its not that old barely used less than 1000 mile on it, it been in storage most of it time mostly of because of this issue, could it be the one wire connector or maybe psi thin alternator to starter wire which is what powers the whole car or is the taurus fan draw too much amp for the alternator
i have an issue with my voltage dropping to 12.8 or even below when my fan is on and it keep killing my battery, the alternator is from 19370821 i think, its wired with one wire from the engine harness, the fan is from ford taurus which pulls 30-40 amp.
this voltage drop causing all kind of issues and its bothering me,
i dont think its the alternator as its not that old barely used less than 1000 mile on it, it been in storage most of it time mostly of because of this issue, could it be the one wire connector or maybe psi thin alternator to starter wire which is what powers the whole car or is the taurus fan draw too much amp for the alternator
Agree on battery health. If it is 5 years old or more, ditch it. If it has went totally dead several times, regardless of age, ditch it.
You can run a modern GM alternator to add a lot of extra oomph. I just did on my 5.3L Colorado, boosted alternator by 100amps production rating just by using a current model one, all direct from GM or Rock Auto, not a black magic shop that says high output. My alternator went from like 140 to 240 amp rating. Same size, same connectors, same everything. Plug and play. Hate to hear you not using the ride because of it. I work for the company that makes the current GM LS mass production ones, so easy for me to know what fits/works. Mine was truck accessory drive, FYI.
You can run a modern GM alternator to add a lot of extra oomph. I just did on my 5.3L Colorado, boosted alternator by 100amps production rating just by using a current model one, all direct from GM or Rock Auto, not a black magic shop that says high output. My alternator went from like 140 to 240 amp rating. Same size, same connectors, same everything. Plug and play. Hate to hear you not using the ride because of it. I work for the company that makes the current GM LS mass production ones, so easy for me to know what fits/works. Mine was truck accessory drive, FYI.
Last edited by FormulaBoat; May 16, 2019 at 02:16 PM.
Sounds like a weak alternator that can't handle the additional electrical load.
I have a 50 page alternator thread full of my posts and other peoples posts about alternators failing right out of the box and all the replacement alternators for F bodies being absolute junk.
Upgrade to the 145 amp truck alternator and be done with the issues.
https://ls1tech.com/forums/generatio...failure-s.html
I have a 50 page alternator thread full of my posts and other peoples posts about alternators failing right out of the box and all the replacement alternators for F bodies being absolute junk.
Upgrade to the 145 amp truck alternator and be done with the issues.
https://ls1tech.com/forums/generatio...failure-s.html
TECH Resident
Joined: Mar 2012
Posts: 860
Likes: 404
From: Texas
Hi,
i have an issue with my voltage dropping to 12.8 or even below when my fan is on and it keep killing my battery, the alternator is from 19370821 i think, its wired with one wire from the engine harness, the fan is from ford taurus which pulls 30-40 amp.
this voltage drop causing all kind of issues and its bothering me,
i have an issue with my voltage dropping to 12.8 or even below when my fan is on and it keep killing my battery, the alternator is from 19370821 i think, its wired with one wire from the engine harness, the fan is from ford taurus which pulls 30-40 amp.
this voltage drop causing all kind of issues and its bothering me,
I ran a 2000 Mustang GT fan* on my '89 Firebird because I happened to have one lying around. It cooled great, but I had a lot of problems with relays not being able to handle the amperage, and the factory 105 amp alternator couldn't cut it, so I had it upgraded with a 160 amp kit. This fan immediately melted the factory fan relay, and I dicked around with some 70 amp universal relays for awhile, before finally settling on a Bosch 75 amp relay with 8 gauge wiring.
*Taurus, Mustang, Crown Vic, Thunderbird, etc. all use the same fan with different shrouds.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo I believe what he was referring too is the Ford solenoid is just that, a solenoid, which is a relay, low current controls high current.
To answer the question what the Ford solenoid is rated at, that I don't know. I've been using it to control high amp fans for years as many people have.
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
i know for sure that its not the battery fault as it would die when its less than week old because the fans discharge the battery and the alternator cant keep up
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
Agree on battery health. If it is 5 years old or more, ditch it. If it has went totally dead several times, regardless of age, ditch it.
You can run a modern GM alternator to add a lot of extra oomph. I just did on my 5.3L Colorado, boosted alternator by 100amps production rating just by using a current model one, all direct from GM or Rock Auto, not a black magic shop that says high output. My alternator went from like 140 to 240 amp rating. Same size, same connectors, same everything. Plug and play. Hate to hear you not using the ride because of it. I work for the company that makes the current GM LS mass production ones, so easy for me to know what fits/works. Mine was truck accessory drive, FYI.
You can run a modern GM alternator to add a lot of extra oomph. I just did on my 5.3L Colorado, boosted alternator by 100amps production rating just by using a current model one, all direct from GM or Rock Auto, not a black magic shop that says high output. My alternator went from like 140 to 240 amp rating. Same size, same connectors, same everything. Plug and play. Hate to hear you not using the ride because of it. I work for the company that makes the current GM LS mass production ones, so easy for me to know what fits/works. Mine was truck accessory drive, FYI.
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
Sounds like a weak alternator that can't handle the additional electrical load.
I have a 50 page alternator thread full of my posts and other peoples posts about alternators failing right out of the box and all the replacement alternators for F bodies being absolute junk.
Upgrade to the 145 amp truck alternator and be done with the issues.
https://ls1tech.com/forums/generatio...failure-s.html
I have a 50 page alternator thread full of my posts and other peoples posts about alternators failing right out of the box and all the replacement alternators for F bodies being absolute junk.
Upgrade to the 145 amp truck alternator and be done with the issues.
https://ls1tech.com/forums/generatio...failure-s.html
I would run a ground from the battery, directly to the engine block. If the alternator plug is 4 pin, I would add a wire from the S terminal to the point where your fans are getting power, as this is likely the point in the system that sees the biggest voltage drop when the fans kick on. Having the S terminal wired there will boost alternator output when the fans kick on.
Andrew
Andrew
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
Relays are rated that way.
I believe what he was referring too is the Ford solenoid is just that, a solenoid, which is a relay, low current controls high current.
To answer the question what the Ford solenoid is rated at, that I don't know. I've been using it to control high amp fans for years as many people have.
I believe what he was referring too is the Ford solenoid is just that, a solenoid, which is a relay, low current controls high current.
To answer the question what the Ford solenoid is rated at, that I don't know. I've been using it to control high amp fans for years as many people have.
You have VASTLY underestimated the amperage draw of a Taurus fan. Those things pull about 80 amps when running at full speed, and can spike up to about 100 when turning on; the factory programming for those cars would turn the fan on at partial power in order to keep from overloading the system; I believe they called it a "soft start" setup.
I ran a 2000 Mustang GT fan* on my '89 Firebird because I happened to have one lying around. It cooled great, but I had a lot of problems with relays not being able to handle the amperage, and the factory 105 amp alternator couldn't cut it, so I had it upgraded with a 160 amp kit. This fan immediately melted the factory fan relay, and I dicked around with some 70 amp universal relays for awhile, before finally settling on a Bosch 75 amp relay with 8 gauge wiring.
*Taurus, Mustang, Crown Vic, Thunderbird, etc. all use the same fan with different shrouds.
I ran a 2000 Mustang GT fan* on my '89 Firebird because I happened to have one lying around. It cooled great, but I had a lot of problems with relays not being able to handle the amperage, and the factory 105 amp alternator couldn't cut it, so I had it upgraded with a 160 amp kit. This fan immediately melted the factory fan relay, and I dicked around with some 70 amp universal relays for awhile, before finally settling on a Bosch 75 amp relay with 8 gauge wiring.
*Taurus, Mustang, Crown Vic, Thunderbird, etc. all use the same fan with different shrouds.
Thread Starter
Staging Lane
Joined: Aug 2018
Posts: 57
Likes: 0
I would run a ground from the battery, directly to the engine block. If the alternator plug is 4 pin, I would add a wire from the S terminal to the point where your fans are getting power, as this is likely the point in the system that sees the biggest voltage drop when the fans kick on. Having the S terminal wired there will boost alternator output when the fans kick on.
Andrew
Andrew
do you know how much the alternator output with and without the s terminal ?
I would still add a ground to the block from the battery.
Andrew