Battery Keeps Dying
Thread Starter
|
New User
Joined: Dec 2003
Posts: 7
Likes: 0
From: Kansas City
Battery Keeps Dying
I have a 1970 F250 with a 390. The battery won't stay charged up. I had the voltage regulator, alternator, and battery all tested and they are all good. I have replaced them all anyway recently. If I charge it with a battery charger it will hold a charge, but as soon as I drive around for about a week it is dead again. The battery is not being drained from just sitting there. I let the truck sit for about 2 weeks and the battery was still good. I think the alternater is not charging it. How can I test to see if the alternator and regulator are working, while on the truck? Thanks
Elder User
Joined: Feb 2004
Posts: 940
Likes: 0
From: burlington, iowa
while on the truck is easy, start the truck and unhook the battery, if the truck stays running the alternator is working, if it dont, well you got your answer. then take it off and take it to autozone, they will test it for free.
Thread Starter
|
New User
Joined: Dec 2003
Posts: 7
Likes: 0
From: Kansas City
I have had it tested at Autozone. They said it was good. Besides, in the service manual it says not to take the battery cable loose while it is running because this will damage the regulator.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Since all items tested good, you probably have a wiring fault at a connector. Most likely, the pin inside the connector on the voltage regulator is being pushed out of the connector. Or, the alt. is not receiving ign. on voltage.
Elder User
Joined: Feb 2004
Posts: 940
Likes: 0
From: burlington, iowa
i never read that in my maunal, wait i dont have a manual, lol
well i have a 70 f250 and i have unhooded the battery many a times.
quickest and easiest test to confirm alternator working, cause if it anit, the engine gets no power for spark, it dies almost in one breath.
well i have a 70 f250 and i have unhooded the battery many a times.
quickest and easiest test to confirm alternator working, cause if it anit, the engine gets no power for spark, it dies almost in one breath.
Laughing Gas
Joined: Jan 2002
Posts: 1,008
Likes: 1
From: Tucson
As an alternative to FordLover's remove-the-cable technique, you can check it with a voltmeter. When the engine isn't running the battery should show about 12 volts. Check it again when it's running; it should be around 14 vots. If it's still 12, I'd look at the alternator no matter what AutoZone said. Good luck.
jor
jor
Senior User
Joined: Dec 2003
Posts: 129
Likes: 0
From: Fayetteville, N.C.
Dead Battery
I think there is a fusable link between the alternator and starter solenoid. Check it and see if it is broken. Many times when they blow the insulation in the wire is intact, but the wire will be burned open.
Trending Topics
Elder User
Joined: May 2003
Posts: 520
Likes: 1
From: california
In addition to what JOR said, I would actually rev the engine higher, say 2000 rpm to see if the voltage picks up. At idle, you usually won't see the volts jump up.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Freshman User
Joined: Jul 2004
Posts: 45
Likes: 0
From: Salmon, Idaho
May not charge at idle.
At idle the alternator may not be spinning fast enough to charge the battery. Had terrible problems with my 69, when it was still Dad's, and he just putted around town at 25. It wouldn't keep a charge either.
An old boy up at the machine shop, had a larger pulley that fit, and solved the problem. I'm not sure what it was off of, or if he made it up himself.
An old boy up at the machine shop, had a larger pulley that fit, and solved the problem. I'm not sure what it was off of, or if he made it up himself.
Post Fiend
Joined: Apr 2002
Posts: 7,157
Likes: 1
From: Central Kali
get a voltmeter and see what the battery voltage is at a fast idle. If it is 12.6 or lower, put the voltmeter on the Field terminal of the alternator. If you have around 11 volts, the alternator is bad. If there is no voltage, the regulator or the wiring has a problem.
New User
Joined: Aug 2004
Posts: 6
Likes: 0
From: Tucson, AZ
well, i just bought it last month so i know that's not the problem...
working at autozone, i know for sure that just because a part is new, doesn't mean it works. however, it is rare that things are broken out of the box. personally i'd begin with checking for a burnt link, then make sure that all wiring is tight, clean, intact, not shorted, etc. if all that seems good, take all three parts (regulator, alternator, and battery) to autozone... we can test all three of them individually rather than testing the system as a whole while it's on the truck. it may also be advantageous to install a volt guage. the stock C/D guages are before my time so i don't know how reliable they are, but i do know that keeping a close eye on my voltage has been a big help for me in the past.
Thread
Thread Starter
Forum
Replies
Last Post
brian1985f150
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
19
Feb 7, 2017 05:52 PM
josh390
1973 - 1979 F-100 & Larger F-Series Trucks
18
Nov 8, 2008 04:03 PM