Batteries discharging
Thread Starter
|
New User
Joined: Jul 2005
Posts: 17
Likes: 0
Batteries discharging
Hi,
The batteries in my '89 F-250 are going flat overnight. I'm suspecting the voltage regulator or a bad diode in the alternator. Anywhere else that I should check? Am I on the right track here?
Thanks for any input.
The batteries in my '89 F-250 are going flat overnight. I'm suspecting the voltage regulator or a bad diode in the alternator. Anywhere else that I should check? Am I on the right track here?
Thanks for any input.
Elder User
Joined: Aug 2007
Posts: 728
Likes: 0
disconnect the large charging wire at the alternator and see ifit sparks when you touch it back if not the diodes are ok
next disconnect all of the electrical connetions at the starter solenoid and check and see which one has a draw on it then onto that system
next disconnect all of the electrical connetions at the starter solenoid and check and see which one has a draw on it then onto that system
Hotshot
Joined: Feb 2004
Posts: 11,697
Likes: 3
From: Marengo, Iowa
Wouldn't be a bad idea to get the batteries checked. You might have one good, one bad. Just dealing with that myself. The good batteries drains to the bad one. They should be replaced in pairs if you can.
Thread Starter
|
New User
Joined: Jul 2005
Posts: 17
Likes: 0
The batteries are new. I replaced them last Tuesday and the voltmeter needle has read way higher than it used to... I checked the large charging wire at the alternator and got no sparking.(ignition off) Still have to check the solenoid. My test light shows current flow across both large terminals with the ignition switch off. Should that be?
Post Fiend
Joined: Jan 2005
Posts: 8,402
Likes: 10
Start pulling fuses one by one and see if you can find the culprit. Also try unplugging the alt. and check for draw.
Freshman User
Joined: Jan 2008
Posts: 25
Likes: 0
To find any battery draw..
Disconnect both battery ground cables. Connect volt meter, head lite, trouble lite or horn between cable end and one battery. If there is any draw, the lite will be on, the meter will show voltage or the horn will make noise. Slowly remove the fuses and notice if the lite goes out or the horn stops honking. Next is to remove all connections at the start relay on the passenger inner fender. The fault should quickly become known. After repair, pull on the head lite switch and notice test lite will be on. Frank in Idaho
Trending Topics
Post Fiend
Joined: Oct 2007
Posts: 10,501
Likes: 5
From: Faibanks Ak.
Have you used a volt meter to check your alt output.
Once you know your charging system is working properly.
Remove your negative battery cables both of them.
take a standard test light clip to negative battery post and negative batt cable.
Anothing pulling juice will light up the light (dome light under hood light clock etc) you will need to disable these.
Key off if your test lightis lit you have a constant draw.
Start pulling your fuses rember where they go check test light after every fuse.
When light goes out you have narrowed it down to the circuit that is the problem.
IF your light stays on you can start un hooking wires on solenoid and alt.
I have fount that the problem is usually in aftermarket accessorys or the circuit they were hooked to.
Inspect for discolored wires around the end of the wires around your solenoids and relays.
Once you know your charging system is working properly.
Remove your negative battery cables both of them.
take a standard test light clip to negative battery post and negative batt cable.
Anothing pulling juice will light up the light (dome light under hood light clock etc) you will need to disable these.
Key off if your test lightis lit you have a constant draw.
Start pulling your fuses rember where they go check test light after every fuse.
When light goes out you have narrowed it down to the circuit that is the problem.
IF your light stays on you can start un hooking wires on solenoid and alt.
I have fount that the problem is usually in aftermarket accessorys or the circuit they were hooked to.
Inspect for discolored wires around the end of the wires around your solenoids and relays.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
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
Moderator
Joined: Jan 2001
Posts: 56,980
Likes: 2,735
From: Virginia
Disconnect both battery ground cables. Connect volt meter, head lite, trouble lite or horn between cable end and one battery. If there is any draw, the lite will be on, the meter will show voltage or the horn will make noise. Slowly remove the fuses and notice if the lite goes out or the horn stops honking. Next is to remove all connections at the start relay on the passenger inner fender. The fault should quickly become known. After repair, pull on the head lite switch and notice test lite will be on. Frank in Idaho
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Did you have the alternator checked when you replaced the batteries?
I have had a couple alternators fail so a meter would not catch it.
They were putting out 14.5 volts, but only 5 amps.
When the parts guy checked the batteries, he said they needed charged, and the alternator was fine.
I was running a 150 amp alternator.
So I had to ask why the alternator was only putting out 5 amps if the batteries were low.
He insisted the alternator was fine, I insisted on a new alternator.
5 amps would charge the batteries if you drove long enough and had nothing like the lights or heater running.
But if you had anything on, the batteries are discharging while you are driving.
And they would not start it the next morning.
I have had a couple alternators fail so a meter would not catch it.
They were putting out 14.5 volts, but only 5 amps.
When the parts guy checked the batteries, he said they needed charged, and the alternator was fine.
I was running a 150 amp alternator.
So I had to ask why the alternator was only putting out 5 amps if the batteries were low.
He insisted the alternator was fine, I insisted on a new alternator.
5 amps would charge the batteries if you drove long enough and had nothing like the lights or heater running.
But if you had anything on, the batteries are discharging while you are driving.
And they would not start it the next morning.
Elder User
Joined: Aug 2007
Posts: 728
Likes: 0
you said you have current at both large terminals you are talking about the two with the 9/16 size nuts is that correct
if so disconnect the one that does not have the fuse links attached to it
see if there is voltage at the terminal if not check the wire you disconnected from it
you have a draw either from the fender mounted solenoid or the starter mounted solenoid by discoonecting the ternimals and probing both you will find it
if so disconnect the one that does not have the fuse links attached to it
see if there is voltage at the terminal if not check the wire you disconnected from it
you have a draw either from the fender mounted solenoid or the starter mounted solenoid by discoonecting the ternimals and probing both you will find it