Any electrical guru's here...
Thread Starter
|
Elder User
Joined: May 2008
Posts: 765
Likes: 0
From: Patricia, Alberta
Any electrical guru's here...
I bought a 2006 SD 6.0 PS at an auction a couple of months ago, and the batteries are draining, and it won't start if it sits more than a few days. I did some testing on it yesterday, and this is what I came up with. I disconected the secondary battery positive cable, and the primary negative cable. I put a test light between the negative, and it glowed. Put a multimeter in and it read 12.7 volts. I pulled every fuse out (there's 50 of them!) under the dash and in the power distribution box, and nothing changed. I took the smaller cable off that bolts onto the positive cable, and still no change. I wiggled the ignition switch hoping it might be the culprit. When I first got the truck, the alt was only putting out 13.8 volts, so I changed it, and now it's got 14.2 at the battery. But if I touch the multimeter ground probe to the radiator, I get 14.7 volts. WTF? Before I take this thing to a dealership and get bent over to the tune of $100 an hour, I'd like to try and find out what's causing the leak. Is there a common problem with these trucks that I don't know about?
Senior User
Joined: Sep 2004
Posts: 153
Likes: 0
Take both the (+) and (-) cable off of one battery completely. Then take the (-) completely off of the second battery. Then get a digital multimeter and set it to DC amps and put it between the second batteries (-) post and the (-) cable. This will tell you how much amperage there is when the truck is off and the key is out. There should only be a few milliamp draw from the radio and computer to keep their memory stored. If there is more than that, check for aftermarket accessories that may have been tied into constant hot power instead of ignition power.
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
There will always be a small drain on the battery, that is the way these trucks are designed.
I would first take your batteries out, haul them down to the local auto parts store that does free battery testing and have both of the batteries load tested. It sounds to me like you need two new ones.
I would first take your batteries out, haul them down to the local auto parts store that does free battery testing and have both of the batteries load tested. It sounds to me like you need two new ones.
Tuned
Joined: Aug 2006
Posts: 405
Likes: 42
How CLEAN are your batteries??? You wouldnt believe how much of a draw a dirty battery top will have! I couldnt either until somebody showed me. Also check your ground cables. Corroded grounds can be real funny sometimes.
Tuned
Joined: Aug 2006
Posts: 405
Likes: 42
How CLEAN are your batteries??? You wouldnt believe how much of a draw a dirty battery top will have! I couldnt either until somebody showed me. Also check your ground cables. Corroded grounds can be real funny sometimes.
Good luck
Not sure how the double post happened, but sorry about that!!
Good luck
Not sure how the double post happened, but sorry about that!!
Thread Starter
|
Elder User
Joined: May 2008
Posts: 765
Likes: 0
From: Patricia, Alberta
The batteries aren't even a year old, but if it was drawing for the 3 months or so that the truck sat in the auction mart, they could be toast, but they don't act like it. If you drive it every day, it works fine. There are no aftermarket accessaries on the truck. I'll try the amperage thing, but I'm thinking it must be a lot to run 2 big batteries down in a couple of days. Thanks for the replies guys.
New User
Joined: Apr 2008
Posts: 20
Likes: 0
From: Cleveland Ok
If you have a diode blown in the alternator it will drain down,a diode being a one way electrical check valve lets power go only one way through the alternator,my 2 cents.
Trending Topics
More Turbo
Joined: Aug 2006
Posts: 530
Likes: 2
From: W. Wisc
I'd second Crazyandy's advice to test current draw with the car off. All cars/trucks draw some power when off, but the drain should be less than about 50mA (the common figure I've been told). You should watch it for several minutes as the computers often step down their current draw in stages as they go into standby and sleep modes (doors closed so all lights are off, etc). It can take 20 min for some computers to fully shut down. Then if you see a low current draw, test the batteries and then perhaps the alternator. A good first test for the alternator is to measure voltage across the battery poles with the car running. Helps to have someone to give it a little gas to up the revs too. Typically you see 14V+ if the alternator is working correctly. If you only see 12V or so, then the alt is probably bad, and you should remove it and bring it in for testing at a shop/parts store. But it sounds like you have a new alt so this is unlikely to be the issue.
Never replace a part that you have not confirmed is bad... BTDT
-Dave
Never replace a part that you have not confirmed is bad... BTDT
-Dave
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: Feb 2008
Posts: 38
Likes: 1
Take both the (+) and (-) cable off of one battery completely. Then take the (-) completely off of the second battery. Then get a digital multimeter and set it to DC amps and put it between the second batteries (-) post and the (-) cable. This will tell you how much amperage there is when the truck is off and the key is out. So if he does this can't he check for his drain problem by pulling fuses or unhooking the alternator, etc?
Senior User
Joined: Aug 2006
Posts: 157
Likes: 0
Take both the (+) and (-) cable off of one battery completely. Then take the (-) completely off of the second battery. Then get a digital multimeter and set it to DC amps and put it between the second batteries (-) post and the (-) cable. This will tell you how much amperage there is when the truck is off and the key is out. So if he does this can't he check for his drain problem by pulling fuses or unhooking the alternator, etc?
Freshman User
Joined: Jun 2008
Posts: 40
Likes: 0
The batteries aren't even a year old, but if it was drawing for the 3 months or so that the truck sat in the auction mart, they could be toast, but they don't act like it. If you drive it every day, it works fine. There are no aftermarket accessaries on the truck. I'll try the amperage thing, but I'm thinking it must be a lot to run 2 big batteries down in a couple of days. Thanks for the replies guys.
Ron
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
It doesn't matter how new the batteries are. If you take a new battery and drain it flat, charge it..etc....cycle 10 times, the battery will be shot. Deep cycle batteries can withstand multiple drain and recharge cycles. Stardard batteries cannot.
Like I suggested, get them load tested to know for sure.
Like I suggested, get them load tested to know for sure.
Thread Starter
|
Elder User
Joined: May 2008
Posts: 765
Likes: 0
From: Patricia, Alberta
I was thinking the same thing - if they were dead for that long, they can't be any good. I changed them yesterday, and if everything works out, I'll let this thread die. If it doesn't, I'll go back to testing.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 421
From: Long Island USA
It doesn't matter how new the batteries are. If you take a new battery and drain it flat, charge it..etc....cycle 10 times, the battery will be shot. Deep cycle batteries can withstand multiple drain and recharge cycles. Stardard batteries cannot.
Like I suggested, get them load tested to know for sure.
Like I suggested, get them load tested to know for sure.
If you drain regular batts completely dead, and recharge them immediately, they're OK.
If you drain them and leave them, they're DEAD DEAD DEAD.
Lithium batts, they take a discharge and can handle a long time being dead without a recharge.
Regular lead-acids, they need to be recharged immediately.
Deep-cycles tend to handle the "completely dead" scenario, but even cranking batts can handle a complete discharge.
If they don't, they need to be replaced.
In my experience anyway. "Your mileage may vary"
Elder User
Joined: Jan 2007
Posts: 501
Likes: 0
have the batery's tested first. after that you need to do a draw test. 50 MILLIAMPS is the limit. you truck has computers that need to go to sleep before you can check it. let the truck sit for 30min. remove one battery. on the other batery take a multimeter and put one probe on the neg. post on the batery and the other one on the terminal. have your meter set to amps (milliamps if your meter has it). remove the terminal from the battery making sure that you do not remove the probes. if you loose contact then you will wake up some computers and give you a false high reading. if you are under the 50 milliamp limit then you don't have a drain. if you are over then start pulling the big fuses till you see a drop. once you remove the fuse do not put it back, it could wake up the computers. once you find your big fuse that the drain is on you can look at a wiring diagram to see what is on the that fuse. put the fuse back in and start pulling any small fuse's that are in the curcit till you see a drop. then start unplugging the componets till you find the one. i have had this with 2 fords and both was the GEM.