battery loosing charge
Senior User
Joined: Dec 2005
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your battery could have a bad cell,check wires to make sure there not exposed anywhere, and check the alternator nothing is perfect start the truck and pull the positive off the battery and it dies right away you got a bad alternator go return it
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New User
Joined: Jan 2006
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thanks i will try this but this is the second battery, but it is worth a try at this point anything is worth a try. somebody told me to check the voltage regulator but i am not sure if it is in the alternator on a ford or if it is on the firewall or the starter do you have a clue
Fleet Owner
Joined: Aug 2005
Posts: 23,667
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From: Easton,Ks
NEVER unhook a battery while the engine is running, if you do the voltage can go over 120 VDC and fry anything in your truck. Also all trucks will die with out a battery, as there is no residual magnetic field in an alternator.
Yes the regulator is in the alternator in 1997.
Yes the regulator is in the alternator in 1997.
Postmaster
Joined: Oct 2004
Posts: 4,155
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From: Southern Louisiana
Has never been my experiance, not on my F-150, either Toyota nor S dime. Only time the truck should shut off with the positive cable disconnected is if your alternator is bad. Never has anything fry from it either. I know the alt. is to charge the battery and also powers all things electrical when truck is running, if your above statement is true than wouldnt it start frying stuff when the battery is fully charged. Correct me if I am wrong, but isnt that the purpose of the regulator, hence the name, dosent it regulate the voltage that the alt. puts out?
Last edited by IB Tim; Jan 3, 2006 at 06:37 AM.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
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From: Easton,Ks
The regulator in the alternator monitors the battery voltage to adjust the alternator output. If you disconnect the battery the voltage drops on the sense wire and the regulator goes all out and can peak at over 120 vdc.
If you have done this and got away with it with an internal regulator you were lucky.
Most manuals say that the engine should die in about 3 to 4 minutes when the alternator has lost battery power.
I know Franklin2 has also echoed this caution about disconnecting the battery.
If you have done this and got away with it with an internal regulator you were lucky.
Most manuals say that the engine should die in about 3 to 4 minutes when the alternator has lost battery power.
I know Franklin2 has also echoed this caution about disconnecting the battery.
Postmaster
Joined: Oct 2004
Posts: 4,155
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From: Southern Louisiana
Thanks for clarifying that. I did unhook the positive cable on my F-150 but not for 3 or 4 minutes, maybe just a minute, never left it unhooked that long on the other ones either, I feel an experiment coming on.
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Senior User
Joined: Dec 2005
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i just went out side and pulled the positive all 3 of my truck nothing got fried started right back up ...also ive done this countless times with out having a problem
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Cargo Master
Joined: Aug 2004
Posts: 2,899
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From: Lynnwood, WA
Batteries can be bad, and lose charge because of that, but more often than not, there is something draining the battery.
Turn off *everything*, then remove the positive cable and quickly hook up a 10A range ammeter, and write down the current. If it's under 100 mA, switch to 100 mA range and note the current there. The computer, clock, and few other things may drain up to 50 mA or so (exact numbers will vary somewhat) but anything more than 50 mA is suspicious. A current over 500 mA (0.5 A) is definitely bad.
Turn off *everything*, then remove the positive cable and quickly hook up a 10A range ammeter, and write down the current. If it's under 100 mA, switch to 100 mA range and note the current there. The computer, clock, and few other things may drain up to 50 mA or so (exact numbers will vary somewhat) but anything more than 50 mA is suspicious. A current over 500 mA (0.5 A) is definitely bad.
Senior User
Joined: Oct 2005
Posts: 339
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From: St. Louis, MO
I'm a dummy (with a meter no less) so I'll ask the dumb question. Where do I connect the meter? The battery, the cable I just unplugged? Do I ground the black lead at the battery terminal also?
Sorry, I just want to be clear - I have a definate battery drain problem also on one of my vehicles. I'm on the third battery in a year, covered by dealer, but I'm getting tired of the truck being dead all the time. I purchased one of those jump-start battery deals (with air compressor and light) because of this. I also purchased a "priority start" that is supposed to keep the battery from going dead - I can hear the mechanical components in this thing running all the time when the truck is turned off and sitting in the driveway!
Thanks!
Sorry, I just want to be clear - I have a definate battery drain problem also on one of my vehicles. I'm on the third battery in a year, covered by dealer, but I'm getting tired of the truck being dead all the time. I purchased one of those jump-start battery deals (with air compressor and light) because of this. I also purchased a "priority start" that is supposed to keep the battery from going dead - I can hear the mechanical components in this thing running all the time when the truck is turned off and sitting in the driveway!
Thanks!
Senior User
Joined: Oct 2005
Posts: 339
Likes: 5
From: St. Louis, MO
Originally Posted by aurgathor
Turn off *everything*, then remove the positive cable and quickly hook up a 10A range ammeter, and write down the current.
If I connect to the battery with the positive cable disconnected, won't I just get a read for the battery output?
Sorry - Like I said, I'm not familiar in this area.
Moderator
Joined: Jan 2001
Posts: 56,980
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From: Virginia
Originally Posted by oojbearoo
i just went out side and pulled the positive all 3 of my truck nothing got fried started right back up ...also ive done this countless times with out having a problem
Now if there is really something wrong, you can definitely fry things, I have personally done it. I had an old truck that was not charging correctly. I pulled the + cable off, and it ran for about 20 seconds more and then quit. It never would start again till I replaced the electronic ignition module. Come to find out, the regulator in that case was bad, the alt went to wide open and fried the module.
Cargo Master
Joined: Aug 2004
Posts: 2,899
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From: Lynnwood, WA
Originally Posted by Miescha
I'm assuming aurgathor means I should connect the meter to the cable I just disconnected
so I can determine the current draw from the vehicle - not the output from the battery. Is this correct?
If I connect to the battery with the positive cable disconnected, won't I just get a read for the battery output?
Sorry - Like I said, I'm not familiar in this area.
Moderator
Joined: Jan 2001
Posts: 56,980
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From: Virginia
Originally Posted by Miescha
I'm a dummy (with a meter no less) so I'll ask the dumb question. Where do I connect the meter? The battery, the cable I just unplugged? Do I ground the black lead at the battery terminal also?
Sorry, I just want to be clear - I have a definate battery drain problem also on one of my vehicles. I'm on the third battery in a year, covered by dealer, but I'm getting tired of the truck being dead all the time. I purchased one of those jump-start battery deals (with air compressor and light) because of this. I also purchased a "priority start" that is supposed to keep the battery from going dead - I can hear the mechanical components in this thing running all the time when the truck is turned off and sitting in the driveway!
Thanks!
Sorry, I just want to be clear - I have a definate battery drain problem also on one of my vehicles. I'm on the third battery in a year, covered by dealer, but I'm getting tired of the truck being dead all the time. I purchased one of those jump-start battery deals (with air compressor and light) because of this. I also purchased a "priority start" that is supposed to keep the battery from going dead - I can hear the mechanical components in this thing running all the time when the truck is turned off and sitting in the driveway!
Thanks!
An easy way to see if you have a drain is to hook up a testlight like shown below.
