Electrical draw on battery

jodyfj40

Well-Known Member
Joined
Oct 16, 2008
Location
clayton
i have a lt1 in a cj and i'm hoping someone can help me with what is pulling the battery down. i can hear a humming noise coming from the alternator with the truck off and i assume that is the problem just not sure how to fix it.
thanks
jody
 
Alternator diodes are bad. If you take the belt off it will turn like an electric motor.
 
tknopp said:
The humming your hearing is the Jeep God. He is upset with you for removing the amc power plant and installing a bowtie!
Click to expand...


Nah it is the Chevy gods...they are pissed they were shoved in a Jeep
 
battery draw

so if the diodes are bad is the alternator still charging? It seems to be keeping the battery up ok.
Thanks
 
jodyfj40 said:
so if the diodes are bad is the alternator still charging? It seems to be keeping the battery up ok.
Thanks
Click to expand...

think of a diode as a check valve for electrical current.

Normally the diode allows the alternator to output electricity but not receive or consume it.

If the diode(s) are bad it will allow current to flow in and spin the alternator I.E. become an electric motor.

Hence the comment to test remove belt and see if alt. spins while engine is off.

So in short, yes it will still allow current to flow out and charge while running, but it will also allow it to flow in while off
 
tknopp said:
The humming your hearing is the Jeep God. He is upset with you for removing the amc power plant and installing a bowtie!
Click to expand...
What he said! AMC rocks.....:flipoff2:
 
do you have a digital multi meter? If so set it on the amps setting and connect one end to pos post of battery and the other to the positve cable, see what kind of draw you have. Disconnect a circuit at a time and see what makes it drop.
 
Is the FE (field excitor) wire voltage switched or constant ? Alot of people will connect it 12v constant, it should be switched.

PS. FL(field lamp) goes to idiot light.
 
jeepn-jason said:
do you have a digital multi meter? If so set it on the amps setting and connect one end to pos post of battery and the other to the positve cable, see what kind of draw you have. Disconnect a circuit at a time and see what makes it drop.
Click to expand...


to expand on this point
1) You will have to re arrange the wire plug in at the bottom of the meter. there should be one set for just amps on almost all meters.

2) You will have to disconnect the battery cable to get a reading.
 
draw

Thanks for all the ideas guys, can someone help me with what the field excitor is so I can check to make sure it is switched? Also are the diodes replaceable on the lt1 alt.?
thanks
JODY
 
An alt. requires power in to build the magnetic field. There should be a small plug on the side of alt. with 2 wires. The FE wire should have 12v on it when the ign. switch is on. Some people will connect the FE wire to the larger 12v out lug and call it a "one wire alt". This will drain your battery.
 
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