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post #1 of (permalink) Old 01-08-2005, 04:04 PM Thread Starter
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Battery Drain??? Voltage Regulator to blame?

I drove the CJ for the first time in a few months and have a few issues. The big one is that the battery has a slow drain to it. Its had the problem since I parked it, however I never got around to diagnosing it till now. In the past I've gone through a few voltage regulators. My alternator is the style with the external regulator so its pretty easy to swap out. What I can't figure out is why do I go through them so quickly, or are they a cheap part that is easy to fry? I buy the $14 Autozone ones, not the $40 NAPA ones. So anywho, I was out trying to diagnose my problem today and here's what I noticed. With the engine running the alternator was putting out 14 volts as I believe it should. Thats with the headlights and blower motor on, it was still putting out plenty of voltage to compensate. I turned those off and the voltage dropped some but was still above 14V. I turn the engine off and turn off the headlights and blower motor and the charge on the battery slowly trickled down. It would drop about 1/100th of a volt every 2 seconds. It did this until it got to about 12.95V and then the rate of drain slowed. In the past 5 minutes or so its gone from 12.92V to 12.89V according to my digi multimeter. Is this normal? What I did notice though, was that with the battery at 13V I disconnected the + side of it and the drop in voltage stopped. This is what makes me suspect I've got a drain somewhere. In the past when I've had a drain like this I've replaced the voltage regulator and it worked great for a while again. So whats goin on here? Anyone know? I can also gather more data for you if you need it in diagnosing, I just wanna fix this.
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post #2 of (permalink) Old 01-08-2005, 09:15 PM
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Re: Battery Drain??? Voltage Regulator to blame?

full battery charge is 12.65 with the enigne off.
your multimeter has an AMPS setting right? use the 10 amps setting.
disconnect your positive cable, install a short jumper wire form your batty terminal to the cable. turn your key on, then back off. then hook up your mulitmeter PARRALLEL to your jumper wire, turn the meter on, then disconnect the jumper wire, thus putting your meter in series with the system.
this will show you rate of draw, should be under 50 milliamps. if it is high, start disconnecting fuses and accesories untill your amp reading drops. when it drops, you found your draw.
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post #3 of (permalink) Old 01-08-2005, 09:38 PM
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Re: Battery Drain??? Voltage Regulator to blame?

[img]images/graemlins/goodpost.gif[/img] Zach....

Good way to find the always on load to the battery.

Sometimes things get hooked up directly to the battery supply, or there could be a short (not a dead short but a high resistance short). Rust, corrosion and mashed wires can come into all of that.

As with all trouble shooting, divide and eliminate. Knowing what isn't the problem can be very important along the road to knowing what is the problem.

Keep digging, you will find it.

Dale
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post #4 of (permalink) Old 01-09-2005, 01:18 PM Thread Starter
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Re: Battery Drain??? Voltage Regulator to blame?

Well I put the multi meter in as Zach said and found there was a 30 miliamp draw on the battery. I started pulling fuses and found one which dropped the draw down to 10 miliamps. Now I'm just tracking down what that fuse is for. But 30 miliamps is under what Zach said is acceptable so I'm wondering if I've got a problem at all or if I just misdiagnosed a low battery 6 months ago. With the battery disconnected all night the voltage is at 12.65 volts so maybe later I'll hook it up to see if it drains hooked up.
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post #5 of (permalink) Old 01-09-2005, 02:08 PM Thread Starter
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Re: Battery Drain??? Voltage Regulator to blame?

Well its narrowed down to either my brake stop switch or the anti theft stuff I wired in. I leaned towards the anti-theft stuff and think I've got it. However I've got another question. With the anti-theft system activated the draw on the battery was 30mA. With the anti-theft system deactivated the draw was around 250mA. The anti-theft is connected to the ignition systems power wire so when activated there's no power to the ignition. So why is my ignition system drawing such current? Its easy for me to activate the anti=theft but I'm still wondering about the draw. I figure the 30mA draw when the system is activated is from the LED I use to know the system is activated.
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post #6 of (permalink) Old 01-09-2005, 08:50 PM
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Re: Battery Drain??? Voltage Regulator to blame?

[ QUOTE ]
With the anti-theft system activated the draw on the battery was 30mA. With the anti-theft system deactivated the draw was around 250mA.

[/ QUOTE ]

So you are saying that if you don't activate the anti-theft system you are drawing 1/4 amp?

If so something is wrong. Or maybe it's 250uA?

Will assume that you did all of the typical things like cleaning the battery connections, checking the alternator wiring, checking belts... bla bla bla...

If all else fails go to your local Auto Zone and have them check the battery/charging system for free.

Dale
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post #7 of (permalink) Old 01-09-2005, 09:25 PM
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Re: Battery Drain??? Voltage Regulator to blame?

Hmmm. With the anti theft device turned off it's ready to start the jeep so it allows current to flow to the ignition coil. What if it's wired wrong so it bypassed the ignition switch or the ignition module and allows current to flow into either one when it's deactivated??

OR does the theft device activates a relay to control the ignition that will draw 1/4 amp on it's coil windings when the relay is activated. I'm thinking that deactivating the alarm activates the relay.
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post #8 of (permalink) Old 01-09-2005, 10:51 PM
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Re: Battery Drain??? Voltage Regulator to blame?

Sounds strange -- activating the alarm stops the draw.

But it may not be so strange - if it's disconnecting the power to the ign switch.

Try pulling off the wires on the alternator - see if it goes away. Did you do the GM conversion?
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post #9 of (permalink) Old 01-10-2005, 02:13 AM Thread Starter
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Re: Battery Drain??? Voltage Regulator to blame?

The anti-theft is a system of two relays, one which controls the other.

I'm not sure what you mean by the GM conversion. Its got the motorcraft alternator with the external voltage regulator. I'll be away from my Jeep for a couple days but will be able to tinker more when I get back. This will be the true test to see if there's a drain on the battery with the ignition cutoff activated.
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