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Discussion Starter · #1 ·
Hi,

I've just encountered a problem with my '95 YJ Rio Grande.

A couple of months ago I replaced the battery of my YJ. But now the problem starts again that the battery is running empty after a couple of days. So I did some measurements. When the Jeep is running idle, its charging the battery with 12.5 Volts, when I'm revving up the engine, it is charging with 13.5 - 13.8 Volts. Looks quite normal to me.

After a long trip, I measured the voltage of the battery, this was about 12.1 Volts. I left the Jeep for about 20 hours, when I measured again, the voltage of the battery was about 11.3 Volts. This doesn't looks good to me. But I'm not an electrician :)

So my best guess is that the electricity system of the car is "leaking" somewhere.

So, where do I start to check what is going on.

Thanks in advance.

Rene
 

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I believe that a healthy alternator should bring voltage up to just over 14 VDC. It also sounds like you may have a parasitic draw. Y'all chime in here and correct me if I'm wrong, but I believe that even for your year the alternator was internally regulated. It may have failed. In the PI do they have auto parts stores that can test it for you on a test bench? That's where I'd start.

To check for a parasitic load draw, I start by unhooking either battery cable and letting the vehicle sit for at least one hour. The "surface charge" of a healthy batter should be somewhere around 12 to 12.5 VDC. If the battery voltage drops off while disconnected, then there is probably an internal short in one or more cells. If the battery voltage remains stable, then you will have to start the process of elimination to find the short to ground. If it has an aftermarket radio added, I would start with the wiring to it. I have found more problems with jackleg installed stereo equipment than I care to mention. If all looks good with the audio system, start by pulling fuses one at a time until the voltage remains steady. If you have a good DC ammeter, that would help. You connect it between the battery post and ground terminal and measure actual current draw. That can help you eliminate some items (small draw most likely small load, i.e. dome light circuit, etc.).
 

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Clean up the top of your battery, the terminals, and the terminal posts. Everything should be bare metal. Before cleaning it, leave the battery sit for a few days, as mentioned before. If it loses charge, you may have continuity between the posts because of dirt. The problem seems to be your alternator or a small electronic draining such as a relay stuck closed or some sensor or dash light getting constant power.
 

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Discussion Starter · #4 ·
Hi, thanks for the replies. The battery will not be the problem, it is brand new. I will check first if it is draining somewhere. When I'm checking, should the amps be completely zero? Or is a small current allowed?

I hope it is not the alternator. Spares for an YJ are simply not available in the Philippines. I have to check then if I can find a similar alternator from a different brand.
 

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There should be a tiny current for the clock, and computer memory, but that's about all.
Fractions of an amp, if I recall correctly

Your alternator should be a Denso brand and will most likely interchange with other Japanese stuff. Search the part number on it if it comes down to that.

Its regulated by the computer.
 

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You might have better luck trying to do the alternator swap from a V8. Most 5.9L V8 Chrysler vehicles around 1998 use it. I know the Grand Cherokee 5.9 Limited and Dodge Durango (both 5.9 V8 1998 vehicles) have them.

If you fully charge the battery (with an external charger) and leave it sitting in the Jeep, that should tell you if the issue is in the alternator or a drain from your electrical system. If the battery is dead after a few days, your alternator is fine and you have some sort of drain.

How can you keep your YJ up and running without access to many parts? I buy parts every other week, but my Jeep was abused in the past without proper maintenance.
 

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You might have better luck trying to do the alternator swap from a V8. Most 5.9L V8 Chrysler vehicles around 1998 use it.
Uh oh, thread hijack time.
Reading your post has got me to thinkin'....
I have a rebuildable alternator core sitting in my garage. I am pretty sure it is a Denso. It needs bearings - they're toast and the reason I had to help my son change it last weekend. He bought a new one off of Amazon (no core return) and I have been toying around with the idea of getting a rebuild kit and going through it. I would bet that since it came off a newer vehicle ('02 PT Cruiser Limited) it has a higher amperage rating than the OEM one in my YJ. I should probably look at the attachment points and field control input coupling to be sure before I start.
Hmmm, another project for the winter months.
 

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Uh oh, thread hijack time.
Reading your post has got me to thinkin'....
The rebuild would make a good write-up thread. You should start one, I'm sure someone might stumble upon it some day. I have a few tips but I don't want to clutter the thread. You can PM me or quote me in a new thread, this is interesting...
 

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Remove the alternator and the battery and take them to your local auto parts store. Have them tested. Most parts stores will check them for free.
I expect the problem is in your alternator.
Even brand new batteries can fail so get it checked too.

If both prove good, then start looking for the parasitic draw.

Good Luck, L.M.
 

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Remove the alternator and the battery and take them to your local auto parts store.
If you don't have the convenience, try removing the battery with the Jeep running, or starting it with a push or jump with the battery out. A bad alternator won't be able to keep the plugs firing. I'd say let it idle for 10 minutes, or drive it around in a safe place (where it's safe to stall) with a friend able to tow you home with a strap.
 

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Discussion Starter · #11 ·
Hi guys,

Thanks for the advises. I started today to tension the belt which I just renewed. That helped already a lot. On idle it is charging now with 12.8V, on 3000rpm it is charging with 13.9V, and it stays steady. The batt was completely empty, after half an hour drive it was about 12.5V, so that looks good.

The batt itself is ok, tomorrow I will check again the voltage and start with the search for the parasetic draw (which I suspect)

Rene
 

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Thanks for the advises. I started today to tension the belt which I just renewed. That helped already a lot.
The belt was so loose that it wasn't turning the alternator??? That's either just a REALLY loose belt, which would squeal like a pig with its nuts in a vise, or a bad pulley on the belt drive system.

Do you have A/C?

Do you have an impact gun?

Check the AC fan clutch and remove the pulley from the alternator with the impact gun. Make sure all of the bearings are fine, give them some oil/grease if they need it.

Look at other pulleys like water pump, power steering pump, and idler pulley. Turn each individually to listen for a squeak. Try to turn them with a drill (not an impact) at a high speed to look for resistance and squeals.

A stuck pulley would be something that would have other symptoms that would be noticeable, like RPM changes and audible noises.
 

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Discussion Starter · #14 ·
Hi Drednot, thanks for the input, that looks a little bit different from mine I have to say. Will look into it.

Hi Mudmagnet YJ. I saw somewhere here on the forum, if you can turn the belt with 90 degrees, it is too loose, that was the case. It was not squealing, but tighten up a little bit.

I have no AC installed.

Today I looked into it again. After 2 days I had only 2.99V left in the battery. It was 12.5 when I put it away.

So, after jump starting again, I drove the Jeep for 45 min. The Voltage again was 12.5. I measured a parasitic draw of 19 mA, when I removed the fuse from the horn, it was only 1mA.

I had already some problems with the horn, sometimes working, sometimes not, so will start there.

Rene
 

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So, after jump starting again, I drove the Jeep for 45 min. The Voltage again was 12.5. I measured a parasitic draw of 19 mA, when I removed the fuse from the horn, it was only 1mA.

I had already some problems with the horn, sometimes working, sometimes not, so will start there.
That sounds like a bad relay. It probably gets stuck open and closed. It will drain if it's stuck closed. Replace that and see if it helps. Or you could have a bad switch. You can take apart the steering wheel and sand down the contacts with some WD-40.

For the sake of your neighbors, unplug the pigtail clip from your horn... You can judge the quality of your switch by the click of the relay.
 
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