Charging System Question

[avjeepfreek]

The other day I noticed that the Voltage Meter in the Jeep was sitting at 12v (last notch before the RED on the guage). Since I've had the Jeep, it has usually sat at 14v. I thought maybe it was the alternator going out so, I replaced the old stock 90 amp Alt with a 160 amp high output Alt. Got'er installed and all buttoned up and it still reads the same at 12v.

So, the question is, What could be causing this? Could it be the guage? Is the Voltage regulator built into the alternator or is it external? What am I missing???

It's a '93 YJ 2.5L 4 banger. I've read through the Hanyes Manuel and it's no help at all!

I'm not great at the whole electrical thing so any help would be appreciated!

Thanks, Scott

[Jason]

How's the battery? I may be wrong here but I believe the alternator will only charge what the battery can take.

[aw12345]

Use a volt meter at the alternator first then move it to the battery, if voltage is low at the alternator. you might be in need of a ECM, since the voltage regulator is in the ECM, if I am not mistaken.

[OU812]

The voltage is regulated by the ECM in my 92 6cyl.

[randysjeep]

I would check system with meter at battery should read just over 12 volts engine off and about 14 engine on. if reads 14 engine on and dash guage reads 12 its the guage. it happened on my 95, switched guages(Autometer) now reads just over 14 at dash guage.

[Jerry Bransford]

Essentially, the higher the voltage, the more the alternator is charging the battery. If the battery has a full charge on it, the alternator doesn't need to be doing much, if anything, at all.

[aw12345]

The Voltage, should stay near 14 volts low battery state of charge or not. The amperage will go down as the battery nears a full charge, but the voltage should stay fairly steady it actually goes up a bit when the battery is fully charged. After it sits for a while you should read atleast 12.7 to 12,8 for a fully charged battery, after you crank the engine for say about 3 to 4 minutes to remove the surface charge. Your most likely problem is either the alternator wire to the ecm, a poor ground connection between the alternator and it's ground or the ecm it self.

[chris142]

Forget about the stock guage for now. Get a volt meter and see what it says. With the Jeep running it should be somewhere between 13.2v and 14.6v.

If it's lower then it's not charging. Could be a bunch of reasons including bad connections, blown fusible link, loose belt etc.

[avjeepfreek]

***UPDATE***


Okay, I got the new 160 Amp Alternator installed and then went down and bought an all in one Voltage Meter/Battery Tester/Charging System Tester and hooked it up at the battery.

It read just over 12v not running.

I did a load test on the battery and it was just fine.

I started the Jeep and the meter shot right up to just above 14v and it stayed there.

I shut the Jeep off and watched the meter slowly drop to around 13v and it stayed there.

While I was running the Jeep I took a gander at the gauge on the dash and it read 12v while the new test meter read 14v.

Everything seems fine so, my only deduction is that I have a bad Guage in the dash.

Would you all agree??

Scott

[chris142]

Yes something is up with the stock guage. They are known to be wrong, especially the oil pressure one but any of them can show a weird reading at any time. You are charging but the stock guage is reading low.

[OU812]

When you turn your heater on(blower motor) does your voltmeter drop? Mine does. All the way down to 10volts. The OEM guage is crap.

[aw12345]

Scott, see if you can buy or borrow a Digital volt meter and then take the instrument cluster out and see how much voltage you actually get to the volt gauge with the Jeep running. There is a pretty good change you have a poor connection somewhere either to the ignition switch or in the wiring to the instrument cluster.
This actually goes for both Scotties

[Ol Man]

Could be a grounding issue at the dash.

[avjeepfreek]

Thanks Guys,

Art I'll do that for sure! I had it apart yesterday and cleaned all the dust and crap out from inside the dash (Years of Dust and Crap to be exact!) I was real happy to find that the charging system is working properly and if all thats wrong is the OEM Guage, I got lucky!

Thanks again for all of you guys input!

Scott

[OU812]

Scott I have a complete set of center guages in my garage. If you find one of your guages is bad let me know.