Battery Gauge volt droperage

2001 RED XJ · Sep 2, 2015

I recently have had issues with the Battery Gauge. Sometimes it work fine and some the voltage dropsl. When it drops the Alternator squalls and then I turn my air off and it goes back to 13.5. This doesn't happen all the time. My belt is not to tight or to loose. I have noticed when the engine starts on cold startup I do hear a chirping sound. But when it warms up the chirping disappears. Is this a alternator problem? I checked the battery and alternator when the motor is on and off and it checks out ok. Can a alternator randomly act funny or is it something else.

2001 RED XJ · Sep 2, 2015

Re: Battery Gauge volt dropage

2001 RED XJ said:
I recently have had issues with the Battery Gauge. Sometimes it work fine and some the voltage dropsl. When it drops the Alternator squalls and then I turn my air off and it goes back to 13.5. This doesn't happen all the time. My belt is not to tight or to loose. I have noticed when the engine starts on cold startup I do hear a chirping sound. But when it warms up the chirping disappears. Is this a alternator problem? I checked the battery and alternator when the motor is on and off and it checks out ok. Can a alternator randomly act funny or is it something else.

old_man · Sep 2, 2015

OK....how much does the voltage drop?

2001 RED XJ · Sep 2, 2015

One time it went to 0 but last time it went to 9 to 10.

2001 RED XJ · Sep 2, 2015

I recently just had an engine put on. I have checked the grounds. I have read something about the starter and the coil. Do they have grounds too.

md21722 · Sep 2, 2015

Check the brushes. If worn down to knubs or faulty, replace them or replace the alternator. If it is the brushes, it will get worse. Sometimes you can beat the alternator with a rod and hammer to wake it up.

devildog0 · Sep 2, 2015

If the belt is screeching when the voltage drops I wonder if you have bad bearings in that ALT making the pulley stop.

Digger87xj · Sep 2, 2015

tighten the belt a little more. the only reason for it to squeal under load is if it is too loose.

Tim_MN · Sep 2, 2015

If the belt squeals it is loose. If the gauge drop to 9 volts, the alternator is suspect. It probably has bad brushes and will randomly drop to 9 volts. If the alternator squalls, it is suspect, and probably has bad bearings.

ehall · Sep 3, 2015

sounds like a dead alternator to me

2001 RED XJ · Sep 3, 2015

That's good on the alternator. I did find a loose ground wire and I thought I fixed it. Don't wanna hunt for loose wires.

techno1154 · Sep 3, 2015

2001 RED XJ said:
I recently have had issues with the Battery Gauge. Sometimes it work fine and some the voltage dropsl. When it drops the Alternator squalls and then I turn my air off and it goes back to 13.5. This doesn't happen all the time. My belt is not to tight or to loose. I have noticed when the engine starts on cold startup I do hear a chirping sound. But when it warms up the chirping disappears. Is this a alternator problem? I checked the battery and alternator when the motor is on and off and it checks out ok. Can a alternator randomly act funny or is it something else.

If the belt squeals it is slipping. When the belt slips the alternator speed will be reduced (maybe to a complete stop). If the alternator is not spinning fast enough the voltage will drop especially when the AC is on. Check the condition of the belt and pulleys then tighten the belt. If all else fails then have the alternator checked.

Every time I cross deep water in my XJ (and other vehicles) the belt squeals, the voltage drops and I loose power steering,.....for a short while.

Matthew Currie · Sep 6, 2015

While checking things don't forget to check the AC pump. If something is going wrong with the clutch there, it might cause the belt to squeal, and affect the alternator too.

The XJ engine does not have a belt tensioner, and if you're not used to it you may be really surprised at how tight that belt must be. There's a tension gauge made for these (NAPA sells it, it's called the CRIKIT II, and many Napa clerks will look at you as if you're crazy when you ask for one, but they exist and can be ordered). For a quick and dirty check, find the longest unsupported span of belt. You should be just able to twist it 90 degrees by hand. If you can get it past 90 degrees, it's almost surely too loose.

DieselSJ · Sep 8, 2015

Matthew Currie said:
While checking things don't forget to check the AC pump. If something is going wrong with the clutch there, it might cause the belt to squeal, and affect the alternator too.

The XJ engine does not have a belt tensioner, and if you're not used to it you may be really surprised at how tight that belt must be. There's a tension gauge made for these (NAPA sells it, it's called the CRIKIT II, and many Napa clerks will look at you as if you're crazy when you ask for one, but they exist and can be ordered). For a quick and dirty check, find the longest unsupported span of belt. You should be just able to twist it 90 degrees by hand. If you can get it past 90 degrees, it's almost surely too loose.

I haven't been a big fan of my CRIKIT tool. When I adjust to FSM setting per the tool, the belts shred within a few days. IMHO they are WAYYY over tight. I use the 90 degree twist method and it works great.

md21722 · Sep 9, 2015

DieselSJ said:
I haven't been a big fan of my CRIKIT tool. When I adjust to FSM setting per the tool, the belts shred within a few days. IMHO they are WAYYY over tight. I use the 90 degree twist method and it works great.

90 degree twist or about 1" deflection is all I've ever done. And if I've ever erred on the side of too loose, turning on the A/C lets me know immediately!

DieselSJ · Sep 9, 2015

md21722 said:
90 degree twist or about 1" deflection is all I've ever done. And if I've ever erred on the side of too loose, turning on the A/C lets me know immediately!

Yes, exactly. Just turn on the A/C and tighten the belt until the squeal stops.

Tim_MN · Sep 9, 2015

DieselSJ said:
....... turn on the A/C and tighten the belt until the squeal stops.

Works every time.

2001 RED XJ · Sep 10, 2015

I thightened the belt and problem solved thanks.

Battery Gauge volt droperage

2001 RED XJ

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2001 RED XJ

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old_man

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2001 RED XJ

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2001 RED XJ

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md21722

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ehall

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2001 RED XJ

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