Voltage meter

[mo2058130]

It’s been a few weeks now. Volt meter will read between ~11.5v and ~14.5v. The battery light is on but when I check the battery voltage after several days/ week or two if driving the battery reads 12.65(vehicle off). Not too concerned but don’t wanna be stranded either.

Wife’s daily, she’d be upset! [emoji51][emoji51][emoji51]
Any insight would be appreciated.

2005 GMC Yukon XL

 

[mo2058130]

It’s been a few weeks now. Volt meter will read between ~11.5v and ~14.5v. The battery light is on but when I check the battery voltage after several days/ week or two if driving the battery reads 12.65(vehicle off). Not too concerned but don’t wanna be stranded either.

Wife’s daily, she’d be upset! [emoji51][emoji51][emoji51]
Any insight would be appreciated.

2005 GMC Yukon XL

2005 GMC Yukon XL

 

[Fless]

What does the voltmeter read with the truck running? Should be high 13s, 13.8 or maybe more. Battery light is on for one reason or another....

 

[mo2058130]

What does the voltmeter read with the truck running? Should be high 13s, 13.8 or maybe more. Battery light is on for one reason or another....

I’ll definitely check with engine running. Accessories on or off don’t seem to affect it. Thx for the reply.


2005 GMC Yukon XL

 

[Larryjb]

Forget the dash voltmeter and get one of these:
https://www.amazon.com/gp/product/B000EVWDU0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

So far, the plug in voltmeter seems accurate when I've checked it against my other voltmeters.

Charging voltage (engine running) should be over 14V, but not over 14.7V. Electrical loads like headlights, electrical heaters (seats, rear window) will cause the charging voltage to be lower.

Resting voltage should be 12.5 V, but other vehicle loads even with the engine off may drop this a little. Ideally, you should read the resting voltage after 24 hours. I don't think I've ever had a voltage this good though. Even new batteries can be sulfated on the shelf if they've sat too long in the store.

Voltage with the ignition on but engine off will likely be below 12V depending on what electrical loads are on (headlights, radio, etc).

 

[Larryjb]

Specifically when is the battery light on? Just when the ignition is on with the engine off?

 

[alaska_guy]

I don't know why they put a battery label on those clusters. The voltage being low is actually being read off the alternator not the battery.

Stop by an auto zone etc and have your alternator and battery tested. They do it for free.

 

[wjburken]

As @alaska_guy stated, the volt meter reads what is coming off the alternator. In addition to getting the alternator tested, I would also check the condition of all your power and ground cables and connections. Corrosion can sneak in and cause issues with voltage drop as well. While your getting your alternator tested, might as well have them test the battery.

 

[mikeyss]

The voltage regulator inside the alternator may be going bad. When my alternator started to go bad, I had the battery light come in, and I had a service charging system message. I also wonder if your sensor on the negative battery cable may be going bad.

 

[mo2058130]

Specifically when is the battery light on? Just when the ignition is on with the engine off?

Light is on all the time. Whether the voltage reads 11.5 or 14.5.


2005 GMC Yukon XL

 

[mo2058130]

I don't know why they put a battery label on those clusters. The voltage being low is actually being read off the alternator not the battery.

Stop by an auto zone etc and have your alternator and battery tested. They do it for free.

This is my next step. It’s the wife’s daily I and work 24 hr shifts. So things happen after two or three days for me.


2005 GMC Yukon XL

 

[mo2058130]

Voltage reads 13.5 with acc. on (a/c and lights) just running voltage reads 14.6 (pic)
Thanks all for the replies it really helps as I’m trying to learn as I go. Autozone hopefully tomorrow to check alternator.
As far as checking grounds; can you point me towards a good video? Thanks again.


2005 GMC Yukon XL

 

[mo2058130]

This is the reading just after I turned the car on. No acc. on.

2005 GMC Yukon XL

 

[alaska_guy]

Hmm... has the battery light done that always or just recently?

 

[mo2058130]

Hmm... has the battery light done that always or just recently?

HA! Now that you say that, I recall that it came on after I installed my aftermarket car stereo. The acc. were on for long periods of time (with car not running) while I tested and finished the install. A couple of times the car had a hard time starting
(presumably because of low voltage on batt.)
But, it always did start and after some driving I figured the batt. would be charged to normal by the alt. If that is the case how do I “reset” the light???

This was all about 3 weeks ago.


2005 GMC Yukon XL

 

[Larryjb]

I can't see a reason why your alternator would be bad. Charging voltage appears well controlled (~14.5V). I'm wondering, though, if the alternator should be able to keep up with headlights and AC on better. I'll see what voltage I get with headlights and AC. I'll be curious to see how this all ends up.

If you are handy, and you have to replace your alternator, I highly recommend you rebuild your own alternator. It's really hit and miss what you get with alternators out there. I've used this guy a few times now: https://alternatorstarterrebuildkits.com/

I replaced my starter with a "new" ACDelco starter. It broke within a week! I got the rebuild kit and me, working at my usual slow pace, took me only about 1h extra to rebuild it. My sister had her alternator rebuilt by a local "reputable" company and it too died in a year. I rebuilt it myself and it was good for the life of the car after that.

 

[Jeff O]

GM trks/yukon/tahoe etc these years have notorious problems with bad meter movements, & shorts and intermittents in the instrument cluster. Unless your battery is in poor condition it should be about 12V and then go to about 13.75 when running. First advice is to check battery with load tester as suggested. If you are draining down below 12 over time, you can begin the process of finding the draw which is a complex procedure of elimination and troubleshooting discussed many times on this forum.

 

[Larryjb]

With headlights, I still get over 14 volts measured at the battery.

 

[Larryjb]

What is the voltage of your battery after 12-24 hours?

 

[shegarty]

I would pull the cluster and check for bad solder connections. I looked down one day to see mine pegged at about 19V and nearly shi* myself as I had just installed a new battery about 6 months prior. Turns out it was just the motor for the gauge. It went haywire for a little while after that and now it is totally non-functional and fell right over off the scale. I never had the battery light come on though.