The indignities...

[wsteele]

I've never checked the voltage drop on my NBS when opening a cabin door, but doing that draws about 4.5 amps from the interior lights as well as wakes up a few modules (they do go to sleep relatively quickly after closing the door, as long as nothing else is operated).

When you're testing the voltage of the battery, it should rest for an hour or so after being charged so it's the resting voltage that's being tested:
https://haynes.com/en-us/tips-tutorials/how-test-car-battery-multimeter

I watched the "draw" pretty rapid for the first few minutes after shutdown and tapering off. I didn't know it was an hour, but that does make sense from what I have observed.

I did find a TSB for my model year for a BCM SW upgrade that addresses charging and battery issues. I am wondering if maybe opening the door triggers something else in the BCM that it shouldn't, hence causing a higher than normal draw. I don't get my Tech 2 for about a month, so I think I might drop by the dealer and see if my 2007 Yukon has that software rev.

 

[iamdub]

The engine wasn't running, in fact the key was out of the ignition.

Good, cuz that'd be terrible if just the interior lights loaded your alternator that much.

 

[Tonyv__]

The other day I replaced the alternator because the original unit was beginning to really make a ruckus. It seemed a tad weak on charging, but certainly was working.

Yesterday I was checking my emissions monitors with my cheapie ODB scanner and noticed the voltage levels seemed pretty low.

I had replaced my battery about 16 mo ago with an AGM unit from Napa. The truck starts fine, but the nominal voltage seems to hover around 12.2 to 12.3 after a normal jaunt to the grocery store, Home Depot, etc. My first reaction was maybe my old alternator was not as good as I thought it was and my 16 month old AGM had taken a real beating in its short life.

I then wondered if I picked up an abnormal parasitic drain along the way, but nothing looks out of the ordinary after a few hours of rest.

My final conclusion is I just am not driving the truck the same during these Covid times and the battery rarely ever gets a good solid charge. I realized we aren’t going anywhere far these days, so the poor battery just isn’t getting a full charge.

I saw that Costco has a 4a automated charger/tender for like $50. I think I will pick one up, hardwire a pigtail and try and find a clean spot up front to access it with the charger.

Oh the indignities, a battery tender! Next thing I will be shopping for depends...

Just went through something similar with my wife’s car. It barely gets driven now with COVID. She had intermittent starting problems last month. Put it on charge overnight and it’s been fine since. I worry that my Yukon is on the same path. But no signs of poor battery yet

 

[iamdub]

I watched the "draw" pretty rapid for the first few minutes after shutdown and tapering off. I didn't know it was an hour, but that does make sense from what I have observed.

I did find a TSB for my model year for a BCM SW upgrade that addresses charging and battery issues. I am wondering if maybe opening the door triggers something else in the BCM that it shouldn't, hence causing a higher than normal draw. I don't get my Tech 2 for about a month, so I think I might drop by the dealer and see if my 2007 Yukon has that software rev.

If I recall correctly, the Tech2 can show battery condition. @swathdiver's mentioned it a few times. He's been MIA lately since his bout with COVID. I hope he's still improving and just taking a break from us monkeys.

 

[Harold Pierson]

The other day I replaced the alternator because the original unit was beginning to really make a ruckus. It seemed a tad weak on charging, but certainly was working.

Yesterday I was checking my emissions monitors with my cheapie ODB scanner and noticed the voltage levels seemed pretty low.

I had replaced my battery about 16 mo ago with an AGM unit from Napa. The truck starts fine, but the nominal voltage seems to hover around 12.2 to 12.3 after a normal jaunt to the grocery store, Home Depot, etc. My first reaction was maybe my old alternator was not as good as I thought it was and my 16 month old AGM had taken a real beating in its short life.

I then wondered if I picked up an abnormal parasitic drain along the way, but nothing looks out of the ordinary after a few hours of rest.

My final conclusion is I just am not driving the truck the same during these Covid times and the battery rarely ever gets a good solid charge. I realized we aren’t going anywhere far these days, so the poor battery just isn’t getting a full charge.

I saw that Costco has a 4a automated charger/tender for like $50. I think I will pick one up, hardwire a pigtail and try and find a clean spot up front to access it with the charger.

Oh the indignities, a battery tender! Next thing I will be shopping for depends...

Costco sells depends also, it's what happens with age.

 

[wsteele]

Costco sells depends also, it's what happens with age.

Thanks for the tip, I will keep that in mind for when that time arrives. Of course, when that time arrives, I may not be able to keep much in mind. I wonder how far out Apple will let me schedule a reminder on my iPhone?

 

[wsteele]

I did a little testing over the evening and this morning, armed with the enlightenment of the apparent drain the lights and systems place on the battery when just a door is opened.

First thing, I do like the CTEK charger/tender I bought. I don’t know if the “conditioning” mode worked some or the charger section just does a better job than my Die Hard big charger does, but the starting voltage measured with a DVOM, after the charger indicated a complete charge and just after I disconnected it from the battery, the battery reads 12.91v, much higher than the same condition with the Die Hard charger.

I left it overnight without the tender and just the truck’s normal parasitic draw to work on it and this morning the battery showed a solid 12.63v before touching a door handle, etc. That is quite a bit higher than the exact same timing of measurement after I had used the Die Hard charger and left it overnight.

I then opened the drivers door and went back to measure and the battery showed 12.18v (lights on in the cabin, CD searching in the Nav/Radio, who knows what other systems spooling up, etc.

After closing the door and letting the lights fade out, the battery climbed back up to 12.3v. I am going to wait a little over an hour and remeasure, hopefully with all the systems spooled back down, I will be back closer to the 12.6v starting point.

I did go back and check my receipt and I have one more month left on the free replacement guarantee from Napa for it’s Legend AGM battery, so I think I will take it back and have them test it. With the free replacement sitting there, I think maybe I will get a good shot at an honest assessment of its condition.

Right now, if the battery recovers anywhere close to the 12.6v, I have to conclude it likely is fine and all my fears were driven by measuring the battery still connected to the truck, with systems not fully spooled down.

In the olden days, when you turned the lights off and closed the door, things were off...

 

[wsteele]

OK, final update.

I went out after about an hour and a half of everything powered down (door closed) and the voltage has climbed right back up to 12.62v (as measured with a DVOM on the battery).

I have to conclude the battery is fine and what I was seeing were voltage reading on the battery terminal while the systems in the car had not fully spooled down and the battery had time to recover.

I am going to still pop it out and take it down to Napa for a test, but I am pretty sure the problem was with my lack of understanding how all the systems are triggered, how much power they use when spooled up and how that is reflected when measuring voltage at the battery posts.

I swear, I learn something every day.

PS - I am still going to use the CTEK tender as it may have actually done some good on the conditioning front as the peak static voltages after everything is spooled down is higher than I was seeing in my blind man's bluff mode of testing I was doing before. Maybe it will actually allow me to get past the prorated warranty period of that battery for once, since I replaced the original factory unit (which lasted like 8 years).

 

[iamdub]

OK, final update.

I went out after about an hour and a half of everything powered down (door closed) and the voltage has climbed right back up to 12.62v (as measured with a DVOM on the battery).

I have to conclude the battery is fine and what I was seeing were voltage reading on the battery terminal while the systems in the car had not fully spooled down and the battery had time to recover.

I am going to still pop it out and take it down to Napa for a test, but I am pretty sure the problem was with my lack of understanding how all the systems are triggered, how much power they use when spooled up and how that is reflected when measuring voltage at the battery posts.

I swear, I learn something every day.

PS - I am still going to use the CTEK tender as it may have actually done some good on the conditioning front as the peak static voltages after everything is spooled down is higher than I was seeing in my blind man's bluff mode of testing I was doing before. Maybe it will actually allow me to get past the prorated warranty period of that battery for once, since I replaced the original factory unit (which lasted like 8 years).

You have to let the battery rest for at least an hour after removing it from the charger to get an accurate resting voltage. That 12.91V taken immediately after disconnecting the charger is irrelevant. So, don't think your battery is failing anything by not maintaining that .28V.

Conditioners can't really show much improvement in just one night, unless there's really nothing for it to recondition. It's a slow, gradual process involving dissolving. I doubt NAPA has equipment so advanced that they can detect such a minute degradation in capacity. However, having them measure it now will give you a baseline to compare if you were so inclined to return after a month or so of keeping it on the CTEK to see if the capacity goes up. This would tell you (1) your battery's true condition and (2) if the CTEK helped any. In the meantime, try to keep it on the CTEK for as long as possible with no interruptions.

 

[wsteele]

You have to let the battery rest for at least an hour after removing it from the charger to get an accurate resting voltage. That 12.91V taken immediately after disconnecting the charger is irrelevant. So, don't think your battery is failing anything by not maintaining that .28V.

Conditioners can't really show much improvement in just one night, unless there's really nothing for it to recondition. It's a slow, gradual process involving dissolving. I doubt NAPA has equipment so advanced that they can detect such a minute degradation in capacity. However, having them measure it now will give you a baseline to compare if you were so inclined to return after a month or so of keeping it on the CTEK to see if the capacity goes up. This would tell you (1) your battery's true condition and (2) if the CTEK helped any. In the meantime, try to keep it on the CTEK for as long as possible with no interruptions.

Thanks, yeah, I was pretty sure the "conditioning" functions probably couldn't do much in a few cycles. The peak voltage right after disconnection fades really quickly, and is way above all the charts I have found say is 100% anyway, so I assumed it was a very temporary thing. I will say though, I think the CTEK may actually do a better. job of charging the battery because everything is measuring higher than I ever got after a rest periods with my Die Hard charger.

I am thrilled with the 12.62v resting rate after all the gizmos spool down, so will continue to use the CTEK all the time. Who knows, maybe when I take it down to Napa for the test, if they say it is bad, I will whip the receipt out and maybe get a new battery in the process...

I appreciate the guidance along the way.