Service charging system

[97audia4]

Alternator took a dump on my yesterday night but I was able to make it home.

Got the new one installed this morning before work but the batteries might be dead for good.

Last night batteries tested at 9.4 volts

After installing the battery light was still on but went off briefly on the highway and then back on while in stop and go traffic.

 

[97audia4]

Well two new batteries and it's still not charging correctly . New alternator is on and is putting out 14.5 to 15.5 volts, passenger side batter is already at 11.4 volts while running and drivers side battery is 12.5 while running. This is after 5 miles after new batteries and letting it idle for about 10 minutes

I need to check grounds now, passenger engine side ground is tight but I can't see where the small ground off of that goes too.

Any insight is appreciated.

09 Yukon Denali xl with the 6.2

 

[97audia4]

All grounds we're good and clean but I did find the mega fused trashed . Ordered one from the dealer and will be installing today.

 

[thompsoj22]

read my thread "chasing low voltage" change battery current sensor module, install 2" overdrive alt pulley and verify the charge circuit wiring integrity and your charge system will change completely. idling for ten minutes is placing the alt under unsat test as it is spinning below its rated rpm for max output. RVC will work alternators to a point of failure IMO. The overdrive pulley is an absolute necessity!!!

 

[Doubeleive]

I'm thinking it's a fuse or still possibly a ground wire, from what I know the NBS trucks ground wires can corrode from the inside, you do not need to change the pulley, if that was the case there would have been a recall years and years ago, also if your mega fuse was burnt or melted that's also a sign of a bad ground or your old alternator fried it which is possible but pretty unlikely.

 

[97audia4]

I'm thinking it's a fuse or still possibly a ground wire, from what I know the NBS trucks ground wires can corrode from the inside, you do not need to change the pulley, if that was the case there would have been a recall years and years ago, also if your mega fuse was burnt or melted that's also a sign of a bad ground or your old alternator fried it which is possible but pretty unlikely.

Water got behind the mega fuse and grounded against the fire wall where a spot was rubbed through.

 

[Doubeleive]

yep that would a problem right there

 

[thompsoj22]

That **** fuse is a good find and absolutely an issue! replacing it will get the circuit back to designed function. But i still advise researching "overdrive pulleys" on the alt. measure the alt/crank pulleys, devide the large by the small than multiply by the "idle" RPM and i think you will find the alt is spinning below it's rated output. Add the overwhelming draw of electric accessories and a little RVC and the design seems flawed. Or just keep running it as the factory produced it. Also "Doubeleive" google GM RVC complaints and review the info, i simply fixed it as opposed to trying to sue GM with a class action in regard to RVC as you will see many other owners tried. Im not saying you are wrong, just defining how i reached the decision to change the pulley and what a difference it made.

 

[swathdiver]

That **** fuse is a good find and absolutely an issue! replacing it will get the circuit back to designed function. But i still advise researching "overdrive pulleys" on the alt. measure the alt/crank pulleys, devide the large by the small than multiply by the "idle" RPM and i think you will find the alt is spinning below it's rated output. Add the overwhelming draw of electric accessories and a little RVC and the engeniering design is flawed. Or just keep running it as the factory produced it. Also "Doubeleive" google GM RVC complaints and review the info, i simply fixed it as opposed to trying to sue GM with a class action in regard to RVC as you will see many other owners tried. Im not saying you are wrong, just defining how i reached the decision to change the pulley and what a difference it made.

Why would anyone sue GM over RVC when all they have to do if they don't like it is to unplug it?

My little one drained the battery a couple of months ago. Got jumped and the next day hit the road and within 3 hours of highway driving it was fully charged again.

As for me and my house, now that I know what RVC and EPM are and do, I think it's pretty cool. In the old days we stuffed the biggest batteries that would fit under the hood and upgraded our 55 amp alternators to 60, 63 and then 80! By the mid '80s we were astounded when GM came out with 120 amp alternators thinking how could we ever need more? LOL

 

[97audia4]

My voltage never fluctuated at all while I have owned it. Now it's steady and above 14 at all times .

 

[kbuskill]

That **** fuse is a good find and absolutely an issue! replacing it will get the circuit back to designed function. But i still advise researching "overdrive pulleys" on the alt. measure the alt/crank pulleys, devide the large by the small than multiply by the "idle" RPM and i think you will find the alt is spinning below it's rated output. Add the overwhelming draw of electric accessories and a little RVC and the engeniering design is flawed. Or just keep running it as the factory produced it. Also "Doubeleive" google GM RVC complaints and review the info, i simply fixed it as opposed to trying to sue GM with a class action in regard to RVC as you will see many other owners tried. Im not saying you are wrong, just defining how i reached the decision to change the pulley and what a difference it made.

Just curious... where did you get the smaller pulley and did you have to run a shorter belt???

 

[thompsoj22]

First, glad to hear it is fixed! When the alt dumps it is "side of the road time" and no fun. The fact that your voltage never decreased under the right conditions may have been a result of the battery/alternator doing battle with that bad connection. When the system senses the bat is fully charged the RVC should dial back the charge voltage to save alt, bat and fuel. It may be specific to my vehicle but sitting in stop and go traffic at 106 degrees with the front/rear ac on high, both radiator cooling fans on high the alternator could not handle the load at an idle. The previous owner per the service records requested at 26k and 80k miles to "check charge system" and both times the dealer documented "charge system functioning as designed" no repair required. Also i only referenced the "sue" word! I have never sued anyone in my life!

 

[thompsoj22]

Just curious... where did you get the smaller pulley and did you have to run a shorter belt???

Got it on ebay, $9.75 free shipping. Original belt is working for me and the "new" idler tensioner marks are in the middle. No slipping at all. It is worth it in my opinion.

 

[swathdiver]

It may be specific to my vehicle but sitting in stop and go traffic at 106 degrees with the front/rear ac on high, both radiator cooling fans on high the alternator could not handle the load at an idle.

Related to the above and from the previous page, I had my Tech2 running yesterday while driving. It was 92 outside, coolant in the 190s and the fans would run on high especially when I was idling waiting to pick up one of the kids for school. The draw on the battery never saw even 2 amps. It was usually taking a charge from the alternator but never saw 2 amps either. This was while idling and shortly after after continuous running for 4 hours.

 

[thompsoj22]

Related to the above and from the previous page, I had my Tech2 running yesterday while driving. It was 92 outside, coolant in the 190s and the fans would run on high especially when I was idling waiting to pick up one of the kids for school. The draw on the battery never saw even 2 amps. It was usually taking a charge from the alternator but never saw 2 amps either. This was while idling and shortly after after continuous running for 4 hours.

As stated it must be specific to my vehicle, and i could be completely wrong in my opinion and repair procedure. The design of RVC and the components used to control it are rock solid and the charge systems should give years of trouble free service. just for kicks plug a 5amp breaker into your cooling fan high circuit and see if it will support your tech2 data? We did take the car on a 300 mile trip yesterday with all the same accessory use, the charge gauge never dropped below 14 volts, When we stopped the vehicle at the mall i popped the hood and did a little "sniff" test on the alt and there was no "burnt" smell. i swear before my repair the alt would be "smoking" hot. I do feel the battery current sensor/module and the pulley did the trick.

 

[swathdiver]

I wondered about my fans too, they are 700 watts each which I reckon the alternator was supporting. Electrical stuff I'm no fan of but have been forced to learn about it but certainly no expert, even after staying at a Holiday Inn Express last night! I liken the RVC and EPM systems to the "smart chargers" folks use for their radio controlled electric cars, you know the ones with the 6 C-Cell batteries soldered together? I have a charger for those batteries that slows the charge down when they're hot or jolts them with juice when they're cold but showing too much resistance. I was able to keep most of those batteries going for about seven or eight years.

My truck usually keeps the battery charged at around 76-80%. The battery is an ACDelco Professional, 48PS, the lowest with a 30 month warranty. It was made in August of 2016 and installed in December of that year.

One wonders if the mods you did are covering for something amiss. Either way, your solution works.

 

[thompsoj22]

I wondered about my fans too, they are 700 watts each which I reckon the alternator was supporting. Electrical stuff I'm no fan of but have been forced to learn about it but certainly no expert, even after staying at a Holiday Inn Express last night! I liken the RVC and EPM systems to the "smart chargers" folks use for their radio controlled electric cars, you know the ones with the 6 C-Cell batteries soldered together? I have a charger for those batteries that slows the charge down when they're hot or jolts them with juice when they're cold but showing too much resistance. I was able to keep most of those batteries going for about seven or eight years.

My truck usually keeps the battery charged at around 76-80%. The battery is an ACDelco Professional, 48PS, the lowest with a 30 month warranty. It was made in August of 2016 and installed in December of that year.

One wonders if the mods you did are covering for something amiss. Either way, your solution works.

Ok, I purchased this vehicle july 19, 2018 from a dealer, I could tell the alt was a reman and recently installed. The battery is identical to yours, the date code is P078R which should indicate a manufacturing date of july 2018. The battery looks, And i assumed it is new but what are the odds of buying a used vehicle on the 19th day of a month that the battery was manufactured in? Could this be the orignal battery? Ie a manufacturing date in 2008? O'reilleys says the bat load tests good. At this point im confident with the charge system reliability but id hate to be overcoming the burden of a ten year old battery.

 

[swathdiver]

Could this be the orignal battery?

No, these did not exist before March of 2012. Prior to that they were called 7YR (seven year), 6YR etc. I would not think it unusual for you to get a freshly made battery.

It may be that the weak link is your remanufactured alternator. I do not know how or what they test them for. This is just conjecture but your previous owner may have brought it in under warranty not knowing why the needle was moving around, not having read the owner's manual. I have same reports in my vehicle's warranty history.

 

[thompsoj22]

No, these did not exist before March of 2012. Prior to that they were called 7YR (seven year), 6YR etc. I would not think it unusual for you to get a freshly made battery.

It may be that the weak link is your remanufactured alternator. I do not know how or what they test them for. This is just conjecture but your previous owner may have brought it in under warranty not knowing why the needle was moving around, not having read the owner's manual. I have same reports in my vehicle's warranty history.

Thanks for the info. I am considering a "Mechman G240 alternator". It is made in the US and brand new with a 2 year warranty at $300 ill give it a shot to give me some peice of mind.

 

[swathdiver]

Thanks for the info. I am considering a "Mechman G240 alternator". It is made in the US and brand new with a 2 year warranty at $300 ill give it a shot to give me some peice of mind.

Pretty cool, I have not heard of them before. The description with that one says you cannot come drag racing with us, no running over 5,000 rpms with the little pulley! LOL