- Jul 22, 2015
- 2,724
So, the last couple of times I've started the Sierra up, I noticed a low in volume (but high-pitched) squealing, coming from high up in the bay.
I've also started noticing that my voltage gauge has started reading lower than normal (in the past, it would register just about the midpoint ('14' volts) when it was first started and charging the battery back to 'normal'.) Now, it's showing two notches below that, and occasionally dipping to the large notch between the 'too low' 9 and 'just right' 14) The 'quarter notch', if you were reading it like a gas gauge. Apologies for the inexact description; just relaying what I'm seeing, without quantifying it with a multimeter.
Anyway, taking those two things into account, I figure the alternator is on its last legs. Might have been hastened by me converting to the e-fans; not sure. I can definitely see the voltage drop when they come on in series, even before it started reading 'low', as it does now.
Since we've been discussing our current favorite toy, the bluetooth-based battery monitor that littleblazer, blckshdw and myself all use from Amazon, I figured I'd run a 'charging test' from the app, and share that with you, just as an 'FYI'...
(background -- to run this test, the app instructs you to start the vehicle, turn off all electrical loads (such as radio, HVAC), and turn the headlamps 'on'... then run the engine at 2500rpm for a minimum of 5 seconds)
So, what we see here, relatively speaking, is an alternator that's marginal. Just enough to keep the battery from draining, but not charging it at the normal rate (which would be > 13v at idle, and as high as 14v under rpm load (not constantly, but cycling between 12-14)
My alternator, since the truck is an 'HD', is a 145 amp -- the 'DR44' / DR44G. I'm pretty sure it's a reman, too. Didn't put a new one in when I did my cam / head swap, because: a): it was working just fine, b): it's literally at the top of the engine bay and takes 5-10 min to R&R, and c): I have a spare alternator from the Envoy for emergencies (not the same amperage, but it's a 4-pin, just like the one in the Sierra.
But now... since it looks like this alternator is about to bite the dust, I have some options to consider...
First... there are rebuild kits available for this thing. Less than $50, shipped. Not a ton of skill needed (although if the issue is with the diodes, it's a lot of trouble, because they're soldered on, etc.) However, because of how the alternator is disassembled to replace the front / rear bearings, it's apparently better to rebuild a 'new' alternator, and not 'rebuild a previously rebuilt one'.
That's fine... new ones aren't *that* expensive, relatively speaking.
But... if I'm going to need to fix the charging system, I may as well consider upgrading what I've got.
The full-size pickups have provision for two 12v batteries (trucks with the 6.6L Duramax require two batteries, because of the extra power needed to start that beast). I'd need a battery tray, a couple of cables & relays, and a couple hours to give myself a nice upgrade, from a standpoint of amp-hours. And for my future mod plans, camping, etc. -- it just makes sense.
In addition to the dual battery setup, I'm also thinking about boosting the alternator. I've got a couple of different options there, as well.
- Higher output alternator (I can get a 220A from RockAuto, for about $175 or so)
- Dual output alternator (with two charging lugs -- I think the DMax uses these - ? Not sure)
- Dual alternators (I don't like this option, but it's an option)
And, of course, on my local CL, there's a guy that's been trying to sell a chromed 240A alternator for probably a year now. Yes, I said 'chromed'... (cue Ric Flair 'woooooooo' sound) He's a bit of an @sshole; I'll spare the story for now.
But... since it looks like I need an alternator now... ?
I've also started noticing that my voltage gauge has started reading lower than normal (in the past, it would register just about the midpoint ('14' volts) when it was first started and charging the battery back to 'normal'.) Now, it's showing two notches below that, and occasionally dipping to the large notch between the 'too low' 9 and 'just right' 14) The 'quarter notch', if you were reading it like a gas gauge. Apologies for the inexact description; just relaying what I'm seeing, without quantifying it with a multimeter.
Anyway, taking those two things into account, I figure the alternator is on its last legs. Might have been hastened by me converting to the e-fans; not sure. I can definitely see the voltage drop when they come on in series, even before it started reading 'low', as it does now.
Since we've been discussing our current favorite toy, the bluetooth-based battery monitor that littleblazer, blckshdw and myself all use from Amazon, I figured I'd run a 'charging test' from the app, and share that with you, just as an 'FYI'...
(background -- to run this test, the app instructs you to start the vehicle, turn off all electrical loads (such as radio, HVAC), and turn the headlamps 'on'... then run the engine at 2500rpm for a minimum of 5 seconds)
So, what we see here, relatively speaking, is an alternator that's marginal. Just enough to keep the battery from draining, but not charging it at the normal rate (which would be > 13v at idle, and as high as 14v under rpm load (not constantly, but cycling between 12-14)
My alternator, since the truck is an 'HD', is a 145 amp -- the 'DR44' / DR44G. I'm pretty sure it's a reman, too. Didn't put a new one in when I did my cam / head swap, because: a): it was working just fine, b): it's literally at the top of the engine bay and takes 5-10 min to R&R, and c): I have a spare alternator from the Envoy for emergencies (not the same amperage, but it's a 4-pin, just like the one in the Sierra.
But now... since it looks like this alternator is about to bite the dust, I have some options to consider...
First... there are rebuild kits available for this thing. Less than $50, shipped. Not a ton of skill needed (although if the issue is with the diodes, it's a lot of trouble, because they're soldered on, etc.) However, because of how the alternator is disassembled to replace the front / rear bearings, it's apparently better to rebuild a 'new' alternator, and not 'rebuild a previously rebuilt one'.
That's fine... new ones aren't *that* expensive, relatively speaking.
But... if I'm going to need to fix the charging system, I may as well consider upgrading what I've got.
The full-size pickups have provision for two 12v batteries (trucks with the 6.6L Duramax require two batteries, because of the extra power needed to start that beast). I'd need a battery tray, a couple of cables & relays, and a couple hours to give myself a nice upgrade, from a standpoint of amp-hours. And for my future mod plans, camping, etc. -- it just makes sense.
In addition to the dual battery setup, I'm also thinking about boosting the alternator. I've got a couple of different options there, as well.
- Higher output alternator (I can get a 220A from RockAuto, for about $175 or so)
- Dual output alternator (with two charging lugs -- I think the DMax uses these - ? Not sure)
- Dual alternators (I don't like this option, but it's an option)
And, of course, on my local CL, there's a guy that's been trying to sell a chromed 240A alternator for probably a year now. Yes, I said 'chromed'... (cue Ric Flair 'woooooooo' sound) He's a bit of an @sshole; I'll spare the story for now.
But... since it looks like I need an alternator now... ?