Alternator Upgrade Suggestions?

[j91z28d1]

2025 ppv alternator 250A.. little graph vs temperature.. no idea if it fits.
It's got the freewheel on it, but a standard '25 tahoe does not..

More Information for GM GENUINE 85063115

View attachment 470039

I've often wondered why some have the one way clutch and others don't. I notice in the corvette world the manual cars had standard pulley and auto had the free spinning one during the c6 years but by c7 I think they all have the free spinning.

I chose and fixed normal type to be eaiser to swap pulley size if needed. but still wonder if the other is better for something.

 

[gmartin1215]

Thanks for the feedback on alternator options.
With the 220 A alternator upgrade, is it worth doing the big 3 upgrade, too, even though I am not running high-powered audio equipment?

 

[gmartin1215]

@Doubeleive
I am considering to get the same Mechman alternator you got (the 250 amp one)

I think you said you upgraded the wiring, too?

Can you send a picture or drawing of how you have your wiring?

I was chatting with Tony at Mechman and he said all I really need to do for my load is just run a 0-gauge wire from the alternator to the battery directly, and leave all the OEM wiring alone.

 

[Doubeleive]

@Doubeleive
I am considering to get the same Mechman alternator you got (the 250 amp one)

I think you said you upgraded the wiring, too?

Can you send a picture or drawing of how you have your wiring?

I was chatting with Tony at Mechman and he said all I really need to do for my load is just run a 0-gauge wire from the alternator to the battery directly, and leave all the OEM wiring alone.

ya I ran 0 gauge from alternator to main battery, the 2nd battery positive goes to the starter and bolts up with main battery positive there, the 2nd battery negative I had a 4 gauge cable made by a battery shop long enough to reach from the 2nd battery negative along the firewall to the main battery negative and bolted them together at the main battery negative, just like in the diagram on the previous page I posted the other day.
I paid $399 for the 250amp in 2019 with free shipping
now they are $429+17.99 shipping

250 Amp high output alternator for GM Truck 05-13

Shop Mechman 250 Amp high output alternator for GM Truck 05-13 8302250, best prices, fast ship time & top notch customer service! @ Mechman Alternators

www.mechman.com

if I had to do it again I would get the 4 pin alternator and the little 2pin adapter they sell to bypass rvc

 

[gmartin1215]

ya I ran 0 gauge from alternator to main battery, the 2nd battery positive goes to the starter and bolts up with main battery positive there, the 2nd battery negative I had a 4 gauge cable made by a battery shop long enough to reach from the 2nd battery negative along the firewall to the main battery negative and bolted them together at the main battery negative, just like in the diagram on the previous page I posted the other day.
I paid $399 for the 250amp in 2019 with free shipping
now they are $429+17.99 shipping

250 Amp high output alternator for GM Truck 05-13

Shop Mechman 250 Amp high output alternator for GM Truck 05-13 8302250, best prices, fast ship time & top notch customer service! @ Mechman Alternators

www.mechman.com

if I had to do it again I would get the 4 pin alternator and the little 2pin adapter they sell to bypass rvc

Thanks for that!
Did you still use the fuse-distribution block on the firewall near the battery with the OEM wire from that block to the alternator, too, or did you just remove that?

Why would you go with the alternator with the RVC bypass?

 

[Scrappycrow]

I've often wondered why some have the one way clutch and others don't. I notice in the corvette world the manual cars had standard pulley and auto had the free spinning one during the c6 years but by c7 I think they all have the free spinning.

I chose and fixed normal type to be eaiser to swap pulley size if needed. but still wonder if the other is better for something.

One-way clutches were first implemented for diesels because drastic spikes/drops in RPM were causing alternators' internal inertia to damage components. Thus, the alternator only got a "kick" when RPM was increasing and not a "jerk" when RPM was decreasing. The reason they were implemented on automatics is that quicker shifts were causing the same sort of damage, but with a manual, the RPM drop is less severe.

One minor critique on verbiage is that these are not "free spinning." That'd mean they could move freely in either direction.

ya I ran 0 gauge from alternator to main battery, the 2nd battery positive goes to the starter and bolts up with main battery positive there, the 2nd battery negative I had a 4 gauge cable made by a battery shop long enough to reach from the 2nd battery negative along the firewall to the main battery negative and bolted them together at the main battery negative, just like in the diagram on the previous page I posted the other day.

Did you also upgrade the ground from the primary battery to the frame?

 

[mikez71]

Apparently there is also a kind of pulley that also absorbs the 'kick' with a spring, as well as freewheeling. Not sure which gm uses.

Everything online keeps mentioning belt wear and less tension, so I have to believe it's mostly for fuel economy, maybe little bit performance.. Thinking about trying one, but the pulley will take a dump before the alternator or belt.. So it would have to be worth it performance-wise...

 

[j91z28d1]

Apparently there is also a kind of pulley that also absorbs the 'kick' with a spring, as well as freewheeling. Not sure which gm uses.

Everything online keeps mentioning belt wear and less tension, so I have to believe it's mostly for fuel economy, maybe little bit performance.. Thinking about trying one, but the pulley will take a dump before the alternator or belt.. So it would have to be worth it performance-wise...

the pulley does have a special puller and it can be replaced. but seems like extra effort.

i could see if you had a really high rpm engine and a modded auto that dropped a lot of rpm very fast. might be a good idea in theory. and i haven't looked into it but I don't seem to remember any used on aftermarket race alts. they seem to just pulley them slower and it's fine.

the cheaper 220amp one I used had the standard pulley. so I'm good with standard and that's a higher rpm engine. if my yukon had a alternator I'd a 100% run a standard fixed pulley on it.

 

[Doubeleive]

Thanks for that!
Did you still use the fuse-distribution block on the firewall near the battery with the OEM wire from that block to the alternator, too, or did you just remove that?

Why would you go with the alternator with the RVC bypass?

everything else is still oem, I did add a 0 gauge from the alternator mounting bracket to the drivers side frame just because more grounds in some places are not a bad idea based upon so many reports of electrical problems, If they sprayed salt here I would have this thing looking a octopus under the hood
I did have the wiring different in the past with basically the big3, but while troubleshooting some charging issue's I changed it back to not interfere with the RVC, turned out I had a bad battery it would charge just enough to pass warranty testing but it was bad eniough that it really messed with the RVC. bought new batteries and never messed with it anymore the last set of batterys lasted over 4 years without any issue and I replaced them sometime last year in the spring I think.

AS for bypassing RVC I just don't like how it doesn't charge 100% all the time, I use AGM's they like a good healthy charge.
It's just something they came up with to satisfy c.a.f.e. the benefit being it supposedly will save you .00001mpg under ideal circumstances.

 

[Doubeleive]

One-way clutches were first implemented for diesels because drastic spikes/drops in RPM were causing alternators' internal inertia to damage components. Thus, the alternator only got a "kick" when RPM was increasing and not a "jerk" when RPM was decreasing. The reason they were implemented on automatics is that quicker shifts were causing the same sort of damage, but with a manual, the RPM drop is less severe.

One minor critique on verbiage is that these are not "free spinning." That'd mean they could move freely in either direction.


Did you also upgrade the ground from the primary battery to the frame?

no that is where the RVC sensor is, it can be done if you want to try get that sensor harness unwrapped and get it open to put a bigger cable thru it

 

[gmartin1215]

Thanks everyone, for this discussion!

I am a visual person, so I have to draw things out for my mind to see it. So out comes the handy-dandy whiteboard!

On my configuration, the only accessory load I have on the battery and alternator is a winch and LED lighting.
I also recently upgraded my e-fans from 500w to 700w.

I do want to upgrade from my 160 amp OEM alternator to one that is 220-250A to handle current load and any additional accessories I may put on my rig.
I am not planning to put on any high-output audio.

When chatting with Tony at Mechman, if I go with one of their 250 A alts, he said that I can keep everything OEM and just run a 0-gauge wire from the alt directly to the battery (no fuse). On my drawing, I indicated his suggestion with the green line.

Without considering a dual battery setup or doing the big 3, does this configuration make sense?
I am having trouble believing the two connections at the alternator are OK without the 0-gauge going through a fuse, and Tony did not really give me an answer on that. He just kept saying to leave the OEM alone and just add the 0-gauge wire from the alt to the batt.
"Just pretend you have a stock alternator and just add an additional power wire from alternator to battery post."

I am still on the fence about getting the MM or a OEM. MM seem to be better quality, but OEMs are a lower price.

Anyway, once I get this configuration figured out, I'll try to draw up something for big 3 and dual batt, and verify that everyone so I can have a visual reference.

 

[j91z28d1]

technically just added a 2nd wire will double the overall wire thickness. but it does feel a big hacky for the price they want doe the mm alt. I am surprised they don't sell a thicker power wire.

some mostly older gm cars didn't have a fuse in that alt to bat wire, some other ones used a fuesable link. and then they have the big mega fuse.

you might take a look at what gm did on the newer trucks with the 220amp atl. as far as wire size and fuse size. if possible just copy that if you don't like the idea of adding a extra unfused wire.

 

[gmartin1215]

Thanks.
As far as I have seen, MM does not provide any wires with their alts, but I agree, at their prices, you would think they would give a wire.

I am guessing the OEM trucks with the 220 alts have a bigger wire than what was installed with the 160 A.

Anyway, does anyone see any risk in installing the MM or any +220 alts the way Tony suggested in my drawing?

To me, it makes more sense to replace the alt wire from the fuse to the alt with a bigger gauge, rather than reinstalling the OEM alt wire and then adding an extra-thick gauge wire from the alt to the battery directly, and leave everything OEM-installed. But maybe Tony's suggestion will work. I'm not entirely sure, so I'm asking everyone here if his suggestion will work or not.

My goal is not to restrict a higher output alt with the wires installed for the 160 alt. It would not make sense to spend the money on a higher output alt if the plumbing is too small to benefit from it.

What would you do if it were your truck?

 

[mikez71]

I'm planning on a 4guage cable from alt to 2nd fusebox, (already have 4guage from 2nd fusebox to 2nd battery)
The OEM alternator cable is slighter smaller than 4 guage, and this second alt cable is only 2-3' long..

Reasons to add the second cable:
1) it will charge the second battery directly (instead of passing thru a 175A fuse, the first battery, and 10' of cable)
2) it can carry the additional alt output (all of my addons will be on the second battery fusebox, so don't need to upgrade first battery wiring)

Reasons I'm not planning the Big 3 upgrade:
3) it's cheaper and easier than replacing existing wires with bigger ones
4) I like the factory battery terminals

I might add 1 extra ground from 2nd battery to frame..
..and 5 grounds between frame and body (PPV/SSV UN9 option, I think this is just for radio noise suppression)

https://www.gmupfitter.com/wp-content/uploads/2021/07/UI-Bulletin_173b-1.pdf

 

[kbuskill]

I built my own cables out of 2/0 marine grade tinned copper shielded cable when I did the "Big 3" upgrade. I also upgraded to the factory 220A alternator at a later date.

I ran from the alternator back to the mega fuse and then on to the battery.

I removed the factory ground wire and ran the new 2/0 through the RVC sensor so everything works jist like it did from the factory. The 2/0 is a tight fit through the sensor as you can see.

 

[kbuskill]

Awaiting moderator approval.... really???

 

[Fless]

View attachment 470299
Awaiting moderator approval.... really???

As I understand it, the XenForo platform can automatically place posts in pending status (awaiting mod approval) if there is a picture or internet link within a new post. Don't take it personally, it's just random. It may even select a post for approval without one of those items if another member's post with either item is quoted.

 

[kbuskill]

As I understand it, the XenForo platform can automatically place posts in pending status (awaiting mod approval) if there is a picture or internet link within a new post. Don't take it personally, it's just random. It may even select a post for approval without one of those items if another member's post with either item is quoted.

Wasn't taking it personal, just never seen it before.

 

[gmartin1215]

I built my own cables out of 2/0 marine grade tinned copper shielded cable when I did the "Big 3" upgrade. I also upgraded to the factory 220A alternator at a later date.

I ran from the alternator back to the mega fuse and then on to the battery.

View attachment 470295
View attachment 470296View attachment 470297View attachment 470298

I removed the factory ground wire and ran the new 2/0 through the RVC sensor so everything works jist like it did from the factory. The 2/0 is a tight fit through the sensor as you can see.

With your configuration of adding a larger wire back to the fuse on the firewall and adding the 220 A alt, have you had any issues with that fuse since it is only rated at 175 A?

My concern is if I put on a higher output alternator, like the MM 250 A, and run the wire from the alt back to the main fuse is that this fuse won't handle the higher output of the alt.
I read somewhere that it is not a good idea to put a higher rated fuse in place of the 175 because that will put other critical electrical components at risk.

Anyway, I just want to be sure on the best wiring configuration that will be able to handle a higher output alt.

 

[kbuskill]

With your configuration of adding a larger wire back to the fuse on the firewall and adding the 220 A alt, have you had any issues with that fuse since it is only rated at 175 A?

My concern is if I put on a higher output alternator, like the MM 250 A, and run the wire from the alt back to the main fuse is that this fuse won't handle the higher output of the alt.
I read somewhere that it is not a good idea to put a higher rated fuse in place of the 175 because that will put other critical electrical components at risk.

Anyway, I just want to be sure on the best wiring configuration that will be able to handle a higher output alt.

I haven't had any issues in all the years since upgrading, which has been quite a few.

Keep in mind that just because an alternator has the ability to provide 220A doesn't mean that it is putting that out constantly.

The alternator is only going to put out as many amps as the current draw requires.