# 95 k3500 5.7l...100A vs 120A alternator



## Brettny (Jul 12, 2017)

Last season my volt gauge was getting a bit low and lights a bit dim durring longer storms. To combat this i turn my blower heater down and it did help slightly. The battery is larger than factory and new last year. All the connections were clean and tight...i cleaned them all last season. The alternator charging wire was changed to 4ga. My accounts are all real close to each other and my house.

Is 20A worth the $140 or so upgrade? 
Does anyone know if i can just replace the 100a with a 120a and change to the 120a belt?

This is a 95 k3500 5.7l NON vortec.


----------



## ConnorExum (Jan 5, 2010)

What make is your present alternator?


----------



## ConnorExum (Jan 5, 2010)

Here you go:
https://www.autopartswarehouse.com/chevy-parts/chevy-k3500-parts/k3500-alternator


----------



## Brettny (Jul 12, 2017)

Not sure on the make but i know its 100A. I replaced it 2 yrs ago...back when i had a gear clutch pump fisher and not an EzV.


----------



## Leland Lawn (Sep 27, 2011)

Can you simply add a second battery?


----------



## Brettny (Jul 12, 2017)

I thought about that but having more reserve would only help if i had longer drives between driveways.


----------



## Randall Ave (Oct 29, 2014)

At the driver's side front by the radiator. Don't you have an empty battery tray? If not there should be enough room there for a second battery.


----------



## ConnorExum (Jan 5, 2010)

I like the bigger alternator plus the extra battery myself. Obviously, you need the extra juice to operate the plow since it takes 230 to 250 amps to operate the plow so the extra battery would give you a quick extra jolt when necessary. But, if you put two batteries you need more amperage to top them off and not to mention amount of power that a vehicle uses while plowing.

Myself I would get a 230 or 250 amp alternator that way you can really maximize the charging time and I would put two 800 CCA batteries. I like having power when I need it.

I have 4x1100 CCA Batteries for my Cummins NH250 and a 120amp alternator but I am going to get a 280amp unit for the truck to make sure it can recharge quickly.


----------



## Brettny (Jul 12, 2017)

No empty battery tray. My charcoal canister is there. This was sold as a cab and chassis so really its a C35. But really its a k3500 with a dump bed.

I spent some time looking for voltage losses while useing the dump pump, headlights and heater motor for a load. I got the charging volts up to 14.26 at the battery and it recovers a bit better. I found my alternator wire to be 8ga not what i originaly said. I changed it to 2ga and the frame ground to 0/2ga...just something i had around. I still may look into the 120A altetnator upgrade but i need to connect the plow up.

I am seeing that the car versions of the 5.7l put the alternator in the AC compressor location. I have no AC and a 140a sc144 is roughly $110. Has any one put one there?


----------



## cwren2472 (Aug 15, 2014)

Have you tested the amp draw on your plow motor? I'm wondering if the motor is drawing more than it should be and that is why the alternator is struggling to keep up.


----------



## Randall Ave (Oct 29, 2014)

If you want to, relocate the charcoal canister. Get a battery tray from GM. There's threads here on how to wire it up. Go to a electrical facility and get the highest output factory alternator.


----------



## Philbilly2 (Aug 25, 2007)

I am also for the more storage route than the high output route.

I have never put a single alternator on any one of my plow trucks that was not factory specs. I have however added more batteries to the system to help the the draw demand of the plows.


----------



## Randall Ave (Oct 29, 2014)

Philbilly2 said:


> I am also for the more storage route than the high output route.
> 
> I have never put a single alternator on any one of my plow trucks that was not factory specs. I have however added more batteries to the system to help the the draw demand of the plows.


I had the same truck he has, just two years older. Did the two battery set up. Factory alternator, never had a problem. Poor truck just turned to dust.


----------



## Brettny (Jul 12, 2017)

cwren2472 said:


> Have you tested the amp draw on your plow motor? I'm wondering if the motor is drawing more than it should be and that is why the alternator is struggling to keep up.


I need to get my hands on a DC amp gauge but the plow motor is new last year.

I do know that i can add $250 in high output alternator and another $160 for a second battery but i just dont want to spend that kind of cash on this truck. Its not like the truck shut off plowing last year.


----------



## Philbilly2 (Aug 25, 2007)

Brettny said:


> I need to get my hands on a DC amp gauge but the plow motor is new last year.
> 
> I do know that i can add $250 in high output alternator and another $160 for a second battery but i just dont want to spend that kind of cash on this truck. Its not like the truck shut off plowing last year.


True, but the high draw without proper storage is hard on all the other components when they receive less power than they should be seeing as your plow draws it.


----------



## Randall Ave (Oct 29, 2014)

Brettny said:


> I need to get my hands on a DC amp gauge but the plow motor is new last year.
> 
> I do know that i can add $250 in high output alternator and another $160 for a second battery but i just dont want to spend that kind of cash on this truck. Its not like the truck shut off plowing last year.


I'm not trying to be a jerk, but I have no way for you to upgrade your electrical system with it costing you some $$$.


----------



## Brettny (Jul 12, 2017)

I realize its going to cost money.


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> No empty battery tray. My charcoal canister is there. This was sold as a cab and chassis so really its a C35. But really its a k3500 with a dump bed.
> 
> I spent some time looking for voltage losses while useing the dump pump, headlights and heater motor for a load. I got the charging volts up to 14.26 at the battery and it recovers a bit better. I found my alternator wire to be 8ga not what i originaly said. I changed it to 2ga and the frame ground to 0/2ga...just something i had around. I still may look into the 120A altetnator upgrade but i need to connect the plow up.
> 
> I am seeing that the car versions of the 5.7l put the alternator in the AC compressor location. I have no AC and a 140a sc144 is roughly $110. Has any one put one there?


I have a question is your current alternator actually producing 100 amps or whatever it is supposed to produce?


----------



## Brettny (Jul 12, 2017)

ConnorExum said:


> I have a question is your current alternator actually producing 100 amps or whatever it is supposed to produce?


Thats definitely something i need to test when i can get a DC amp clamp. I really dont trust the parts store clowns to do that properly. I also know it dosnt do 100A at the rpm i plow at. I plow prety slow and when in gear my truck is about 500/600rpm.


----------



## Philbilly2 (Aug 25, 2007)

Brettny said:


> I also know it dosnt do 100A at the rpm i plow at.


You just answered the reason for why more storage is more important than high output. Thumbs Up


----------



## Mark Oomkes (Dec 10, 2000)

Brettny said:


> Thats definitely something i need to test when i can get a DC amp clamp. I really dont trust the parts store clowns to do that properly. I also know it dosnt do 100A at the rpm i plow at. I plow prety slow and when in gear my truck is about 500/600rpm.


Are you plowing in 1st gear? If not, you should be. Keeps the alternator spinning, transmission from shifting and building heat as well.


----------



## Brettny (Jul 12, 2017)

Yes 1st gear plowing.


----------



## Mark Oomkes (Dec 10, 2000)

500-600 RPMs in gasser?


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> Thats definitely something i need to test when i can get a DC amp clamp. I really dont trust the parts store clowns to do that properly. I also know it dosnt do 100A at the rpm i plow at. I plow prety slow and when in gear my truck is about 500/600rpm.


I was betting on a scenario like this one: you cruise around at say 45-55mph for what 30% to 40% of the time spend during your route getting a full charge. Then you spend about 60% to 70% of your time at 10mph or less getting somewhere like 70% to 85% of your alternator's full capacity so like 70 to 80 amps. You are drawing upwards 230 amps on the plow every time you move it. Not mention heater, lights, radio, and other accessories that sap power. I don't think your alternator is big enough to be honest to really cope with two batteries. Now, let's say your alternator is only giving you 90amps at full speed. That could really put you in a whole. Then let's say you motor is pulling 240-250 instead of the 230 or so it once did due to wear factors in the system. But you have to test to figure this out.

But, if I were you I find alternator that made 100 to 120amps at idle. Then I would install the second battery. Storage I think is a problem for your setup. However, something has to be drawing more power or not creating enough since you indicate this is a new development in the truck's behavior.


----------



## Ajlawn1 (Aug 20, 2009)

Mark Oomkes said:


> 500-600 RPMs in gasser?


Maybe the ultra rare 3.07 pozzee Dana 60...


----------



## dieselss (Jan 3, 2008)

You need a high amp at idle alternator.
120, 140, 160 etc means nothing at 2k when your plowing under that.
Search the interwebs for companies that offer high amp st idle units


----------



## ConnorExum (Jan 5, 2010)

dieselss said:


> You need a high amp at idle alternator.
> 120, 140, 160 etc means nothing at 2k when your plowing under that.
> Search the interwebs for companies that offer high amp st idle units


Delco Remy does


----------



## BUFF (Dec 24, 2009)

Mark Oomkes said:


> 500-600 RPMs in gasser?


Not in a straight 6 or V-8, maybe a single or twin cylinder
Old JD horizontal double lungers idle down low


----------



## Mark Oomkes (Dec 10, 2000)

BUFF said:


> Not in a straight 6 or V-8, maybe a single or twin cylinder
> Old JD horizontal double lungers idle down low


I told you I only had 1 thought this year so far...


----------



## Brettny (Jul 12, 2017)

Yes 5.7l is a chevy 350.

Connor your prety correct..for one thing. This truck hardly ever sees more than 50mph all year. in the winter with the plow and durring a storm i hardly ever see more than 35mph. My route is about 20-30mi including going to the gas station. 

I may try plowing in low gear for one storm if the heavier wireing dosnt help.


----------



## Philbilly2 (Aug 25, 2007)

Brettny said:


> I may try plowing in low gear for one storm if the heavier wireing dosnt help.


Lower than 1st gear?


----------



## Mark Oomkes (Dec 10, 2000)

Philbilly2 said:


> Lower than 1st gear?


Haven't you ever heard of .5 gear?


----------



## ConnorExum (Jan 5, 2010)

Philbilly2 said:


> Lower than 1st gear?


Maybe, he installed an old fuller 7LL in this truck?


----------



## Philbilly2 (Aug 25, 2007)

This is on a fischer plow, but have a look... I don't think you are apprication the amount of AMPs needed to run this operation...

Posted in another thread by Sno.


Solenoid Coil Resistance =
7 Ohms at room temperature
• Solenoid Coil Amp. Draw =
1.5 Amp.
• Motor Relay Coil Resistance = 16
- 17 Ohms
• Motor Relay Amp. Draw =
0.7 Amp.
• Motor Amp. Draw = 190 Amp. at
1750 psi
• Switched Accessory Lead Draw =
0.75 Amp

Take a look at your amp draw on your motor at operation pressure...


----------



## Mark Oomkes (Dec 10, 2000)

Philbilly2 said:


> Posted in another thread by Sno.


Too bad he's bizzie catching smelt...


----------



## Ajlawn1 (Aug 20, 2009)

Philbilly2 said:


> Lower than 1st gear?


Granny gear.... Oh nevermind it's not a Furd...


----------



## Mark Oomkes (Dec 10, 2000)

Ajlawn1 said:


> Granny gear.... Oh nevermind it's not a Furd...


Or Tata, FWD, Oshkosh, Walter's and nauseum...


----------



## ConnorExum (Jan 5, 2010)

Ajlawn1 said:


> Granny gear.... Oh nevermind it's not a Furd...


Maybe he is referring to high and low range on his transfer case? That would give him two speeds for first gear one high and low.


----------



## ConnorExum (Jan 5, 2010)

Mark Oomkes said:


> Or Tata, FWD, Oshkosh, Walter's and nauseum...


What is not to love about a Walter?


----------



## Randall Ave (Oct 29, 2014)

Mark Oomkes said:


> Too bad he's bizzie catching smelt...


I thought he was catching Brook trout. Or we're ghey old pictures, at the other office.


----------



## Randall Ave (Oct 29, 2014)

Let's get this train back on track. The second battery tray parts are not that expensive. Look at LMC truck parts. Use a dual terminal battery. Remember you can never have enough ground cables.


----------



## Mark Oomkes (Dec 10, 2000)

Randall Ave said:


> I thought he was catching Brook trout. Or we're ghey old pictures, at the other office.


And rainbows...


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> Yes 5.7l is a chevy 350.
> 
> Connor your prety correct..for one thing. This truck hardly ever sees more than 50mph all year. in the winter with the plow and durring a storm i hardly ever see more than 35mph. My route is about 20-30mi including going to the gas station.
> 
> I may try plowing in low gear for one storm if the heavier wireing dosnt help.


I have a short list of follow up questions:

1) is your truck automatic or manual transmission?
2) what is your actual average plowing speed?
3) what rpm does the engine run at while you cruise around at 25 to 35mph?
4) does this truck operate year round?

I still believe that you need a two prong solution to your issues: one, I think you need to really check the output of present alternator and the draw of the present pump motor I think part of the problem is there; two, I think you need a bigger alternator but also one that makes at least 100 amps at idle and more would be better. Storage is a good idea as well.

I don't think putting two batteries in a system that cannot handle one battery is going to be a happy solution. I think you will need both a second battery and a high output alternator to get satisfactory results. I think a big factor are the slow speeds that yield lower amps from the alternator and high demand from the pump motor. I just don't see your system overcoming the deficit between usage and output at present even with a secondary battery. That secondary battery is just one more draw on the alternator which if you ask me doesn't seem up to the task.


----------



## Philbilly2 (Aug 25, 2007)

ConnorExum said:


> What is not to love about a Walter?


You come with it...


----------



## dieselss (Jan 3, 2008)

ConnorExum said:


> ) is your truck automatic or manual transmission?
> 2) what is your actual average plowing speed?
> 3) what rpm does the engine run at while you cruise around at 25 to 35mph?
> 4) does this truck operate year round?


It's an auto.....he said. Not sure how this matters.
Plowing speed is relevant to type of plowing. Betting it's under 10mph.
Betting its 15-2200 rpms....not sure why this matters as any alt will charge more at higher rpms.
He said pretty much no.


----------



## ConnorExum (Jan 5, 2010)

dieselss said:


> It's an auto.....he said. Not sure how this matters.
> Plowing speed is relevant to type of plowing. Betting it's under 10mph.
> Betting its 15-2200 rpms....not sure why this matters as any alt will charge more at higher rpms.
> He said pretty much no.


Some of it just basic curiosity and some in the hopes to find a baseline for the vehicle's operation.


----------



## Brettny (Jul 12, 2017)

dieselss said:


> It's an auto.....he said. Not sure how this matters.
> Plowing speed is relevant to type of plowing. Betting it's under 10mph.
> Betting its 15-2200 rpms....not sure why this matters as any alt will charge more at higher rpms.
> He said pretty much no.


What he said.

I just changed the oil that was in there for 15 months. I drive 66mi a month.


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> What he said.
> 
> I just changed the oil that was in there for 15 months. I drive 66mi a month.


The reason why it reminds me of a problem I had with devils chevy S1500 that in great storm of 2010. It started to show excessive draw on the battery too.


----------



## Brettny (Jul 12, 2017)

After much online parts look up searching and alot of looking at google images i bought a 140A CS144 alternator for a 97 k3500 with 5.7L. It took a little massaging of one bolt hole and i had to bend the rear bracket a bit. But my original belt fit perfectly and the wireng just plugged right in.

My voltage is slightly higher at idle and goes up quicker after a load.


----------



## ConnorExum (Jan 5, 2010)

That is a good option... 140amp . I hope it works out for you.


----------



## Randall Ave (Oct 29, 2014)

Brettny said:


> After much online parts look up searching and alot of looking at google images i bought a 140A CS144 alternator for a 97 k3500 with 5.7L. It took a little massaging of one bolt hole and i had to bend the rear bracket a bit. But my original belt fit perfectly and the wireng just plugged right in.
> 
> My voltage is slightly higher at idle and goes up quicker after a load.
> 
> View attachment 184325


OK, now for just for the heck of it. You need to increase your grounds. Run an extra ground cable from the alternator to the negative battery terminal. Run an extra ground strap to the frame, and to the body. Basically so you have an extra loop so to say. This is why on the chevies I always install duel terminal batteries.


----------



## Philbilly2 (Aug 25, 2007)

Randall Ave said:


> OK, now for just for the heck of it. You need to increase your grounds. Run an extra ground cable from the alternator to the negative battery terminal. Run an extra ground strap to the frame, and to the body. Basically so you have an extra loop so to say. This is why on the chevies I always install duel terminal batteries.


I second this!


----------



## ConnorExum (Jan 5, 2010)

I am curious as to see if the draw of the plow will be solved by this alone. So, when you say load what did you have operating?


----------



## Brettny (Jul 12, 2017)

Today i hooked up the plow after the new alternator was in. The voltage stays above 12.00 even after cycling the plow about 5x. 

I did change the plow fluid with an opened bottle (from last year) of fisher blue fluid. It had odd sludge chunks in it that. Has anyone else seen this with a open yet sealed jug of plow fluid?


----------



## dieselss (Jan 3, 2008)

Yes have seen the blue chunks from sealed bottles, never had any issues.
As randall said, don't forget to add them grounds


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> Today i hooked up the plow after the new alternator was in. The voltage stays above 12.00 even after cycling the plow about 5x.
> 
> I did change the plow fluid with an opened bottle (from last year) of fisher blue fluid. It had odd sludge chunks in it that. Has anyone else seen this with a open yet sealed jug of plow fluid?


But, during the season you cycle the plow I would bet 50 times that much during even a mild storm. I think you need to try to simulate something like that with all you accessories operating and see what happens.


----------



## Brettny (Jul 12, 2017)

I did cycle the plow way more than 5x with all the acessories on. The voltage climbs way faster and stays higher than my old alternator.


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> I did cycle the plow way more than 5x with all the acessories on. The voltage climbs way faster and stays higher than my old alternator.


Great, I hope this fix works for you.


----------



## ConnorExum (Jan 5, 2010)

I am still curious about the original alternartor’s output myself. I think it must have been less than 100amps. So, about your new alternator how many amps does it make at an idle? 

Hopefully, this will be a good snow year for NYS...


----------



## Brettny (Jul 12, 2017)

I dont doubt the old one put out 100a at idle. Even if it was a 120a it wouldn't do 100a at idle. It was a cs130 and they dont charge well at idle. I put in a cs144 there suposto be alot better at idle.


----------



## ConnorExum (Jan 5, 2010)

Brettny said:


> I dont doubt the old one put out 100a at idle. Even if it was a 120a it wouldn't do 100a at idle. It was a cs130 and they dont charge well at idle. I put in a cs144 there suposto be alot better at idle.


No, I meant I was curious to see if the peak output of your old alternator was in spec.


----------



## EWSplow (Dec 4, 2012)

ConnorExum said:


> No, I meant I was curious to see if the peak output of your old alternator was in spec.


At this point what difference does it make. 
The guy has a new alternator and it puts out enough amperage.

There's an old saying , "curiosity killed the cat".


----------



## ConnorExum (Jan 5, 2010)

EWSplow said:


> At this point what difference does it make.
> The guy has a new alternator and it puts out enough amperage.
> 
> There's an old saying , "curiosity killed the cat".


Why not? I am curious guy...


----------



## Randall Ave (Oct 29, 2014)

MJD, ya might as well kill this, or my post count is gonna go in reverse.


----------



## BUFF (Dec 24, 2009)

ConnorExum said:


> Why not? I am curious guy...


Then go see if you can stop an oncoming locomotive by standing in the tracks.....
We look forward to reviewing the results....Thumbs Up


----------



## EWSplow (Dec 4, 2012)

There's an old saying , "curiosity killed the cat".[/QUOTE]

Let me rephrase, "curiosity killed the thread".


----------



## dieselss (Jan 3, 2008)

Randall Ave said:


> MJD, ya might as well kill this, or my post count is gonna go in reverse.


Mine just did.....


----------



## EWSplow (Dec 4, 2012)




----------



## Randall Ave (Oct 29, 2014)

dieselss said:


> Mine just did.....


I hope to mabey hit ten thou before I die.


----------



## ConnorExum (Jan 5, 2010)

There is a very good reason why I am curious— finding the root problem. The original poster said the problem first occurred last year. So, no one is curious why all of a sudden the truck wasn’t maintaining the battery?


----------



## BUFF (Dec 24, 2009)

Randall Ave said:


> I hope to mabey hit ten thou before I die.


Since your dad made 95yo you have plenty of time.


----------



## Randall Ave (Oct 29, 2014)

ConnorExum said:


> There is a very good reason why I am curious- finding the root problem. The original poster said the problem first occurred last year. So, no one is curious why all of a sudden the truck wasn't maintaining the battery?


That alternator I Believe uses a Diode Trio, one of the Diodes has failed. It will still charge, but not to its full capacity. Basically its internal voltage regulator took a crap. In laymans terms. 
Guys come on here looking for an end to a problem, most do not need the reason something failed, just the fix so they can get back to work.


----------



## ConnorExum (Jan 5, 2010)

Randall Ave said:


> That alternator I Believe uses a Diode Trio, one of the Diodes has failed. It will still charge, but not to its full capacity.


Which would explain the issue at hand. But, wouldn't a pump motor that is drawing too many amps also potentially cause the same problem?


----------



## ConnorExum (Jan 5, 2010)

Randall Ave said:


> That alternator I Believe uses a Diode Trio, one of the Diodes has failed. It will still charge, but not to its full capacity. Basically its internal voltage regulator took a crap. In laymans terms.
> Guys come on here looking for an end to a problem, most do not need the reason something failed, just the fix so they can get back to work.


But, if you don't understand why a failure occurs then you often repeat it.


----------



## ConnorExum (Jan 5, 2010)

I still think you guys are right he will need the second battery as well.


----------



## dieselss (Jan 3, 2008)

ConnorExum said:


> I still think you guys are right he will need the second battery as well.


Pretty sure you've said this at least 4 times in this post already


----------



## ConnorExum (Jan 5, 2010)

And that matters?


----------



## dieselss (Jan 3, 2008)

ConnorExum said:


> And that matters?


Just working on your post count then.

Just keep saying the same thing over and over and over again. Definitely a nice troll move


----------



## ConnorExum (Jan 5, 2010)

dieselss said:


> Just working on your post count then.
> 
> Just keep saying the same thing over and over and over again. Definitely a nice troll move


Do you understand what trolling means?


----------



## dieselss (Jan 3, 2008)

ConnorExum said:


> Do you understand what trolling means?


Exactly what you do.


----------



## Randall Ave (Oct 29, 2014)

ConnorExum said:


> Do you understand what trolling means?


Yes, we all do.


----------



## Mike_PS (Feb 28, 2005)

agreed on closing this and Connor, for the last time, quit posting to stir the pot. You are not in the industry any longer so stay in the off topic or non commercial forums...and, for everyone else, place him on ignore rather than continuing to engage.

Thanks


----------

