Moving from a 240 amp alternator to a 400 amp-- any change to the big 3?

[FatBaldandWheeling]

My 240 amp alternator is failing unfortunately. I had a sneaking suspicion but the dealer had only checked the batteries (I still have a warranty with them). More recently I've had some hiccups while hauling uphill from time to time, and it was emphasized while going over Monarch-- but I relieved it because my voltage would jump up to 14 while going downhill without load.

Long story short, I went to an auto place, they tested it and it's only outputting about 6 volts now. The big question is in the title:

Can I move to a 400 amp alternator without replacing the big 3? Or is the gauge they offer on the max tow package too small for that? The alternator I am looking at is recommending 1 or 0 gauge.

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[VA6489]

Big Three??

 

[jav_eee]

Big Three??

a mod as old as time. Refers to upgrading the alternator to battery, battery to chassis ground,, and engine to chassis ground wires with big 0 or 1 gauge wire.

 

[bd100]

In case you need to upgrade:
https://www.jeepcables.com/products/gladiator-jt-big-7-kit-2020-2023

 

[IamPro2A]

In case you need to upgrade:
https://www.jeepcables.com/products/gladiator-jt-big-7-kit-2020-2023

Wonder why the the JL kit for the 1/0 is $20 more than the JT kit?

 

[Maximus Gladius]

My 240 amp alternator is failing unfortunately. I had a sneaking suspicion but the dealer had only checked the batteries (I still have a warranty with them). More recently I've had some hiccups while hauling uphill from time to time, and it was emphasized while going over Monarch-- but I relieved it because my voltage would jump up to 14 while going downhill without load.

Long story short, I went to an auto place, they tested it and it's only outputting about 6 volts now. The big question is in the title:

Can I move to a 400 amp alternator without replacing the big 3? Or is the gauge they offer on the max tow package too small for that? The alternator I am looking at is recommending 1 or 0 gauge.

I’m watching.
When you do upgrade and figure that out, let this tickle your fancy.

 

[DanJT]

Another option for those with electrical accessories (lights, winch, ect...)
the kit looks heavy duty and Dummy proof.

Jeep Cables Installation Wrangler JL Gladiator JT 3.6L Engine

 

[LouisvEarlleJT]

Do you need the extra amperage though? Sounds like the 240 amp was just failing and replacing it with another 240 amp that doesn't have such a short life would be the solution.

 

[ChadM]

Long story short, I went to an auto place, they tested it and it's only outputting about 6 volts now. The big question is in the title:

it is a variable output alternator but shouldnt ever be as low as 6v. How did they test?

 

[IamPro2A]

Another option for those with electrical accessories (lights, winch, ect...)
the kit looks heavy duty and Dummy proof.

Jeep Cables Installation Wrangler JL Gladiator JT 3.6L Engine

Looks like the same kit as already mentioned above:

In case you need to upgrade:
https://www.jeepcables.com/products/gladiator-jt-big-7-kit-2020-2023

 

[smlobx]

In case you need to upgrade:
https://www.jeepcables.com/products/gladiator-jt-big-7-kit-2020-2023

Now I’m going down a new rabbit hole!
Does anyone know what gauge wiring is stock?
I’m already running lights and a few things and am getting ready to install a winch

 

[FatBaldandWheeling]

it is a variable output alternator but shouldnt ever be as low as 6v. How did they test?

I misquoted. It's not providing enough voltage, regardless.

 

[FatBaldandWheeling]

Do you need the extra amperage though? Sounds like the 240 amp was just failing and replacing it with another 240 amp that doesn't have such a short life would be the solution.

I believe I do. Outside of winching a heavier vehicle (I am sitting just under 7k lbs.), there are a few other reasons:

• I have a third battery for an AluCab setup that is 130 amp hour that charges from the alternator when the engine is running (accessory fuse tap to turn the charging on and off). This will eventually be maintained with a solar panel when the engine is off, but I don't always have sun.
• I will eventually try to swap out for the Gen 3 battery conversion and install some deep cycle primary and secondary batteries
• Having the overhead helps to ensure it's not hitting near Max, and if I need to stand away from the gas pedal while winching, it will provide more amperage overall. I use the Tazer feature for brake stand and higher revs.

Overall it will be a good add for my setup.

 

[DanJT]

Looks like the same kit as already mentioned above:

Fair but it gives you options for upgrading to 7 piece wire upgrade as well as up to 400 amp alt.
But then again I already have the 1/0 wire from alt to pos batt. then when I did the aux delete i ran the neg post to the firewall and the pos terminal to the pos on main battery. all I need to do is run the neg from starter to chassis. working on getting the 240 alt.

 

[@californiajeeping]

Your alternator is pcm controlled it will only show 12.6-12.8.

It charges to a higher float voltage based on load and engine rpm.

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