370 AMP Alternator installed

Brien2002 · May 7

I just installed a 370 Amp alternator and did the big three upgrade in my 2017 Silverado 1500, and i'm wondering if there's anything else i need to do safety wise to ensure nothing ever catches fire or overloads the truck. I have a decent size sound system and a decent amount of exterior lighting and my dash lights started flickering with my stock alternator so thats the reason i upgraded. Thanks in advance

03GMCSS2 · May 23

Excellent upgrade, sounds like you took care of the important parts. I too did the same upgrades and added second battery.

AZ_SS · May 27

Do you have the Big 3 parts listing and installation diagram?

Forgot · May 29

You could never even use half of that output unless your truck is so modified as to be unrecognizable...

No, not for stereos, unless you are some kind of world champ. Not for exterior LED lights. Welding maybe? If your dash is "flickering" that has noting to do with your alternator, more likely a bad cluster.

When you're tying to make so much power, drop 12v and go with a 24v or 48v system. (My truck has a full 48v electrical system) 12v at ridiculous amperage is incredibly inefficient and hard to make use of. It also increases risk of fire. My truck does not have an alternator, it has a 200A solid state 48v>14v converter to be my "alternator" and 10KW of lithium batteries onboard.

I can also power my entire house with the truck when the power is out.

Edited May 29 by Forgot

MikeBMW · June 1

On 5/29/2024 at 5:40 AM, Forgot said:

My truck does not have an alternator, it has a 200A solid state 48v>14v converter to be my "alternator" and 10KW of lithium batteries onboard.

I can also power my entire house with the truck when the power is out.

Seems rather unhelpful, given the question.
I installed a Mechman 250A alternator (mine had a 150A from the factory.)

It will power whatever I need without draining the battery under power.
And, yes, my truck has many added accessories.
Still, you do you.
@Brien2002, just be sure you used the "ring" around the battery wire for the voltage governor and you'll be good.

kickass audio · June 1

I have a 370A mechman alternator on my 2014 silverado and it's still left from that truck and I want to put it in my 2023 Silverado. Same mounting style except the bastard GM engineers used stretch belts and not a tensioner system and they plugged the holes for my water pump to allow adding a bolt on kit for an automatic tensioner. I may be able to get it to work but Mechman has a alt for my new truck that uses an external voltage regulator.

With your truck if you re-used the 2 pin alternator wire you will have the factory ECM turn your voltage up and down as it sees demand so you won't always get 14.4v of power. You can override this by getting a 4 pin alternator with an external voltage regulator and use a shunt on the factor 2 pin wires to short them together and not trip the battery light on your dash.

The only issue I will warn you about that I had in my 2014 was when it was colder outside, my voltage would go above 14.8v and whenever that happened, the HVAC system would freak out and shut down until my voltage went below 14.8v. Immediately after my voltage hit 14.8v it would kill the interior fans for the climate control and they would restart a few times. This only happened on super heavy loads and on a cold startup event so it was manageable but is worth noting.

Also I managed to stuff 1/0 gauge wire through the ring terminal on the battery ground cable. I don't recall if the late year K2's had switched from the round hall effect sensor to the sensor being around the battery ground terminal but if you have the round sensor that looks like a donut around the battery ground cables then you need to pass the ground for the alternator through that sensor or it will screw up your voltage since the truck can't calculate your actual amp draw/demand. How I wired mine was I had the big-3 upgrade done and the negative terminal from the alt to the battery passed through the hall effect sensor, I then had a direct connection going along the firewall near the top of my + and ground wires to the second battery on the drivers side. My amplifier power and grounds were coming off the second battery on the drivers side through the firewall and to the back seat where I mounted a sheet of 1/4" plywood to the metal bracing on the bottom of the seat to bolt down the amps to.

edit: forgot to add, if you want protection, install a 350-400amp rated fuse on the alternator positive wire so that if something gets burned or pinched and shorts out it won't keep stealing power from the alternator or battery and cause a fire on you. I personally live dangerously and never used a fuse on my alternator positive power wire lead. Keep the wires up and away from your exhaust manifold and you will be just fine.

And depending on if you got the real alternator for your truck with a side mount positive stud not like mine where Mechman goofed up and sent me one with a back facing positive stud, you can keep the wire protected easily. Mine however I Had to leave the wire alone unless I pulled the battery power and needed to work on it since I had to slit the side valve cover beauty panel to fit the wires in there next to the PCV hose. No big deal but worth noting should you have a goof up like I did.

If you need to know the upgraded alternator belt part number that works fantastic for your alternator let me know. Since the upgraded alternator from mechman will have a smaller pulley so you can have high output at idle speeds you MUST get a shorter drive belt. In a pinch you can drive to the store with the OEM belt on but DO NOT under any circumstances keep using that, you have got to get a shorter belt which involves going to napa or somewhere for it and slicing off the extra ribs with a utility knife.

Edited June 1 by kickass audio