I’m interested in replacing the “Remanufactured” alternator with one with a little higher output. It looks like everywhere I look they all come in about $350-$450.
The digital volt meter mounted where the factory cig lighter was reads 13.6 - 13.8 volts. It’s my understanding that this is a little low and it should be closer 14.2 vdc.
I tow infrequently, have a 900 watt audio amp from Alpine, HID headlights and led literally everywhere except the front corner lights. So this means with the load on the current alternator, it’s probably getting stressed a bit and that justifies a little more output but not crazy.
Any suggestions on what alternator to get without going crazy are helpful. What do you recommend?

 

Leese Neville or Mechman. Leese Neville is often times used in fleet vehicles that need extra power... fire trucks, ambulances, patrol cars etc. and Mechman is a well known aftermarket brand as well.

LN is a 230 amp unit and Mechman starts as low as 240 amps and runs up to 400. so I would think the bottom end Mechman or a LN will take care of you. If you need less power then there is also the nippondenso alternator swap, its a stock part for one of the newer trucks but goes in fairly easy from what I understand.

 

I'm just installing a MechMan 400 amp alternator for charging the LiFePo battery on our 5th wheel, they're a quality item & although I'll probably never need the 400 amps, it's better to be oversized than under......

 

did you DIy your battery bank or buy a pre-made?

 

I have the 320A MechMan, no regrets.
as all Alternators do, they only supply "enough current" to regulate the voltage at the required amount.

mine seems to regulate at 14.6-14.8 depending on temperature and how much AC fans I want blowing on me.

just an FYI, it takes at least 14.6 volts for wet cell to equalize, and that is for a quite lengthy amount of time.

Folks who crank up their car/truck and make 10 minute drive and shut it off, are keeping their battery in a Depleted condition, causing them to fail earlier than they should.






this is an Equalization chart, you will need to Pay Close Attention to it, to understand its' full meaning. NOTE, it takes 15.6 volts for an extended time to fully Equalize a 12 volt wet cell battery

 

While the stock output alternator (110 amp, IIRC) is easily able to keep up with 900 watts, what isn't being mentioned here is the factory wiring harness is only designed for accomodating that 110 amp factory alternator. Simply throwing a 300 amp alternator on there without upgrading the charge circuit won't make a bit of difference when the loads get heavy. Blown fusable links are what comes to my mind.
So you really need to beef up the charge circuit right along side of getting that bigger alternator. John has done an excellent job from what I can tell with his truck. On mine, I still run the stock rated alternator, but just to be sure, have installed a couple of auxiliary wires between the alternator and the battery. The red one goes straight to the positive post and the black one goes to the negative post. In addition make sure that there is no corrosion anywhere at any connection at any location on the vehicle to avoid voltage drop at any given connection.

 

you are quite correct, that is why my setup has a 2-O cable from the MechMan to the battery

 

I have a 560ah Fogstar Drift-Pro LiFePo battery (They're a UK company so don't know if available in the USA) which is Victron compliant, as I the rest of my off grid system is from them.

 

Nice, many of my acquaintances use victron....I call them the True Blue Smurf Cult. Its all in fun of course. I use magnum and morninstar myself and have a DIY 1300aH 48 volt bank for my off grid cabin. and a diy 600 aH 12 volt bank in my camper. (caravan) currently looking at selling the tow behind and buying a slide in camper.

 

I'm trying to understand why the separate ground from alternator to battery? There are 4 bolts holding an aluminum frame alternator to the bracket. Seems to me that there is a lot of grounding surface area already. You also have a ground cable at the lower edge of the block, if you really feel the need to ground the alternator, why not run it to the block ground?

 

Cleanest possible connection between the internally regulated alternator and the battery. Charge levels are measured in tenths of a volt and a poor connection I've seen take more than that.

 

That's exactly what I did. I ran another block ground cable to the back of the alternator (a Leece Neville, which has dedicated ground post on the back, which can be converted to an isolated ground for the entire alternator with the addition of a rectifier membrane from a sister model of the same rotating assembly and series of alternator).

It's a good thing too.

Years ago, back when I first installed the Leece Neville alternator, there was no write up or pattern to follow, other than the recommendations from Ford and Leece Neville to upsize the charge cable to handle the additional output capacity of the Leece Neville in the 4.5L LCF application.

On the surface, this task was simple enough, but the devil is in the details. I always disliked large megafuse holders that many car stereo folks use to fuse the larger battery and amp cables they run. Surface mounting space in an engine compartment is a rare commodity, and I wasn't about to give up any remaining surface to a megafuse box.

I had seen single post Marine Rated Battery Fuse holders (manufactured by Buss, best marketed by Blue Sea Systems) mounted on batteries. But no one had ever mounted these things directly to alternators. Fuses should be mounted as close to the power source as possible, and while a battery is a constant power source, the alternator is a powerful power source too. In some vehicles, fusible links are attached directly to alternators, before being spliced into the charging cable.

I thought... why not try attaching an MRBF directly to the alternator? And while at it, why not double down and use a double post MRBF, since there are two batteries to send an additional charge cable to?

So thrilled I was at having incorporated a compact solution to high amp circuit protection, directly at the power source, that didn't involve sacrificing any surface area to a mega fuse box... that I forgot to torque the mounting bolts to the alternator.

Good thing I had added that extra ground cable!

I didn't notice that the alternator bolts were loose until showing off the alternator to a friend of mine, some 25 miles away. The big new alternator and freshly wrapped charge wires are gleaming, I am beaming, and he asks... "How come these bolts are loose?" I was mortified.

 

Ok, so the alternator bracket has 4 contact pads, let's say each pad is 1/2 inch square, and 4 bolts threaded in about 1/2 inch, figure 9/16 bolts roughly equal to 1/0 wire in size. Total contact area is roughly equal to 6.5 4/0 cables, and should be able to handle close to 1800 amps. 2/0 cable is good to 175 Amps.

Thanks for helping me understand.

 

Except that there are only three (3) mounting bolts for the alternator.

And, the alternator doesn't bolt to the block. It bolts to the power steering pump bracket.

To be fair, the power steering pump bracket does have four (4) mounting bolts.

But those bolts don't bolt to the block either. They bolt to the driver's side head, where there is a head gasket.

This doesn't mean that there isn't continuity to the block through the head bolts, but the surface area of the three alternator mounting pads to the power steering pump bracket is not a straightforward calculation of contact area with the engine block.

 

The alternator may have a great physical & electrical connection to the engine, but the weak link is the ground connections from the engine to the chassis & then to the battery. By adding a direct additional cable from the alternator (or as I'm doing) or one of the mounting bolts just eliminates the possibility of a high resistance path.