I ran mine direct with no fuse to the passenger battery. within 18" used to be the norm for 12 volt stuff. suppose it has changed, but the distance between the alt and the pass battery is close enough i am not concerned...nothing to cut it anyway, and if i get in an accident bad enough to pinch the cable there are other issues to concern myself anyway.

 

why would you run an extra 6’ when the drivers side battery is only a foot away?
I have a 2/0 cable between the batteries so a short cable from the alternator to the drivers side battery is much shorter reducing resistance from the cable. There’s no reason to not fuse it. As I mentioned earlier, it’s safer.

 

sorry did not make that clear, I meant that if over 18" a fuse is a must have. even though the stock wiring does not have one between the batteries

 

Fuse on the alternator? You bet.

My method link: https://www.ford-trucks.com/forums/1...l#post17789538

 

What a great read! Thank you for providing such fantastic and educational material...

I have been shopping and posting questions here on FTE trying to get educated on the best charging system within a reasonable cost. So far the Mechman seems to be the top choice. the Mechman 240amp Part #7796240

https://www.mechman.com/alternators/...d-powerstroke/
6 phase Hairpin stator technology, twin rectifier plates, and 12 massive diodes

If you were to do it all over again, what alternator would you go with?


On another note with regards to wiring, I like the direct connection from the alternator to each battery independently and retaining the battery to battery connection. Since I have the B-B connection already as supplied by Custom Battery Cables, the addition of the independent connection from the alternator to each battery should be an easy addition. Here is the kit I had installed. Each cable is 2/0 size with the exception of the starter cable is a 3/0
https://custombatterycables.com/prod...2003-3-0-2300/

I'm trying to assemble a list of material I will need. So far it looks like I will need:
1ea- Positive cable from the alternator to DRIVER side battery 2/0 size. (Length TBD) How long is yours?
1ea- Positive cable from the alternator to PASSENGER side battery 2/0 size. (Length TBD) How long is yours?
1ea- Fuse Dual MRBF Terminal Fuse Block - 30 to 300A

Do I need a negative cable from the alternator body to either battery or both, or just the block?

Here's what I have now. Note that the batteries will be replaced with a pair of Odyssey batteries as soon as these start to fail or I get a windfall of cash, whichever comes first.

 

Is there a specific reason you went with the Mechman? My O’Reilly alternator is on its way out and the Ford reman I have is garbage too so I’m thinking of upgrading to a better quality one. I’ve seen that FICMRepair has a 7.3 alternator wiring kit but they only supply a 250 Amp fuse.

 

[QUOTE=Rainmaker1;21315902]will do that tmw for you.
I have a 12k lb winch up front, which is what prompted me to get a Big Alternator... I was stranded in the high desert in Price, UT and the local auto stores didn't have a single alternator that would fit the truck.

so, I ordered the best one I could find on the web.... at the time.
Google slants what you find, but as I have been a radio/electronics tech since 1958, I knew that if I bought a high dollar, high quality alternator, the Diode Blocks would be more than sufficient to prevent a short internally to ground.

in my life time, only one diode has ever gone bad on an alternator, 1 out of the six that are inside them. no shorts to ground, just low output.

the MechMan at idle, will hold 14.85 volts with the AC on, both fans on high.

 

my truck only has ONE (1) cable from the Alternator to the driver side battery.
that is ALL that you need, there is a Cross-Over cable between the two batteries, that is the same gauge as the one from the Alternator.

no point in making life more difficult, both batteries will charge to the same voltage when equalized... IF, you keep the cables clean and bright, and spray with with FLUID FILM,




they Stay Wet and Clean... with Fluid Film






these batteries are about 18 months old now, and still look just like this, with one spraying of fluid film.

I keep a 4.5 Amp Battery Tender on them all the time, year around.
there is some Parasitic Draw because of stuff installed on the truck,
the Pats System for one,
the ARM Research electric steps for another,
and something in the truck pulls a tad bit...

they will drop to 12.5 volts in about a week, I do NOT let them get lower than 12.5 volts, ever....


I have been thinking about that fuse.
I am NOT going to use the Fuse Block,
I am going to bolt the ends of it to the cable terminals, and slide Shrink Wrap over the whole thing..... it is only there for Emergencies, not to be able to change it out every day.

 

Reading the post from Sous above, My thought and probably his too, is that a direct connection the each battery INCLUDING the crossover B to B connection seems like it would provide an unimpeded path to each battery for the current to travel. Maybe he can chime in for clarification?

Having just one cable from the alternator to the drivers battery, then another going between the batteries seems like the driver side battery would get preference. Electricity travels the path of least resistance. I could be wrong but it makes sense to me. Maybe it's not necessary?

 

The Resistance in the 2 ought cable between the batteries measures in the Milli-ohms... I don't have an ohm meter that can read that low, and you don't either.

let's see, 0.005 times 300 amps gives you 1.5 volts drop, providing the passenger battery would pull that much.

get realistic, the max it will pull for a brief time, after the engine starts, is something like 150 amps for 15 seconds and that is 0.75 volts

in about two (2) minutes with the MechMan, the voltage is going to be 14.8 or higher, I dare you to find any voltage difference between the two batteries.

just for grins, when I take that picture for you, I am going to make a Video of the DVM on the power port, while the Glow Plugs are sucking juice, and let you see how "long" it takes to get up to 14.8 or more.

when I start the truck, I watch the DVM, depending out Ambient temps, it can drop to 11.5 volts in 80* Wx or 11 volts in 30*F Wx

don't matter, the MechMan is pushing 14.8 in less than two (2) minutes.

oh, that Power Port voltage?
guess where it comes from???

the Passenger side battery.

 

That high of voltage isn’t causing an issue? I would be a little concerned of voltage above 14.4. I have seen and had issues above them at number

 

ohms law dictates that as the voltage rises either the impedance or the current has to change. which means either higher temps (impedance went up) or lower temps (current went down). the only issue that I am aware of (not a pro here folks) is the glow plugs hence that big long thread about glow plugs and high output alternators.

I am still at the turn key and let it sit for 2 minutes stage as I have not had time to dink with a relay system to shut the alternator down until the glow plugs have shut off, but that is the poor mans solution, just wait two minutes.

 

On my old e99, I upgraded my alt to the Leece-Neville. Part of that upgrade, I was able to run a single cable from alt-driver batt-pass batt- back to alt using the terminals shown, for essentially a continuous circuit. With BlueSea fusing.

When my e99 was retired, I pulled all that stuff out and have since installed on the '02. Unfortunately I had to cut the cable at one terminal to get the whole smash out (it had snaked through a hole in the rad support to keep the crossover section out of the way). Now the 2 ends meet inside the terminal for the next best thing to a continuous circuit.
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Choices would be Leece Neville or Bosch 6.0L 160A based on my requirements and expectations at the time. Mechman would take the place of the LN if it was unavailable.

I followed the guidance and work of Y2KW57 when I installed the high output alternator and the additional positive and negative cabling. Some people feel these additional cables are pointless and there was a thread on it a few months back.

Based on what I know from my previous life in electronics and following the path of engineers and people a lot smarter than me, I went with the additional cabling.

 

I'm late to the party. I have a leece neville on one truck and a 160 bosch on another. Unless your pushin HUGE power and jumpin off dead big rigs on a regular basis my vote is the 160 bosch.