Inverter AGM questions

Ok thanks that helps, so I am thinking direct cable. I will have probably 10' to the bed plug and figure another 6' at least to the camper batteries, so this 1/0 would work?

https://www.skycraftsurplus.com/14awgdlo2kvblack-1-1-1-1-1-1-1-1.aspx

I use the term "Chassis Negative Return" because GROUND should be reserved for the EARTH circuit in Alternating Current circuits.

Bonding negative to a vehicle chassis is almost an art-form. In your case I would do it with one-AWG cable. AWG is not SAE, it is larger and if you use a quality supply house like genuinedealz.com you will get American Wire Gauge size wire. (1) AWG is a single cable one-AWG wire is a particular cable size smaller than 1/0 and larger than 2 AWG.

You can run this cable from the engine block, cylinder head, or intake manifold, a bolt at least 3/8" diameter or 10mm THREAD size or 13mm wrench size bolt. Stacking it under the manufacturer's ground cable would be ideal. Then run it to the main chassis rail frame. Not to a riveted crossmember. Too much amperage for trusting to a riveted crossmember.

Drill your bolt hole. Then the frame steel that contacts the cable lug must be cleaned until the steel is bright and shiny. I use standard plated bolts, lockwasher, and nuts. Clamp the lug to the frame. Tighten as tight as bolt torque specs suggest. This is important. When finished with this clamped cable, smear chassis grease on the lug-cable side and underneath on the nut. It will last forever unless washed off. This is one area I refuse to deal with as a problem child later on. Be meticulous and you will never have to deal with a bad connection here.

The same thing for the same reasons apply to the chassis negative cable to camper battery negative posts apply. Sometimes it is easier just to run a direct cable, but if longer than ten feet total distance I would recommend one aught cable one size larger than one AWG.

I use black SPIRAL WRAP on frame cables. Protection.

Here is a lifetime crimper.

https://www.ebay.com/itm/16-Ton-Hydraulic-Wire-Terminal-Crimper-Battery-Cable-Lug-Crimping-Tool-w-Dies/271428289917?epid=1679827079&hash=item3f3263057d:g:gEcAAOSwstJZQMbX

HEAT SHRINK TUBING

https://www.ebay.com/itm/700-3-4-Dual-Wall-Adhesive-Lined-4-1-HEAT-SHRINK-TUBING-TUBE-ES-4-ES20004B/112139639898?hash=item1a1c0b1c5a:g:vrAAAOSwMHdXSwjO

CABLE

https://www.ebay.com/itm/1-AWG-Gauge-Tinned-Copper-Marine-Battery-Cable-Boat-Wire-By-the-Foot-RED/272262960794?hash=item3f6423169a:g:p70AAOSwepJXUZCD&vxp=mtr

TERMINALS

https://www.ebay.com/itm/1-AWG-Gauge-Tinned-Copper-Marine-Battery-Cable-Boat-Wire-By-the-Foot-RED/272262960794?hash=item3f6423169a:g:p70AAOSwepJXUZCD&vxp=mtr

When using true american wire gauge cable always select a lug that is one size LARGER than the cable AWG. One gauge cable, use 1/0 lugs, 2/0 cable, 3/0 lugs. 2 gauge cable, 1 gauge lugs. Trust me on this. The school of hard knocks.

Play with the crimper to select the correct set of dies for the cable lug outer diameter. Crimps should almost solidify the copper wire stranding inside without tearing up the copper lug. When crimped properly the end of the wire becomes stiff.

Ok so I found the spot to tie into, the second alternator is wired through a 175amp fuse that is attached to a buss bar on the aux battery. There is a 3/8" stud just past the 175amp fuse, I will install a 120amp breaker and a automatic charging relay by the battery.

I am looking at the 4 AWG wire at the link you posted, any advice on connectors and a crimping tool? I want to have a charging circuit in the back seat area and also have a plug mounted in the bed to hook up to the camper batteries, would I be better off running a dedicated line to each spot from the charging relay or splitting the wire under the cab?

ETA

Also you say "with chassis negative return" what does that mean? Do I run the positive from the engine bay and then just bond the negative to the chassis close to the battery bank? I was thinking about running the negative from the main post in the engine bay, would this affect my wire sizing?

Not the starter battery please. You would end up with a dash fault code. Check Engine Light. Please read the factory manual before commenting :)

The second battery powered by the 2nd alternator can be tapped. The secret is to do the tapping without butchering the wiring harness. With a potential full 120 amperes (minus field current), total wire run length up to 15' with chassis negative return can be made with number six american wire gauge cable or four gauge sae automobile wire.

Mount a Bussman 120 ampere circuit breaker on the fenderwell. Then pass the wire to it's destination.

The #6 or # 4 cable must be protected by a sheath from damage or shorting. Here is a link to some good and easy to use sheathing.

https://www.ebay.com/itm/8-10-12-14-16mm-Flexible-Spiral-Wire-Wrap-Home-Desktop-PC-Manage-Cable-Cord-2M/272877383692?var=572042287635&hash=item3f88c2700c:g:UDAAAOSwfDtZ4INT



I prefer to over-size the loom and leave the coils completely closed when running cable down and alongside a frame rail. Use large BLACK nylon ties to secure the loom/cable to fender-well and frame rail attachment points.

IS IT WORTH ALL THIS?

**** Tootin'! The vehicle is set up for this excellent modification. Pass the cables through the bed or fenderwell using these strain relief gland nuts.

https://www.ebay.com/itm/5-Pcs-PG11-16mm-Inner-Diameter-Plastic-Cable-Gland-Anti-splashing-Black/232532543804?hash=item362405093c:g:gIIAAOSwySlZ7ADj

Then and this is important no matter what kind of battery to battery power transfer is involved...

USE A SECOND 120-amp BUSSMAN BREAKER appropriately located near the bed mounted batteries.

When done right, this system should add an easy two thousand dollars to the resell value of the vehicle. RV'ers COVET a properly installed system. I know. The owners of vehicles I have done similar projects on have sent notes or phone calls of glee when they recouped their investment.

Just before I departed my business I housed a near-new 1992 Ford dually diesel that had a 200 ampere 3875JA Leece-Neville aux alternator. Two buyers almost got into a fist-fight over rights to buy the truck - priced almost sixteen hundred hundred dollars more than high blue book. The owner decided to sell after his wife passed away. This alternator charged a bank of six T-105's running crossways across the bed. It charged if I remember correctly almost 115 amps at in-gear idle engine speed and 170 amperes just above idle. A machine shop adapted an additional stepped crankshaft pulley onto the original and I used an idler pulley to give the drive belt additional wrap around the alternator pulley. A fun project. Armando, worked under supervision to install the system.

And just for the heck of it, here is a link to the sturdiest, highest quality cabling I have ever found. Far far tougher than the stuff West Marine or genuinedealz.com sells, rope stranded, tinned nylon sheathed EDPM wire. It is sold in minimum lengths. Only the Space Shuttle refit wire could compare with this stuff...

https://www.skycraftsurplus.com/search.aspx?find=dlo+wire

Don't ask what this cable sells for from suppliers....EGAD

S Davis wrote:
Ok so where would be the best spot to tie into the trucks charging system, and what do I fuse the circuit to? 125amps.

Without having the truck I would tap straight off the start battery.

Fuse will depend on wire. #6 maybe 80 amps, #4 maybe 100-120.

On some Automotive forum I thought it was a newer model chevy on which some guy asked what the strange ring looking thing on his main battery cable was.

It was a hall effeect sensor measuring amps into or out of the battery.

I'd pull power for some hi amp solenoid directly from the alternator (+) stud as opposed to anywhere else in teh charging circuit.

There are some DC to DC converters like from Sterling, or even Ctek, designed to rais voltage to a secondry battery system, but they are not cheap.

The secondary alternator has a cable coming from it. Follow it. It's probably crowded under the hood but what you are looking for is a junction point where that wire has ring terminals and is bolted to something that looks like a block. That most probably will be the factory 125-amp fuse. Are there enough threads or whatever to connect another cable to this junction?

We'll take it step-by-step

Ok so where would be the best spot to tie into the trucks charging system, and what do I fuse the circuit to? 125amps.

Connect up your batteries. Even half a dozen 8-D's will charge just fine. All the auxiliary batteries have to be same type of construction and age. Rely on your 120 volt AC charger to be the mainstay and the alternator as a viable auxiliary charging source.

No worries sir.

Wow thanks for all your input, I don't get why they would put a dual alternator on the truck and make it so difficult to use the power. Don't most EMS vehicles have battery banks or do they just pull power from larger alternators? I wonder if tuning could change the charging parameters, I have a EFI Live V2 tuner for my other truck.