I'd like to make a request to have a separate TCU sticky thread on upgraded charging systems. I've posted about my system in my camper mod page, and there are a couple of other threads floating around about doing the same thing. This topic comes up often enough that it seem like a good idea to have a tread with one stop info on people's various systems.
I'll start with a repost of my setup, and I invite those in the 6 gauge, 4 gauge or 2 gauge club to join in.
(Note that all pictures as scaled down, but are clickable for a full screen view.)
I'm using 4 gauge wire for all of the power connections between the alternator on the truck and the camper batteries. I debated several locations to tap power, but settled on the alternator to get the maximum voltage in the system to the camper batteries. I measured drops as much as .5V between the alternator and the engine compartment fuse box. I measured .25V between the alternator and the batteries when charging the batteries back up right after the glow plugs kicked off. By going to the alternator direct, no truck wiring is in the equation. For ground, I ran wire up to the front and tied the ground wire to the accessory mount bracket for the passenger side, right under the alternator.
I bought a 100A solenoid from NAPA to isolate the camper and truck. I picked up power for the solenoid from the glow plug relay. It's right near the alternator, and is only powered when the key is on. The PCM grounds the other coil terminal of the relay to turn the glow plugs on. I decided to connect the other terminal of the camper power solenoid coil to the glow plug wires so that the camper solenoid isn't powered when the glow plugs are on. When the glow plugs are off, the solenoid coil grounds through the glow plugs... at 160A nominal draw, the .6A of the coil is trivial. This keeps the camper batteries from trying to feed either the glow plugs or the starter. If they did, it would trip the breaker every time the truck starts. If you're wondering about the diode in the coil wire... it eliminates the possibility of back feeding the coil the wrong way.
For the camper to truck connector:
They are meant for powering lift gates on semi trailers. They are rated for 100 AMPS and take up to 4 gauge wire. To give a sense of scale, they are the same size as semi 7 pin connectors, which are a little bigger than the 7 way RV connector
For the remaining connections, I used a common 4 pin round connection.
Connection at alternator:
The upper wire is the factory connection, the new one goes out the bottom of output stud.
The control wires for the solenoid slip under the vanity cover, and connect to the glow plug relay:
I mounted the solenoid and breaker in front of the battery. It's a pretty well protected location.
The lower wire is the feed from the alternator, and the upper heads back to the connector.
Here is the connector ready to load. Both the negative and positive leads are inside the loom.
And now the connectors in place:
Behind connector:
The view with the plugs installed:
The 4 pin connector attaches to a 4 wire 14 gauge cable and joins the wire loom.
I drilled a hole through the wing of the camper, and ran the loom through:
Behind the converter I have a power distribution block. I now added the two new wires to the distribution block. The 4 conductor cable from the 4 pin connector is spliced into the existing camper wiring:
After trying it out with batteries near 50%, I got 65A feed from the truck to the camper at idle, with .55V drop... .2V in the negative, .35V in the positive.
If I was doing this again, I'd add a second plug like the one in the truck bed to the bottom of the camper. If I did that then I'd have a free removable pigtail that I could take off the camper and store inside.
Just one suggestion. The 100 amp breaker might be replaced with a 60 to limit alternator output. That is what my original RV wiring was fused at. It there is a higher amperage alternator (mine is 130) then probably the 100 is fine.
I know you probably never go below 50% state of charge--but I think it is best to make things "fool proof" if possible. Others might go too low which might possibly burn out their alternator.
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
When the battery isolation relay went bad in my motorhome, I replaced it with a forklift battery relay, rated at 100,000 open and close cycles before failure, and has silver allow contacts. Graingers part #6C017. I remember it by thinking of interstate 17. It is rated at 125 amps, uses a 12 volt continuous coil.
I like your system, yet I have to agree with Piano Tuner, that you might be overloading the alternator for that short time that the engine starts, and then your draw to refill the batteries is over 60 amps. For some reason, they put pairs of 30 amp circuit breakers in my motorhome, and I can see the engine battery voltage drop just after starting, if my 4 coach batteries are low, then after a few minutes, then the engine voltmeter returns to normal, while I am guessing the 30 amp circuit breakers cool off for a little while. I have 2 - 30 amp breakers protecting the feed from the factory installed isolator relay to the engine battery power line.
What I think my motorhome engine and alternator are doing when I start with mostly dead coach battery bank is this. Starts to recharge the coach battery, with little power to the engine battery. After a few minutes the pair of 30 amp breakers trip, and they will re-set in a couple of minutes. By that time, the engine battery is nearly full again, and I would be driving at highway speeds.
At over 1,800 engine RPM, the alternator will be going over 4,000 RPM, making the full amperage available. At that time, then the circuit breakers re-set and start to charge the coach battery bank around 55 amps, and everything is fine.
But remember that your alternator bearings will be under a lot of stress while making that 100 amps to recharge the engine and coach battery bank. At least you will get yours charged in a short drive, many coaches and campers require miles and miles to recharge the batteries. Travel trailers and fifth wheels take hours to recharge a 200 amp hour battery pack with the standard 15 amp per hour factory wiring.
Thanks for the post, it is nice to know there are 100 amp DC rated receptacles and plugs. I was thinking that only Anderson connectors (sometimes used in recharging forklifts or forklift batteries) where the only 100+ amp DC connectors. Anderson connectors are rated at 50, 335 and 500 amps.
I'm actually duplicating Matthew_b's wiring setup, I've almost finished the 110 volt side of my new inverter system, then I can upgrade the charge wires coming from the solenoid switch back to the camper.
I too, have the same 100amp breaker and a 130 amp alternator (dual v-belt), but I have a gas engine vs a diesel, so I only have one smaller starter battery to recharge and 3 deep cycles (2 of which are the normal heavy use battery, with a less used on-board group 27 in the truck.
The reason I chose to upgrade to the similar wiring is I'm setting my system up to run the 2-way fridge on 110 going down the road vs propane and will need sufficient wiring to handle the 20-30 odd amp load.
Follow me as I full-time the Redneck Way at The Journey of the Redneck Express CBChannel 17Redneck Express '1992Dodge W-250 "Dually" Power Wagon - Club Cab Long Bed 4x4 V8 5.9L gashog w/4.10 Geared axles '1974KIT Kamper 1106 - 11' Slide-in
Question..... If the alternator has an external voltage regulator (some are, some aren't) isn't it possible to fry your batteries connecting directly to the alternator?
Second question.....if you run down the camper batteries to stone dead and you have two older marginal truck batteries, is it possible that you could burn up your alternator without first charging the truck batteries first, then charge the camper batteries in second?
The only thing that sticks in my mind is the close proximity of the electrical wires to the copper propane line. Imagine that battery wire shorting out on the propane line. Instant uncontrollable fire, until you turn the propane off. My guess by then it would be too late. So I think I would wrap that copper propane line with some electrical tape at a minimum or even better split some rubber fuel line and wire tie it to the propane line after you have wrapped it with some electrical tape. Just to be on the safe side.
Allen
2005 Ford F-350 CC Dually 6.0L Diesel 4x4 King Ranch loaded, Supersprings, Coolant filter, Oilguard bypass filter.
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