Truck electric system protection when charging batteries

[NASCAR9]

Added a bolt to positive battery mount

Short wire from fuse block to the battery

Top of fuse block. I made simple bracket out of angle iron and mounted it to a tab that was already there for something else.

[wjpatter]

Added a bolt to positive battery mount

Short wire from fuse block to the battery

Top of fuse block. I made simple bracket out of angle iron and mounted it to a tab that was already there for something else.

Great pictures. I'm looking forward to pictures when you get the coach wired. Good idea about the spacer. That will save skin in the future. I worries about mounting vertical because of water pentation but have limited options. My connector is in the mail so my plans may change when I'm able to touch it. I'm planning to run two 4 gauge (hot and ground) the length of the entire run. In addition to changing while driving, I want to be able to charge the batteries in camp without connecting the 5th wheel. With the layout of my second battery, I have good connection access directly to it, which should help installation.

I've ordered a fuse block after looking at your parts list and plan on putting it immediately downstream of the manual reset circuit breaker. I bought a fuse holder block to provide additional splash/dust protection for it. I think I can hog out the fuse block and mount the breaker inside. The vote is out whether that will work. I tend to end up with a lot of extra parts at the end of the project of the "really good ideas that didn't work".

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[wjpatter]

Installed 2000w Aeliussine Inverter and 50 Amp Renogy DC-DC Charger.
I think I’m happy with how it turned out. I’ll have to put it on the road to see if it lives up to expectation but the bench test worked almost as planned.

Inverter
Wiring the inverter was straight forward. I opted to go simple with an extension cord to the 50 amp to 15 amp adapter. It isn’t fool proof but it is simple. Turning off the converter circuit breaker is mandatory. One of the tests that I ran was to leave the converter power on with the inverter power on, just to see what happens. It took an immediate 30 amp discharge from the battery. Left unattended, I’m confident the current draw would increase until the inverter over loaded and kicks off. Nothing I’m going to attempt. Below are the individual DC and AC system current draws measured in battery amp. I isolated each load to have a measurement for each element. The microwave and Keurig are hogs. I calculate 20 minutes using each will cost me an hour of generator time each. The coffee plunger is looking pretty good. All told, I think our living will eat 10% of the battery each day but that has to be verified.


Parts List
Inverter: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Power Switch: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Terminal Blocks: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Hydraulic Crimper: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

DC-DC Charger
I went with the Renogy based on Amazon reviews but I hope I’m not going to regret it. Their website forum and support is terrible. I just couldn’t get an answer about the 12v line from the truck’s 7-pin connector when I activate the DC-DC Charger. My worry is about higher voltage from the house batteries feeding back into the truck charging system. I disconnected it from the fuse block going into the RV to be safe. I hope it isn’t important for the trailer breaks! I’m running 4 gauge wire from the truck batteries through Anderson (175 amp) connectors to the DC-DC charger. Selecting the battery type was easy. It defaults to SLA and changing it to other battery types is a button push. The battery temperature sense line is taped to the top of the battery. For testing, I left the ignition sense wire connected but loose.

Performance looks good but I’m seeing something that I didn’t fully understand or expect. First of all, there is no on or off. Power at either the output or the input and it comes alive. With no input power, only output connected to the battery, I immediately got the Battery Type Indicator and Service Battery Indicator (Level of battery charge). I don’t know that this is bad but it was unexpected with nothing on the input.

When I connected the Anderson connectors with the truck off, I had no Input Battery Light on the Renogy nor was any power (amps) delivered to the house batteries. Results expected. I started the truck and 15 seconds later 23 amps were delivered to the batteries. It is a good design feature to delay start of the charger; however I wasn’t expecting anything to happen. It was my understanding that until the Ignition Sense line went positive, the truck electrical would not be taxed. When I did connect the Ignition Sense line to 12V, the current to the house batteries went to 44 amps. The Ignition Sense line works but isn’t a charger cutoff as I had expected. It does look like the Renogy charger is sophisticated to measure the state of the truck battery voltage. If the alternator isn’t producing voltage, the DC-DC charge doesn’t start, which is a good thing. The last test I performed was to turn off the engine with the Ignition Sense line at 12v. DC-DC Charge continued to charge the house batteries at the current charge rate. When I disconnected the Ignition Sense line, the power stopped.

So, I was surprised seeing things that I didn’t expect but when I evaluate how it performed, I think I’m happy. If it weren’t for their god-awful website, I would be very comfortable. I would like a better explanation for how it operates. I think this setup will do the job very nicely with one exception and that is self inflicted. I’ve wired my Ignition Sense line to my running light. I can control the DC-DC charger with my light switch, which I think many have done. My risk is that I have to insure my lights are off when my truck is connected and not running. I’ll have to manually turn the lights off as a matter of practice and that isn’t fail-safe.

Here is how I installed it.

At the Truck:
I ran red and black 4 gauge wire, encased in split conduit, from the driver side battery (I have two) to a 175 Amp (Red) Anderson connector, mounted in the bed. Near the battery, I installed a water/dust proof box that contains the 120 amp circuit breaker in series with a 100 amp ANL fuse. I used waterproof cable glands for the wire in and out of the box. I like the idea of being able to turn off that much power when I know I’m not going to be towing. In the bed, I used the same waterproof cable glands going to the Anderson connector. In addition to being a good weather seal, they provide very good wire strain relief and keep the wires from rubbing the metal hole. I was very apprehensive about routing the cable harness under the truck. Several said run it along the existing harness next to the frame. My solution involved a $100 bill and the mechanic down the street with a lift. The rest of it looks like this:

[wjpatter]

In the Bed


On the 5th Wheel:
I fished the two 4 gauge wires between the sheet metal housing and the steel frame structure securing the pin box. It was easier than I expected. Once past the steel frame, the area opens up. Grand Design actually insulates that area as it is directly below the bedroom. This is what the Momentum front frame looks like, 5 steel support. The reflection has 3.

[wjpatter]

Inside the front compartment, I routed the wires in split conduit around the top with the red power line going to an on/off battery switch then to the DC-DC Charger. The output is connected to the house battery via a 100 amp ANL fuse. The ground is common with the output and I connected that to a Ground/Chassis Terminal Block that I installed for the inverter. The input side looks lonely, only a single 4 gauge power line. The Renogy has a second input for solar Input. When I connect that, maybe it will look balanced.


Parts List:
DC-DC Charger: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Waterproof Box: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Circuit Breaker: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Fuse Holder: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
175 amp Connector: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1