Choosing the dummy method instead of the right way, solar + alternator charging

[TommyinMiami]

I usually do things the best way I can BUT with this build, I'm doing it the dumdum way. Think it's ok?

I'm partially disabled and I need a way to help me with loading and unloading the boat from the trailer. I am installing an electric winch and an electric boat jack on my boat trailer. Also work flood lights, and a 110 outlet for tools etc.

The plan:
I already installed a dry box on the front of the trailer. It'll house a 100Ah LI battery to power everything.

The setup:
The battery will charge in 2 ways. I'll be getting 1 Amp from solar to keep her topped off and after I use powertools and works light etc. On days I use the boat the, trailer battery will be getting a charge from my towing vehicle. I have a 7 way hookup and can draw 30 amps from there, it has a 40 Amp fuse installed.
So this is where I chose not the best method. Instead of running a 20A DC-DC charger or an Xantrex Echo 15A charger, which is like a battery combiner relay type device, I suppose, Well anyway, the method I chose to do is run my tow vehicles 40A fused 12v aux wire to power a 1,000W inverter, then plug in a 10A or 20A battery charger into that, which will charge the trailer battery when it's in tow. I'll run a relay to the ignition to make sure it turns off when my tow vehicle turns off. I went this route because I have too many inverters and charges and no extra spare DC-DC chargers. I have a Renogy 40A DC-DC charger but that's too big.

So think this is ok, good to go? Or I should rethink this and do it the right way? It's obviously not the most efficient to do from DC-AC-DC but I don't think that matters much because my truck's alternator will gladly make an extra 20Amps.

The little details:
Inverter is Gowise Power (Same as Greiner)1000W cont. 2,000W surge
Battery Charger is waterproof NOCO on board charger
Tow vehicle From Alternator through 7 way tow harness to trailer battery is 10ga
Battery to Inverter wire - 6ga with a 100A fuse (MRBF terminal fuse)
Adding a 30A fuse between 20A charger and trailer battery.
The winch and electric jack will run to the battery on the trailer, all fused also.
All wiring is Ancor tinned copper marine wiring.

Questions:
The inverter has a ground plug on it... Do I wire that to the trailer chassis? and the negative at the inverter to the trailer battery?
Do I need to run a ground wire from the trailer battery neg terminal to the chassis of the trailer also?
The tow vehicle's harness has a ground wire that I've already attached to the trailer's wire that goes to the chassis.
Would you make any changes? Should I go bigger than 6ga 100A fuse on the wire from inverter to battery. I don't have any tools that are over 1000 watts and I don't think the inverter would even run anything over 1,000 but do you ever fuse and gauge to the surge watts? I fused at 1,200 watts I assume and 6ga can handle a little more I believe.

Thanks for any feedback.

 

[timselectric]

It should work. But as you said, it wouldn't be the most efficient.

 

[pollenface]

You don't need to ground the inverter. The fuse should be 125% of the load. 100A sounds okay, but you could go to 125A by adding 15% for inverter efficiency loss. 6guage cable should be fine, obviously wanting to keep cable lengths as short as possible to minimize voltage drop.

I wouldn't fuse for surge watts, wires can handle big amps for a split second, it is sustained heavy load or a short which creates heat.

 

[timselectric]

I missed the whole question section.

I'm confused about the location of the inverter and charger. If on the tow vehicle, then everything makes sense. But not if it's on the trailer.
Otherwise I agree with the answers above.

 

[TommyinMiami]

Thank you guys much appreciated! So I will not ground the inverter to the trailer either and I'll bump it up to 125A fuse. I use terminal fuses. Im like obsessed with them. I have them on every single battery. In my mind there's no closer you can get than to right on the battery. I have the doubles and the singles. They can be a tad pricey but I use them for anything between 30-300A. I tried finding out in the past what kind of initial surges they will allow but couldn't find out exactly how fast or slow they are. I even run a 250A terminal fuse for my outboards even though most don't fuse a starter. I started at 300A and it never blew, I moved down to 250A and am still good but I have yet to start with a semi-dead battery. I guess I'll find out eventually if my starter surges over 250A when its voltage is low, and if that will pop it or not. Hope its slow enough to not act on a milisecond of Amps over.

Tim,
My tuck (the tow vehicle) only has a 7 wire hookup in the back.
The trailer plugs into the truck. This trailer then takes the power from my truck to power the trailer lights, the trailers brakes, and it will take up to 40 amps on a separate wire called aux wire, and use that to charge a 100Ah battery and that battery will power the inverter. The battery, charger, and inverter are all mounted inside a water-tight box at the front of the trailer, only about 6ft back from the truck and hook up connection. A wire leaves the box and powers my winch, which is about 3 ft up from the box, and a jack, which is about 3 ft front of the box. I have a waterproof outlet on the box also that I can plug into any time I want to run some light-duty tools like my tire inflator.

 

[timselectric]

Maybe I misunderstood something.
I thought that you were going to plug the charger into the inverter to charge the trailer battery.
But if the inverter is being fed from the battery that is being charged. This wouldn't make sense.

 

[sunsurfer]

Seems like a lot of power going through that 7 pin plug. If you don't need the full capacity of the battery for one trip, you could go a lower power option. DC-DC that is setup for that batteries chemistry would be best. Victron makes nice stuff. Also, low temp charge issues need to be considered.

 

[TommyinMiami]

Maybe I misunderstood something.
I thought that you were going to plug the charger into the inverter to charge the trailer battery.
But if the inverter is being fed from the battery that is being charged. This wouldn't make sense.

Sorry I left out a couple words: my trucks aux wire will power ONLY the charger, the 100Ah trailer battery will power the inverter.

Sunsurfer - My truck has the highest rating for an aux wire. 40A and its a 10ga wire that goes wight to the side nut on the battery, that fuse is called STUD 2, I lucked out with it being so high, I've seen other aux wires be 10 or 15 Amps only.

Today I looked around 1 last time for either an Echo 15A charger or a Victron 10-25A Charger and I found a warehouse deal on a Renogy 20A DC-DC charger for $80. So I pulled the trigger. I was aware of the extra heat for the inverter charger method and was using a NOCO sealed waterproof charger to mitigate the extra heat other chargers make but now I don't have to sweat it at all. I don't know how long the Renogy DC charger will last in the humidity but I'll find out soon I suppose.

 

[timselectric]

Looks like you have it all worked out, now.
Sounds like a fun project.