Camper solar schematic, did I do this correctly

[bmklawt]

I know a tiny bit about electrical and a whole lot less about solar, that said, I drew this up from different layouts I saw on Victrons website for a possible install in my camper, could someone kindly look at this and tell if I got any of this right.
4 @ 12v 100 watt solar panels
2 @ 100amp Battle Born Batteries
Victron Multiplus Compact 12/2000/80-50
Victron MPPT Not sure what size I need yet
Victron BMV 712
Victron Cerbo GX
Victron GX Touch 50
Victron Smartshunt 500A
I was told by a Battle Born tech that I could hook up my existing power, 12awg, from the 7 pin trailer plug into the system for a minuscule charge from the tow vehicle and I would in no way harm and of the solar components, truck battery or alternator, is this true?
15 years ago I put a solar panel on the roof and ran a 12AWG wire to my control panel, that run is about 7' long, can I use his with this setup or do I need to up grade to 10AWG size wire that I would be using everywhere else.

Your help is greatly appreciated,

 

[FilterGuy]

Hooking the alternator directly to the system without a DC-DC charger is asking for problems.

 

[Ranger Rick]

Hooking the alternator directly to the system without a DC-DC charger is asking for problems.

Or, one can fully charge your LIFePO4 batteries before traveling, disconnect the charging wire in the 7-pin and get by. DC-DC charging systems are pricey and aren’t the only fix.

 

[mikefitz]

Direct charge from the alternator using cable resistance to limit charge current is a crude technique possible leading to cable, 7 pin plug, overheating and series fuse failure. Since there is no termination of charge volts battery over charge is possible.

 

[RVLiFe]

Why use 4 separate solar panels when you can get the same amount of power using only two or even one panel? Aren’t you limiting your available space right from the start? Also, not sure you need BB batteries and all the extra Cerbo gear for a small system but I’m certain BB will be happy to sell it to you.

 

[jimcalf]

The BB batteries are quite expensive, for no real benefit over other options, such as a single 200ah SOK. I'd buy the SOK and use the savings to buy a proper DC-DC charger to really take advantage of your alternator power. Keeping batteries charged is always a challenge with little roof space for solar. Your alternator can make a huge difference if you can maximize its power delivery without hurting it, but to do that, you need something like the Orion DC-DC chargers.

 

[HRTKD]

You have redundant equipment. Do this instead:
(Victron BMV 712 or Victron Smartshunt 500A)
and (Victron Cerbo GX and Victron GX Touch 50)

The Touch 50 makes the display of the BMV-712 unnecessary so I would go with
Victron Smartshunt 500A and Victron Cerbo GX and Victron GX Touch 50

The Cerbo GX gives you insight into the AC output of the inverter along with DC output of batteries as well as DC input from the MPPT. All on one screen.

I had the BMV-712 first and used it for 20 months. I just added the Cerbo GX and Touch 50. I'll keep the display of the BMV-712 (some people hide it the entire display behind a wall or compartment) just because I already have it.

 

[jbird526]

You failed to mention the size of your camper, specifically the roof dimensions. What obstacles are there to adding solar panels eg: roof fans, ac units, tv antennas? That will help on decisions as to panel size, shape and numbers. You may be able to use 100, 200 or 400watt panels depending on your limitations. Grab a tape measurer and start playing Tetris.

Also as mentioned the SOK or Amperetime may be Battleborn alternates. The Cerbo while nice could be overkill and the money used for an Orion DC to DC and a Lynx Distributor instead of the cheaper busbars. Maybe add the Cerbo later if desired.

 

[HRTKD]

@bmklawt , are you sure you want the 12/2000 inverter? The output is only 1600 watts. That is just a few more watts than the microwave in my RV pulls.

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-2000VA-120V-EN.pdf

Regarding the DC-DC charger to get charge from the two vehicle, this is not a simple topic. Lets say you simply install the DC-DC charger inside the RV where the cables from the tongue come in. That's good for your LiFePO4 batteries. It's really bad for the trailer breakaway system, which requires a connection to a battery bank to work. The DC-DC charger is a one way power supply. It will not allow power to go from the LiFePO4 battery bank to the trailer breakaway system. You'll need to address that critical issue if you put in a DC-DC charger.

For safety, I would go with the BB recommendation of connecting the LiFePO4 batteries just like the old batteries. It's not the ideal charge profile for your LiFePO4 battery bank. If you're good at tracing wires then you can take care of getting power to the trailer breakaway system.

 

[jbird526]

Regarding the DC-DC charger to get charge from the two vehicle, this is not a simple topic. Lets say you simply install the DC-DC charger inside the RV where the cables from the tongue come in. That's good for your LiFePO4 batteries. It's really bad for the trailer breakaway system, which requires a connection to a battery bank to work. The DC-DC charger is a one way power supply. It will not allow power to go from the LiFePO4 battery bank to the trailer breakaway system. You'll need to address that critical issue if you put in a DC-DC charger.

Not sure I understand where you are thinking the DC to DC will be going in this scenario. Are you saying putting in the DC to DC from the 12 volt pin going into the trailer?

Wouldn't it be safer, and more expensive, to run 4awg cables straight from the battery, with a fuse, to an Anderson connector at the back of the tow vehicle. Then from the Anderson, into the trailer to a DC to DC which then charges the LFP battery bank.

I say 4awg assuming an Orion 30amp isolated unit and based on the voltage drop of 3%.

 

[HRTKD]

Not sure I understand where you are thinking the DC to DC will be going in this scenario. Are you saying putting in the DC to DC from the 12 volt pin going into the trailer?

Wouldn't it be safer, and more expensive, to run 4awg cables straight from the battery, with a fuse, to an Anderson connector at the back of the tow vehicle. Then from the Anderson, into the trailer to a DC to DC which then charges the LFP battery bank.

I say 4awg assuming an Orion 30amp isolated unit and based on the voltage drop of 3%.

View attachment 86794

That's a great alternative to using the charge from the 7 pin, but you haven't address the need to energize the trailer breakaway system which requires a battery. Most RV owners aren't likely to go to that length. Running heavier gauge wire from the engine compartment to the hitch, then from the hitch to the inside of the trailer isn't for folks that are typically found camping only in campgrounds with hookups. I may be slighting a lot of RV owners, but many of them wouldn't put in that much effort.

Assume this is how the RV's electrical system looked when it came from the factory.


If you were to wire it up right, without running a separate set of cables (bypassing the 7-pin) it would look like this.



With the above diagram, the trailer breakaway system will still work, the LiFePO4 battery gets the right charge profile and everybody is happy. Happy as long as they're comfortable with getting only about 18 amps out of the DC-DC charger.

 

[bmklawt]

I have a 25' Airstream and only have enough room for 4, 100 watt solar panels, I choose Renogy solar panel that are 21" X 43", that's what will fit on my roof without the solar panel overhanging the curved part of the roof. I do not want to run a new line from the truck battery to where the batteries will be in the camper, running a 4awg wire from the battery to the back of the truck wouldn't be so bad but from the tongue to the back of the camper would be a pain and just not worth it to me. I just though if I could use the existing power from the 7 pin trailer plug I would, realizing it would only amount to a minuscule charge going to the camper batteries. Talked to a different tech at Battle Born today, he also assured me hooking up my power from the 7 pin trailer plug to the camper batteries would not harm anything, both guys said this is a myth Battle Born has been trying to dispel for some time. I originally drew up my plans with a Orion-Tr Smart 12/12-18 and see they even have a 12/12-9 and would probably use one of those for piece of mind, I just can nail down documentation that says that would actually charge the batteries and protect the truck battery and alternator.
What does a Lynxs distributor do for me? as far as I could tell it looks like a positive and negative bus bar that has an LED on it that tells me when a fuse is blown, I don't all this stuff is new to me.
I can camp now for about 4 days with the current lead acid battery, using the furnace, fridge and hot water, all are propane with 12 controls and being super stingy with the lights, I just want to be able to use the lights watch some TV and maybe reheat my dinner in the microwave and it would be nice if coffee was ready in the morning instead of having to boil water on the stove. I have a Honda EU2200i for the air conditioning, my wife and I boondock it whenever possible.

New drawing attached:

 

[bmklawt]

Never thought about the breakaway not working, could I not address that buy adding a breakaway battery to the tongue.

 

[HRTKD]

Never thought about the breakaway not working, could I not address that buy adding a breakaway battery to the tongue.

Yes! That's what I did. I have two distinct and separate 12 volt systems in my trailer. The small, lead acid, battery on the tongue is for the breakaway brakes as well as the starter battery for the generator. It gets charged by the 7-pin circuit as well as a 150 watt solar panel.

 

[jbird526]

What does a Lynxs distributor do for me? as far as I could tell it looks like a positive and negative bus bar that has an LED on it that tells me when a fuse is blown, I don't all this stuff is new to me.

The Lynxs is just as you stated, a positive and negative bus bar. It just makes things tidy, although quicker and more expensive than putting together a bunch of Blue Sea ANL fuse holders. DO NOT buy any fuse holders that are lesser than ones from Blue Sea or equivalent. Also if you purchase ANL fuses don't buy the ones on eBay that are audio fuses, they are of lower quality. Probably not an issue but an Airstream is not a cheap piece to replace. There are some items you should not skimp on quality. You are looking at Victron components so you obviously are looking at tier one components.

Wasn't thinking that your house batteries may also be in the back of your Airstream so yes that is a good distance to run additional wiring. Its all about how much additional charge you need and sounds like 18 or 9 amps may be enough, so the diagram from @HRTKD looks like a good and SAFE solution.

 

[STW]

I just completed an install with 4x100 hqst panels (same as renogy) using a Victron 100/30. I have a pair of GC2 batteries. I am seeing over 20a charge rate most of the day (southwest).

Based on your comments this might be all you need.