safety check on first 30A RV install

[xebra]

Greetings!!
New to the forum but not new to electrons flowing around. I've been reading, researching and asking question of knowledgeable folks and have put together a system I'd like to have someone poke at to see if it's safe or not.
I'm going to use MRBF fuses at each battery, but not certain if it should be 125 Amp or not.
I've attached a second draft of the project. Let me know what should be improved if anything.
THANKS for having a look!

 

[xebra]

I see that I left out the battery disconnect switch that is already in the rig.
I've updated the drawing to reflect the switch

 

[HRTKD]

1. You don't need a combiner for the panels. Run the panels in series. Your solar charge controller can handle 100 PV input volts. In fact, when you add two more panels, put those in series too. It will be just under 80 volts which is still well within what that solar charge controller can handle. If shading is expected to be a significant issue then put the first two panels in series, the second two panels in series and use a 2-into-1 MC4 Y cable to parallel those two strings. The amps will still be well under what the MC4 connectors are rated for (30 amps).
2. Use a dual-pole circuit breaker so that you disconnect both PV legs at the same time. Make sure it is a DC breaker. I prefer breakers from Midnite Solar. You don't need a fuse between panels unless you plan to run 3 or more panels in parallel.
3. I like to put a breaker between the solar charge controller and the Lynx Distributor. That allows you to isolate the solar charge controller (for maintenance) without having to pull a fuse. But pulling a fuse is also an acceptable way to isolate the solar charge controller.
4. If you're going to install a Victron charger, why keep the existing RV converter? You'll need a switch on the existing converter so that it doesn't run when the inverter is active.
5. Why 2/0 going into the Lynx Distributor from the batteries but 4/0 to the inverter? Is the distance to the inverter significantly longer?
6. Which battery disconnect are you going to use? Not all disconnects can handle the 166+ amps that the inverter can pull.
7. I don't remember what your loads were going to be. I have a 2400 watt inverter and there are times I wish it was a bit bigger so that I could run two heavy load items at the same time (microwave/120v water heater, air conditioner/coffee pot, etc).

 

[xebra]

Thanks for the reply!
Thanks for the comments and suggestions, they will make a better system
1. Originally, I was thinking the panels would be in series, two on the right front of the rig, close to the edge and then two in series on the left side, and then connect in parallel before going to the SCC. The thinking was that if there was shading on one side of the rig, that the may not be shading on the other and the output voltage from at least two of the panel would be at least above 17 V for SOME charging to happen. Does that make sense??

2. Good idea, I'll see what I can find for dual pole DC breakers.

3. A breaker is a good idea. I've used a fuse in a previous rig, and it was a pain to disengage.

4. The thought is that the converter (that I just bought to charge Lithium's) would only turn on when the shore power is connected and not in the circuit when the inverter is on. I would rewire the auto xfer switch so that the power would be applied to the converter only when on shore power. The Victron charger is there only because of voltage drops observed from converter to batteries that the charger will overcome. The Victron charger would be connected when the generator is attached or I ran an extension cord from another outlet to the charger. Plus I spent the money on the converter and won't get the same money back if I sell it.

5. Good point. I won't be a significant distance to the inverter. I have been puzzling over the correct amperage fuse to put in place to the converter though.

6. At the moment I'm planning on using a Blue Seas mini 6010 that specs at 300 amps. I'm all for other recommendations, because that was one of the first I found.

7. The AC loads will be less than 20 minutes a day microwave use and less than 10 minutes a day coffee maker. That's about it. everything else either can run on DC, or has a smaller inverter directly to them, like TV/DVD/Sound bar is on one 700W inverter that can be turned off. The sleep number bed controller is on a 300W inverter that can be turned off. I downloaded an energy audit excel form and put in watts and period of use. The result of lights and AC use was 2 days of useable power in the batteries if I didn't charge at all. Until I can budget for the solar panels, I'll be charging with a 2000W Honda generator periodically on days I don't have shore power.

Thanks again for ideas and comments. I'm hoping the information I put as a response doesn't look like I'm arguing with you, only explaining my thoughts behind what I put in the drawing.

It looks like with some minor changes to components and wire gauges, the system might work, safely?

 

[HRTKD]

It looks like with some minor changes to components and wire gauges, the system might work, safely?

I think you're on the right track.

 

[xebra]

Well, I had some more consideration about simplifying the system and came up with the one attached. I have a sense I'm missing something, maybe a Lynx power-in component?
The only thing I'm a little concerned about is that the batteries (Wattcycle) have a built in BMS and the Multiplus wants to talk to the BMS. Not gonna happen with the Wattcycle. I know the Victron software can be modified. If anyone has experience with this type of software modification and how well it works for you, let me know.
Thanks for reviewing.

 

[HRTKD]

Communication between the LiFePO₄ BMS and the Multiplus is optional and requires a Cerbo GX I believe. That communication is called "closed loop". I'm using "open loop", no communication. With multiple batteries, one of the BMS needs to function as the master BMS. I don't know if the Wattcycle can do that or not.

With a Multiplus in the system, the existing RV converter would become mostly redundant. The Multiplus can exceed the battery charging amps that the converter can provide. Keep it in the system if you want, but I suspect it will remain off (at the breaker) until you sell the unit.

You re-used the dual-pole breaker image on the circuit from the solar charge controller to the rest of the system. It's on only one leg and that's the correct representation since it would be a single-pole breaker. However, the circuit would be attached to your busbar, not to the Multiplus. You're out of studs on your busbar and it wouldn't do to attach the solar charge controller cables to it since it would be on the wrong side of the shunt.

So now you're looking at a Lynx Power In for the batteries. That's a nice solution and could be more compact than using two standalone busbars. Add a Lynx Distributor and that's where your Multiplus, solar charge controller and the trailer 12 volt system would connect.

In my first RV system I used a pair of Blue Seas PowerBar 1000. Those provide a ton of connecting points but are monsters which take up a lot of room. The Lynx Distributor I used in my current system doesn't provide as many connecting points, but it takes up less room.

If you're going to use the Power In and Distributor, consider the Lynx Shunt. It's not as nice to see from within the VictronConnect app as the SmartShunt or the BMV-712. To see the battery state of charge with the Lynx Shunt you need to add the Cerbo GX. If you're not going to add the Cerbo GX then I would definitely not add the Lynx Shunt. Which shunt are you planning to use? SmartShunt of BMV-712?

Take a look at the Victron Battery Switch. It's a bit more compact than the Blue Seas switch. I directly connected my VBS to the Lynx Shunt rather than running a cable between the switch and the shunt. One less connection and it's a bit more compact in the compartment. In your case, the switch would be placed between the Power In and the Distributor. You may be able to do the same thing with the Blue Seas switch. Either way, check the size of the stud on the switch and order your Victron components to match (8mm or 10mm holes). I ordered mine as 8mm and I had to drill out the hole to make it work.

My OEM battery disconnect is a switch on the wall panel. It trips a relay near the Main Distribution Panel. I've given some consideration to bypassing the switch/relay because when I walk into the camper in the dark I hit that switch instead of the adjacent light switch, turning off 12 volt power to the camper.

 

[xebra]

There's a lot to digest here, I'll need to read a couple of times. Thanks for the detailed reply!
BTW, you are correct, I only reused the image of the CB from the SCC to Multiplus in that diagram. I planned on a single pole.
I see I'll need to replace the shunt that is in the rig now it's only rated to 100A. The Victron BMV-712 is a consideration, it might fit in the same hole in the wall as my current one..
This project is rapidly becoming more expensive that I had first considered.

 

[xebra]

OK, now that I've had some time to work through the connections I have another question.

WHAT IF, when using a Lynx Power-in, I used the two large connections that stick out to go to the Multiplus and used the two connections at the other end of the power-in that are under the cover, for the SCC connection? ( Fuses / CB in appropriate places)
You mentioned getting a distributor between the power-in and the multiplus to connect the trailer DC to the batteries I presume that it's not appropriate to attach the connection to the trailer on to the same lugs in the Multiplus that go to the batteries?
I mention this to try to save the cost (and space) of the Lynx distributor.

 

[HRTKD]

Yes, you can use the connections on either end of the Power In to do what you want. They're designed to connect to another Lynx component, but there are many of us, including myself, that are using those connections to go to something other than a Lynx component.

Usually there are a number of smaller wires that need access to power. You can hang a small set of busbars off of one of the ends of the Lynx for this.

These projects often have "scope creep". They start off small but grow as you get deeper into the project.

 

[xebra]

I've concluded that one of the kits from explorist life will work for my needs, just gotta pony up the cash.
Before I purchase I have a question about programming the Multiplus. If I get the Bluetooth dongle, do I still need the USB adapter MK3-USB-C to program it? I'm hoping the bluetooth connection will allow me to program it and save the money by not buying the USB adapter.
I have the Explore 30A towable lite in my cart at Explorist, without most of the wire, because I can get the lengths I need locally.

 

[xebra]

I think I've found my answer:
Victron documentation confirms that the Bluetooth dongle and MK3-USB-C serve different purposes: Bluetooth for monitoring/control, MK3-USB-C for configuration/programming.