Electrical System integration advice…

[Camjamcur]

Hey y’all! I own a 1991 Dodge B250 Roadtrek 190 versatile. I’m preparing to install solar, a battery, and an inverter into the existing electrical system. I’m very inexperienced, and this is my first project involving electrical work. I’ve been cramming as much info as possible in preparation for the install, and I’ve even illustrated a (very crude) diagram laying out the components and connections(attached file). I’m not certain if my setup is viable as I have designed it, and I’m looking for the more experienced folks on this forum to basically tear it apart and let me know what’s wrong with my plan so that I can do this correctly the first time. There are some connections in the diagram that I assume are possible, but I suspect there may be quite a bit that I have yet to account for, hence this “call for help”. Any and all advice/info is greatly appreciated, as well as any online resources that y'all think might be useful for this project of mine.

[booster]

Originally Posted by Camjamcur

Hey y’all! I own a 1991 Dodge B250 Roadtrek 190 versatile. I’m preparing to install solar, a battery, and an inverter into the existing electrical system. I’m very inexperienced, and this is my first project involving electrical work. I’ve been cramming as much info as possible in preparation for the install, and I’ve even illustrated a (very crude) diagram laying out the components and connections(attached file). I’m not certain if my setup is viable as I have designed it, and I’m looking for the more experienced folks on this forum to basically tear it apart and let me know what’s wrong with my plan so that I can do this correctly the first time. There are some connections in the diagram that I assume are possible, but I suspect there may be quite a bit that I have yet to account for, hence this “call for help”. Any and all advice/info is greatly appreciated, as well as any online resources that y'all think might be useful for this project of mine.

You must be going to use a solar controller with the second input for the alternator?


The AC output from the inverter would normally go to an automatic transfer switch before the breaker panel so it could select which AC to use, shore power or inverter.

[Camjamcur]

UPDATE: learned that I can disconnect the battery charger part of the power converter, eliminating the death loop workaround. Here is my new simplified plan. Feedback is appreciated!

[Camjamcur]

Also, the shore power connection will be plugged into the the inverter, eliminating the need for an AC input switch.

[booster]

Originally Posted by Camjamcur

Also, the shore power connection will be plugged into the the inverter, eliminating the need for an AC input switch.

I think you need to read up on the rules for neutral/ground bonding requirements and locations. They pretty much eliminate having the shore and inverter output tied directly together.


Your inverter should have automatic bonding when it is on, but may be permanently bonded so be sure to find out. Shore power is required to be bonded all the time. Both should not happen at the same time.


Your grounds are to the chassis and having things tied together can give you AC voltage on the body of the van which can be very harzardous.


Best to put in the auto transfer switch and be done with it so you have isolated neutrals for both sides.

[Camjamcur]

Thank you for your responses! After looking Into it, the inverter is internally bonded, if that means that the neutral and ground are connected internally. Is a ground wire from the negative battery terminal to the chassis the only ground connection I’d need to worry about?

[booster]

Originally Posted by Camjamcur

Thank you for your responses! After looking Into it, the inverter is internally bonded, if that means that the neutral and ground are connected internally. Is a ground wire from the negative battery terminal to the chassis the only ground connection I’d need to worry about?

If the inverter is internally bonded permanently which it sounds like and not auto bonded at use, that inverter cannot be connected directly to the same connections as shore power as you would have two neutral ground bonds in different places and one and only one are required for safety reasons. Keeping the shore power and inverter separated all the time is what the automatic transfer switch does as it switches both the power and ground leads on and and off for each source.

[@Michael]

1. I think you need to fuse the chassis battery lead.
2. I'm not understanding the 200A fuse on the 120V side of the inverter. Seems like the wrong value, and perhaps isn't necessary at all.
3. Best to have a disconnect on the solar side of the MPTT. Makes maintenance simpler.

[booster]

Originally Posted by @Michael

1. I think you need to fuse the chassis battery lead.
2. I'm not understanding the 200A fuse on the 120V side of the inverter. Seems like the wrong value, and perhaps isn't necessary at all.
3. Best to have a disconnect on the solar side of the MPTT. Makes maintenance simpler.

Yep, I agree, no fuse at all normally needed on the 110vac side as that is usually built in to the inverter and 2000 watts will not overload correctly sized wiring that includes surge anyway.


Probably would be good to fuse the chassis battery line, unless current limiting is built into the controller, which it might be.



It would be nice to see what all the components will be by brand and model so we could get a look at the voltages/profiles involved as it will be lithium and holding at high voltages isn't a great thing to do and if the voltages are badly mismatched some sources may not contribute very well. Same with the lithium battery as how the BMS handles things will be important in that system as it doesn't appear that there will be no independent charge controls in place so all control will be with the BMS itself. Personally, I don't care for having the BMS cycling all the time on what originally were probably designed to be safety protections, but apparently lots of manufacturers think it is OK now?

[Camjamcur]

This is my current iteration of the diagram. I did read your reply about the 200a on the 120v side, makes sense, I’ll take that one out. Can you explain what you mean by fusing the chassis?

[booster]

Originally Posted by Camjamcur

This is my current iteration of the diagram. I did read your reply about the 200a on the 120v side, makes sense, I’ll take that one out. Can you explain what you mean by fusing the chassis?

You are closing in on it. You do need a fuse in the solar output to the battery line and also on both ends of the cable from the alternator to the battery that is sized properly to what the alternator is capable of.


Be aware that the lithium battery is likely to absorb more amps than the alternator, and maybe the wiring, can handle so some kind of limiting will probably be needed. Most people use a b to b charger for that purpose. I would not even start the engine with the lithium battery in place until you get that worked out our have fusing in place to protect the wiring and alternator and you will probably blow them quickly. For 200 amps you are going to need to have a big alternator and big cable, but most limit to 40 or 80 amps with a b to b and have about a 6ga cable that can handle 80 amps. Many alternators can spare that much without overheating.

[@Michael]

Originally Posted by Camjamcur

I’ll take that one out. Can you explain what you mean by fusing the chassis?

For any current source that can produce enough current to overload the wire attached to that source, you fuse as close to the current source as possible. The chassis and lithium batteries are sources which can produce enough amps to smoke wires, therefore wires from those batteries must be fused close to those batteries.

You also might have to fuse any place where you step down in wire size. For example, if all sources feeding a bus bar are fused with 200A fuses, but you are taking power off that bus with 10ga wire, the source side of that 10ga wire should be fused to protect that wire against a possible 200A surge if it's accidently shorted out.

AFAIK - If you have at least 10ga. wire from the panels, your solar panels might not need to be fused. The max current from two 200W 12v panels will be around 25 amps, which can be carried by 10ga. wire, thus a fuse might be optional.

See: https://explorist.life/how-to-fuse-a...y-not-need-to/

In an earlier version, you had a combined MPPT/DC-DC controller/charger. That was a much better idea, as it eliminates the need for a combiner.

I would not cut into the wire between the alternator and battery. In most cases it will be better to take power from the battery terminal directly, properly fused of course.

[silverchris]

The other reason you probably want a battery to battery charger between the house and chassis systems is the voltage from the alternator may not be enough to fully charge your lithium batteries. I had mine connected through a battery isolator/disconnect, and the house batteries could never be fully charged by the engine

[phantomjock]

I believe if you are combining a house Lithium battery bank with a starting battery that is lead acid/sealed maintenance battery; the isolator is the wrong device. The reasonable choice is a battery to battery (DC2DC) charger.

The isolator still has a place with a house bank that is AGM or Gel and a "standard" starting battery and a "smart regulator."

Cheers - Jim

[Camjamcur]

Thanks for your reply! I’m looking at either a renogy 20a B2B or the renogy 50amppt/30aB2B combo unit. My main concern is the small alternator in the van may not be powerful enough for a 30a draw. What do you think about those options?

[Camjamcur]

Also, would I need to remove the existing isolator and relays, or could I just plug in the B2B somewhere in between the house battery and isolator? The alt is a 90a just fyi.

[booster]

Originally Posted by Camjamcur

Also, would I need to remove the existing isolator and relays, or could I just plug in the B2B somewhere in between the house battery and isolator? The alt is a 90a just fyi.

That is a tiny alternator for this kind of stuff as you will probably have only about 30 amps max to put to charging and that would be with not a lot running except the engine. AC on high fan, headlights, etc on and you would be even worse off.


Are you counting on solar for all your power needs?


If you add a b to b, removing the isolator is best because it would give you about a .7v drop just going through it and you don't have any voltage or power to waste. 20 amp b to b would be as big as you could go, I think.

[Camjamcur]

Alright, I'm gonna go with the 20a B2B. So the path will look like; alt→starter battery→B2B→positive/negative bus bars?

[Camjamcur]

Here's another question, the cords coming in and out of my transfer switch are all 3wire, but the switch only takes positive and negative inputs and outputs, no ground. what do I do with those 3 ground ends around the transfer switch?