Proof my RV plans....

[kbeefy]

Rough draft for the 1978 motorhome.

EDIT: Added multiple Transfer Switches and rerouted some 110. Added Switch to Sense wire of DC-DC Charger.

Edited plan:



Original:



Pardon my google drawing skills, alot of you have some amazing diagrams!
I know I cheaped out on a couple of the components, this is still by far the largest and most complex solar I've put together. I had to cut a few corners to still eat dinner.
Pretty much all will be new install except the inverter, Transfer switch, Generator, and both RV fuse/breaker panels.
Solar Panels are en route from Rich solar, Planning on running series/parallel through a breaker to a renogy 40A MPPT.
Vehicle alternator to a renogy 40A DC-DC charger. This will be set at half throttle until I upgrade the alternator and wiring.
Ampretime 200aH 12v lithium battery with a renogy shunt/displav for simple monitoring.
Battery Protect between the positive buss and 12v loads.
Existing Onan Generator, Heart Interface Inverter and 110v shore power are already wired to a pair of AC transfer switches.
I will be adding an AIMS 75A converter/charger for shore power and generator charging.

The only significant inverter load at this time is a microwave. I'm use to boondocking w/o 110v so having it available will be a learning experience for us.
I am only planning on using the AC on shore or generator power, I know I don't have the battery or inverter to handle that sort of load.

I haven't yet worked out all the wire size or lengths yet as I haven't settled on a location for everything yet.

Let me know if you see any problems or omissions, Thanks!

 

[John Frum]

Does your transfer switch support 3 inputs?
This inverter/charger supports 2 inputs https://samlexamerica.com/products/2200-watt-pure-sine-inverter-charger-evo-2212/#

 

[time2roll]

40 amp DC-DC charger might be a bit much for a 1978 MH alternator regardless of the wiring. I recommend 10 to 20 amps. The rating is the output... input can be 20% to 50% higher. The solar works while in transit (assuming they are on the roof) and the battery is modest so I don't see the reason to max it out.

Battery is a good start and may need to produce close to 200 amps depending on loads. Microwave alone will be close to 150 amps. Leave room for a second battery if needed. With max loads limited it may serve fine.

I assume someone will actually look at the monitor and make the BP65 unneeded. Can be added later if needed.

I would tend to skip the battery switch. With solar maintaining the battery it might be rare to use the switch. I lift a cable or the fuse. Could be 3+ years before any service is needed. Can be added later if there is a compelling need.

The 30 amp fuse from the panels is not needed as the panels can be shorted all day without issue or the fuse protecting anything. Same for the breaker but at least the breaker provides a switch.

 

[kbeefy]

Does your transfer switch support 3 inputs?
This inverter/charger supports 2 inputs https://samlexamerica.com/products/2200-watt-pure-sine-inverter-charger-evo-2212/#

There is actually a series of 2 transfer switches, I'm unsure how many inputs each will support. That is something I will have to investigate.

 

[kbeefy]

40 amp DC-DC charger might be a bit much for a 1978 MH alternator regardless of the wiring. I recommend 10 to 20 amps.

Battery is a good start and may need to produce close to 200 amps depending on loads. Microwave alone will be close to 150 amps. Leave room for a second battery if needed. With max loads limited it may serve fine.

I assume someone will actually look at the monitor and make the BP65 unneeded. Can be added later if needed.

I would tend to skip the battery switch.

The 30 amp fuse from the panels is not needed. Same for the breaker but at least the breaker provides a switch.

As I understand it the dc-dc charger can be limited to 20a. I already own this one so I'm using it because it was free. I may skip it all together with an onboard generator.

The battery switch and solar breaker are both for maintenance and isolating the battery when it's in storage. I'm don't believe this battery has a low temp cut-off, and would rather error on the safe side.

The bp65 was inexpensive and seemed like a good idea. With solar I've only drained my rv batteries when they are parked indoors, so it's probably irrelavant.

 

[John Frum]

You have configurable low voltage disconnect for the dc distribuition panel but not for the inverter.
That is another reason to use an inverter/charger.

 

[John Frum]

The bp65 was inexpensive and seemed like a good idea.

I think its a great idea.

 

[kbeefy]

You have configurable low voltage disconnect for the dc distribuition panel but not for the inverter.
That is another reason to use an inverter/charger.

Technically it is an inverter/charger, but it's pretty old. I haven't investigated it too much, but I don't anticipate using it often. This microwave will be the first 110 item we've ever taken camping. If my wife likes it I may have to invest in a newer one...

 

[John Frum]

Technically it is an inverter/charger, but it's pretty old. I haven't investigated it too much, but I don't anticipate using it often. This microwave will be the first 110 item we've ever taken camping. If my wife likes it I may have to invest in a newer one...

Typically inverter/chargers contain a built-in transfer switch and of course a charger.

 

[LB3]

Add a switch to your ac charger. As is right now you will be using your inverter to charge your battery which will make for a nice heater but won’t do much for your batteries State of charge.

 

[eXodus]

Not sure how your transfer switch is wired, there is lots of potential to mess that up.

In my RV i got a plug which goes into a generator outlet. So it's either grid or generator. It's manual, so you can wrongly connect things.

I got my inverter 3000w always powering the RV circuits. When I'm plugged into the grid or generator I'm just recharging.

It's less efficient but also less the break.

 

[kbeefy]

Not sure how your transfer switch is wired, there is lots of potential to mess that up.

The whole transfer switch portion is something I'm gonna have to work on.

 

[kbeefy]

Found a very basic writeup on Automatic Transfer switches.

Eaton ATS Description

I have 2 transfer switches onboard and wired up already, I'll map out the logic and put something together similar to this...



I'll need to get out my own cocktail napkin and map it out, I'm thinking Shore Power > Generator > Inverter.

 

[eXodus]

Found a very basic writeup on Automatic Transfer switches.

Eaton ATS Description

I have 2 transfer switches onboard and wired up already, I'll map out the logic and put something together similar to this...

View attachment 121665

I'll need to get out my own cocktail napkin and map it out, I'm thinking Shore Power > Generator > Inverter.

That sounds like a good idea.
If your load 1 is your RV power panel. You have an issue wiring your charger. You want to be able to recharge from shore and generator.
Put shore and gen at the same ATS (right), so you can tap into the wire between the two ATS for the charger. Never should the inverter be able to power the charger. That's a loop and will drain your battery rather quickly

 

[kbeefy]

Yeah, lb3 mentioned the same thing. I was working out in my head if there would be a sequence or leg to tie the charger into that would prevent it running off the inverter.

 

[LB3]

Yeah, lb3 mentioned the same thing. I was working out in my head if there would be a sequence or leg to tie the charger into that would prevent it running off the inverter.

If you end up with double transfer switches, you would put the charger between the two ATS’s depicted here:

 

[kbeefy]

Copy. I still need to inspect the existing ATS's and verify their function, but I think that's the simplest solution. A little embarrassed it wasn't obvious to me yesterday, I was trying to over-complicate it. K.I.S.S. I'm still learning about the ATS.

Cheers!

 

[camelCase]

One thing I would suggest is a manual on/off switch on the sense wire for the DC-DC charger. With a marginal charging system like yours, it would be a good idea to be able to turn if off in the case of stop and go or idling with lots of accessories turned on.

 

[kbeefy]

One thing I would suggest is a manual on/off switch on the sense wire for the DC-DC charger. With a marginal charging system like yours, it would be a good idea to be able to turn if off in the case of stop and go or idling with lots of accessories turned on.

Thanks, good idea.
I happen to have a 'Boost' switch (factory installed) on the dash that triggers a relay to combine the house and chassis batteries.
I will be disabling that function, and both the switch and the relay could very easily be repurposed as you suggest.
It does have a large case alternator on it already, I am still unsure of it's output but it could pretty easily be upgraded if desired.

At this point I'm leaning towards leaving out the DC-DC charger all together and not connecting the vehicle charging system to the House battery at all. On previous builds that was always my primary source of DC charging, but the 6k generator and 75A DC charger could render almost unnecessary. I already own the DC-DC charger, so I can always add it later if that proves not to be the case. I do like the availability of any additional charge source as a backup, but it's not like I'm building this for a 6 month trip into the outback or something.

 

[kbeefy]

Well, after a bit of research it seems that I likely have a 145A alternator installed, assuming it hasn't been replaced with something else.
There are several accounts of people getting over 50A to their house batteries, so I think I will go ahead and use the DC-DC charger, and also repurpose the dash switch as mentioned above.

I should start a tally of how many times my plans change before the system is complete.