newbie questions, solar/lithium in a 5th wheel, where to start?

JoeRV33

New Member
Joined
Jan 4, 2022
Messages
4
I am entirely new to solar and how electric works in my RV. I have a Grand Design 5th wheel.

I'd like to add lithium/inverter/solar to my 5th wheel and want to do so in stages.

Specifically I want to start by just replacing my lead acid batteries with a couple of 200amp hour SOC batteries and add an inverter. I do not currently have an inverter, but have a converter to convert shore power to DC.

I'm just starting my investigation on what I'll need and would love some pointers. I'd like to be able to power the entire RV off this system when not using 30amp shore power (TV, fridge, lights, phone/laptop chargers, etc..).

Initial questions:
1) I think I'm looking at a device such as a victron multi-plus. i.e. this would house my converter, inverter and charger all in one, is that correct? If so, would I simply replace the converter with this device and wire up the same way the converter was?
2) If I'm not understanding the victron multi-plus correctly, What all parts am I looking at for this phase? inverter, converter, charge controller, batteries, monitor, switch - what else?
3) What about my alternator charging from my truck, what handles that?
4) any links to typical RV diagrams for this type of setup would be great! Any other input would be welcome!
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
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Somewhere South of Denver
If you want to do it in stages, I recommend you put in solar first. You can do that without affecting the existing components. Once you change to LiFePO4 there's a whole lot of other changes that should be made. Just dropping in a LiFePO4 battery bank is only the beginning. You need to remove/replace the existing converter, handle the tow vehicle charge, account for cold weather, etc.

This is the Victron you probably want: https://www.victronenergy.com/inverters-chargers/multiplus-ii-2x-120v
 

Cajunwolf

Solar Addict
Joined
Sep 23, 2019
Messages
360
Location
Houston, the free state of Texas
I am entirely new to solar and how electric works in my RV. I have a Grand Design 5th wheel.

I'd like to add lithium/inverter/solar to my 5th wheel and want to do so in stages.

Specifically I want to start by just replacing my lead acid batteries with a couple of 200amp hour SOC batteries and add an inverter. I do not currently have an inverter, but have a converter to convert shore power to DC.

I'm just starting my investigation on what I'll need and would love some pointers. I'd like to be able to power the entire RV off this system when not using 30amp shore power (TV, fridge, lights, phone/laptop chargers, etc..).

Initial questions:
1) I think I'm looking at a device such as a victron multi-plus. i.e. this would house my converter, inverter and charger all in one, is that correct? If so, would I simply replace the converter with this device and wire up the same way the converter was?
2) If I'm not understanding the victron multi-plus correctly, What all parts am I looking at for this phase? inverter, converter, charge controller, batteries, monitor, switch - what else?
3) What about my alternator charging from my truck, what handles that?
4) any links to typical RV diagrams for this type of setup would be great! Any other input would be welcome!
How old is your trailer? I have a 1988 28-foot Mallard Class C and have that same type of power station I'm replacing; yeah, it needs to go. There are many as well as myself working on basically the same type of system. You will need to decide on 24 or 48-volts, 12-volts won't cut it. Read this thread, it has a schematic and a very educational conversation without starting a new one on the same system. Go to this link. 24-volt system thread
 

corn18

Village Idiot
Joined
Sep 9, 2021
Messages
428
How old is your trailer? I have a 1988 28-foot Mallard Class C and have that same type of power station I'm replacing; yeah, it needs to go. There are many as well as myself working on basically the same type of system. You will need to decide on 24 or 48-volts, 12-volts won't cut it. Read this thread, it has a schematic and a very educational conversation without starting a new one on the same system. Go to this link. 24-volt system thread
Why do you say 12V won’t cut it? The multiplus II 12/3000/12x2 is a great 12V solution for a 50A RV.
 

luckielab

Solar Enthusiast
Joined
Nov 26, 2020
Messages
81
I am entirely new to solar and how electric works in my RV. I have a Grand Design 5th wheel.

I'd like to add lithium/inverter/solar to my 5th wheel and want to do so in stages.

Specifically I want to start by just replacing my lead acid batteries with a couple of 200amp hour SOC batteries and add an inverter. I do not currently have an inverter, but have a converter to convert shore power to DC.

I'm just starting my investigation on what I'll need and would love some pointers. I'd like to be able to power the entire RV off this system when not using 30amp shore power (TV, fridge, lights, phone/laptop chargers, etc..).

Initial questions:
1) I think I'm looking at a device such as a victron multi-plus. i.e. this would house my converter, inverter and charger all in one, is that correct? If so, would I simply replace the converter with this device and wire up the same way the converter was?
2) If I'm not understanding the victron multi-plus correctly, What all parts am I looking at for this phase? inverter, converter, charge controller, batteries, monitor, switch - what else?
3) What about my alternator charging from my truck, what handles that?
4) any links to typical RV diagrams for this type of setup would be great! Any other input would be welcome!
This is not apples to apples for what you want to do but I think you’ll probably get a lot of good info from watching the Victron parts of this install.

 
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JoeRV33

New Member
Joined
Jan 4, 2022
Messages
4
How old is your trailer? I have a 1988 28-foot Mallard Class C and have that same type of power station I'm replacing; yeah, it needs to go. There are many as well as myself working on basically the same type of system. You will need to decide on 24 or 48-volts, 12-volts won't cut it. Read this thread, it has a schematic and a very educational conversation without starting a new one on the same system. Go to this link. 24-volt system thread
It's relatively new, 2017.
Why won't 12 volts cut it? Most everything in my rv is running 12v as I understand it.
 

JoeRV33

New Member
Joined
Jan 4, 2022
Messages
4
If you want to do it in stages, I recommend you put in solar first.
The reason I want to start with an inverter/lithium is that I'm simply looking to get a couple of days boondocking usage in the near term. i.e. if I could boondock for 48-72hrs between shore power charges, that's all I need right now. In a few years as I get closer to retirement, then longer boondocking stays will be more likely and solar will come into play, but right now, a couple of solid lithium batteries should easily handle my needs.
 

kenryan

Solar Addict
Joined
Jun 29, 2021
Messages
180
You could replace your converter with an "inverter/charger." An inverter/charger is a device that includes the inverter, the battery charger, and a relay that automatically switches you to shore power when plugged in. Something like the Magnum MS2000 might work for you. This would allow you to do what you want to do, charge up from shore power for a 2-3 day trip. Based on your stated loads (TV, fridge, lights, phone/laptop chargers, etc..) your 400 amp hour LiFePO battery will probably be sufficient. I really like Magnum inverters, and I always get the optional remote, which allows for monitoring the system and programming the charger.

For charging from your truck, you probably want to go with a DC-DC (also called b2b or battery to battery) charger. You don't want to connect directly to your truck alternator for a number of reasons. You will need to size the b2b charger based upon the size of your battery and the output of your alternator. Both the batteries and the alternator can be damaged by too much charging current.
 

Cajunwolf

Solar Addict
Joined
Sep 23, 2019
Messages
360
Location
Houston, the free state of Texas
Straight numbers for demonstration pur[poses only. No efficiency, power factors, etc.

2000 watt load:
@12-volts = 166 amps
@24-volts = 83 amps
@48 volts = 41.5 amps

3000 watt load:
@12-volts = 250 amps
@24-volts = 125 amps
@48-volts = 62.5 amps

Are you starting to see the picture? Now, if all you want to run are your standard 12-volt items with a low current draw and no long wiring runs, then 12-volts is fine. But, if you're going to run a whole plethora of things like airconditioning, microwaves, hair driers, multiple TVs, big refrigerators, or anything with a high current spike when switched on, then you might want to up your DC voltage. Your components, especially COPPER wiring, will be cheaper. Did you check out the thread I suggested?
 

corn18

Village Idiot
Joined
Sep 9, 2021
Messages
428
Straight numbers for demonstration pur[poses only. No efficiency, power factors, etc.

2000 watt load:
@12-volts = 166 amps
@24-volts = 83 amps
@48 volts = 41.5 amps

3000 watt load:
@12-volts = 250 amps
@24-volts = 125 amps
@48-volts = 62.5 amps

Are you starting to see the picture? Now, if all you want to run are your standard 12-volt items with a low current draw and no long wiring runs, then 12-volts is fine. But, if you're going to run a whole plethora of things like airconditioning, microwaves, hair driers, multiple TVs, big refrigerators, or anything with a high current spike when switched on, then you might want to up your DC voltage. Your components, especially COPPER wiring, will be cheaper. Did you check out the thread I suggested?

For a 30A single phase RV (which I think the OP might have), 24V is a great option. For 50A split phase, it is a terrible option.

I would rather have a Multiplus II 12/3000/120x2 running at 286A in my 50A RV than any 24V system out there currently. The thing is dirt simple for 50A RV folks and works. Sure, I gotta use 4/0 wire instead of 2/0, but that is a really small price to pay for what that MPII offers.

IMG_5045.jpg
 
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Cajunwolf

Solar Addict
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Sep 23, 2019
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360
Location
Houston, the free state of Texas
Hey, if you've got the bucks, why not. I'm just saying that when you get to loads of 2kw and above, 24-volt is more efficient with less heat. Victron works with 12/24/48, so that's not a problem, but I'm not a bells and whistles type, nor is my budget. I was just making suggestions from lessons learned, that's all.
 

Paul_R

Solar Enthusiast
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May 7, 2021
Messages
89
Location
Northern California
If you don't already have an inverter of any kind I would start with the Multiplus and I would get a pair of the SOK 24v 100ah batteries. Series connected 12v SOK batteries won't work because discharge current will be limited to 100a. Parallel connected 24v batteries will give you 200a discharge current. All you need is a Victron Orion 24/12/70 to feed your 12v system. In my case, the OEM WFCO converter/charger is simple to remove and replace with the Orion. With a 24v battery system your battery cables are much smaller and less expensive and you can double the size of your solar array (I suggest 24v panels in parallel).
 

CamoGreg

5 yr RV Fulltimer
Joined
Jun 18, 2020
Messages
156
Why do you say 12V won’t cut it? The multiplus II 12/3000/12x2 is a great 12V solution for a 50A RV.
Agree.
The Multiplus II 2x120 is tailor made for what the OP is looking to do.
That system is mostly already designed here.

It's nearly perfectly matched for adding a reasonable amount of panels to a 5th wheel roof.
Will it allow for full time off grid living? No. But for a boondocking 50amp 5th wheel It's probably to closest thing to a turnkey solution.
 

CamoGreg

5 yr RV Fulltimer
Joined
Jun 18, 2020
Messages
156
I have a 42' Montana also a 2017.
Nearly 2 years ago I started looking at doing the same as the OP. Read, read, read.
My situation as changed and planning to build a 48V system. But I'm not boondocking. Rather full-time living on property.
I don't need alternator charging and I have more real estate for panels.
Still going with Multiplus II. Only the 48/3000 version. Not nearly as easy to install since it doesn't have the 4 wire 50amp pass-through the 12/3000 does. Mine will have 2 MPL units in parallel.
Here's another GD where they installed a Multiplus II 12/3000
 

Butcher

Solar Enthusiast
Joined
Nov 14, 2021
Messages
69
@Cajunwolf, You are correct about raising the voltage to reduce the cable size/current draw, but if your inverter is close to the batteries, then then it really is not that big of a concern. The large current is mostly consumed by the inverter since most microwaves, AC, refrigerators, etc do not use 12v.

The further the batteries must be from the inverter, then the more a higher voltage system would be beneficial. I'm still designing and gathering parts for my set up, but I do not expect the battery to inverter run to be much more than a couple feet. If I was stuck with 10+ft, I certainly would look at my project differently.
 

AndyRonLI

Solar Enthusiast
Joined
Mar 13, 2021
Messages
110
It would be nice if they added an all in one version of that Multiplus (include the solar charge controller) at 12V with the 50amp pass through / transfer switch. The all in ones I see don't look like they are happy in 30amp mode, i.e. where L1 and L2 input are really the same leg of shore power. Though I could be misunderstanding what I am reading.
 
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Butcher

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Nov 14, 2021
Messages
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With having an 'all in one', what happens when that fails? Does it become 'all is none'? I would rather have individual components so when something fails, then it would be one component.

Something to think about.
 

Ampster

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Kenwood, California
With having an 'all in one', what happens when that fails? Does it become 'all is none'? I would rather have individual components so when something fails, then it would be one component.

Something to think about.
It all depends on where you are standing. I like the simplicity and cost of an All in One inverter compared with buying components. I have done both. Depending on which component fails the whole system could be down anyway.
 
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