Simple design for using an inverter to power your 50 amp service RV using a $30 Change over switch

[Scott Helmann]

I just thought I would put this info out as this change over switch (Available on Amazon) allows you to easily power your RV from shore/generator power or from your solar /battery/ power inverter setup. It might be something Will might like to do a video on at some point as it solves a myriad of problems of switching from different power sources in an RV and this particular design will keep you from every worrying about damaging your inverter, or from having to turn off your AC to DC battery charger converter.

-Scott

Change over Switch: https://www.amazon.com/gp/product/B075GVLV2V/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

 

[snoobler]

The moment I had to turn my head sideways and squint was the moment before I gave up.

 

[Scott Helmann]

Let me try again with a better photo with higher resolution (6meg)

 

[HaldorEE]

My multiplus has automatic switch-over and even has a relay to ground the neutral when shore power is not connected.

I can see the value of that switch if using an inverter by itself.

 

[jvbutter01]

Thanks scott for your layout of the switch. My issue is remembering to switch over. I tend to not always remember things. I'm thinking automatic is better...
@HaldorEE what model do you use?

 

[Zil]

Why not use a quality switch? Blue Sea as an example; https://www.bluesea.com/products/category/7/38/Switches/Rotary_Switches

 

[HaldorEE]

Thanks scott for your layout of the switch. My issue is remembering to switch over. I tend to not always remember things. I'm thinking automatic is better...
@HaldorEE what model do you use?

It is built into my Victron Multiplus.

You could accomplish the same thing with a 3 pole, 2 position relay. The contacts of the relay will need to be rated for 50A (this will not be a cheap relay).

Connect the hot, neutral and ground wires of your loads to the common contacts of the relay.

Connect the inverter output to the normally closed contacts of the relay. Bond the AC neutral and ground together on the normally closed contacts of the relay.

Connect shore power input to the normally open contacts of the relay and the coil of the relay.

If shore power is not connected, the relay is not energized and the inverter output will be connected to your loads. The AC neutral and ground will be bonded together by the relay. The shore power input will be completely disconnected from your inverter and load wiring.

If shore is connected, the relay is energized and the inverter will be disconnected from your loads. The shore power will be connected to your loads. The AC neutral and ground will not be bonded together in your system.

This system will never bond shore power neutral and ground together (which would violate code requirements).

I will sketch up a schematic for this when I get a chance.

You could add a relay to automatically turn the inverter on and off as the shore power is powered up and down if you want.

 

[HaldorEE]

The relay I specified may not exist. I can find 3PST 50A relays and 2P2T relays but no 3P2T relays rated for 50A.

If that case I would use a 50A 2P2T relay for hot and neutral wires plus a 50A SPDT relay for the grounds.

 

[jvbutter01]

It is built into my Victron Multiplus.

You could accomplish the same thing with a 3 pole, 2 position relay. The contacts of the relay will need to be rated for 50A (this will not be a cheap relay).

I will sketch up a schematic for this when I get a chance.

Nope, I was looking at the Victron units also, with built in switching.. I will pay the money to get a "Hands Off" system.

 

[HaldorEE]

Found a relay that should work. Only $250

https://www.mouser.com/ProductDetail/TE-Connectivity-AMP/ACC533U20?qs=G2joM5IiDEvGRtZ7OhrLqQ%3D%3D

 

[HaldorEE]

Nope, I was looking at the Victron units also, with built in switching.. I will pay the money to get a "Hands Off" system.

That was my choice also.

Once I started figuring out what it is going to cost to add the features I wanted, I realized that the Multiplus was the least expensive way to get there.

 

[HaldorEE]

Now THATS the way to do it. Just like Dr. Frankenstein.

 

[HRTKD]

Now THATS the way to do it. Just like Dr. Frankenstein.

View attachment 23427

I can't figure out how you operate that. The instructions are in Chinese!

FWIW, Jared in the All About RV's channel on YouTube just put out a video on this topic.

 

[TedH]

I just thought I would put this info out as this change over switch (Available on Amazon) allows you to easily power your RV from shore/generator power or from your solar /battery/ power inverter setup. It might be something Will might like to do a video on at some point as it solves a myriad of problems of switching from different power sources in an RV and this particular design will keep you from every worrying about damaging your inverter, or from having to turn off your AC to DC battery charger converter.

-Scott

Change over Switch: https://www.amazon.com/gp/product/B075GVLV2V/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

I currently have two simple switches to choose:

1. Between park and generator. This is a lever switch similar to residential. Up-Shore. Down-Generator
2. Between shore/gen and inverter. This is a $50, 64amp rotary switch. 1 = shore/gen. 2 = inverter
   1. This IS the switch you are considering. I have mine in a metal enclosure. 50amp in on 1 and 30amp in on 2. It runs 24x7, 365. No failure. Solid and reasonable price.

The rotary switch is in use because my inverter is 30amp and shore/gen are 50amp. It can't be used as an automatic transfer switch since I would need to run all 50amps thru the input and output AC connections. That is why I just spent $1,600 for a 6000watt, 240in/120-240out inverter. I will have automatic transfer between the inverter and AC in. Also, I can use it to charge my Lifepo4 bank when on AC power. Plus, down the road, I can convert my generator to have automatic start using the inverter. I have an Aims Power product.

 

[HaldorEE]

I currently have two simple switches to choose:

1. Between park and generator. This is a lever switch similar to residential. Up-Shore. Down-Generator
2. Between shore/gen and inverter. This is a $50, 64amp rotary switch. 1 = shore/gen. 2 = inverter

The rotary switch is in use because my inverter is 30amp and shore/gen are 50amp. It can't be used as an automatic transfer switch since I would need to run all 50amps thru the input and output AC connections. That is why I just spent $1,600 for a 6000watt, 240in/120-240out inverter. I will have automatic transfer between the inverter and AC in. Also, I can use it to charge my Lifepo4 bank when on AC power. Plus, down the road, I can convert my generator to have automatic start using the inverter. I have an Aims Power product.

The Samlex Evo and Victron Quatro both handle the Shore Power/Generator/Inverter dance. Magnum probably has a model with both shore and generator power. I just haven't researched Magnum. I am not at that level of complexity.

Which AIMS are you getting?

 

[TedH]

The Samlex Evo and Victron Quatro both handle the Shore Power/Generator/Inverter dance. I am not at that level of complexity. Which AIMS are you getting?

It is the PICOGLF60W24V240VS: https://www.amazon.com/gp/product/B00HHNCQ00/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

It has all of the features of my 3000watt, 24v inverter (120AC In/120 AC Out) but DOUBLE capacity (6000watt, 18000 max, 240AC In, 120/240 AC Out).

I am adding my Solar array, charge controller (also Aims) and a bank of Lifepo4 24v, 200ah batteries (2, 24v, 100ah packs in parallel) to the mix. Previously, the 3000watt inverter's only purpose was to invert the 24v power from the 8D batteries on my bus (MCI 102AW3 bus conversion).

 

[HaldorEE]

I looked at lower power AIMS inverters. The sum total of the programability consisted of being able to select between different battery chemistry. As I recall the low voltage disconnect on the lithium setting was a lot lower than I was willing to let my batteries discharge to.

What is this on the inverter you picked?

 

[TedH]

I looked at lower power AIMS inverters. The sum total of the programmability consisted of being able to select between different battery chemistry. As I recall the low voltage disconnect on the lithium setting was a lot lower than I was willing to let my batteries discharge to.

On my 3000watt and the 6000watt inverter, I can select 10 or 10.5vdc low voltage disconnect. I recall that 10 (x 2 for my 24v system) is the recommended low voltage disconnect from Will P. There are five different DIP switches. One other that I recall is to choose grid or battery priority and several others. It has integrated battery temp sensor (BTS) low temp cut-off (both my 3000w and 6000w units). This is in addition to the programmability of my Aims Solar Charge Controller that also has BTS and User charging settings that I can adjust in 1/10 DCV.

I have triple low/high voltage, temp and other settings across the BMS's, Solar Charge Controller and Inverter. I feel safe.

The only beef I have with Aims product is the LACK of software to take the RS485 output and display/record. I hear it is coming from third parties. I am willing to wait as I have added a pair of $30 monitors and a Victron app.

 

[HaldorEE]

I looked it up, same as the 2000W version I was considering.

• Nominal Input Voltage: 24.0Vdc
• Low Battery Alarm: 21.0Vdc-22.0Vdc
• Low battery Trip: 20.0Vdc-21.0Vdc
• High Voltage Alarm: 32.0Vdc
• Low battery Voltage Restart: 26.6Vdc
• Idle Consumption: 76.8 Watts
• Idle Consumption in Power Saver Mode: 29 Watts

20V low voltage disconnect is a lead acid battery setting. That is why I decided to skip this one and kept looking.

Get the remote control option, so you can use a battery monitor to turn off the inverter when the battery gets too drained. You don't want to be hammering into the BMS every time you run the battery down.

The battery chemistry option only controls the charging function, the discharge function is the same across the board.

 

[TedH]

I looked it up, same as the 2000W version I was considering.

• Nominal Input Voltage: 24.0Vdc
• Low Battery Alarm: 21.0Vdc-22.0Vdc
• Low battery Trip: 20.0Vdc-21.0Vdc
• High Voltage Alarm: 32.0Vdc
• Low battery Voltage Restart: 26.6Vdc
• Idle Consumption: 76.8 Watts
• Idle Consumption in Power Saver Mode: 29 Watts

20V low voltage disconnect is a lead acid battery setting.

20V low voltage disconnect MINIMUM also applies for 24v LifePO4.