A/B switch to switch between AC shore power and DC house battery?

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sprinterlivingkc

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Campervan setup with two 6v golf cart deep cycle batteries and an inverter.  Id like to install some sort of switch to select either shore 30a power common in state parks and rv parks, or my house batteries.  Goal would be convenience; right now, if I want to use shore power, I have to manually move the plug in heads for all appliances from the inverter to the incoming shore power outlet, which is mounted in an out of the way area. 

Is there some simple 2-position switch that would accommodate this?  Not looking to spend a whole lot.  Thinking up to $15-20.  Would a simple light switch work?  DC battery connected to the off position and the shore power connected to the on position?  Or something like this? 

https://www.amazon.com/uxcell%C2%AE-Mounting-2-Position-3-Phase-Changeover/dp/B00NWGLYCM/ref=pd_sim_sbs_86_3?ie=UTF8&dpID=51onOjxATCL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=77C72SZNBMDTVDT0JXKF

Are there issues with the different types of power on the same switch?  AC/DC?  Am I niave to think it is this simple to change between power sources? 
 
You are way out concerning electricity! Some appliances, like the roof air conditionner and the microwave only work on 115VAC, all the rest, works on 12 VOLTS, therefore, you cannot use the same switch to control 2 different voltages.
So this means that without electricity from the campsite or the state park, you won't have any air conditionning, or microwave and probably no TV unless you have a 12 VOLTS TV, which I doute.
 
He has an inverter to run some AC appliances off the battery.  He's not talking about switching the AC and DC.  I doubt he's running the air and a microwave.
When he plugs into shore power he has to move the AC plug from the AC output of the inverter to the outlet for shore power.

My question would be why isn't shore power running a converter that charges the house battery?  It should and then no moving the AC plug is needed.
The shore power should be hooked up to a converter which in turn could supply the DC to run the inverter and charge the battery.
 
He mentioned "campervan" setup... I doute that he even has an converter !  ;)  If he does have a converter, it should be wired properly to charge the batteries and to run his 115VAC appliances, if he has any !
If he's not plugged in, he'll only have the batteries to run the 12 VOLTS appliances, like a propane fridge and furnace and some lights.
 
Are you looking for something like this. When hooked up to shore power, it goes right through the switch. When you disconnect, it automatically switches over to your batteries.

https://www.amazon.com/Xantrex-Inline-Transfer-Relay-PROwatt/dp/B004S5Y158
 
yeah, its a homemade campervan, so no converter present.  Is that how this is handled for all the people using manufactured RVs and such?  I'll be dry camping more often, so the batteries will be the primary source, and no ac or microwave with those.  Im basically running LED lights, fantastic fan, and coffee maker......although Id like to get a small 3.5 cu ft fridge going if possible (but Im guessing that would completely drain and kill my batteries in just one night). 

Looking at the Xantrex unit, it seems to be exactly what Im needing but cant believe the cost for something that simple (easier and cheaper to simply continue moving my plug heads)...appreciate the tips and comments all, I'll just keep noodling on this....thanks fellas!
 
Plug all the appliance cords into an outlet strip, either portable or a large hardwired one.  Then plug that strip into either the inverter outlet or a shore outlet, using an extension cord if needed. Here are a bunch of outlet strips, and you can get most sizes inexpensively at Walmart, Home Depot, etc.
http://www.tripplite.com/products/power-strips~20

You can make a simple power transfer switch using a DPDT (Double Pole, Double Throw) switch. Not a light switch. They are not expensive, under $10 for even a large size (30A or so).
http://www.learningaboutelectronics.com/Articles/Double-pole-double-throw-switch-DPDT
 
We use a 20amp DTDP switch to go between shore (E) and Xantrex inverter (I).  Center position is OFF.  We also have two 6v golf cart batteries and a small 3.2cf refrig.  ~$7 Home Depot, ACE Hardware, etc.
 

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I'm getting ready to install a DPDT again, in our new hauler. My way is harder to set up but has the best outcome- totally automatic, you don't have to think to remember to flip a switch.
 
Len and Jo said:
We use a 20amp DTDP switch to go between shore (E) and Xantrex inverter (I).  Center position is OFF.  We also have two 6v golf cart batteries and a small 3.2cf refrig.  ~$7 Home Depot, ACE Hardware, etc.
Click to expand...

ooooh!  thats the exact fridge and batt combo that Im setup with!  Can I ask how long you can get away with running the fridge before the batts get too low?  Ive also just ordered a new xantrex 1500 watt inverter....curious what you're experience is with running that fridge? 
 
Gary RV Roamer said:
Plug all the appliance cords into an outlet strip, either portable or a large hardwired one.  Then plug that strip into either the inverter outlet or a shore outlet, using an extension cord if needed. Here are a bunch of outlet strips, and you can get most sizes inexpensively at Walmart, Home Depot, etc.
http://www.tripplite.com/products/power-strips~20

You can make a simple power transfer switch using a DPDT (Double Pole, Double Throw) switch. Not a light switch. They are not expensive, under $10 for even a large size (30A or so).
http://www.learningaboutelectronics.com/Articles/Double-pole-double-throw-switch-DPDT
Click to expand...

You read my mind....I realized after posting the question that I could simply extend the shore power outlet under the bed with a power strip and mount it next to the inverter.....

I was looking at the DpDT switches and wondered if theyd actually work....thanks!  I may still do that!  And theyre nice and small....and cheap!  thanks again guys.
 
supermanotorious said:
I'm getting ready to install a DPDT again, in our new hauler. My way is harder to set up but has the best outcome- totally automatic, you don't have to think to remember to flip a switch.
Click to expand...

Can I ask how you install that dpdt switch?  Im not sure I'll get it done before leaving, but sure would be nice to have it be automatic....Im a forgetful guy.
 
Refrig run time depends on your specific power draw.  We can run 2 days in hot weather (85F+) and 3-4 days in cooler weather (72F-).  BUT the Xantrex has a low battery warning alarm build in the triggers at 11.5 volts.  When our batteries get to about 70% SOC the Xantrex will beep for a half second when the refrig kicks on.  So not wanting to hear that we recharge at 75% SOC with the generator (assuming parking in shade and solar not keeping batteries charged).
 
sprinterlivingkc said:
Can I ask how you install that dpdt switch?  Im not sure I'll get it done before leaving, but sure would be nice to have it be automatic....Im a forgetful guy.
Click to expand...

It's not automatic if you have to physically switch it back and forth.
 
The DPDT relay I linked above, your inverter output goes to the normally closed contacts on the input side of the DPDT relay, your incoming shore power goes to the normally open contacts on the input side of the DPDT relay, you also connect incoming shore power to the magnet (coil), then your coach wiring goes to the output contacts of the DPDT relay

I'll make a diagram and post soon

Page 4 of this thread shows my work http://www.rvforum.net/SMF_forum/index.php/topic,91264.90.html

I'll make a cleaner write up with the next project, your install will be more simple as you do not need to worry about bypassing a converter's charging wire
 
here it is (I hope)

the bottom middle terminals are the coil, which when shore power is present, automatically throws the relay to shore, you only need to piggy back a thin gauge wire from shore power to the coil

hopefully you can see that since the inverter is on the normally closed or connected side, you  waste no energy keeping the inverter selected

 

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I have an inverter that powers SELECTED outlets on this RV when I'm not plugged into shore power

Microwave
Televisions and associated electronics
GFCI chain (kitchen, Bath, patio, Dining Table)
And the outlet at the co-pilot's feet. (Television circuit)

Optionally (30 amp DPDT switch) it can power the fridge and bedroom outlets (same circuit)

The switch came from an electrical supply house,, Yes they are expensive.

The Inverter is an "inline" type True Sine wave

What this means is simply this.. When the fuse failed and half the park (My half of course) lost shore power a couple weeks ago.. The Televisions and computers did not BLINK,, they kept on working,,, ,The Microwave clock did not go out or blink 12:00 12:00 when power came back.. In fact had the Air Conditioenrs not stopped I'd not have noticed.

The switch is built into the Inverter.

In-line inverters not only make 120 vac out of 12vac when no shore power is present.. but if you have shore (or generator) power they do the INVERSE and convert 120vac to 12vdc to recharge. ... Kind of like a UPS. (Kind of exactly a UPS)
 
When I had the "B" I ran 12/2 wire parallel to my existing wiring and connected to different color recepts.  The other end had a male 20 amp plug to use with the inverter. If I need the inverter I would plug in my yellow recepts, turn on the inverter and use as needed.  It would run everything except the A/C. It ran the small Microwave OK. 
SEE PICTURES
Marvin




 
If you are mainly running on batteries you might want to ditch the electric coffee pot and get an old fashioned percolator and use it on the stove. We've been using one for a few years and don't miss an electric at all.  My wife thinks the coffee tastes better.
 
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