3 way transfer switch

[justinredt91]

Working on designing electrical system for a future skoolie build. Want a battery bank system charged by solar. Shore power hook up. And gen set. Very crude thought design right now. What would be a suitable 3 way switch for the application ?

So solar panels to mppt system. to battery bank. To inverter. To 3 way transfer switch to breaker box

Gen set to 3 way to break box

Shore power to 3 way. To breaker box

Does this sound about right?

[PNW_Steve]

I am not completely following your post but I'll give it a shot.

You don't need a three way switch. You can have your solar and your converter both charging the battery at the same time.

If you go with an auto transfer switch for your Genny/shore power and an inverter with an ATS you can completely automate the process.

That is what I did in my first bus and over 7 years and 250k miles it worked flawlessly.

[Ciscokid]

I used a standard transfer switch for each power source I added. The Cummins gen set and battery bank in the first, the 50 amp shore power added to the second. Be sure if you have a battery charger you have a separate switch to turn it off while using your inverter. Feeding your charger with ac from power your batteries are producing creates a loop and it will blow your circuit breaker in your inverter every time.

www.skoolieadventures.com

[justinredt91]

Would the batteries not over charge?

I apologize for my ignorance. Electricity is my strong suit.

[Ciscokid]

Your solar charge controller will do all that work for ya. Your AC charger will do the same they call it floating. I have a 55amp I bought from camping world I would sell for half price. I run lots of batteries and a large cb box so I went to a 75 amp converter. It drains my generator but I work for the manufacture so parts and service isn't a factor. The 75 amp requires a dedicated 20 amp circuit if you go that big.

Scott

www.skoolieadventures.com

[justinredt91]

10-4. Appreciate the input. Did not realize how many components there are to an electrical system.

[Ciscokid]

You will know all about during your bus creation. Best thing is there are some really sharp people on this forum and they are all very nice. I have not met a bad person yet on here. They are full of information and always glad to help you on your journey. Rule of thumb and i would think that most people agree on here that you will build your bus three times before your satisfied. The first time was the way I thought it should be, the second was the way I seen someone else do it, and the third was the way one of the very experienced experts on here told me how to do it the right way. Some people think they know it all, some have been finding out he hard way for few years (me), and some here have been at this all their life. Anyway don't get discouraged pick up skoolie.net and just ask. You will come out smiling, I always have. Doing your research always pays off in the long run.

Scott

www.skoolieadventures.com

[PNW_Steve]

On my first bus I used a typical automatic transfer switch to switch between shore & generator.

My inverter also had a built in transfer switch.

That fully automated my power switching.

Air conditioning and converter only received power if we were on shore power or generator.

Really pretty simple to install and worked very well.

[justinredt91]

I'm going through all the posts I can. Absorbing like a sponge.

[JDOnTheGo]

Originally Posted by justinredt91

Working on designing electrical system for a future skoolie build. Want a battery bank system charged by solar. Shore power hook up. And gen set. Very crude thought design right now. What would be a suitable 3 way switch for the application ?

So solar panels to mppt system. to battery bank. To inverter. To 3 way transfer switch to breaker box

Gen set to 3 way to break box

Shore power to 3 way. To breaker box

Does this sound about right?

Hi Justin,

Like Steve, I don't completely follow. It helps (me) to be clear about AC or DC side of things.

For automatic operation of the AC side of things, you need a transfer switch to flip between shore/generator and inverter. This can be done manually if you prefer that approach.

The DC side of things is much easier. As always, lots of options but let's assume you will have a solar charge controller and AC/shore power charger. These components are semi-intelligent and charge based on battery state. A variety of things can happen when both have power to provide to the battery but all are acceptable and it boils down to one component providing that power and the others detecting that there is nothing to do (read this https://shop.pkys.com/multiple-charge-sources). Bottom line is that you can have these components all connected and operating without concern. That changes a bit if you have a 'preference' for which one is providing power. For example, some would prefer to charge from solar rather than shore power (maybe on a metered connection). I think that's different than what you asked so will leave it alone.

My coach is kinda complicated but my wiring diagram is here if interested.