Inverter and Relay for Battery Power Backup?

Can I wire an inverter through an 8 pin relay as per the attached PDF in order to have the inverter kick in automatically to power my boiler, circulator, and zone valves (collectively here referred to as "users") when house current drops such as during a power outage?

Looks nice but,
I think those inverters use signifigant power even with no load.
You might want to switch the DC power before the inverter additionaly, switching after the invertor is probably still required to prevent backfeeding into invertor
Better advice will probalby follow

pm freddy

jim d wrote:pm freddy

Will do!

Hey! I've been PM'd! Much better than BM'd *phew!* OK... down to the serious side. Can you have a battery back up? Sure, anything is possible if you throw enough money at it. The first step is for you to do the math & have enough inverter to drive all that you want to drive. This tells you what size inverter you need....and don't forget it must be a pure sine wave inverter. Then you decide how long you want it to last on batteries. This tells you if you need one batter or thirty seven batteries. Are you looking to drive the AHS? Ohhhhh, I hope you are rich! I'm pretty sure you'll find that you'll need a whopper of an inverter. AHS uses a big motor on the fan and it takes even more juice to get it started. Add in circulators and such & oh, gosh, it will blow your mind just before your wallet.

Let me say this.... the people that use battery back ups are those that have rice fed stokers. Those systems have tiny blower motors and tiny motors to move the coal. A "tiny" inverter will do the job. Anyone that has a battery backup also has a generator. The whole idea of the back up is to give time to hook up the generator. You see, the rice stoker will out-fire in a matter of minutes without power. The back up gives the owner time to get the generator hooked up and running and not lose the fire. An AHS does not need it. You can go for hours without power and not lose your fire.

So, if you really really want to, start adding up the wattage of everything you want to run and then report back.

Freddy, I think you have scared me out of this idea. Was the relay idea workable though, perhaps for some more down to earth needs like lighting, and keeping a computer up and running?

I pondered the idea of a battery backup system too, but like Freddy said, its expensive - AND then the designing, installing and maintaining look to be more effort than the payoff.. So, I got a 5 Kilowatt generator that can handle over 8 KW bursts. It can run my 220 volt water pump, my coal furnace, refridgerator and a coffee maker (some things are nessessary lol), and more! I can have it in position and running inside of 10 minutes but I usually wait longer to see if the power out is only short term. The safe and dummy proof way is to run a sub panel off the generator to power all your important things. The cheap and easy way is to back feed it thru a 220 breaker to feed your fuse box, but you better know what your doing (this is what I did)... DISCLAIMER - there is a specific order for turning on and off breakers when using this method, otherwise, there could by a mushroom cloud over where your house once stood

Heres the one I built....
Building a TRUE Sinewave UPS for My DVC-500

The diagram for the relay is on the 2nd page.

It is still running to this day.
I use it alot as a regular battery charger, when its not tending the coal stove.

lsayre wrote:Was the relay idea workable though?

Oh, sure! The idea is sound. I did not take the time to wrap my brain around the diagram that you drew, but 009's link shows a proper relay. I myself have built several 300 watt pure sine wave back up's. They cost about $120 for the part not including the batteries or charger. I also built a 1,000 watt. All are working and working well. Here's a photo of a relay I have that's "ready to go". Just follow the directions on the green tags & voila!

And, yes, the inverter is OFF until the power is lost. No need to keep the inverter "on" all the time. So, when they are on line & doing their job, when the power goes out, the relay drops closed, the inverter starts, the power now comes from the batteries instead of from the outlet.

The relay that I diagrammed is "double pole, double throw" (8 pins, with 4 pins to each independent side). Are you guys using "triple pole, double throw" relays (12 pins)?

The diagram I made is not capable of turning on the inverter, so for my schematic the inverter would have to be kept "on" all the time. How do you wire the inverter to come alive only when the homes power drops?

lsayre wrote: Are you guys using "triple pole, triple throw" relays (12 pins)?

12 pins? 14! There are four double throw switches in the relay plus the two terminals that carry the power to the relay. I guess they might be called "quad pole double throw". So, one of the switches is connected to the "on off" switch of the inverter. The inverter remains off until the power is lost, then the switch closes & turns the inverter on.

Aah, thanks Freddy! I could accomplish the wiring of the inverters on/off switch by either adding an additional relay (since I already have a couple of the 8 pin type DPDT relays), or by simply buying a new one with 14 pins.