Standby home generator controller with timer

Newbie here, got an Arduino starter kit under the Christmas tree so hope to start playing it with soon.
One project I'd like to build is a timer for a standby generator. What I want is when the purchase power goes out is for the generator to wait for 4 hours then start and run for an hour then shut down, and repeat until power is back on. That should keep the refrigerator and freezer cold while we are away on extended trips. I don't want the generator to run continuously while we're away. I can also use a 2 position switch to allow the generator to autostart and run normally when we're home.
I think I can accomplish this using a relay and timer to simulate a power outage/return signal to the generator which will have an automatic transfer switch and autostart features.
Any thoughts?

Certainly possible with an Arduino and a real-time clock. My former company had a commercial backup system similar to what you describe. It is actually a bit more complicated than you suggest.

But first, what type of fuel does the generator use and is it located outside in the weather and what weather extremes can you expect?


If you are planning for the generator to operate when you are not there to supervise it I think you should get written approval from your house and liability insurers to confirm that that is acceptable to them.

My guess is that it would NOT be acceptable unless the installation is formally approved by some approvals body - which would probably make the whole idea prohibitively expensive.


Haven't bought one yet but it will be natural gas since that is available in our neighborhood and other neighbors have them. It will be outside in south Louisiana so temp is moderate. Mainly I'm concerned about being away during a hurricane event and power being out for a week or two, which has happened before. Don't want a generator running until we can get back.

Robin, I hadn't considered the insurance issues but don't think that will be a problem since it will only be between the generator and electric sensor which is standard on standby generators. I'm only looking at simulating the power being out and back on using a timer and relay.

Be sure your generator is set up for remote control. Both turn on and turn off, as well as monitoring various parameters, such as “running”, “not running”, fuel(NG) available. Engine oil level and temperature. Also generator voltage, frequency and current being drawn, if possible. For the transfer switch, indication of it’s status.

For the Arduino side, need separate power for when the commercial power is off. A thermal printer would really be nice to keep a log of operation.


Robin, I hadn’t considered the insurance issues but don’t think that will be a problem since it will only be between the generator and electric sensor which is standard on standby generators.

I was not thinking solely about the part of the system you plan to create. You need to get confirmation from your insurers that unattended operation of a generator is acceptable. They may insist that it has certain fail-safe features. Talk to them before you waste any money.


Robin -
I don't understand what your concern is with having a home standby generator run while unattended. This is a perfectly normal thing and more and more people are getting them every day. Do you think that a homeowner is supposed to disable their generator every time they leave the house to buy groceries? I think what folivier wants to do is a great idea. It sounds like he wants to make the gen run for only one in four hours if he is away for extended periods of time. I will definitely be hooking up to my generator with my Arduino once I pull the trigger and get one. And you can be sure I'll be monitoring and logging everything possible!

From what you've described you don't need a real-time clock.

This isn't much more complicated than the basic Blink Example. Although, you may need some kind of feedback to make sure the generator actually starts when the relay closes.

You should be able to run the Arduino from the same battery that runs the starter for the generator, but the voltage may "droop" when the starter is engaged.

This is not addressed to anyone in particular as it is certainly not intended to be a personal comment ...

When I suggest (and not just in this Thread) that someone should get approval from his/her insurer before implementing some project it seems very strange that the person seems intent on doing everything EXCEPT picking up the phone and asking the insurer about it.

The obvious conclusion (in my mind) is that the person is afraid the insurer will say NO.