Wireless On Off Switch for Inverter

[greg8325]

Hey guys, and gals, I'm new to solar power and this community. I've done a DIY solar panel system with 2 100 watt panels hooked up in parallel that run through a solar charge controller to 5 car 12 volt car batteries and then to a DC to AC converter. Is it ok to leave the inverter on all the time even if no current is being pulled from it? If that's bad or wasteful is there a way to wirelessly turn the inverter off with something simple? I have a Bestek 1000w inverter for reference. Here's an amazon link if you need to see what inverter I'm talking about. I can't wait to learn more about adding more solar power to my house! I can post some pics of my very DIY project so far. It's nothing amazing but I'm new and trying to learn and I figure this forum would be a good place to start! Thanks for any help in advanced!

http://www.amazon.com/BESTEK%C2%AE-Outlets-Inverter-Notebook-Cigarette/dp/B007SLDDHQ/ref=sr_1_4?ie=UTF8&qid=1430043677&sr=8-4&keywords=dc+to+AC+inverter

[Mike90250]

I can use wifi to turn my inverter ON-OFF via the ComBox. But generally, better inverters have a wired/less remote control panel. Trying to add something is not likely to work well

[greg8325]

Ok, got it. That's what I figured. Is hitting the off switch enough for a standard inverter or do you need to completely disconnect the leads to stop any battery draw?

[Johann]

I think what you are looking for is like this. You tube video

[greg8325]

Thanks for the video! That's a pretty cool hack. I just assumed that there was some device out there that would do this. Doesn't seem that complicated. Is there a way to tell if the inverter is still sucking power from batteries when power switch is off? It may draw some current but it must be pretty minimal so I'm thinking of just turning the power button off when not in use but if disconnecting the leads is better for the batteries I can do that as well. Just wondering if anyone has any experience with that. Thanks for the replies! I'm super new to solar power!

[SunEagle]

Thanks for the video! That's a pretty cool hack. I just assumed that there was some device out there that would do this. Doesn't seem that complicated. Is there a way to tell if the inverter is still sucking power from batteries when power switch is off? It may draw some current but it must be pretty minimal so I'm thinking of just turning the power button off when not in use but if disconnecting the leads is better for the batteries I can do that as well. Just wondering if anyone has any experience with that. Thanks for the replies! I'm super new to solar power!

All DC to AC inverters always draw some power. They usually have a "no-load" rating in watts or amps or a % of the Inverter watt rating. The cheaper models are less efficient and use more wattage.

Easiest way to reduce waste is to just turn off power button on the inverter.

You can measure the amperage using a DC clamp on meter in the wires between the battery and inverter. That way you can compare how much is being drawn when the inverter has a load, has no load or is turned off.

Here is a hint about batteries. More than 2 wired in parallel will cause an imbalance in how they are charged and discharged which results in one or more failures. Having 5 car 12volt batteries in parallel will cause them to have a very early death.

[greg8325]

So you can only have two 12 volt batteries in parallel if you want them to last? I though you could just hook the positive side battery hook up from the solar controller to the first battery and the negative side battery hook up from the solar controller to the negative side battery last in the chain? Wouldn't that balance out charging them? Shows how much I have to learn!

[Mike90250]

connecting batteries on the "Diagonal" is the best way to connect 2 in parallel, but that does not mean it's the best way to use the batteries. There is a large write up here

http://www.smartgauge.co.uk/batt_con.html

about the math behind the difficulties of parallel batteries.

[Mike90250]

For a small inverter, I suppose the remote switch in the video will work. But above a couple hundred watts, the power in the wire will fry the module.

12V 200w = 16a and 10 ga wire
12v 400w = 33a and 8 ga wire Above that, and the little wires on the module will get all melty and burned.

edit - after getting the entire video to load and play, I see the inverter gets opened up and the remote spliced into the place of the front panel switch. This takes it out of the high amp path, and is less of a fire hazard.

[greg8325]

That website about the parallel wiring was really interesting. Sounds like the second method is fine for batteries under a total of 8 or if the batteries aren't very expensive. Good to know though. That's a really good write up.

[SunEagle]

So you can only have two 12 volt batteries in parallel if you want them to last? I though you could just hook the positive side battery hook up from the solar controller to the first battery and the negative side battery hook up from the solar controller to the negative side battery last in the chain? Wouldn't that balance out charging them? Shows how much I have to learn!

The problem with wiring in parallel is all of those terminations need to have the same resistance. Even if one was a few ohms more than the others the current flow would not be even to all the batteries. That means they will not discharge or charge evenly so one battery will get "worked over" more than the others causing it to fail sooner. Once one battery starts to go the entire bank starts to slip to an early death.

When batteries are wired in series they all have a better chance of being charged and discharged evenly so they perform the same amount of work as a team.

[greg8325]

The problem with wiring in parallel is all of those terminations need to have the same resistance. Even if one was a few ohms more than the others the current flow would not be even to all the batteries. That means they will not discharge or charge evenly so one battery will get "worked over" more than the others causing it to fail sooner. Once one battery starts to go the entire bank starts to slip to an early death.

When batteries are wired in series they all have a better chance of being charged and discharged evenly so they perform the same amount of work as a team.

So by saying the same terminations do you mean the exact same wiring cables? I'm sure there can be a little difference in resistance from cable to cable even if it's the same cable but by doing that they would charge and discharge better? I had no idea wiring up solar batteries in parallel was so complicated.

[SunEagle]

So by saying the same terminations do you mean the exact same wiring cables? I'm sure there can be a little difference in resistance from cable to cable even if it's the same cable but by doing that they would charge and discharge better? I had no idea wiring up solar batteries in parallel was so complicated.

I also didn't understand and wired 4 x 12volt 50Ah in parallel before I found out about the imbalance due to resistance issue.

Your system will work for a while but at some point either one in the middle or at each end will start to fail. You will not get the full life out of them.

[greg8325]

I also didn't understand and wired 4 x 12volt 50Ah in parallel before I found out about the imbalance due to resistance issue.

Your system will work for a while but at some point either one in the middle or at each end will start to fail. You will not get the full life out of them.

So how did you solve the problem? Did you use a different wiring pattern?

[SunEagle]

So how did you solve the problem? Did you use a different wiring pattern?

You can try that "diagnol" pattern that Mike showed you. That should make it a little better.

When this set of batteries finally die, you should look into getting batteries at the desired Ah rating in lower voltages like 2, 4 or 6v. Then you build your battery system by wiring them all in series.

I could have used 2 x 6volt 232 Ah FLA batteries to make a 12volt 232 Ah system instead of the 4 x 12volt 50Ah AGM batteries that made a 12v 200 Ah system. I spent twice as much with those 4 x 50Ah batteries and will get less Watt hour capacity then using the 6 volt with a higher Ah rating.