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Author Topic: Wiring a Small Inverter  (Read 360 times)

Heli_av8tor

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Wiring a Small Inverter
« on: December 12, 2017, 02:14:07 PM »
Eventually I want to add solar and a whole house inverter. But for this winter's trip I'll be using a couple small inverters for the TV's and a 400 watt one mainly to power a crockpot (250 watt on hi) while on the road. The two for the TV's run fine connected to existing wiring at each location. The 400 watt inverter will require heavier wiring.

 I'm considering a couple placement options for this inverter.
  A.  My batteries are under the entrance stairs. Thinking of running from the batteries to some type of jack close to the stairs. This run would be less than 5 feet so #8 wire should be adequate. The inverter could be plugged in as needed and a short extension cord to get to the crockpot. I'd need to find a suitable plug and jack for this that could handle 40 amps and a way to make it look good.

  B.  My converter (battery charger) lives under a cabinet that houses the washer/dryer. The back of it adjoins the kitchen/dining area. It is wired to the 12 volt load center about 6 feet away then on the the battery. I've not sure of the wire gage, but I'm guessing 4 or 6. I could mount the inverter close to the converter and wire to the 12 volt connections on it. A standard 120 volt outlet could be installed in the cabinet. This would still require an extension cord to the crockpot. This would be a cleaner look and no need to store the inverter someplace when not in use. The downside I see is the inverter power current would be added to whatever other 12 volt loads are on. Also, the inverter draws 70 ma. when turned off.

All suggestions welcomed.

Tom
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

QZ

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Re: Wiring a Small Inverter
« Reply #1 on: December 12, 2017, 03:04:50 PM »
So the crock pot only pulls 2 amps @120 volts or 20 amps @12 volts DC. Does the rating decal or plate on the crock pot say 2 amps?

How many batteries and what type will you be using? Regular old marine RV 12 volt is about 95 AH with less than 1/2 of that useable before volts drop too far so just say 40 AH useable so crock will run two hours until battery is depleted.

Multiply from there if bank is bigger

Lou Schneider

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Re: Wiring a Small Inverter
« Reply #2 on: December 12, 2017, 03:09:39 PM »
The closer you can put the inverter to the batteries, the better off you will be.  The problem is the inverter's low voltage cutoff will be triggered too soon if there's any significant voltage loss along the wires between the batteries and the inverter.

You said it's about 6 ft. from the (B) location to the load center, how far is it from there to the batteries?

While you're underway the main engine alternator will charge the house batteries.  It is usually connected directly to the battery posts so the voltage loss between there and the inverter still comes into play.

Heli_av8tor

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Re: Wiring a Small Inverter
« Reply #3 on: December 12, 2017, 03:33:11 PM »
Thanks Lou and QZ

The label only lists the wattage and that is 250 w on high. That is 20.83 amps at 12 volts. The inverter specs say 87% efficiency. That would bring the draw to 23.94 amps. i figure the 87% is optimistic. 80% efficiency would bring the draw to 26.94 amps.

So ya, 2 hours and the meal gets cold. However, I'm only looking at using this when going down the road. I think the engine alternator will easily keep up.

My two deep cycle 6v batteries are rated at 110 AH. I estimate 12' of wire from the battery to the load center. Now that I think about it this wire likely runs to the battery disconnect then to the load center. That could add another 30'. (Starting to get ugly!)

Maybe plan A is the best bet. Do you know of an inexpensive plug/socket combo that would be suitable?

Tom
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

QZ

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Re: Wiring a Small Inverter
« Reply #4 on: December 12, 2017, 03:39:47 PM »
Also, yes seeing .5 to .7 would be normal for an inverter. For many RV's it's common to see 1 to 1.5 amp draw with Propane fridge running, propane detector, radio off, monitor panel. It will vary a little as the fridge propane solenoid kicks on and off.

It's most efficient to run things like cell chargers etc directly on 12 volts but I don't worry about it and consider an inverter load as part of my energy management program. So with the rig at idle with fridge on and an inverter idling you could see 2 amps/48 AH in 24 hours. Size it all into the solar build.

QZ

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Re: Wiring a Small Inverter
« Reply #5 on: December 12, 2017, 03:45:57 PM »
I see you were typing when I posted. Two gc 2 six volts usually give you 200 AH. It's a whole different story if you are running down the road on your vehicle alternative too.

Distance and wire size  are the two factors when dealing with resistance big wire works. Look at Anderson connectors if that is the type of connector you are talking about. They come in various sizes from about 50 amps to 500 amps

QZ

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Re: Wiring a Small Inverter
« Reply #6 on: December 12, 2017, 04:04:05 PM »
If you do much cable building you can get a hydraulic crimper on eBay or Amazon for under $40

Heli_av8tor

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Re: Wiring a Small Inverter
« Reply #7 on: December 12, 2017, 05:17:41 PM »
This is one of the plugs I found:  https://www.amazon.com/gp/product/B014FEV6EU

Also saw this crimper:  https://www.amazon.com/gp/product/B07744NQ3B

Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

Gary RV_Wizard

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Re: Wiring a Small Inverter
« Reply #8 on: December 12, 2017, 06:27:09 PM »
Quote
Also, yes seeing .5 to .7 would be normal for an inverter.
Any inverter designed and built in the last 10 years or so is probably much better efficiency than that. I would think 85%-90% is typical nowadays.
Gary
--------------
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Heli_av8tor

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Re: Wiring a Small Inverter
« Reply #9 on: December 12, 2017, 06:57:45 PM »
Id like to think that.

But this one is from Harbor Freight. LOL
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

QZ

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Re: Wiring a Small Inverter
« Reply #10 on: December 12, 2017, 07:45:13 PM »
This is one of the plugs I found:  https://www.amazon.com/gp/product/B014FEV6EU

Also saw this crimper:  https://www.amazon.com/gp/product/B07744NQ3B

That crimper is similar to the one I bought. Since it's $36 not $1,200 so you will find that the dies are not perfect. In fact iirc I think it was the 6 gauge die that I had to "modify" in order to get enough squeeze on the terminal. It sounds half arse but what can you do? Depending on the die and the particular terminal or what company made the terminal you see that the die will want to leave two pinched metal ears sticking out on the sides of the terminal. Before you compress fully, release the pressure and rotate the terminal and compress again.  Some high quality terminals vs lesser quality will have different wall thicknesses. If you venture off into doing your own check the terminals closely for variations in quality and buy extras so you can practice. i bought cheap ones on ebay and higher quality on solar sites. The other option is to have someone crimp them for you. I wanted the tool because of how much I had to do and I often end up helping someone out. I wasn't going to buy an industrial quality tool like I had used all my career.

https://www.ebay.com/itm/GREENLEE-TEXTRON-EK1240LX11-Crimping-Tool-Li-Ion-12-tons-Force-G8042091/332410409130?hash=item4d653450aa:g:9BYAAOSw9KhaFqSn

That connector is the Anderson style but I dont know about that companies quality. They may be exactly like Anderson.

« Last Edit: December 12, 2017, 08:03:20 PM by QZ »

HueyPilotVN

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Re: Wiring a Small Inverter
« Reply #11 on: December 12, 2017, 08:03:44 PM »
Tom.
Will you be at the rally at Q next month?

I have a crimper, cable, and lugs.

We will help you with your project.
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

QZ

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Re: Wiring a Small Inverter
« Reply #12 on: December 12, 2017, 08:25:48 PM »
Tom.
Will you be at the rally at Q next month?

I have a crimper, cable, and lugs.

We will help you with your project.

Heli=av8tor, jump on that offer. Hueypilot is the  high quality overachiever type.  :)   look at his set ups. 

Heli_av8tor

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Re: Wiring a Small Inverter
« Reply #13 on: December 12, 2017, 08:58:41 PM »
Bill, we plan to arrive in Q by the 19th. Will you still be around then?

Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

HueyPilotVN

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Re: Wiring a Small Inverter
« Reply #14 on: December 12, 2017, 10:30:59 PM »
I will be there before then and plan to stay maybe even longer than most everyone.
« Last Edit: December 12, 2017, 10:32:32 PM by HueyPilotVN »
Bill Waugh
40' Country Coach DP
34' Stacker Trailer, Trailer Toad
Jeep Commander
Mustang Bracket Race Car
35 years on the road

Heli_av8tor

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  • Posts: 257
Re: Wiring a Small Inverter
« Reply #15 on: December 13, 2017, 11:27:04 AM »
Bill, good to hear. I've been hoping our paths would cross someday.

Tom
Tom & Theresa
2004 Pace Arrow 37C, Workhorse W22, 8.1 Vortec
2014 Honda CR-V Toad, Roadmaster -5 Base and tow bar
SMI Stay and Play Duo Brake system

 

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