Electrical Thinking of installing an inverter

Macca_75

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Morning Brains trust.

As we plan for our big trip I am still in 2 minds about purchasing a generator. An alternative I am considering is installing a second battery and an inverter. Not sure on the size however I am thinking something that will run any of the 3 below (1 at a time):
- Be able to run the coffee machine and milk frother simutaneously
- Be able to boil a kettle
- Be able to run a 2 slice toaster

Other than the Air conditioner I think most of our "240v" needs could be met with this. Not sure if it's worth buying an hauling a generator around the country.

So, if we buy an inverter can it be wired to auto-sense if 240v is available. If it is, run from mains. If it is not, all 240v plugs in the van run from the inverter. I'd like to run the inverter across the shunt for the Drifter panel so it knows whats coming out of the battery(ies).

On Battery(ies) - it's a short burst of power required, not a continuous load. Would 1 x 120aH cover it or would we need 2?

Anyone have recommended brands? Happy to pay the right $$$ for the right equipment first time.

Also sizing - I am thinking 3000W (as most house circuits are 2400W). I'll have a look at the draw of each of the 3 lines above (only expecting to run 1 line at a time) and see what is largest.
 

Drover

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While I will let others go for it I will say you will need 2x batteries and lots of solar to replace what the invertor will burn up to boil a kettle or toaster, they are both high power uses, gas far better....boiling the kettle with it at tea time could very well leave your batteries low until sunrise. A mate runs that stuff but he has 700w solar, 700ah lithium batts and a 3000w invertor, cist a fortune just so he can have coffee and not use gas, $4000...nice coffee though.
 

Macca_75

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Reading other threads....

Maybe I could run a small 10A extension lead to the external AC input... If I run it through my (unused) 10A -> 15A adaptor (https://ampfibian.com.au/product/rv-plus-15a-caravan-power-adaptor/) I think it will offer a fuse on the 240v side.

With regards to the Drifter panel, if I run the inverter through the shunt it will charge the batteries (which is ironic since the power comes from the batteries). If I bypass the shunt will the panel still know the correct battery level (is it done from voltage or does it monitor and calculate in vs. out power?)

Will short bursts in use (it would usually be a morning thing, and very minimal) really drain the batteries that much?

I currently have the Jayco "upgraded) 150W panel. I'm about to swap the PWM Solar charger to a MPPT unit (hoping for some gains there) and am considering a 120W Kings solar blanket. I note on the Drifter panel when travelling (Anderson to car and panel on) I was putting about 15A into the battery. We plan to move every 2nd day or so when free camping.
 

Drover

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I do know that using an invertor to run a charger doesn't work as the power drawn is more than the power made .
 
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Macca_75

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I do know that using an invertor to run a charger doesn't work as the power drawn is more than the power made .
You can't make power from nothing.....

My previous should have read

With regards to the Drifter panel, if I run the inverter through the shunt it will *try to* charge the batteries (knowing it will draw more energy than it will put back in - resulting in a net loss).
 
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millers

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MY first question would be can you life with using gas? After that look at the power consumption and compare it with that of what else you run (12V). Note comparision should be of normal load not just maximum. If you compare Power (W) then 12V and 240V comparasion is ok minus the efficiency of the inverter. If you compare a 1200W kettle with a 120W TV this will mean that 1 minute of kettle is 10 minutes of TV + efficiency of inverter. (multiply by 1200/120). If you TV is 60W then that is 20 minutes of TV gone. If you use 12W for light (LED) you have lost 100 minutes of light.

This may give you a guide as to how much energy you are going to lose (power = energy x time)

Some thoughts on the auto-sensing for 240V.
First thing is to make sure that the installation is compliant with the electrical standards as it is a 240V installation. With the inverter wired to supply 240V when there is no 240V to the van means that the power points will be live all of the time (potentially dangerous).

My second question is can you life with independant sockets for the 240V for the inverter as this makes it easier wiring. I beleive that there are a number of members that have done this.

The items that you have mentioned in general do not need continous power so interupting the power to transfer over is not an issue so the use of Uniteruptible Power Supplies (UPS) should not be required. UPSs ussually sit between supply and outlets and will takeover 240V supply from batteries when external supply is lost.

I would not recommend feeding the inverter back through the caravan external plug. For this option I beleive that it is essential to "interlock" the battery charger so that the battery charger(s) do no take power from the inverter. Simple lose calculation as each device is not 100% efficient meaning that you create a heater (the loses) and flatten you battery.

This would require that it is possible tp split the external supply and the inverter. You would also need to guarentee isolation so that there is no posibility that the sockets are able to be supplied from both at the same time (even for an instant). 240V does not like two supplies that are not syncronised. So you would need an isolation relay that detects the external supply and turns off the inverter output (and also the input if required, but most will go into standby).

This isolation should also extend to the air-conditioner so that if someone turned on the air-con it would not kill the a/c or the inverter or battery.

I like the chalenges of this, however even I have considered that it may not be worth it. I would be installing an independant socket for the inverter (different colour) and having a socket that includes RSD and CB capabilites installed per the regultions.

Sorry if the response is long winded
 

Glen Bundesen

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I had a 3000/6000w inverter in a prev van and it would run the small coffee machine or the microwave, but sucked the power out of the 2 100amp batteries. I put in a 2000/4000w inverter and to my surprise the microwave in the latest van, requires more than this inverter can provide! So I can have a morning coffee but not microwave my breakfast porridge.
Yes - just have a dedicated inverter supplied 240v double pole GPO - a lot less complicated. Maybe look for an inverter which has a remote on/off, that way you can have it permanently wired and out of the way.
 

Macca_75

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Thanks for the feedback.

Good points about needing to isolate the battery charger (I already thought about the issue but not the solution).

Running it to an isolated, different colour point is possibly the best, easiest solution for so many reasons. I will need to see if it's feasible to run this to a point on the kitchen bench (that's where the Coffee machine/Milk frother/Toaster would live).

For my case, the Microwave is being removed. It's something we seldom use (and can get away with not using) and as we do our lap to space occupied could be better used (kids school stuff, etc).

Also for the record whenever playing with 240v I will always use an Electrician. 12v I may or may not do myself, depending on my personal level of comfort.

Seems like effort and money for Coffee and Toast, but if I'm living on the road I'm happy to set it up.
 

Drover

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I like coffee but not liking milky coffee a plunger brew nice and hit is my vice....
.I cook my toast in a few seconds on an old camp toast rack on the gas burner.....money saved spent on bourbon....lol,lol........ Our nukavator gets little use but it was fitted first in our van then they built the van around it.....its now the bread bin.
 
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Macca_75

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I like milky coffee and the kids like hot milky chocolates.

I wouldn't say it's a must, but highly desired if it's our house on wheels for 6 months.

And Toast - it's a must under my Bacon and eggs. Also an easy hot breakie for everyone else
 

Drover

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Yep I certainly understand and firing up a Genny at brekky is not a popular thing, so really fitting an invertor along with plenty of storage and panels to recover use would really be the appropriate way.
 
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Crusty181

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Macca, i have a 5000/3500w inverter connected a permanently wired GPO next to the Setec inside the van. (That point is appropriately labled) We use that the charge/run the laptop charger, some battery charger that only have 240v chargers, the cryovac machine, Crusketts Xbox etc etc

The inverter is in the front roadside boot and has 2 outlets, one is permanently connected to the inside point, the second i use randomly and also to connect a 10amp lead to the vans mains inlet primarily for either the microwave (rarely) or the washing machine because i cant conveniently get at their GPOs so its simpler to fire them up via the vans mains when required. Ive only used the micro a handful of times on the inverter because it thumps the batteries and ive got a generator which i think is more appropriate; but ocassionaly a short micro blast doesnt warrant hauling out the genset on the side of the road.

When the inverter is plugged into the vans mains, isolating the Setec from the battery solves the perpetual battery charging itself issue. Im the only inverter pilot, its out of bounds for my family

I dont use the inverter/van GPO often, but its there if i need it.
 
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Boots in Action

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I like milky coffee and the kids like hot milky chocolates.

I wouldn't say it's a must, but highly desired if it's our house on wheels for 6 months.

And Toast - it's a must under my Bacon and eggs. Also an easy hot breakie for everyone else


Hi @Macca_75 , noted your desire to use inverter to power some of your "essential" 240 volt goodies. Someone has already given a good explanation of how much power is drawn from batteries and how the load of a appliance gives the batteries a "thump". Just so you can work out your problems in going down that track (disregarding the setting up and safety issues with GPO's etc) , here is a formula for calculating the loads of inverters as provided by "Australian Direct".

When calculating the loads of inverters, use a multiplier of 1.2 in the following formula for a 1200 watt 2 slice toaster.

Wattage X 1.2 divided by voltage (of battery). So, using that formula, your toast at breakfast will use the following amps.(For the time it is toasting).
1200 multiplied by 1.2 equals 1440 divided by 12 equals 120 amps. That is a lot of juice even for a short time and your batteries (and cabling) will need to be in good condition to continue to keep your toaster/coffee machine etc going on a daily basis!! And that power will have to be put back into battery/ies asap. Your solar will need to be up to the task ALL the time with daily uses for your toast and coffee machine!
 

achjimmy

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I just wired up one of the new projecta 1800w pure sine wave inverters last weekend. Has an optional remote which I’ve put by the door. Tested it on the nespresso machine and milk frother and ran both without raising a sweat. It’s wired to a GPO under the table. I used a CMS gpo so I could piggy back off it and put another point in kitchen and bathroom when I could be arsed

87363755-8F42-4F18-BFC7-36692D8C1429.jpeg
 

Crusty181

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I just wired up one of the new projecta 1800w pure sine wave inverters last weekend. Has an optional remote which I’ve put by the door. Tested it on the nespresso machine and milk frother and ran both without raising a sweat. It’s wired to a GPO under the table. I used a CMS gpo so I could piggy back off it and put another point in kitchen and bathroom when I could be arsed

View attachment 63038
Did you strip off the inverter end of the cms loom for a plug?
 

Macca_75

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Aug 3, 2016
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I just wired up one of the new projecta 1800w pure sine wave inverters last weekend. Has an optional remote which I’ve put by the door. Tested it on the nespresso machine and milk frother and ran both without raising a sweat. It’s wired to a GPO under the table. I used a CMS gpo so I could piggy back off it and put another point in kitchen and bathroom when I could be arsed

View attachment 63038
What battery and Solar setup do you have supporting this @achjimmy
 

Base23

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Jan 17, 2016
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I have a Projecta 2000w inverter with a built in auto change over relay and safety switch and is wired to run the every power point the Van (excluding battery charger, hot water service power points and Air con )

Works seamlessly with how it changes over from 240v and inverter power with no input from the user and runs coffee machine, milk frother, microwave and toaster with out a problem.

Having the auto change over means that any family member can use what they want when they want with out me having to stuff around.

I have 2 x 100 amp batteries and 2 x 120w roof mounted solar panels and seem to have plenty of battery storage. The longest I have free camped at any one time is 7 nights and I did not flatten the batteries. That was making about 4 coffees a day, microwave most nights and charging a laptop every now and then. We had a good week and the days were full sun so that would have helped.

To rewire the van so it could work like it does was not an easy task but I feel it was worth it.


inverter mounted in pantry
2016-09-20 19.11.44.jpg

inverter remote control
2017-01-17 18.35.58.jpg

Basic Wiring diagram
2016-08-22 12.58.40.jpg


Cheers