Let's Talk Power Planning

[Ozarker]

After 16 pages of information in this topic, let's address planning an electrical system.

Requirements:

1. A 12 V fridge @ 25 Ah a day,

2. A 115/120 V, 15 amp window A/C,

3. A 115/120V 800 watt microwave

4. A 120 V, 2.5 amp portable air compressor

5. A 115/120 V, 800 watt coffee pot

6. 12 V, 25 watt lighs

7. 12V mobile transciever can operate on 10 amp

8. 12V adapters for computer, phone or other similar devices for charging

Nope, no flat screen TV! Maybe later.....

Sorry I couldn't break all this down for amps, watts and volts, but you get the idea.

These are probably the basic requirements of many Overlanders who are married, we need to zap lunch going down the road or at camp. That means the micro runs off house battery(ies) and inverter. Let's say the micro doesn't need to run for more than 3 minutes in a 4 hour period. We need our morning coffee and as it warms up, we'd like to cool down, neither must run from an inverter. While most run 12V air compressors, 120 V are faster and the tanks are on board. (Besides, that's what I got)

The fridge is the only full time duty appliance and it can be disconnected if needed to run other things.

None of the items need to be running at the same time.

So, here are the questions.....

Generator, battery (bank), inverter, solar, shore power at times.

What is the most economical set up? A combination of what? Let's keep the whole power system under a grand!

A generator could run the big appliances, A/C, coffee pot, compressor and charge the battery bank, but what size, maybe a 1500 watt would do, but 3500/4000 watt is about the same price, is bigger better?

How big of an inverter is really needed?

Is solar really a viable option? 100W to 200 W?

Off grid for a week requires power conservation, how long can a small mobile set up last?

What we're looking for here is a combination of power sources, not just off batteries but not from a generator running 24/7. How would you mix it up?

:coffeedrink:

 

[Bbasso]

With the A/C alone you'll need a generator, might as well use it for everything else...
Just seems like you need to reduce your electric needs.

I'm a full-time Vanner and have everything you have on the list except for A/C and live comfortably with 200wt of solar.
And I have a 26 inch tv...

Can be done, but there are compromises

 

[Scoutn79]

You mention a lot of items and say they don't all need to run at the same time bit how long will each run in a 24 hr period?
You don't mention if you are in a vehicle where you could run the engine to charge the batteries if need be, or a camper.

Your A/C might draw less. An 8k btu window unit typically draws 9A.
As mentioned your going to need a genny to run the A/C, might as well fire it up for the coffee and nuker too. It's always nice to have a backup power source.
That leaves the 12v stuff. Figure the 12v usage over a 24 hr period. Will a 100W panel put out enough over the available daylight hrs? Is it typically shady/cloudy where you camp? Are you going to be able, and willing, to make sure the solar panel stays in the sun all day?

These questions need to be answered by you based on where and what time of year you camp. For instance in the summer you may get power to some extent or another from 7am -8pm and in the winter maybe only 8am to 4pm. I figure my 100w panel puts out around 45a (unscientifically measured) on a summer day in full sun just laying flat on the top of the camper.
Obviously if you had a big enough battery bank you could run this stuff all for a week easy, you could also do it on a small car battery, if you had enough alternative sources. I always try to figure unlimited staying power, IE I have a way to keep my battery charged no matter what the weather or how long I go for.
In my small camper I have a single gp31 battery and 100w solar but it is a pop up camper with a 12v fridge, led lights and a small fan that runs all night. The solar keeps me in juice easily. If all else fails I can hook jumper cables from the truck to the camper battery, but never have had to.
In our hardsided camper for elk hunting, with maybe 8 hrs of usable light, we have 3 gp31 batteries, 100w solar and a D/C genny. Hunting partner uses a CPAP w/ heater, the furnace runs quite a bit at well below zero temps, we watch a movie or two at night and charge batteries for radios, tablets etc. In the morning I run the genny for an hour or so (since we watched a movie, ran the CPAP and furnace all night this puts the bulk back into the batteries) and then the solar tops off the batteries during the day and gets us ready for the next night.
We took the nuker out as we never used it and do coffee on the cooktop.

Darrell

 

[Ozarker]

With the A/C alone you'll need a generator, might as well use it for everything else...
Just seems like you need to reduce your electric needs.

I'm a full-time Vanner and have everything you have on the list except for A/C and live comfortably with 200wt of solar.
And I have a 26 inch tv...

Can be done, but there are compromises

I'm thinking you have a large battery bank then, can you explain more about that? And.....26 inch in a van, very cool!

Can't run the genny while driving, as Scoutn mentioned I didn't say what vehicle....it's an Astro van and trailer similar to a Jumping Jack but with a different tent layout, homebrewed utility type. Thanks for the info

 

[dwh]

As mentioned your going to need a genny to run the A/C, might as well fire it up for the coffee and nuker too.

Or just use the stove, which is probably propane, and leave the microwave at home.

I figure my 100w panel puts out around 45a (unscientifically measured) on a summer day in full sun just laying flat on the top of the camper.

Gotta be a typo there. Either 4.5a (per hour) or 45ah (amp*hours) (per day) makes more sense. Though the 4.5a per hour makes the most sense.

the heater runs a bit

RV style furnaces can draw a lot. there's another load the OP will have to figure if he uses the camper in the cold.





So...under a grand eh?

Pair of 6v golf cart batteries in series to start with.


Small Champion genny:

http://www.championpowerequipment.com/products/generators/

I used to have a 1200/1500. $200. They upgraded it and now have a 1400/1800 version. Saw it at Tractor supply for $250.

Should run a 5k btu window shaker. And is a lot smaller and lighter than a 3000. Loud enough to irritate the neighbors.

Halfway decent battery charger. Maybe a 25a Iota with IQ/4 brain. Small enough to run off the genny.


Can also run the air compressor off the genny. Or get whatever size inverter to run it.

Big inverters aren't cheap though.

Without the a/c, micro or air compressor, you could get by with a small inverter. 400w might even be overkill.

 

[dwh]

If there's anything left out of the grand, add some solar.

 

[john61ct]

What is the most economical set up? A combination of what? Let's keep the whole power system under a grand!

Sorry, but completely ridiculous budgeting there! Even if you spend six months smart shopping Craig's List and eBay just not realistic.

Just a decent genny is more than a grand, you're going to be racking up the hours with A/C.

A decent battery bank at least a few hundred, a good charger a few hundred, maybe combine with inverter, then lots more.

And unless you're getting to overnight shore power frequently, solar is required to get the bank up to 100% full, which is needed for longevity. Some consider a battery monitor optional, I don't.

Do you want to charge House off alternator while driving? Combiner or Echo Charger, and/or LVDs. . .

Wiring, crimping, switches, buss bars, fuses, distribution box etc needs a fair amount to be done right.

 

[Ozarker]

You mention a lot of items and say they don't all need to run at the same time bit how long will each run in a 24 hr period?
You don't mention if you are in a vehicle where you could run the engine to charge the batteries if need be, or a camper.

Your A/C might draw less. An 8k btu window unit typically draws 9A.
As mentioned your going to need a genny to run the A/C, might as well fire it up for the coffee and nuker too. It's always nice to have a backup power source.
That leaves the 12v stuff. Figure the 12v usage over a 24 hr period. Will a 100W panel put out enough over the available daylight hrs? Is it typically shady/cloudy where you camp? Are you going to be able, and willing, to make sure the solar panel stays in the sun all day?

These questions need to be answered by you based on where and what time of year you camp. For instance in the summer you may get power to some extent or another from 7am -8pm and in the winter maybe only 8am to 4pm. I figure my 100w panel puts out around 45a (unscientifically measured) on a summer day in full sun just laying flat on the top of the camper.
Obviously if you had a big enough battery bank you could run this stuff all for a week easy, you could also do it on a small car battery, if you had enough alternative sources. I always try to figure unlimited staying power, IE I have a way to keep my battery charged no matter what the weather or how long I go for.
In my small camper I have a single gp31 battery and 100w solar but it is a pop up camper with a 12v fridge, led lights and a small fan that runs all night. The solar keeps me in juice easily. If all else fails I can hook jumper cables from the truck to the camper battery, but never have had to.
In our hardsided camper for elk hunting, with maybe 8 hrs of usable light, we have 3 gp31 batteries, 100w solar and a D/C genny. Hunting partner uses a CPAP w/ heater, the furnace runs quite a bit at well below zero temps, we watch a movie or two at night and charge batteries for radios, tablets etc. In the morning I run the genny for an hour or so (since we watched a movie, ran the CPAP and furnace all night this puts the bulk back into the batteries) and then the solar tops off the batteries during the day and gets us ready for the next night.
We took the nuker out as we never used it and do coffee on the cooktop.

Darrell

Well, I almost got it, the nuker might run 3 min in 4 hours, going down the road in an Astro Van, It sits on top of a Truck Fridge with a small freezer.
At camp the nuker may run 10 minutes, cooking and that would be a generator thing.
A/C will be on for up to 10 hours a day, that requires a generator.

Generator with the air compressor, but that's as needed, it could run off an inverter, say 5 minutes worth from 12 V.

Everything else can run off the house battery as needed or the vehicle battery. Movies are from a lap top, stereo is on the cell phone or other goodies, that won't see much use really.

I listed the coffee pot and may well use fire instead, it won't take long with propane.

You're probably right about the draw from the AC, it's in the storage building and don't want to dig it out yet, but it is an efficient unit.

As to solar, we generally hang out in the woods, so that is shaded but there are sunny spots to reel out the wire for. As we head west we'll be in more sunlight all day. Let's say half the power of a rated set up, 50 for a 100 watt unit and that's pushing it. Probably not much of a sun chaser since we won't be at camp much of the daylight hours, at least we don't plan to be.

I was thinking of slapping a solar array on the roof of the van, but just realized that won't be practical unless we are on the rod, so that means the solar needs to be movable.

Now comes the economics, solar vs generator, I'm thinking the genny wins and is more reliable.

Again, what size generator, is it to run the AC and then charge a battery bank or just use a single battery and more of the generator? Where is the happiest medium?

And, additional info, say you stay in one place for 3, 4 days tops, then basically driving for 2 or 3 days with sleep overs ad not setting up the full camp site....basically on the road. In more remote areas the generator could charge a battery in the evening/night.

I thought I'd have one house battery in the van and one in the trailer, plus my starter battery, hope there is no need for more than 110 Ahr deep cell types.

But. lets start from a clean slate, we have the power requirements, but what mix and match might be best?

 

[Ozarker]

Sorry, but completely ridiculous budgeting there! Even if you spend six months smart shopping Craig's List and eBay just not realistic.

Just a decent genny is more than a grand, you're going to be racking up the hours with A/C.

A decent battery bank at least a few hundred, a good charger a few hundred, maybe combine with inverter, then lots more.

And unless you're getting to overnight shore power frequently, solar is required to get the bank up to 100% full, which is needed for longevity. Some consider a battery monitor optional, I don't.

Do you want to charge House off alternator while driving? Combiner or Echo Charger, and/or LVDs. . .

Wiring, crimping, switches, buss bars, fuses, distribution box etc needs a fair amount to be done right.

Well, I see your point, higher quality pieces might take 5 times that budget or more, I have more than that in my radio and more than that in my entertainment unit.

But. sticking all this in my AWD Astro would triple the value of the vehicle, LOL.

I have one trolling motor type battery, that can do something, I can get another one as well.

Lots of decent portable generators can be had for $400 or less, no, not state of the art but they put out juice. I have no real need for pure sine wave juice really.

Lots of 1500/1200 watt inverters for under $300 too, again, not state of the art, but they can produce 110V from 12V.

Solar can be had for $200, not state of the art, but Harbor Freight stuff, controller included.

$100 in wire and you're there......

But, that's not including additional batteries or $50 switches or marine panels.......point taken.

Okay, budget is $2,000.00, now throw in the Alpine and we surpassed that vehicle blue book value; LOL!

That also might get some better stuff than the China cheap stuff, but throw away can work and over ten years be cheaper to use.

 

[calicamper]

Sounds like heavy power gear for a small van to cart. It seems like the long timer types dump the AC by simply being in more enjoyable climates.

 

[Ozarker]

Or just use the stove, which is probably propane, and leave the microwave at home.




Gotta be a typo there. Either 4.5a (per hour) or 45ah (amp*hours) (per day) makes more sense. Though the 4.5a per hour makes the most sense.




RV style furnaces can draw a lot. there's another load the OP will have to figure if he uses the camper in the cold.





So...under a grand eh?

Pair of 6v golf cart batteries in series to start with.


Small Champion genny:

http://www.championpowerequipment.com/products/generators/

I used to have a 1200/1500. $200. They upgraded it and now have a 1400/1800 version. Saw it at Tractor supply for $250.

Should run a 5k btu window shaker. And is a lot smaller and lighter than a 3000. Loud enough to irritate the neighbors.

Halfway decent battery charger. Maybe a 25a Iota with IQ/4 brain. Small enough to run off the genny.


Can also run the air compressor off the genny. Or get whatever size inverter to run it.

Big inverters aren't cheap though.

Without the a/c, micro or air compressor, you could get by with a small inverter. 400w might even be overkill.

Thanks, I know you like the old Champion, I've been looking at them based on your comments from other posts.

Momma won't leave without her micro or AC, but yes, the coffee pot is up for debate.

I just upped the budget, so I wouldn't look so cheap but I think it is doable at about a grand. I can make a switch out of a piece of 2x4 and two 16 penny nails! LOL Anyway.......

Hoping you'd chime in, I'm really trying to approach this as a way of planning a system of pieces to the whole, not just what "I" can use but anyone might consider helpful in putting a similar power source together.

I'm wondering.....large battery bank, larger inverter, small gen set for additional heavy lifting and charging with more solar? Or, big en set, small battery bank, mid size inverter nominal solar?

Looking for combinations that offer the best value and that would be reliable power, not state of the art required for instruments or gizzmos.

 

[Ozarker]

Sounds like heavy power gear for a small van to cart. It seems like the long timer types dump the AC by simply being in more enjoyable climates.

LOL, If you only knew what this "little van that could" has to haul, between the van and a trailer it can take it, plus more dog food

Need to go everywhere, I could go the snowbird path, but that's not an adventure.

BTW, heat will be propane, kerosene and wood if needed. Electric isn't needed for the heaters.

 

[jonyjoe101]

Go to hurriedyear website and you can see what it will take to run an AC in a van, he runs his with just solar and 500 lbs of agm batteries (3x 260ah agm batteries). The small AC he has can probably run off one of the small fuel efficient honda generators. Very informative website it shows you what parts he used to make his system.

But on a small astrovan it will be very cramp. The AC is the only thing that will probably need a generator, everything else can be run off a large enough batterybank. If your in a drier climate a swampcooler can replace the AC and that can run all day just on batteries. Thats all I been running on my astrovan for the past 4 years, uses less than 3 amps. It works good enough for me and I'm always parked in the sun. Don't overlook installing thick foam insulation. The foam insulation will make the AC or swampcooler more efficient.

If your going to get solar, get at least a 240 solar panel, thats what I have on the roof of my astrovan. With a cheap ecoworthy mppt controller I can get up to 15 amps of charging current. You want to quickly top off your batteries the following day.

The elephant in the room is the batteries. I moved to lithium about a year ago and wouldnt go back to lead acid. They are expensive but there performance is worth it. For all your power hungry appliances, lithium would be perfect. I build my own lithium batteries, I have a 94ah, 65ah and 33ah lithium batterypacks, for the past 2 weeks I have been using the 33ah batterypack as my house battery, I run my netbook/lights and swampcooler until midnight with that 10 pound batterypack. I'm getting ready to build another 100ah (30 pound) lithium battery pack. You can never have too much power.

Power to weight ratio of the lithium is at least a 3rd of what lead acid is. There is a video on youtube that shows the performance between lead acid and lithium "lithium battery test versus gel". On worst case scenario where you put a heavy load on the battery and run it until low voltage shutoff, you get 94ah of usable power from the 100ah lithium and the 220 ah lead acid only gives you 73 ah of usable power, the 100ah quit after only delivering 31 ah of usable power. In other words to run a microwave or coffepot you need at least 200 ah of lead acid. The smaller lead acid will drop too much in voltage requiring the battery to compensate with more amps and draining itself even quicker.

 

[dwh]

Momma won't leave without her micro or AC, but yes, the coffee pot is up for debate.

Well if you gotta have the microwave, which means a big inverter, the coffee machine becomes a non-issue (except maybe running its hot plate for hours).

You won't run the a/c off the battery bank. So you need a genny big enough to run the a/c or the air compressor (whichever is the heaviest load).

And preferably, the a/c and the battery charger (what the hell, the genny is running anyway, might as well).

I'm wondering.....large battery bank, larger inverter, small gen set for additional heavy lifting and charging with more solar? Or, big en set, small battery bank, mid size inverter nominal solar?

Depends on what you mean by large battery bank. Four Trojan T105 6v GC batteries rigged series/parallel for 12v can get you a 450ah bank.

To make the math easy let's assume 600w for the a/c with compressor running.

450ah x 12v = 5400 watt*hours
5400wh ÷ 600w = 9 hours.

So if you are prepared to sacrifice the batteries, you could get 8 hours of a/c run time (more if the compressor doesn't run constantly) before the bank was dead.

With T105s you can do that around 500 times before they are shot.

Now figure the 1400w Champ. Battery charging at 14v would be 100a to the battery. But that's a bit much load for a 1400w genny. So say a 55a Iota.

55a x 14.5v = 800w

Enough to run the a/c and still have 200w (÷ 14.5v = 14a) going into the battery bank.

So run the gen during the day to recharge and power the a/c. Run the a/ off batteries at night.

IF you treat your house batteries as disposable and IF the a/c is small. If you want long battery life, then you would need to double the bank to 8 batteries.

And of course that's running the a/c off the inverter (couldn't run the a/c and 55a battery charger both from a 1400w gen, so you run the charger off the gen and run the a/c off the charger).


And the battery/inverter will be big enough to run the micro or air compressor for a good long while without firing up the gen.


If you go with the small battery, large gen scenario, you'll be running that gen all the time.



And forget the HF solar, get something decent. You want more watts per square foot of limited space.

 

[Bbasso]

I'm thinking you have a large battery bank then, can you explain more about that? And.....26 inch in a van, very cool!

Can't run the genny while driving, as Scoutn mentioned I didn't say what vehicle....it's an Astro van and trailer similar to a Jumping Jack but with a different tent layout, homebrewed utility type. Thanks for the info

sorry if my post was misleading. First my battery bank is 310 amp hour. The house batteries are charged two ways one, by solar, second, by the vehicle dual alternators through a blue sea 7622.
All of my cooking is done with fuels, alcohol or propane.
I have two 110 Appliances, my tv and electric shaver. Everything else I have uses 12-volt. My heat is also 12-volt but the fuel is diesel, espar D4.