How long can you run appliances?

[Kroswind]

I'm pretty new to all this and am looking to build a stealth camper van. What I'm wondering is, how long will my appliances run for on a solar battery system and what would I need to achieve long run times? I plan on spending most of my time in the van and want to run some appliances all day generally speaking. What I want to run generally all day is a TV and a high end laptop. The other electrical needs in my van would be a coleman portable hot water heater, and a hair dryer. These wont need to be run all the time and will be ran by themselves without anything else on in the van and will only run for short intervals.

What kind of solar panel/battery bank system would I need to be able to achieve something like this? Is this even possible to do with a solar set up in a van? I have also been looking at the yamaha ES2000 inverter generator that I would like to get. From what I could gather so far, this will probably be the best route, as I dont think you can generate much solar electricity in a cargo van and battery banks generally dont last that long and take a really long time to recharge. The inverter generator seems to generate 1600 watts of electricity and I think that would be enough for what I need, but I'm not sure. They say this yamaha generator can run for about 10 hours on 1 gallon of fuel, but I have no idea what kind of load thats under.

I know this probably all sounds somewhat vague, but is there any advice anyone can give me? What kind of set ups do you guys run and how long can you run stuff on them? I dont know much about amps, watts, and how to calculate all this honestly, so I'm a bit in the dark and dont really know where to start my research.

 

[highdesertranger]

well it is somewhat vague. you need to do the math. I know yuck math. you must find the watt/hr or amp/hr for everything you want to run, then figure how long you want to run in hours per day. then you can see what type of battery and how much solar you need. highdesertranger

 

[akrvbob]

You don't give us much info. here are some thoughts:

My TV draws 25 watts so including the inverter loss that's about 3 amps an hour. If it's on 8 hours a day that's 24 amps. That's doable.

The laptop is the unknown. You're going to have to find its draw. I have a 15 inch intel I7 with 12 gigs of memory and Nvidea video card and with inverter loss it draws about 8 amps. Again, that's doable. If it's on for 8 hours thats 64 amps.

Together they draw 100 amps per day. If you have 400 watts of solar and 4 golf carts you have 200 amps available per day. That's marginal, you really don't want to plan on taking your batteries down by half every day. You can, but less draw would be preferable.

The hair dryer is almost certainly a no-go, much too high a draw. Tell us more about it so we can be sure.

Bob

 

[LeeRevell]

I watch TV via my laptop (Netflix and Hulu). No need for a dedicated TV/DVD combo. I do not watch TV and try to use a computer at the same time. A small portable stereo provides background sound while I am on the laptop.
Just trying to get an idea of why certain things are being used at the same time?

 

[Kroswind]

Thanks for the replies guys. I'm still at the planning stages and I'm trying to gauge what kind of set up other people have, and just how much could possibly be run for extended periods of time. My budget at this point in time is basically unlimited as I still have plenty of time to actually build the system and the van before I'd head out on the road, so I'm open to many different types of set ups.

For reference, this is the type of laptop I would be looking at http://www.newegg.com/Product/Product.aspx?Item=N82E16834232276

My friend has a very similar laptop to this one, just a year or so older than this model but with very similar specs and he says it draws about 9.5 amps. So the kind of laptop I'm looking for would be quite similar to what akrvbob referenced in his post. As for the TV, I would probably be looking at something around a 19-22 inch, or possibly smaller. Most likely a 19 inch since the living space wont be too big.

A little bit of background: I make 3D computer graphics, and spend most of my free time making them. I'd be running a TV and a laptop at the same time because I could potentially use the TV as a second monitor so I could have up reference images or tutorial videos while I'm working on something. I went with the TV idea instead of just a second LCD monitor because the TV is more dual-purpose. If I run in to a situation where wifi isn't available, it would be nice to have a TV handy for entertainment, which reminds me, I would also be running some kind TV antenna to pick up those free, local over the air channels, as well as an extended range wifi antenna. I started looking at alternative living and came across van dwelling and it seemed like the route to go. My goal is to be able to work less hours so I can focus on practicing my art/trade and hopefully get a job doing it one day. So these 2 thing will be ran a great majority of the time, as I plan on staying in the van full time.

So I guess the next question I should ask is, what types of solar panels do most people use? Whats the maximum watts I could get from a solar panel that would fit a van, and how many batteries are appropriate for that set up. In akrvbob's post, he says 4 golf cart batteries would work for the TV and laptop, but it would drain them to 50% each day as I understood it. What type of solar panel would you need for that set up, and would it still be beneficial to add more batteries to that bank to store more power, or would the panels used in that set up not be sufficient to support more batteries?

Regardless of the solar set up, I still plan on having a small generator in addition to the battery bank/solar set up, as I've seen other van dwellers on youtube use a set up like that. This is the generator I was talking about in the first post: http://www.amazon.com/Yamaha-EF2000iS-4-Stroke-Generator-Compliant/dp/B002RWK9N2

I would use this to run what would seem to be heavier-duty items, and also potentially help recharge the battery bank. It generally seems like a pretty handy thing to have and doesn't consume that much fuel as long as its not under real heavy loads it seems. As for the hair dryer, would that be able to run off this generator, or still a no-go? I was positive it wouldn't work on a solar set up and had intended to use it with this generator from the start if possible. Its really just a luxury item, as I have long hair and planned on keeping a camp style shower set up with me. But thats not too important, I can find work-arounds for that. The portable hot water heater seems like it holds a charge on its battery for quite a while, so im not too worried about that and am pretty positive I could recharge it with that generator.

Hopefully this provides more information and gives people an idea of what kind of power needs I have. I can try to provide more information if necessary. I don't really know how much wattage you can generate with "van sized" solar panels so to speak, which is why I'm wondering what type of set up most people have and how long theirs lasts. Obviously it depends on how much you run, so I guess you could say I'm looking for the more "extreme set ups" out there I guess. I want to be able to generate as much power as I can as I run a lot of electronics.

 

[akrvbob]

I have 570 watts of solar and 6 golf carts. I can easily run my

laptop 4-6 hours a day
Jet Pack Verizon internet and Wilson Sleek amplifier 4-6 hours a day
20 inch TV and Satellite Reciever 4-5 hours a day
Whytner 12 volt fridge as needed
microwave 5-10 minutes a day
LED lights 4-6 hours a day.

None of that taxes my system at all. I don't hesitate to use anything I need during the day within reason like small power tools drill, skill saw. I also use my 12 volt Roadpro oven whenever I like.

Bob

 

[SternWake]

Regarding the hair dryer, I ran some numbers for a 1300 watt induction cooktop on another forum. This will give you an idea what a battery can realistically power. Sad to say once you get up in these super high draws, then fulfilling them by battery power alone is just unwise in the extreme.

But having a generator, and using it not only for these high draws, but to recharge the batteries at a high amp rate is what you will have, which most/many will not.

Anyway here is what I wrote on another forum when I saw yet another person think cooking or heating Via battery power was simple and easy and anybody with a single extra battery could pull it off.

The induction cooktop linked, draws 1300 watts on the highest setting, and 600 watts on the lowest setting.

Inverters are usually around 85% efficient so figure 1495 watts on high and 690 watts on low taken from the battery.

Let's also assume these induction cooktops have no issues with Modified Square Wave inverters. It does not specify that it will work on a MSW inverter, it only says that it must be plugged into a standard 15 amp power outlet. It might very well require a true or Pure sine wave inverter, which are significantly more expensive than a modified sine/square wave inverter.

It might not work at all on a MSW inverter, or it might work poorly on a MSW inverter, or it might only work for so long on a MSW inverter before releasing the magic blue smoke.

So on Low, this cooktop draws 56.55 amps at 12.2 volts.
And on High this cooktop draws 122 amps at 12.2 volts.

i use 12.2 volts for figuring out the amperage, but in reality a 56 amp load will very quickly draw a good healthy battery below 12.2v quickly and a 122 amp will likely drop it below 12.2v instantly. As the volts drop the amp draw rises, so the amp draw above is very generous toward the battery and the numbers below.

Factoring in the Peukert effect, which basically states the higher the load the less overall capacity the battery has to give, a 115 amp hour battery under a 56.55 amp load only has 76.82 hours to give, total, and if we take that and cut that in half, since one should really not discharge a lead acid battery more than 50% we have 38.41 amp hours to use.

Under a 122 amp load the induction cooker's highest setting, this healthy and fully charged 115 amp hour battery only has 71.13 amp hours to give until complete discharge and 50% of that is 35.56 amp hours.

This healthy and fully charged 115 A/H battery can power this induction cooker on its highest setting for about 17 minutes before falling below 50% charged.

A healthy fully charged 115 amp hour(at the standard 20 hour rate) can power this induction cooker, on its lowest setting, for ~ 41 minutes before falling below 50%.

Now there is some room for uncertainty/inaccuracy here depending on the actual efficiency of the inverter, and the actual battery voltage under such high loads, as well as the health of the battery and if it was fully charged when the cooking cycle began. There can also battery power wasted heating the copper cables between battery and inverter.

Also, different batteries have different peukert numbers and I used a 1.1 which relates closer to a healthy AGM battery, rather than an abused older flooded battery.

If I use 1.14 as the peukert number that 115 amp hour battery under a 122 amp load becomes a 56.7 amp hour battery, and 50% of that is only 28.35 amp hours to give safely. Once a battery ages the peukert number approaches 1.3 and beyond.

At a Peukert number of 1.3, the 115 amp hour battery under a 122 amp load, only has 27 amp hours to provide until total discharge, and 13.5 amp hours until 50% is reached. Such a battery could power such a load for very little time before the low voltage alarm of the battery starts screaming and shuts the unit off. I doubt you would have enough time to fry an egg over easy.

So in conclusion, if used on an inverter and a small battery bank, these induction units will suck a battery dry very quickly. Even if used on a large battery bank these induction cookers represent a huge draw on the battery bank, and recharging them to full is not as easy as 99.95% of people assume.

Such high loads on a battery are very rough on a battery.
Recharging a battery requires at least 105% and upto 150% the energy taken from it to fully recharge, average is 112 to 115% for a healthy flooded lead acid battery discharged to 50%.

If the battery is not fully recharged every 15 or so cycles it will quickly lose capacity.

While a battery can be recharged quickly to 80% charged with a high amp charging source and adequate cabling, it cannot go from 80% charged to 100% charged in less than 5 hours no matter how big and shiny the alternator.

However if you start the engine and hold it at ~2K rpm you can largely negate the draw of the induction cooker, if the cabling between alternator and battery and inverter are thick enough, Think 0 AWG wiring.

I'll be sticking with Propane for cooking.

Batteries are too expensive, and recharging them properly so that they have a chance at a long life in deep cycle applications is more complicated than most care to think about.

Sorry to be the stick in the mud, but when battery power comes into play, I got to run some numbers and spread the word, so that people have enough battery power to play their music and still start their engines, and not render an expensive battery bank useless, due to overdischarging them followed by chronic undercharging, which equates to batterycide.

If the budget is really unlimited, then look into Lifepo4 batteries and their appropriate chargers/ solar charge controllers, as then one need not deal with all the petulance of lead acid batteries, and their proper care and charging to get an 'acceptable' lifespan from them.

 

[MK7]

I have 570 watts of solar and 6 golf carts. I can easily run my

laptop 4-6 hours a day
Jet Pack Verizon internet and Wilson Sleek amplifier 4-6 hours a day
20 inch TV and Satellite Reciever 4-5 hours a day
Whytner 12 volt fridge as needed
microwave 5-10 minutes a day
LED lights 4-6 hours a day.

None of that taxes my system at all. I don't hesitate to use anything I need during the day within reason like small power tools drill, skill saw. I also use my 12 volt Roadpro oven whenever I like.

Bob

How much does all of this power capabilities cost Bob....all the parts, including fuse boxes, solar controllers, cables, etc.....I bet she needs to know this. I'm guessing, about $3000?

 

[AuricTech]

Since you stated that your budget is "basically unlimited," you might want to look into LiFePO4 batteries, instead of using any of the lead-acid battery types.  They are lighter per Amp-hour stored than lead-acid batteries, and they are far more tolerant of being partially discharged for extended periods of time.  They also have much lower internal resistance, so you can draw power from them at a higher rate than you can from lead-acid batteries.  The big downside, their higher upfront cost, doesn't seem to apply in your case.

I agree with the other posters that any device that uses electricity to generate heat is a non-starter for a vehicle-based photovoltaic system.

Check out the solar power forum to which my sig file links for more information.

 

[akrvbob]

I started building my system 6 years ago and back then paid more for a 50 watt panel than I paid for my 240 watt panel last year. So my numbers aren't relevant.

You can buy a 400 watt kit from Renogy for $670. http://smile.amazon.com/RENOGY®-Solar-Panel-Starter-400W/dp/B00BSZUHRC/
You'll need a few more things like fuses but it shouldn't be more than $50
Four golf carts will cost about $450

So a complete 400 watt system would cost about $1200. That's plenty of power for nearly anyone.

I recommend to most people they start with the Renogy 200 watt kit for about half that price and then add another 200 watt kit if that isn't enough.

Bob