Running a Computer Off a Battery

[KayakGirl]

OK -- probably a silly question, but I am going to ask it anyway as I know next to nothing about these kinds of things.
Does anyone know approximately how long you could run a computer off a battery? Nothing else on the battery, just the computer, before the battery would need to be recharged (no solar panel involved, just the inverter to get the power to the computer)?

 

[blars]

Without knowing the battery or computer, it's imposible to answer. Somewhere between seconds and years.

 

[freenez2]

If you're talking about the starter battery, a volt meter that plugs into the cigarette lighter will tell you what the charge state of your battery is. That way you'll know how far down the battery is and when to stop using it. Volt meters are pretty expensive too. As a rule of thumb, using the starter battery for things like that is a no no. The starter battery should only be used for starting your vehicle.

 

[KayakGirl]

No, not off the car battery, a deep cycle battery through an inverter. I am not going to be able to afford solar panels right now, but do want to be able to use my computer if possible.

 

[SoulRaven]

Desktop with 110v ac monitor, laptop, netbook?

What size is the battery?

How do you plan to charge the deep cycle?

 

[KayakGirl]

Mr. LooRead, desk top and monitor unless that is out of the question, then it would be a laptop. I have no idea what the size of the battery will be, but was thinking one of the deep cycle batteries. The recharging of the battery would take place back home (are they charged differently than a regular battery?). You see, I am not van dwelling yet, but checking all options, but want to do a few weekend/week trips here and there for the time being.

 

[Hereandthere]

Definitely go for a laptop rather than a desk top and monitor! It will take up WAY less space, be much more likely to survive the bounces of travel, and you'll be able to go into a coffee shop or library with it... I know this isn't what you asked but it's also going use way less power than a desk top and monitor.

 

[rinella]

There are a lot of variables in your question that need to be answered, and even then, I don't think anyone will be able to tell you definitively how long your battery would last. The best answer you will get will probably just be suggestions on how to maximize battery life.

An inverter is horribly inefficient! You'll be using up precious amps to convert to AC. Without knowing about your battery or laptop, I can tell you that getting a DC to DC adapter for a laptop is going to yield your longest run time. A laptop is nearly always going to have less power draw then a full desktop as well.

 

[SoulRaven]

You are going to have to use the laptop with a 12volt DC adapter vs. an inverter.

The DC adapter will have the amount of amps it takes to run listed on the product.

Also you will need to adjust your power settings to use as little power as possible.

I travel with an Acer Win 7 netbook at the moment and with the DC adapter, it uses 1.2 amps per hour continually. So in theory with a fully charged group 24 70-amp hour battery I would get about 29 hours of use bringing the battery down to 50%.

 

[akrvbob]

Kayakgirl, as you've seen, when it comes to 12 volt electricity, there are no simple questions or simple answers. Let me give you some general guidelines:

1) A desktop draws too much for your plans, get a laptop.
2) Get as energy efficient laptop as you can.
3) Before you buy it, search Amazon or eBay to be sure you can get a 12 volt charger for it. Don't but it without one.
4) Can a tablet meet your needs for short trips? Or a large phone like a Note 3 or iPhone 6+ work for you?
5) The largest Walmart Marine battery will probably charge your laptop just fine for short trips as long as you have an energy effecient laptop.
6) Keep the receipt and if you wreck the battery on these trips, they will replace it. Plus, its cheap enough it won't break you if they won't.
7) Expect to wreck a few batteries in the beginning. It's part of the learning process and so buy a cheap one with a good warranty.
8) Remember, you can always take the laptop into a Library, Starbucks, or MacDonald's and charge it while you are working! Many WIFI hotspots will let you charge it. One cool trick is to put all you electric devices into a book-bag and plug them all into one power-strip. When you go into the Library plug the power-strip in and you are charging all of them at once and no one else will know!
9) get a cigarrete lighter voltmeter to plug into the house battery. It will give you a basic idea of its charge.
10) If the battery gets low, once you are stopped you can take it out, set it on the ground up front and hook it up by jumper cables (you should be carrying those no matter what!) to the starting battery. Run the engine for about 15-30 minutes while you step on the gas so it is above an idle. You'll waste gas but it will put quite a bit of power into the battery.

I predict you will fall in love with it and when you do you should start charging the house battery from the starting battery. Check back with us and we'll tell you how!!!!

You are going to have a great time. And if there are some problems along the way, one day you will look aback at those as the best memories of all!!
Bob

 

[Iggy]

A tablet takes even less energy but there is a definite tradeoff on screen size and things you can do with it versus a real computer. I do most things on an Android which is even more limited. But it works for me. Just need an operation to uncross my eyes now.

 

[KayakGirl]

Thank you to all who answered my clear-as-mud question. Wow, my head is spinning, but looks like the consensus shows me it will have to be a laptop. I do genealogy and need to be able to run my tree program, plus I do occasional transcription work; it would be lovely to be able to do that on the road (a netbook won't run programs and obviously a phone won't work either). Love the idea, Bob, of charging it ALL at a WIFI hotspot. I think for now, that is the way to go, but I definitely have food for thought. And when the time comes, I will definitely be getting back to you on how to start charging the house battery from the starting battery. OK, now where did I put that book bag?...............:-D

 

[SoulRaven]

My netbook is a 2011 model running win 7 with a 250 gig hard drive.

 

[amwbox]

As a long time computer enthusiast, a few options spring to mind:

1. If you simply MUST use your existing desktop, (and you haven't given any specifics about it, so I'm spit-balling, but I do undstand. I'm a designer by trade and NEED a large display) and you have or know someone who has some PC knowledge, there are ATX power supplies that will run directly on 12 volt:

http://www.mini-box.com/DC-DC

This would convert your PC into a 12 volt only device. So, you'd have to do some rewiring to put it back on wall plug AC power. But this is literally the most power efficient option. MUCH better than an inverter.

2. The best option is a small, low power laptop. Mine only draws 35 watts.

3. A low power desktop option, to use with your monitor and accessories, is a Mac Mini. They are basically laptops in a cute little box pretending to be desktops....but they are extremely simple, and use no more power than a laptop would.

Bear in mind, a typical PC and monitor aren't designed with efficiency in mind, and even the low end ones will draw around 200 watts best case. So, compared to a typical laptop, you will deplete you battery about 6 times faster with a desktop than a laptop.

 

[GrayWhale]

You can buy a new, DELL 15" laptop that's very decent for $199 at Micro Center. Win 8, 4g ram, 500g HD.

 

[Optimistic Paranoid]

There is one other option that no one else seems to have mentioned.

You're not living fulltime in your van, you're talking weekend trips and charging a house battery at home. You're also now considering a laptop.

You can buy extra laptop batteries, charge them all at home,and just swap them as needed.

I'm not saying this is necessarily the best way to do this, but just be aware that it IS a workable option.

Regards
John

 

[KayakGirl]

There is one other option that no one else seems to have mentioned.

You're not living fulltime in your van, you're talking weekend trips and charging a house battery at home. You're also now considering a laptop.

You can buy extra laptop batteries, charge them all at home,and just swap them as needed.

I'm not saying this is necessarily the best way to do this, but just be aware that it IS a workable option.

Regards
John

Thanks John. I did look at getting an extra battery or two for the wonky laptop I have and use in my craft room as kind of a last ditch effort to keep me plugged in. The only thing is that I was hoping to begin getting some of the things that would work now AND later on when I begin spending more time on the road. i.e. the deep cycle battery to use now and when I convert over to solar. I don't want to spend money on two different setups if I can help it, but your suggestion looks to be about the least expensive way to go for now.

 

[sephson]

I have a small, 350 watt, portable solar power supply with a 30 watt briefcase style solar panel. I can also charge it from a 12 volt DC power port in my car or from a standard 120 volt AC household receptacle. While on the road, this system does a decent job of keeping my laptop, which has an 82 watt power supply, my cell phone and my camera charged. Granted, if I was full timing on the road or had greater power needs, I would build a house battery system, but as things stand this portable system meets my needs just fine.

The system I have is no longer made, having been replaced with a newer model, but something similar may work for you too.

 

[Optimistic Paranoid]

Thanks John. I did look at getting an extra battery or two for the wonky laptop I have and use in my craft room as kind of a last ditch effort to keep me plugged in. The only thing is that I was hoping to begin getting some of the things that would work now AND later on when I begin spending more time on the road. i.e. the deep cycle battery to use now and when I convert over to solar. I don't want to spend money on two different setups if I can help it, but your suggestion looks to be about the least expensive way to go for now.

Makes perfect sense, but the question then becomes, what sort of time frame are you looking at to go full time? A house battery may only last 5 years or so. You might be better off holding on to your money and putting the house battery in just before you go full time.

Regards
John

 

[GrayWhale]

this: http://www.harborfreight.com/12-volt-jump-start-and-power-supply-38391.html

or this: http://www.harborfreight.com/13-watt-briefcase-solar-charger-68750.html