Laptop on an inverter

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Scout

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For those of you who watch movies on your laptop do you use your computer battery until it gets low and then plug in it or do you plug it in to the inverter right away. It seems like it would use more power to have it constantly maintaining the battery rather than just charging it. If i could get through a whole movie without my laptop dieing then recharge with the computer off i think that would be ideal but it dies too soon.
 

DLTooley

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First off - we believe it is more efficient to charge a laptop straight from 12v rather than use an inverter. This will save inverter load and efficiency loss.

I would design my system to meet my usage patterns and if you need to plug in your computer to finish a movie, do so.

I charge my laptop after my solar goes to float so it never touches my battery. A smaller solar generator in the 1-2 hundred watt hour could be charged during that same period and would provide other benefits as well.
 

Weight

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I'm not a 'we'. I use my small sine wave inverter for my lap top. I do use the direct 12 volt supplies for my tablets and phones. I have far too much invested in the lap top to mess around with less than reliable power supplies. Except for the loss from the inverter, you will use as much energy by having the charger on while you use the lap top as if you wait and charge when needed. Maybe a bit more by waiting and charging a depleted battery.
 

DLTooley

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Laptops aren’t true 12v devices. As I recall they run on 19v. The relative merits of upconverting to 19v or downconverting from 120v are above my pay grade. I don’t see any benefit to a sine ac device when it is converting to dc.
 

Scout

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The reason i asked is because with the laptop on and running, movie playing, or really just on no movie playing the fan on the inverter runs constantly. Obviously becuase its drawing more power being on. This is why I'm not sure the best way to do it.
The actual charging of the battery is the same whether on or off but the extra load of being on draws more from the inverter. Of course not being plugged in draws the computer battery down faster, needs recharged sooner for longer so maybe it evens out. What do you think?
 

RVTravel

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My 13" Macbook Pro uses about 10 watts running on 110V. Have you checked yours? At home I never run it off it's own battery...always plugged in. To run (not just charge) it on 12V I would want a pure sine wave inverter or regulated modified sine wave inverter like Kensington sells.
 

Weight

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Some inverters are better than others.
 

Scout

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I have a Schumacher 410 modified sine wave. $40 from lowes.
 

7wanders

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I have a macbook pro and instead of using 110v and an inverter, I opted to buy a 12v cigarette style plug adaptor which goes directly to the laptop (DC to DC). I've been using it for about 7 months now and it works fabulously well. I found mine on Amazon. you might consider looking for one for your model as a simpler and more efficient solution
 

RVTravel

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7wanders, do you only charge the laptop in sleep mode or off with that adaptor, or do you run the computer while hooked up on wifi?
 

tx2sturgis

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Let me state it this way:

If your power situation is so critical that a few watts either way will make or break your power 'budget' for the day, then either stop watching movies or watch them during daylight hours (with solar input) only.

Now having said that, if you have sufficient power budget, it really comes down to cycling the laptop battery, or not cycling it. Laptop batteries do not last forever. 

Cycling them DOES mean that each charge-discharge cycle removes one cycle from however many cycles it will provide. If it can fully cycle 1000 times, and you fully cycle it 300 times a year, that's around 3 years of life, and then a new battery will be needed.

If however, you only fully cycle it 50 times a year, you could get many more years of battery usability than the hard drive and screen and keyboard and operating system will probably be usable for. 

If at all possible, I run my laptops on external power whenever I have it available.
 

Scout

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tx2sturgis said:
Let me state it this way:

If your power situation is so critical that a few watts either way will make or break your power 'budget' for the day, then either stop watching movies or watch them during daylight hours (with solar input) only.

Now having said that, if you have sufficient power budget, it really comes down to cycling the laptop battery, or not cycling it. Laptop batteries do not last forever. 

Cycling them DOES mean that each charge-discharge cycle removes one cycle from however many cycles it will provide. If it can fully cycle 1000 times, and you fully cycle it 300 times a year, that's around 3 years of life, and then a new battery will be needed.

If however, you only fully cycle it 50 times a year, you could get many more years of battery usability than the hard drive and screen and keyboard and operating system will probably be usable for. 

If at all possible, I run my laptops on external power whenever I have it available.

Thats a good point
 

frater secessus

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Counterpoint:  lithium chemistries don't like being full all the time.  I'd imagine apple hardware is smart enough to charge to 100% then let it fall to something like 95% if left on the charger.


At home I never run it off it's own battery...always plugged in.

At home you might want to consider pulling the battery when plugged in all the time.  Maybe run it down to 50% state of charge before pulling it. 
Car adapters are usually about $20 for third party and $50 for OEM.  eBay usually has a lot of listings for used or NIB OEM chargers for maybe half price.
 

RVTravel

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My lithium ion battery stays 90-100% charged. I bought it in 2010 and it is still going strong, used every day that I am in town ; ).
 

lenny flank

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tx2sturgis said:
Cycling them DOES mean that each charge-discharge cycle removes one cycle from however many cycles it will provide. If it can fully cycle 1000 times, and you fully cycle it 300 times a year, that's around 3 years of life, and then a new battery will be needed.
Meh, after three years the laptop itself will be an obsolete dinosaur and I will already have replaced it once or twice.
:)
 

tx2sturgis

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frater secessus said:
Counterpoint:  lithium chemistries don't like being full all the time.  I'd imagine apple hardware is smart enough to charge to 100% then let it fall to something like 95% if left on the charger.

All of the common, quality brands of laptops employ smart-chargers so the 'storage while fully charged' issue is...well...mostly a non-issue when plugged in. 

Also, many of the replaceable and non-replaceable lithium based laptop batteries have a life counter (charge/discharge cycles) built-in to the smart circuitry. Exceed the factory limit of charge cycles and the battery goes into lock-out mode and essentially dies, even though it still has some usable capacity. 

Hey, its a 'safety' feature. 

But there are software tools available to reset the charge/discharge cycles, and/or allow the owner to change the min and max charge levels reported to the OS. This can extend the usable life of a battery, although with a slight risk of cell-imbalance and the resulting damage that this can cause.
 

tx2sturgis

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RVTravel said:
My lithium ion battery stays 90-100% charged. I bought it in 2010 and it is still going strong, used every day that I am in town ; ).

That's pretty much my experience with laptops. You can extend the life of the battery, by not depleting it very often...just like any other rechargeable battery.
 

tx2sturgis

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lenny flank said:
Meh, after three years the laptop itself will be an obsolete dinosaur and I will already have replaced it once or twice.
:)

Landfill killer!  :p

I have kept several laptops going for years by upgrading the OS and replacing hard drives, batteries, trackpads, and keyboards...in the early days of laptops, it was the stupid hinge or monitor frame/hinge and ribbon connectors, that broke or got weak long before the laptop itself was obsolete. This was usually an expensive, time consuming repair. 

Today it seems the hinges and frames pretty much last the life of the laptop, with the exception of the super-cheap netbooks.
 
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