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Adding a 12v outlet using existing lighting


Solo18

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Am I missing something here? We have traveled extensively with two laptops. We charge them right off of the 110 AC outlets. Don't you have the charging/power adaptor that came with your laptop? Why do you need a twelve volt DC outlet?

 

Ray

 

Not everyone is always plugged into shore power or uses a generator (except when necessary to recharge the battery bank). Running on 12v is preferable to running an inverter in such cases. Running 12vdc then inverting it to 120vac then running it through a cord adapter which will convert it back to 12vdc is highly inefficient.

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What the laptop is charged at (the charger's output voltage) really isn't important here, the voltage that the laptop's charger runs at is. You can buy laptop chargers for inputs of 12, 120 and 240 volts. They usually come with one that matches the most common voltage in the country it is being sold in.

 

Charging a laptop from your batteries through an inverter and the laptop's 120 volt charger wastes a lot of power. The inverter wastes 10-20% of your battery power doing the conversion, the laptop charger wastes more converting back from 120 to the low DC voltage your laptop needs, usually 12 to 24 volts. Using a DC to DC converter to get the proper voltage to the laptop usually is more efficient than using the 120 AC to DC converter and it eliminates the inverter losses completely.

First rule of computer consulting:

Sell a customer a Linux computer and you'll eat for a day.

Sell a customer a Windows computer and you'll eat for a lifetime.

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Good morning oldman, hey your picture doesn't look old !!!!!!!!!!!!!!!

 

You state "Excuse my ignorance, but I've never owned a laptop that could be charged from 12v. What about 120?"

 

FYI I have two HP Laptops, both of which have the standard 120 VAC to DC Charging Power Supply adapters, AND THEY ARE 18.5 VDC POWER SUPPLIES. Like

you I don't recall past laptops that used 12 VDC, BUT THERE ARE A LOT OF BRANDS OUT THERE and I cant say what voltage their power supply

adapter/chargers use?

 

Many of our current small electronic devices like cell phones and my I Pod etc. now charge at 5 VDC using the standard computer type USB outlets. My current 12 VDC to 120 VAC Inverter has two 5 VDC USB outlets mounted right on the front case. I also have several of those cigarette lighter type 12 VDC plugs which have one or two 5 VDC USB ports for charging my phone etc from 12 VDC outlets.

 

It seems like 12 VDC (Cigarette lighter type) or 5 VDC (USB type) are the most common used methods of charging small electronics nowadays while HP laptops at least use 18.5 VDC power supplies while other brands may use no telling what (5 or 12 or 18.5 or more) ????

 

As Yarome points out, if you have 12 VDC or 5 VDC already available, it wastes energy and is inefficient to go back and forth from AC to DC or DC to AC over and over again as none of those devices are 100% efficient (have Heat Losses) WELL DUH

 

John T

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I have two very nice coach batteries that always have plenty of charge, even when I am dry camping. (I admit I don't do that often.) I would really prefer NOT to pull current from my vehicle battery, but to pull it from the coach batteries.

I'm not understanding.. you don't dry camp often, or you don't pull from those batteries very often?

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I'm not understanding.. you don't dry camp often, or you don't pull from those batteries very often?

 

Solo18 was referring to not dry camping very often, but when they do, they want to be able to pull from their coach batteries rather than their chassis battery. Hence the thread.. "Adding a 12v outlet".

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FYI I have two HP Laptops, both of which have the standard 120 VAC to DC Charging Power Supply adapters, AND THEY ARE 18.5 VDC POWER SUPPLIES. Like

you I don't recall past laptops that used 12 VDC, BUT THERE ARE A LOT OF BRANDS OUT THERE and I cant say what voltage their power supply

adapter/chargers use?

 

As far as I know nearly all laptops generally still come with 120vac adapters, but like Stan was saying.. the output voltage isn't really important. It's the input voltage that the charger requires that's important. So even your HP 120vac's that output 18.5vdc are capable of running on 12vdc source with the appropriate charge adapter. Ie., my 12vdc charger for my laptop requires 11.5-15vdc (10amp max) and outputs 20vdc 4.5amp juice. ;)

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My Dell laptop did indeed come with the regular 120 volt charger/cord. However, I bought an additional charger/cord that can plug into a 12 volt outlet. It is very similar to this one: http://www.amazon.com/Laptop-Car-Charger-Dell-Inspiron-15-3520-17-3721-XPS-Studio-15/dp/B002UI2Y8Q/ref=sr_1_1?s=electronics&ie=UTF8&qid=1449718330&sr=1-1&keywords=12+volt+laptop+charger When you buy one of these, you have to make sure it is the correct one for your laptop because they sometimes have different power needs. I have the correct 12 volt charger for my laptop.

 

I did that because I wanted to occasionally dry camp without running my generator. First, many campgrounds with no electric hookups allow generators only during limited hours--like the one in New Brunswick, Canada, I was at in early September this year. Generator hours were listed as 7-9 am, noon to 1:00 pm, and 5-7 pm. Ditto for several national parks I have stayed in where there were no hookups. Thus, it is not always possible to plug into 120 anytime you please.

 

So whether this wastes power or not is besides the point when you have only one choice of power--in this case 12 volts from your coach batteries.

 

And you are right that I don't dry camp very often, but I do want the option to do so. My coach batteries seem to last a long time when I do dry camp. In fact, even using them to run furnaces at night and lights in the evening, plus charging my laptop, Verizon jet pack, and cell phone barely phase them. I am easily able to do all those things and run my generator maybe only an hour a day. I don't like to run my generator more often than necessary because the noise irritates some campers.

 

My problem is the location of my existing outlets, so I am going to just go out and buy a 12 volt extension cord. I don't always need to be working a lot of hours per day on my laptop, but there are times of the year when I do need to work as much as 10 hours each day, so that will do the job.

 

Thanks for the help, everyone.

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Excuse me if I've missed it, but you have completely discounted the use of a small inverter?

 

Why would they want to use an inverter off their battery bank if they don't have to? You save the cost of the inverter for the meager price of a 12v adapter, which in turn, is a much more efficient use of their available energy.

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I do have two cigarette lighter sockets on my dash, and it is very convenient, but twice while using the dash sockets to charge my laptop, I ended up running my vehicle battery dead and then had to use the emergency generator to start it. First time, I got stuck in Joshua Tree National Park and almost couldn't get started. (Long story, but I am "known" there for locking my keys in my RV once and having to have them call CoachNet over their radios and having to wait for hours for someone to come. It is getting embarrassing.) The last time I tried using emergency start battery was so bad, it did not work and I had to replace the battery.

 

On the other hand, I have two very nice coach batteries that always have plenty of charge, even when I am dry camping. (I admit I don't do that often.) I would really prefer NOT to pull current from my vehicle battery, but to pull it from the coach batteries.

 

 

My Dell laptop did indeed come with the regular 120 volt charger/cord. However, I bought an additional charger/cord that can plug into a 12 volt outlet. It is very similar to this one: http://www.amazon.com/Laptop-Car-Charger-Dell-Inspiron-15-3520-17-3721-XPS-Studio-15/dp/B002UI2Y8Q/ref=sr_1_1?s=electronics&ie=UTF8&qid=1449718330&sr=1-1&keywords=12+volt+laptop+charger When you buy one of these, you have to make sure it is the correct one for your laptop because they sometimes have different power needs. I have the correct 12 volt charger for my laptop.

 

I did that because I wanted to occasionally dry camp without running my generator. First, many campgrounds with no electric hookups allow generators only during limited hours--like the one in New Brunswick, Canada, I was at in early September this year. Generator hours were listed as 7-9 am, noon to 1:00 pm, and 5-7 pm. Ditto for several national parks I have stayed in where there were no hookups. Thus, it is not always possible to plug into 120 anytime you please.

 

So whether this wastes power or not is besides the point when you have only one choice of power--in this case 12 volts from your coach batteries.

 

And you are right that I don't dry camp very often, but I do want the option to do so. My coach batteries seem to last a long time when I do dry camp. In fact, even using them to run furnaces at night and lights in the evening, plus charging my laptop, Verizon jet pack, and cell phone barely phase them. I am easily able to do all those things and run my generator maybe only an hour a day. I don't like to run my generator more often than necessary because the noise irritates some campers.

 

My problem is the location of my existing outlets, so I am going to just go out and buy a 12 volt extension cord. I don't always need to be working a lot of hours per day on my laptop, but there are times of the year when I do need to work as much as 10 hours each day, so that will do the job.

 

Thanks for the help, everyone.

I bolded the critical info currently provided by you.

To better address your needs please add the following info to our pool of knowledge.

  1. Coach make, model, & year?
  2. Do you compute with it on charge?
  3. Do you charge un-attended ie. while sleeping or away?
  4. What are the electrical specs of the original AC charging brick?
  5. Where do you intend to use this laptop in relation to the dash 12VDC outlets?
  6. Is there more than one location where you would like to use the laptop?
    • Dinette
    • Bed
    • Lounge
    • etc.
  7. Do you have an inverter already in your coach for entertainment devices?
    • TV
    • Home Theater

My limited experience with laptop charger bricks has me thinking of them as rather inefficient at best. (They get hot) This consumes power from your storage bank. The addition of an inverter fails to eliminate the brick (Their efficiencies matter in this regard though.) so just adds an additional draw to support the inverter. If you already are actively using the inverter to power the HT/Stereo while noodling on the laptop then it is all a wash.

 

Getting 12VDC to the locations of choice will depend largely on the coach layout, construction methods, the material used, and location of the house battery bank. Anything is doable, the complexity is what varies, greatly sometimes to be sure.

 

Good luck with getting your coach to support the lifestyle you wish.

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Solo 18: The what you call "charger cord" you linked to is an electronic device (NOT any passive 12 VDC to 12 VDC or less which a particular brand of laptop might require) that accepts typical standard 12 VDC (like an automotive 12 VDC cigarette lighter receptacle) INPUT but has a 19.5 VDC OUTPUT.

 

 

While my HP requires an 18.5 VDC input for charging, it appears the unit you linked is for a laptop that requires a tad higher 19.5 VDC (but my HP may well work fine with it also)

 

THE IMPORTANT THING TO NOTE IS NEITHER MY HP NOR YOUR DELL USE REGULAR OLD UNCHANGED 12 VDC THEY REQUIRE 18.5 OR 19.5 VDC WHICH YOU NEED SOME SORT OF AN ACTIVE ELECTRONIC DEVICE TO ACHIEVE NOT straight 12 VDC

 

YOU DONT JUST PLUG REGULAR 12 VDC INTO THEM, YOU NEED SOME SORT OF AN ACTIVE ELECTRONIC BOX/DEVICE TO RAISE 12 VOLTS UP TO 18.5 OR 19.5 IN YOUR CASE (NOTE there may be laptops out there that operate on 12 VDC instead of 18.5 or 19.5, and if so you CAN power direct from 12 VDC)

 

Whewwwwwwwwww lol now to my next comment:

 

 

YOU HAVE TWO CHOICES TO CHARGE YOUR LAPTOP WHEN NOT CONNECTED TO SHORE POWER AND NEED TO USE YOUR BATTERTY:

 

A) Use a normal Inverter to first change 12 VDC to 120 VAC and use the regular 120 VAC Power Cord Adapter that comes with a laptop. For cell phone and laptop charging I get by fine with a relatively small 400 Watt Pure Sine Wave (PSW) Inverter (also has 5 VDC USB Outlets for charging phones) which isn't very expensive. Of course, that's going to require not one but two devices, double conversion, each which have inefficient heat losses.

 

B) Use the 12 VDC to 19.5 VDC Adapter you linked to. That's ONLY single conversion, more efficient then double conversion above BUT LIMITED USE.

 

While the adapter you show is CHEAPER then an Inverter, its has limited use, since its ONLY for your laptop. The 12 VDC to 120 VAC Inverter has more flexibility since your laptop likely came equipped with a 120 VAC charger (NO need to buy the adapter you show) PLUS it can power all other sorts of small devices

 

 

EFFICIENCY (goes to Yarome and oldman comments)

 

1) If possible, straight 12 VDC to 12 VDC (NO adapters needed) is most efficient iffffffffffff a certain brand of the laptop can run using only 12 volts (it appears a Dell or HP requires a higher voltage, but I cant say if 12 VDC would run them or not????)

 

2) My "best guess" not having any specs or efficiency data in front of me, is the 12 VDC to 19.5 VDC linked is more efficient (less heat losses) then an Inverter

 

3) My "best guess" absent and specs or data, is the Inverter is less efficient then the adapter you showed.

 

4) HOWEVER and type of double conversion is the least efficient

 

BOTTOM LINE SUGGESTION: I cant imagine if boondocking NOT having an Inverter as it can run a laptop (assuming using factory furnished supply cord) plus all sorts of other 120 VAC small power devices and chargers etc etc and you wouldn't need to by the cord you linked to. A small 400 watt unit with 5 VDC USB computer type outlets will likely (subject to loads) suffice. If you don't have an Inverter, then you need the 12 VDC to 19.5 VDC cord you linked. NOTE they make and its easy to use the 12 VDC to 5 VDC USB plugs for charging cell phones or I Pods etc STILL NO INVERTER REQUIRED.

 

DISCLAIMER I cant help being long winded, the combination of engineering plus legal training just made me what way lol its a curse at times

 

John T

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As long as the cord isn't a tripping hazard, that should be a good solution. At some point in the future you might be parked near one of us and we could help you to put it into a more convenient location, permanently. :P

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

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I think it's more efficient to operate the laptop from its internal battery. When it runs down, then plug in the charger until the laptop says the battery is fully charged, then unplug from external power. Most laptops have a 3-4 hr battery life, by then it's potty-break time or time for a drink, plugged in to re-charge while you're away gives you more battery run-time.

Another factor, most laptop mfgrs. recommend you NOT use external power continually, as it contributes to shortened battery life.

 

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country.  John F. Kennedy 20 Jan 1961

 

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