There is probably a more appropriate forum for this, but based on the activity in this one, I thought I'd stand a good chance of receiving an answer.

I've been using Streets & Trips w/o GPS for many years and just recently purchased S&T 2010 w/ GPS to use with a recently purchased Windows 7 laptop.

For long trips, the (4 hour) laptop battery won't last long enough for a 10 to 12 hour day, so how can I power the laptop for an entire day? I'll be taking a 1345 mile trip (1345 miles each way) soon in my 2000 Dodge Grand Caravan. It has a 12v DC power outlet, but I've heard this isn't a good source of power for a laptop computer.

Is there a solution to this power problem?

If that 12v outlet is a good solution, where can I find an appropriate cable for my Asus laptop?


Brian Conner

The most versatile solution is an inverter which provides 110v ac from the 12vdc outlet. They are inexpensive and reliable as long as the rating is more than the power brick for your laptop says it needs.

Take a look at some of the threads listed below for more discussion on this topic.

Terry

Thank you, tcassidy. That is the solution.

Based on a quick bit of research, it seems the preferred hook-up is direct to battery, but that job is beyond my skills, so it would be an extra cost to have a shop do that for me.

My van has a 12v outlet in the front, rather than a cig lighter outlet, and the inverters I've just looked at have the lighter plug. Do you know how I can bridge that gap? An adapter cable? Or would an inverter's lighter plug go right into the 12v outlet just fine?

My laptop PS says it's 65 watts, so using the 12v outlet with its 80-100w limitation would seem to be adequate.

What kind of 12v outlet does it have? I thought the cigar lighter plug/ socket was standard.

Terry

I just spoke with the guy at the service dept at the local Dodge dealer and he said I can plug a lighter plug directly into that 12v power outlet, so my worry was not justified.

I'm good to go. Thanks you very much, Terry. You helped me tremendously.


Brian

The only time you need a power invertor hooked direct to the battery is when they're large. I've got invertors up to 400 watt that are cig lighter hookups. Over 400 and you'll want it direct. I can run my entire laptop system in my truck on a 200 watt invertor, and that includes the laptop, a wired usb hub and a multi-function inkjet printer.

With the 1,500watt invertor I currently use, I can run a microwave, a hair dryer, etc on it (just not all at the same time).

Thank you for clarifying that point.

Brian, the following is a good discussion on the topic. Info there may be of use to you, too (but is seems like all your questions might have already been answered in this thread).

http://www.laptopgpsworld.com/726-choosing-power-inverter-your-laptop

Brian, just another small thought. If the only thing you want to run is your laptop, and it sounds like that's the case, the cleaner solution is the 12V adapter for your laptop. There is no reason I can think of not to use it.

If you are concerned about the power draw on the 12V power outlet, you are thinking the wrong direction. Getting an inverter increases the power requirement substantially, versus using a 12VDC adapter. The inverter is taking 12V DC (direct current) power and "inverting" it to 120V. In addition it is having to simulate alternating current (AC). That is an inefficient process.

Then you are running the 120VAC power from the inverter through the power brick which converts the power back to DC at, usually, around 19V. That's another inefficient process.

With the 12VDC adapter, the current stays as direct current (that's what your laptop drinks) and all that gets adjusted is the voltage, from 12V up to whatever voltage the laptop takes (19VDC or whatever).

That's a much less inefficient process .. very little loss involved.

And you have a much cleaner connection .. a single cable to run between the power outlet and the laptop versus a cable to the inverter, a cable between the inverter and the power brick and a cable from the power brick to the laptop.

Something to consider if you do not have any actual AC appliances you want/need to operate in the vehicle.

...ken...

Sounds great, but I can't find one online.

What make and model is your laptop?

...ken...

Asus K50.

I have this one which would do the job. However, I know there are less expensive models available.

Belkin : Travel Power Adapter

Terry

Thanks for that, Unfortunately, they don't have the tip for my Asus K50.

I see it isn't on the list but I bet they have one. 19 volts is not uncommon and your connector is probably a barrel type tip. If interested, just email them.

Terry

Found a couple of links for you (found by Googling "asus k50 car power adapter"):

<edit>Expired links removed</edit>

Thank you, that's perfect.

I just went back and checked the search terms I was using, to see if I tried the terms you used. I didn't. Boo, bad search, Brian.

LOL no problem

One thing though - I used one of those with my laptop. Even though it would charge the battery, it couldn't charge it fast enough to charge the battery faster than just using the laptop was pulling.

In other words, it basically just extended the time I could run the laptop before the battery went dead instead of like now when the battery stays @ 100% all of the time with me using the laptop at max performance.

Fortunately, I'd already ordered an inverter, and it arrives later this afternoon.

I might order the DC adapter as a backup, though.

I keep a spare, 75 watt, inverter in my truck for emergency use. That's also what I use when I take the laptop with me in my car.

We use an inverter to power our laptop all the time and have yet to have an issue with keeping the battery charged. It's not uncommon for the kids to watch a couple movies back to back on a long trip. The battery has always kept a 100% charge.

When you get you inverter get one that has a cord going to the power outlet. This give you the most flexibility with placing the unit. Also get a unit with more than one plug-in. It's common for us to have several items connected to the unit. Charging cameras, DSI, cell phones and other small gadgets are common.

Also a small 3in (6cm) extension cord is useful when connecting a device that has a transformer type plugin. A slightly longer cord can be used to share the unit between the front and back seats. A word of warning about connecting multiple devices, make sure you do not overload either the device or the vehicle. Our vehicle has a towing package that includes a larger then normal alternator. So the above suggests may not be suitable for everyone.

If you see a vehicle going down the road with a strange blue glow - wave.

I got the Whistler 400w model. It has a red warning tag on the cigarette lighter cable that says to limit use to 150w to avoid blowing a fuse. (Apparently, it's a full 400w inverter when you connect it directly to the vehicle battery.)

Seems to work fine in a short test yesterday morning. I'll take it for a longer test tomorrow when my wife can come with me to hold the laptop.

...thereby incurring the risk of blowing other fuses...