Charge Laptop in Car

Goal: Charge laptop (whether turned off or using while plugged in) in car. My only power source is the cigarette outlet in the car.

My current AC Adapter has a wide range input of 100-240 V-2 A 50-60 Hz and an output of 18.5 V 6.5A 120 W. However, it says "Caution for indoor use only" and "Connect only to grounded outlet."

My laptop is an HP Pavilion dv7t Select Edition PC:
• Genuine Windows 7 Home Premium 64-bit
• Intel(R) Core(TM) i7-720QM Quad Core processor (1.6GHz, 6MB L3 Cache) with Turbo Boost up to 2.8 GHz
• 8GB DDR3 System Memory (2 Dimm)
• 1TB 7200RPM SATA Dual Hard Drive (500GB x 2) with HP ProtectSmart Hard Drive Protection
• 1GB ATI Mobility Radeon(TM) HD 5650 Graphics + HDMI and VGA ports - For Quad Core Processors
• 17.3" diagonal HD+ High-Definition HP LED BrightView Widescreen Display (1600 x 900)
• Lightscribe Blu-ray ROM with SuperMulti DVD+/-R/RW with Double Layer Support
• HP TrueVision Webcam + Fingerprint Reader + Digital Microphone
• Intel Wireless-N Card
• Full-size island-style keyboard with integrated numeric keypad
• 50% OFF! One 6 Cell (standard) and One 9 Cell (over-sized) Lithium Ion Battery
• NEW! Microsoft(R) Office Home and Student 2010
• HP Home & Home Office Store in-box envelope

After speaking with HP they claim the only option is an HP 90W Smart AC/Auto/Air Combo Adapter; however, I really don't have the money to spend $130 and I find it hard to believe that is the only option. I have also looked into a DC to AC Pocket Power Source Inverter; however, I do not know if that would provide enough power or would be safe.

Basically, I am looking for the cheapest route, completely safe, will not decrease normal performance speed or charging rate (if that is possible) to power my laptop in the car.

Also, sorry if this was meant for the "Accessories" or different forum, I wasn't sure where to post this. Thanks!

 

Just get an adapter like this one:
Amazon.com: Pro Series Car 300 Watt Surge Capacity Travel Power Inverter / Charger with USB port - 110v outlet AC to DC Car Plug Converter for Laptop Computers and Portable DVD Players, iPods, iPhone, iPad and Blackberry **Bonus cable for all Micro a

There are many of them. Read the reviews on amazon. You need a minimum of 120W but I would add 20% to that so get something that can handle 150W or more.

 

targus apm69us - Get great deals on Computers Networking, Electronics items on eBay.com!

The problem with using an inverter is you're converting to AC to convert back to DC, not efficient.

The Targus adapters have a range of different 'tips' for different laptops and they also do adapters that can be powered from Home/Car/Plane that include 'travel' power leads if you travel overseas. In the UK I bought a APM12EU and I've never needed another power adapter no matter where I was in the world, the same adapter in the US would probably be part number APM69US and on E-Bay there's a new one listed for $45.

 

Why add 20%? The standard AC adapter for that laptop is 120W, so why would it need any more than that?

 

There are plenty of DC chargers that will plug in to a cigarette lighter port in your car and charge your laptop. Personally, I like Kensington, so I'd look into something like this for about $60:
Amazon.com: Kensington K33197 120W Auto/Air Ultra Portable Notebook PC Power Adapter: Electronics

Auto / Air chargers like the one I linked are DC-only. You will need a separate power adapter to charge via AC wall outlet.

Several companies make universal wall / auto / air chargers that operate on AC or DC, so you only need to carry one charger to charge your laptop regardless of where you are... very handy if you are travelling a lot and find yourself in random airports, rental cars, and airplanes. Those chargers will indeed run you in the range of $100 - $130, so the price quoted to you by HP is in the right range. I would recommend you stay away from iGo branded chargers. I have owned 2 of them in the past, both of which have died on me within 12 months of ownership.

 

Kent

Did you read my link above? There's a Targus Home/Car/Plane that takes AC or DC input with one on E-bay new for $45.

 

Its never a bad idea to have overhead, and inverters tend to run hot. The idea is, the more overkill your inverter is, the less it has to work to provide the power you need (which also means less heat). Much like a desktop power supply.

I've used inverters before on my laptops and they work fine (as long as you don't overload the cigarette lighter and blow the fuse), but what pinsb linked is probably the most efficient option.

 

The Targus chargers are 90W.

His HP DV7T 17.3" screen w/quad-core CPU will need a charger that can support 120W. A dual-core DV7T can get by with 90W, but 90W will not be enough for what he needs.

From the HP Webpage for the 17.3" DV7T --> Specifications:
Adapter 90W AC (Dual Core Graphics) / 120W AC (Quad Graphics)

 

With a desktop power supply too much overkill is more heat

Reason is that a power supply is designed based on a % of load to obtain maximum efficiency. These 80+ certified PSU's only obtain that 80% efficiency rating when close to load. When they are not under high load the efficiency drops quite a bit.

Yes you should get a PSU for your computer that has more than enough power, yes you should also get an inverter with more than enough power.

This is to make sure your not short on the power you need and to make up for any false power claims from the manufacturer, incase they over rate the product.

Just know that going overkill is not the way to go, if your know your desktop needs about 400w of power get a 500w power supply, getting a 1000w PSU aka "overkill" would produce way more heat than the 500w power supply and would not run as efficient even if it was 80+ certified.

 

I've heard this both ways, but the more common ideology, that I've seen, is that the more powerful your power supply, the less it has to work. Hence why most people get huge power supplies and don't worry about it. I haven't seen anyone actually do a review on it or anything solid, though. I'd be interested to see some if you know of any.

 

Thank you everyone for the responses, you have all been very helpful. After reviewing each post, this item appears to be the best deal (64% off):

Amazon.com: Pro Series Car 300 Watt Surge Capacity Travel Power Inverter / Charger with USB port - 110v outlet AC to DC Car Plug Converter for Laptop Computers and Portable DVD Players, iPods, iPhone, iPad and Blackberry **Bonus cable for all Micro a

However, I just want to confirm that it will be safe to use and not decrease performance? I tried to understand the differences between the other suggestions but I wasn't completely sure as I am by no means an expert at this.

Anyway, I will continue to review these posts and check back a few more times before I make a final decision. The product will likely be used only about 10-15 times a year but it is nice to have when traveling. Thanks again!

 

I work out of my truck daily on my laptop as kind of like a mobile office, and I can tell you that those type of inverters do not perform well. The original HP auto adapters are the way to go. You can get them pretty cheap off of ebay for around $25 or so.

 

It should be safe (enough) to use and won't decrease performance appreciably with one caveat; most cigarette lighter sockets aren't designed to put out more than about 150-200 watts, so plugging that 300 watt inverter _could_ blow the fuse if it needs to draw too much power (unlikely with just your notebook plugged in, but if you plan to plug in anything else as well...). One of the complaints about why this was less efficient was that there are two conversions involved; once from DC to AC in the inverter, and then a second time from AC to DC in your notebook's PSU, which means it's more "wasteful" than a passthrough adaptor like the Targus or Kensington. The inefficiency usually isn't a big deal, though, especially if the car is running; if it's running, it'll generate more than enough overflow power, and car batteries have a rather large energy capacity anyway.

If you're wondering why they rate inverters like that so high when they could blow the fuse in your cigarette lighter socket, it's because these inverters also often come with hookups so you can hook them up directly to your battery, usually for use when you're parked at a place like a campsite or other region where you might not usually have access to a power outlet. This obviously is less than ideal when you're driving, however...

Edit - actually took a look at your link; that one obviously doesn't have connections for a direct hookup. I was thinking more about inverters like this one. You can clearly see the 2 methods of connecting it to power in the thumbnail picture.

 

Thank you for the clarification. It looks like Sima STP ( Amazon.com: Sima STP-325 325-Watt Power Inverter: Electronics) is better buy than the pro series http://www.amazon.com/Capacity-Travel-Power-Inverter-Charger/dp/B00144KS6W. Thanks again!