What size power inverter to charge laptop & camera?

Hi, I am getting ready to go camping for 7-9 days & need to get a power inverter to charge the laptop & EOS10D batteries. How large of an inverter would be sufficient. The packaging on a few I looked at stated that a 150 or 175 Watt unit will handle such tasks. I'm just don't want to get one & find out that the label is a little too generous & have problems.
Thanks for any help.

I have a 150 watt inverter and power/charge my batteries and laptop at the same time. It has two outlets built in. I picked it up from Trak Auto for about $40.

Take a look at the 10D charger. It has to have a UL label on it. Somewhere on the label, it has to say how much power it consumes. Get a unit that is rated higher than that number.

E.J. I did look at the charger but I assumed that the lap top would consume more than the charger? There is not that much difference in price going up to a 400 Watt unit, I suppose that might be the safest bet, plus If I need a bit more juice down the road I wont already be maxed out.
Thanks Guys

I second E.J.'s advice. That said I have a 400watt inverter (800 peak) and it works well with my laptop and 1D charger together and costs me under $50. The 10D charger is surely less power hungry than the 1D charger.

A 400 Watt inverter would run my laptop and my Kodak 8500 printer out of my car. Anyone need some prints made on the road?

I agree that having a little bigger than a getting a cheaper unit is better but a standard inverter can handle the load of several battery chargers and a laptop. Your choice as to how big to go.

C. D. Deards wrote:E.J. I did look at the charger but I assumed that the lap top would consume more than the charger?

If you are going to use it for more than one device, then you need to get one for the device that uses the most power. If you are going to use more than one device simultaneously, then you need to add the power consumption of the two and get one bigger than that. At some point, you end up drawing too much current for what the cigarette lighter is fused and wired for and you start blowing fuses. So you need to check the fuse that your cigarette lighter is on and its rated capacity - I would not hook up a device that draws more than half the rating of that fuse.

For your laptop, if it draws 400W on a 12V system ( which seems WAY too high) - that would be 33 Amps - I seriously doubt that the cig lighter is on a 60 AMP fuse. Careful you don't fry your car. My laptop for example has a power draw of 1.5 AMps at 10.8V or 16 Watts when running off of the battery.

Good input guys, thanks! I did notice that on the larger inverters they are typically set up with power cords designed to clamp directly to the battery, that would eliminate the concern of the cigarette lighter fuse / wiring. But I would probably only use it for one item at a time anyway.

Is there a particular good place to shop for inverters online?

Hey Guys,

EJ makes a really good point. You will not get 400 W out of your cigarrete lighter. For example, my 400W only runs at about 150W (I think, might be 250) when running out of the cigarrette lighter. When it is direct wired to the battery however it will produce 400W. Just a thought.

Drew

I think the power accessory outlets in my Chevys are rated at 30 A.

30 A at 13.8 V (a car battery atr 12V is dead; the system normally operates at about 13.8V) is 414W. But 30A is a heck of a lot of juice, and I'd agree with EJ about keeping it to around half of that. 250W should be reasonable in a car. For higher; use the clamps that attach to the battery directly.

Check out the labels on the camera charger and the laptop power unit (not what it uses from the battery, but what the AC unit uses). If you want to use 'em together, add the two numbers and keep it below 250 W if you want to use the cig. lighter plug. (150W if your cig. lighter fuse is only 20A.)

-Paul

One more thought, don't forget that inverters are not 100% efficient. Assuming an inverter is 75% efficient (just a guess), it would take 333 watts drawn on your battery to supply 250 watts to your charger. To make matters worse, your battery charger just converts that back down to a lower voltage to charge the battery. Kind of a wasteful round trip?

A better option, IMHO, for charging camera/laptop batteries is using 12v battery chargers. I keep a 12v charger for my Canon 10D (about $25 from http://www.batterybarn.com) in the truck and a 12v charger travels with my laptop. Rounding out my low voltage world is a 12v blender to whip up Margaritas after a long day of hiking . Also picked up a small solar panel (about $30 at Radio Shack) that sits on my dash during the day and keeps the truck battery topped off.

Best,

Dave

dpirazzi wrote:A better option, IMHO, for charging camera/laptop batteries is using 12v battery chargers. I keep a 12v charger for my Canon 10D (about $25 from http://www.batterybarn.com) in the truck and a 12v charger travels with my laptop.

I totally agree that this is a much better and safer solution than the inverter route.

dpirazzi wrote: Rounding out my low voltage world is a 12v blender to whip up Margaritas after a long day of hiking .
Best,

Dave

Now that is a great idea!!!

Dave wrote:

Rounding out my low voltage world is a 12v blender to whip up Margaritas after a long day of hiking

Question-- do we a. Have to hike, b. wait for a long day??

Bob Ettinger wrote:Question-- do we a. Have to hike, b. wait for a long day??

a) Nope

b) Must have at least 24 hours (sometimes it seems like they are all long days...)

It still brings a smile to my face each time I hear the sound of the blender while I'm on the freeway (virgin drinks, of course, and it is best to have a passenger to the mixing).

I have two inverters, a 400 Watt and a 60 Watt inverter. Guess which one get's the most use? The 60Watt inverter. Why? Because it is very small and with it I can power a laptop or any of my battery chargers.

RadioShack has a few to consider in small sizes:

This one is 60W
http://www.radioshack.com/product.asp?c ... d=22%2D144

This one is 140W
http://www.radioshack.com/product.asp?c ... d=22%2D148

Having said that, I find that using 12V power adapters for each device is more convinient.

Of course if you do this you will need some splitters for your 12v cigarrete plugs. Again RadioShack has a bunch of these to chose from.

http://www.radioshack.com/category.asp? ... 002&Page=1

Best of luck.

-J