I am looking to buy a power inverter so I can use/charge my laptop in the car. And while looking I noticed there always two kinds of power inverters, 140 Watts and 90 watts. I dont understand anything about Watts, Volts, Ohms, Amps or any of that electrical stuff so could someone tell me what the difference is?
Thanks!

Well the difference is 50 watts. Well here is the the one I have 400 watt one. It is way over kill to run my laptop but it does the job. There is a list of what some things use in watts. I got the one I have from Lowe's for about $30 I think is it about $40 now.

Thanks Robert, I figured 50 watts but i dunno what that means in terms of electricity.
Yeah I dont need something like your super heavy duty thing shown there.
I was looking at either one of these. But the question is which one 90 watt or 140. Im just plugging in a laptop to the AC power.
CyberPower ACMoblie 90W
CyberPower ACMobile 140W

AR, look on your laptop for the power consumption label. It will either give you the number of watts the unit uses or give you a number of amps at a number of volts.

My IBM ThinkPad has "16V 2.6A" on a silver plate on the bottom of the unit. This means 16 volts and 2.6 amps. To get the approximate power consumption watts, multiply the volts times the amps. In my case, 16 volts X 2.6 amps gives 41.6 watts. Becuase of losses between the inverter and your mother board you should kick this number up 10 percent or more. So the 41.6 watts becomes about 46 watts. This is well within the capacity of the 90 watt model.

Be sure you don't plan to run any other devices off the inverter at the same time as the laptop. If you do, you will have to add that device's watts to the laptops to get total load.

In short, watts is basically volts times amps and is a measure of power consumed. Yes you have power factors, losses, etc., but that's beyond what you need to consider here.

There should be a sticker on the bottom of your laptop that tells how many watts it draws. I got the cheapest one from Radio Shack ($19.95) and it powers SWMBO's laptop without problems. (She watches DVD's on long road trips - but won't give it up to me for cachin' - yet)

Rule of thumb: You will eventually need more power.

Get the larger one.
The one I use runs my laptop fine, but I have had to plug in another item and then the inverter starting going through cycles of beeping, warning me that I was pushing it's limits.

Kenneth

I do agree get the bigger one you might need it sometime to run more than the laptop. The link also has a list of how many watts most things would use. It says that a laptop uses about 38 - 45 watts.

I cant check my laptop powers consumption because it is sitting in Hapeville at Air Cargo/FedEx till tomorrow, yipee!
Ill go with the 140 because I dont know if the wattage includes the wattage of the dc plug included with it. Thanks guys!

Good choice.

Well to let you know my laptop uses about 33 watts using the formula above. I got my numbers off my brick (the power supply for the laptop) and that is what I came up with. But glad to hear that you are going for the bigger one.

the whole time I was reading this thread, I kept expecting someone to just tell him to get a longer extension cord... Ya'll really let me down here, I just want ya to know that

Try www.targus.com. I got a power supply for my laptop that plugs into the cig lighter in the car, as well as into airplane power supply jacks (if available). I look forward to trying it out on my next flight. It comes with several plugs so it can work with several models of laptops, with a list on the website of which ones it will work with.

Umm...
I just got my laptop today in fact im on it now. However my brick says 120W.
The only thing abt the 140 is thats its $60 and they are only sold at bestbuy, according to froogle.com.

I've got a Coleman 400Watt Power Inverter. I believe it cost me no more than $39, maybe less. If you haven't already checked these stores, I would recommend doing some price comparisons at:

Walmart
Target
Auto Zone
Pep Boys

I'm sure you should be able to find a 400W Power Inverter between $30-$40. I went with the 400W inverter because it came with a cigarette lighter connector. The higher wattage inverters seemed to only come with battery clips.

Good Luck!

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Originally posted by Amazingracer:
Umm...
I just got my laptop today in fact im on it now. However my brick says 120W.

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Are you sure that is not the Volts input. Cause you need the output stuff to find out how many watts it uses cause that seems way to high for a laptop to use.

Now Lowe's has the 400 watt one for $39.94. and that would be a lot more than you need and a lot cheaper than the price you listed here.

18.5V 6.5A according to the multiplying method: 120.25W
And it says 120W right below all this information.

Man that is a lot of watts for a laptop but your are right on the amount. My laptop is 15V at 2A witch is 30 watts and add 10% for the DC to AC inverter is 33 watts is what my laptop needs. So you might want to go with the 400 watt one with a laptop useing that many watts.

I found a 200watt coleman invereter
http://www.cabelas.com/cabelas/en/templates/links/link.jhtml?id=0025818521517a&type=product&cmCat=froogle&cm_ven=froogle&cm_cat=data_feed&cm_ite=various&rid=7510101020603
That fits in a couple holder. The 400 watt is too much power for me plus i have no where to put it in my car.

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fits in a couple holder

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quote:

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Originally posted by Amazingracer:
18.5V 6.5A according to the multiplying method: 120.25W
And it says 120W right below all this information.

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AR, don't be so concerned with what the brick says. That is ITS CAPACITY, not what the laptop draws. Of course you are considering inverters well above the needs of either.