Note: This post contains pricing information for future reference because it is generally not available elsewhere once the next Woot has been offered.
Newpoint 120W Slimline Power Inverter with USB Port
$9.99 + $5 shipping
condition: Refurbished
product: 1 Newpoint 120W Slimline DC-to-AC Power Inverter with USB Port
Price comparator post ! - Is this a good deal ? Let’s see !
Refurbished Newpoint 120W Slimline Power Inverter with USB Port, for $9.99 + $5 shipping
Product: 1x Newpoint 120W Slimline DC-to-AC Power Inverter with USB Port
WOW! I think this is my personal favorite page off all woot. I mean you got fros and a gasoline powered phone charger. I’m gonna need to get my ribs wrapped after this.
Do we still have to worry this might not provide enough clean power to run and or charge laptops? Even with all of the so called “safety measures” do I still run the risk of blowing the fuse on my car?
If you’d have used the price comparator (linked above), you’d have noticed that I found what seems to be an alternate name for this product.
And this would have led you to this Amazon review.
Too bad you didn’t use it.
120W at 13V is 9amps. Assuming that 120W is output power, and that the efficiency of the inverter is 85%, the inverter would use 9/0.85=10.5A to provide you with 120W.
Check the rating of the fuse of your car power outlet, and you’ll know if you’re at risk of blowing it or not. To be safe, consider that for each amp you get 10 available watts at the output of the inverter, and add 1A for safety. i.e. if your laptop adapter needs 70W, then you’d need a fuse of at least 7+1 = 8A.
I hope this helps you decide.
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For geeks:
Please note that this calculation assumes that you use the adapter with the motor running (or that your battery has recently been charged). If the voltage of the battery decreases, the inverter will use more amps, and this will reduce how much power you can get out of the inverter.
Example: 120W with a battery voltage of 11V is 11amps - if we take the efficiency of the inverter into account, this means that you’d use 13A to get 120W, instead of the <10.5A with a charged car battery. Not to mention the fact that the efficiency of the inverter probably decreases when the battery voltage decreases, making it all even more complex.
This is common with all inverters and is just an application of basic electronics. Do not buy a 500W adapter thinking that you can use it easily: cars are not usually wired to provide 500W on their power outlet.