Rosewill 400W Power Inverter with 1x 2.1A USB Port $15.99 with free shipping (orig. $50)

Thanks! In 4 1...my current one is only 80W...direct wiring should allow me to connect nicer toys when camping!

Quote from gmanvbva : Many laptop chargers would pass this small 3.3A threshold (and overload the unit).

WTF? My Lenovo laptop charger uses 25w at the wall during idle.

Quote from gmanvbva : What kind of math are you people doing? Watts = Voltage * Amps 400w = 120v * A A=3.3 Max this unit can provide is 3.3 Amps. Factor in for inefficiencies in the device and it probably draws 4-5 amps... This also means that the 2.1A USB port uses 2/3rds of the units capacity (when fully loaded). Many laptop chargers would pass this small 3.3A threshold (and overload the unit).

Car batteries are 12V (in 99% of US applications).

Quote from gmanvbva : What kind of math are you people doing? Watts = Voltage * Amps 400w = 120v * A A=3.3 Max this unit can provide is 3.3 Amps. Factor in for inefficiencies in the device and it probably draws 4-5 amps... This also means that the 2.1A USB port uses 2/3rds of the units capacity (when fully loaded). Many laptop chargers would pass this small 3.3A threshold (and overload the unit). Edit: I think some are confusing the input voltage 12v and using that to determine the units wattage capacity.

With direct connection to the battery it would be 6.6 amps as the inverter can produce up to 800W, but good luck powering a device at the full amperage and wattage.

Quote from derelict : Car batteries are 12V (in 99% of US applications).

Those that know nothing about electricity shouldn't comment.

Quote from Bombebomb : I posted this a week ago and it went FP, I figure this will follow suit.

This one is a bit better at only $1 more, as the one you posted did not have the 2.1A USB port.

Quote from derelict : Car batteries are 12V (in 99% of US applications).

Quote from rbreding : Those that know nothing about electricity shouldn't comment.

The 400W rating applies to the 120V supplied... Hence 400W / 120V = 3.33A

A 5000W rating on a generator applies to the output voltage/amperage supplied... Not the diesel/propane/ etc. drawn/consumed.

Exactly

Quote from gmanvbva : What kind of math are you people doing? Watts = Voltage * Amps 400w = 120v * A A=3.3 Max this unit can provide is 3.3 Amps. Factor in for inefficiencies in the device and it probably draws 4-5 amps... This also means that the 2.1A USB port uses 2/3rds of the units capacity (when fully loaded). Many laptop chargers would pass this small 3.3A threshold (and overload the unit). Edit: I think some are confusing the input voltage 12v and using that to determine the units wattage capacity.

Watts = Amps x Volts

400Watts = Amps x 12VDC (input) therefore the 12VDC source will require 33.3 Amps from the car to reach max potential. This will overload the cigeratte lighter capacity.

The USB is 2.1A @ 5VDC = 10.5 Watts which is not 2/3 of the overall output. It is 2.625% of the overall output.

Quote from rbreding : WTF? My Lenovo laptop charger uses 25w at the wall during idle.

Watts and Amps are very different. Wattage is the electrical energy used, whereas Amps (or Amperage) is the strength of the electrical current. So your laptop's 25W is most likely only needing 1.9 or less Amps of current. This requirement would still be true even at full power of say 75W to 150W. This power inverter will power 2.1 Amps which is a requirement for devices like the iPad. This is why lesser USB car chargers will not power the iPad, because they lack the current necessary to charge it.

Quote from rbreding : WTF? My Lenovo laptop charger uses 25w at the wall during idle.

I have one cheap inverter (like this) and two good ones.

My Thinkpad and Lenovo G770 both draw enough (when charging the battery AND being used moderately) to overload the device and make it shut off.

About the only thing I can charge/run off the cheap one is a phone and iPad (simultaneously)... Or just my MacBook Pro.

Last week I ordered on without the usb for a buck cheaper and the reviews are a little better. What I notice was the wires connecting it is only 2 feet long so it does not reach the seat or the floor. In my truck there's a hump between the seats that it can sit on.
Also you can wire a separate accessory (cigarette) outlet in an open 30 amp in a fuse box ( I don't have power windows or locks but the vehicle still wired for them).

Ugg - horrible reviews...

Quote from imabass : Watts = Amps x Volts 400Watts = Amps x 12VDC (input) therefore the 12VDC source will require 33.3 Amps from the car to reach max potential. This will overload the cigeratte lighter capacity. The USB is 2.1A @ 5VDC = 10.5 Watts which is not 2/3 of the overall output. It is 2.625% of the overall output.

Possibly true but now that I think about it... I don't know how the USB port is powered/wired electrically within the unit.