Would a power inverter without a GFCI still be safe for a laptop?

[viivo]

I see in the manual of this inverter I just bought that it does not include an internal ground fault circuit interrupter. I know the purpose of GCFIs since some of the outlets in my house are equipped with them, but would it make any difference in an inverter?

Also, since this thing was only $30 it's not a surprise that it uses a modified sine wave. Is it true that modern laptop power supplies are good at handling that or should I lug a surge protector in my car as well, or pay out the ass for a pure, uncut wave of sine?

Thanks for any help. Apologies if the questions seem simple, but searching has yielded few helpful results and I want to be sure.

 

[bobdole369]

An inverter is typically isolated, thus making the purpose of the GFCI moot.

You don't need a surge protector as the cheap kind (and even the expensive kind) of surges that it will protect against simply don't happen on an inverter.

Most surge protectors are of the clamping type, which means that each leg of the device is tied to the "earth" lead on the power input. Surge devices that sense high voltage and conduct, thus dissipating the high voltage. As this is isolated on the inverter - it makes no difference. The purpose of GFCI is to prevent the oft-cited "hairdryer in the tub" shock death. The hot side of the 120V (or either hot side of the US version of 220V) conducts to the earthed drain plug in the tub, generally killing the tubs occupant as he is part of a conductor. I think mythbusters debunked this. GFCI trips when high ground current exists. Since the AC ground is floating (ideally) in an inverter, the hot side should normally not conduct with the 12V sides "negative". i.e. the chassis of the vehicle or vessel shouldn't be tied to the AC ground.

http://en.wikipedia.org/wiki/Surge_protector

See MOV style or TVSS style a few pages down.

A laptop power supply is a switching style. This means that the brick uses a FET of some sort to turn on and off the incoming power to charge a cap that is monitored by a controller. When the voltage is too low, the duty cycle is increased. When too high, its reduced. This is a simplified explanation but will suffice.

Laptop charging plugs should be just fine on a modified sine wave (or even a full square wave really). Provided the (even square wave) peak voltage is not > expected pure-sine peak - the switching controller "ought" to handle the difference.

When you want to run a standard ATX supply of any decent power - the modified sine becomes actually harmful. It also used to be that tube style tv's relied on the 60hz sine to run the horizontal sweep. It gets funky with a modified sine. Also AC motors require sine, but take that with a grain of salt because hairdryers and whatnot work fine through an inverter.

 

[viivo]

Thank you very much for the detailed explanation.

Is it true that charging with an inverter will degrade a laptop battery faster than a normal outlet?

 

[bobdole369]

Thank you very much for the detailed explanation.

Is it true that charging with an inverter will degrade a laptop battery faster than a normal outlet?

I don't see how. The power brick will supply constant DC voltage just like it was plugged into the wall - as far as the laptop battery is concerned.