I have a solar power which it's power is stored in 12V automobile battery. And use inverter to produce 220V AC to feed common equipments. The inverter as shows symbolic gets a square wave. It mentioned on the charger that its frequency is 50-60Hz.

As we know square waves have harmonics beside main frequency, Is it safe to feed my laptop charger by this inverter?

p.s: My laptop charger is: Toshiba PA3714U-1ACA; Input: 100-240V~1.5A; 50-60Hz


1 Answer 1


Probably yes.

The laptop power supplies (they are not actually "charger", the charger is inside the laptop) are switching power supplies and they first rectify the input AC voltage, then process it to lower DC voltage. The input rectifier can work with square wave form even better than with sinusoidal.

Completely another talk is why you need to double convert the voltage from 12V to 220V and back to some low (what?) voltage.

Most laptops with 3 element Li-ion are powered with 12V external voltage, so you simply can power your laptop directly (well, if it has 3-element battery). Check the laptop power supply output characteristics for that.

Another, even better solution (suggested by Dan D. in the comment) is to use dedicated laptop car power supply (often wrongly called "charger"). There are many types of these and they can power laptops with any battery configuration. The efficiency of such a configuration will be higher than using 220V power supply with inverter.

  • 3
    \$\begingroup\$ I would suggest using a car charger rather than your last suggestion. Like this one at least for that laptop. \$\endgroup\$
    – Dan D.
    Commented Oct 10, 2013 at 7:27
  • \$\begingroup\$ @DanD. - added to the answer. Thanks for the good idea. \$\endgroup\$
    – johnfound
    Commented Oct 10, 2013 at 7:43
  • \$\begingroup\$ @johnfound: Would you mind put reference for the issue that square wave is better for laptop charger? >If the square wave is better for laptop charger; then why buying new charger is better solution? \$\endgroup\$ Commented Oct 23, 2013 at 10:48
  • \$\begingroup\$ The output of your inverter is not a true square wave, but there are voltage overshoots at the edges of the steps. These stress the input filters of the power supply and sometimes but rarely can damage it (example). That makes a DC-DC converter ("car charger") preferable. But more importantly, DC-DC converters are more efficient as there is only one voltage conversion step rather than two. \$\endgroup\$
    – tanius
    Commented Sep 13, 2018 at 23:04

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