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I have a 45 W, 230 VAC fan (this) that I am trying to power through a 12 V 50 Ah deep cycle battery with a BESTEK 300 W modified sine wave inverter (this). The fan works fine from 240 VAC in the house, so it's not the problem. The inverter supplies an 230 VAC -> 12 VDC x 5 A transformer (60 W max total load, ignoring inefficiencies) fine, so neither it nor the battery are fault.

The fan's behaviour is odd. When you power it on mains, it will beep once, then you can control it via an IR remote, or with buttons. Importantly, the motor does not immediately start - you need to press a button to start it. When powering it on via the inverter, it beeps... then it beeps again, repeatedly. Neither the buttons nor the remote allow it to start turning.

I have two considerations here, but I am a little skeptical of both of these, because of the fact that the fan doesn't actually start until you press buttons.

  1. I need a pure sine wave invertor. This thread seems to indicate this might be the case, noting that "anything with an inductive or motor load, pure sine wave is better".
  2. I need a more powerful inverter, because of the inrush current - I could need up to 10x the standard operating 45 W, so perhaps a 500+ W inverter.

(General note is this all UK voltages and for the mains, 230 V 50 Hz)

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    \$\begingroup\$ I lean towards 2. without more information. Does your inverter beep, blink a red light or anything similar when you try to start the fan? \$\endgroup\$
    – winny
    Jul 4 at 21:18
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    \$\begingroup\$ You can test the starting current theory by spinning the fan (the right direction) before switching the power on. That will greatly reduce the starting current. A motor won't need a pure sinewave. Its inductance will smooth out the waveform. \$\endgroup\$
    – Transistor
    Jul 4 at 21:21
  • \$\begingroup\$ @ Transistor, unfortunately motors are capacitive, and will short-circuit the harmonics, rather than blocking them. \$\endgroup\$
    – Jasen
    Jul 4 at 21:27
  • \$\begingroup\$ @Jasen, can you explain that comment further? I've installed several capacitive industrial power-factor correction systems because motors are inductive loads. \$\endgroup\$
    – Transistor
    Jul 4 at 22:05
  • \$\begingroup\$ the resist changes in voltage by sourcing and sinking current like a capacitor. \$\endgroup\$
    – Jasen
    Jul 4 at 22:09
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A simple fan with a high-med-low switch would probably work fine with most inverters. Many single-phase motors have a capacitor in series with one of the windings. That doesn't make it capacitive, but the capacitor might have some difficulty with a poor inverter waveform. However that is probably not the problem in this case.

It is more likely that the remote control is having difficulty with the waveform. A "pure sine wave" inverter may or may not fix the problem. Particularly since there is not standard for what qualifies an inverter to be called "pure sine wave."

It is also possible that the fan has some kind of "brushless DC" motor. That would also include an electronic control of unknown design that may not accept the inverter waveform and may or may not work with a "better" inverter design.

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  • \$\begingroup\$ Thanks for your input. In the end, I purchased the "pure sine wave" version of the inverter I already had, still 300W, although it can allegedly sustain 360W for short periods and up to 700W for shorter still (what do these numbers even really represent when dealing with cheap Chinese electronics anyway?). Regardless, it seems to have done the trick and now both the fan and 60W transformer can be powered together fine. \$\endgroup\$
    – Andrew
    Jul 6 at 21:49

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