Inverter Voltage for MacBook

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I just bought a Stanley Fat Max 140 watt dc to ac inverter $24 Walmart. Looking to power my Mac computer (battery doesn't hold charge anymore) and what ever else I need to power up when on the road.

I plugged in the inverter and it reads 107 volts with just key on acc. and 90 volts with motor running with my volt meter?

Is the 90 volts going to be ok to run my computer, charge batteries or run other electronic device? It powdered a shop light with no problem so far.

I had a more expensive $80 inverter I got from a Apple store that worked fine for many years till it died. Never thought to check its voltage as it didn't hurt the computer.

How many volts should an inverter put out? What is an acceptable voltage range for a inverter?
 
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Your Mac's Specs
A1286 MBP5,3 running 10.9.5, iphone6, Mac mini1,1 A1176 120/2gb
It may run. I looked on my MBP power adapter and it states input voltage of 100-240vac 50/60 hz.
Some motors state 220v but will run on 208. I would just try it and see. Some inverters won't run switching power supplies at all. Just depends. Try it.
 
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You might be just fine on the voltage. Depends if your volt meter is rated for "True RMS". If it is not, it could be reading 2% to 20% lower than what the inverter actually puts out.

The rated voltage is an RMS (root mean square--they square the value to make sure it is always positive, then average it, then take the square root of the average to make up for having squared it in the first place) measurement.

Most volt meters are designed to give correct RMS readings when applied to sine waves, but not when they are applied to other waveforms. Therefore they will read from 2% to 20% low in voltage.

If we use the 20% loss actual voltage would be 128 volts to 108 volts.

So it depends on if you volt meter is rated for "true RMS". If you really are concerned, look for a voltmeter that brags about "True RMS" readings, and that will read correctly no matter what the wave shape is.

As to if the low or even higher voltage will harm you laptop - I don't believe so. Modern laptop power supplies are design to step up or down the voltage at the input to deliver the required voltage.

Lisa
 
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You are right on the money Lisa, thanks.
I called the manufacturer and they said I need to use a TRUE RMS volt meter to get a true voltage output.

The one I got at Walmart was an open box item, I ordered it online and got the already been open item. The manufacturer was not happy that the item was resold as new and its their policy for stores not to resell returned product. They said with my reading with my non TRUE RMS meter my voltage is inline with a working new inverter. But they recommend that I return and or exchange the item as who knows what the last person did to the inverter or why it was returned.

I will exchange it for a new one.
 
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Glad you got the answers you needed.

Lisa
 

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