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I need to bypass an auto-shutdown feature on a power inverter.

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Newbie level 2
Jul 2, 2015
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So this may sound like a horrible idea, but let me explain first.
I put some speakers in my car with an amplifier and bought a little 150w 12volt to 120 volt inverter that you use in the cigarette lighter. The little inverter did the job but it didn't provide enough power to really get the speakers going, so I purchased a 500 watt inverter to get the speakers working well. Now the problem is that the amplifier draws more than 500w because it's meant to power much more than the 2 speakers I have plugged in. Because of this the inverter automatically shuts off because it's more hi-tech than the smaller one I had, even though it would work fine if it the auto-shutoff feature wasnt there. So I'm wondering if anyone knows any way that I can turn the feature off. This is the inverter I'm using:

Now the problem is that the amplifier draws more than 500w because it's meant to power much more than the 2 speakers I have plugged in.

This is puzzling. Do you mean the amplifier draws more than 500W even though underutilized?

As for your question about an auto-shutoff, you probably see a label, "No user serviceable parts inside." You might open up the unit and look around, although it will no doubt void the warranty.

There may be a particular component that senses current draw. Even if you can identify it, and even if it is accessible, you could end up ruining the unit if you try to work on it. Even if you obtain a schematic, your chances are 50-50.

For an experiment, to check whether the inverter stays on, add a load. A light bulb could be sufficient. 25 or 40 or 60W.

The inverter shuts off if the input voltage falls to less then 10.5V. This means that it looks at the voltage at its input and not the battery voltage, so if the voltage drop down the supply line is greater then 12 -10.5 = 1.5 V then the inverter would switch off. So either make sure your battery is fully charged, this would give you 14.6V at the battery or make sure that the leads connecting the inverter to the battery are really thick, say more then 6mm cross section.

The amplifier is rated for 525 watts with all 5 channels in use, but I'm only using 2 channels. So because its rated for over 500 watts the inverter auto shuts off.

If your amplifier draws over 500W then its best that the inverter switches off, else it will burst into flames.
Amplifiers are rated in output power, which should say XX watts RMS any other "power" rating is fiction and sales puff. For a decent amplifier it will be about 50% efficient, so for 50W out it will actually draw 100W of power from the power supply. If the output power is lower which it will be on music the power draw is also much lower, say 20W.
Have you checked the input voltage at the inverter?

My guess is the surge current for the power supply triggers the OCP shutdown.

If so, then solution is use sufficient SERIES ICL surge limiters to satisfy both. ... cheap from D-K.
Put in series in a power bar box.
If 500W then it ought be able to handle 1 cycle surges of 4x current and AMP possibly has 8x surge current but if it trips at 2x then it is just a transient problem.

Avg=500/120V ~4A .. consider 4A ICL give or take an AMP ;)

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