Situation: I live in a semi truck. I have a 1500w inverter which supplies plenty of power for me. However, it produces Modified Sin Wave and some of my devices do not run well on it if at all.

I purchased a smaller 600w (1200 peak) inverter that produces pure sin wave energy.

My question is, can I just run the positive, negative & the ground from the posts on the existing inverter to my new one?

I don't/can't run another set of wires to the batteries without drilling holes in my truck.

I just want to make sure this won't be an issue as I've heard of nightmare stories of inverters causing fires in trucks.

  • 1
    You can if the cables and fuses are rated adequately to power both. – Transistor Oct 7 '16 at 17:08
  • Define not run well? and what gauge wire is used and fuse rating? Beware some AC loads have surges on startup(motors /halogen) and others are sensitive to noise spikes which can be filtered,or cause AM radio interference – Tony Stewart Sunnyskyguy EE75 Oct 7 '16 at 17:15

2100W implies a current rating like 14.2V*148A if using full load and everything was linear and 100% efficient.(which it isn't)

But if your load isn't changing, just moving from one inverter to the new one for some small items, we can assume the overall load won't change (for now) except 10% of 600W additional load loss or 5A at 12V so it might not blow the fuse, but without knowing the details, you can tell if the wire going into the 1500W inverter is warm now or not.

If DC cable is warmer than body temp, then it is beggining to drop some DC voltage that affects the performance of your inverters. ( Load line voltage fluctuations) and you may have to find and install a welder cable to the fuse panel or battery.

Your alternative was to get a 5A-15A line filter to reduce the noise for the more sensitive stuff only. The so called modified sine wave is a switched DC with 3 or more steps or "pseudo" sine wave which is slightly cheaper

The line filters may be harder to find, unless you know where.

The pure sine wave uses a different method (PWM) of creating a pure sine wave and with a bit more cost in magnetics for filtering and a bit more cost in high speed switches.


You can have two possible problems:

1) The wires running back to the battery are not thick enough (low enough gauge) to provide current for both devices. The result could be overheating and fire.

2) Connecting the second device to the terminals of the first device may not yield a connection that is suitable for the current drawn. The result could, again, be overheating and fire.

For #1 there should be a fuse between the battery and the device to ensure that you are protected from drawing too much current. The fuse (or breaker) should be within a few inches of the battery.

For #2 you should make sure you are using good quality hardware to include cable of proper gauge.

Beyond that there is no reason it would not work.

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