Question about inverters - worst case scanario

Discussion in 'Prius c Technical Discussion' started by Paulexander, Jan 6, 2022.

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  1. Paulexander

    Paulexander New Member

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    Hi all - newbie here.

    I see numerous threads from people who have successfully connected inverters to their main 12V batteries. I am looking to do the same, but based on my potential load, I might be treading up towards the upper limits.

    My thought is to have an inverter ready in the event of a power outage. I have a sump pump running in my basement, and if I lose that thing during a rain storm, my stuff would be floating pretty quickly. The specs on the pump list 8.8 amps, at 115V (1012 Watts). I have my eye on a decent 1500 Watt inverter for this task.

    Question is, if I test it and overload it, what are the ramifications for the Prius? Would I just blow the 100 Amp fuse, or would I have other concerns?

    Thanks!
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Most AC motors will present a startup load that is considerably higher than their steady state operating load. This is usually within the surge capacity of an inverter which is sized for that steady-state demand. So that 1500w unit you found is likely able to surge up to 3000w for 5 to 10 seconds without any ill effects.

    The problem is that the car's 100A fuse is pretty likely to give up before then, and in certain versions of the Prius it is difficult to physically access. Not sure about the c. You would definitely want a smaller fuse in line with the inverter, if for no other reason than to have a cheaper and easier time of replacing it.

    Also consider the conversion efficiency of your inverter. Cheaper ones are around 80% and the best are around 90%. This means that producing 1012 watts of AC power will require between 1124 and 1265W of DC input power.

    tl;dr I think your current sump pump is beyond the power budget allowed by a 12v inverter connected to your Prius.

    Consider changing sump pumps. There are twin-pump models where one pump is a classic AC motor like you have now, co-packaged with a whole secondary pump that runs directly on 12V DC power. They are set up so that if the power fails you'd be able to run the second pump from a 12v battery right there in the basement. You could theoretically then run 12V wiring from the basement to the driveway, where you'd be able to replenish that battery (or directly drive the pump) from any car, no inverter needed.

    Also consider that a small generator can easily supply enough power to run your existing sump pump, with the added advantage that it will never be out of town or stuck in the body shop when your power goes out.
     
  3. Paulexander

    Paulexander New Member

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    Excellent advice, thanks. I thought about the in-line fuse as an idea as well, however, if you're saying the Prius wouldn't be able to handle it, then it's probably not worth investing in the equipment.

    This is a rental; the landlord is unlikely to improve the sump pump unit, and I am not going to invest money in his setup. Looks like the generator is my best option, albeit a lot more expensive.

    Again, thanks for the perspective.

    -P

     
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