Best Place To Connect Inverter?

Discussion in 'Gen 3 Prius Technical Discussion' started by Hybrid Hound, May 11, 2022.

  1. Hybrid Hound

    Hybrid Hound Junior Member

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    2015 Prius
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    III
    I just finished a very informative hour reading posts on connecting an inverter to the Prius for emergency backup power, or for supplying juice to run things while doing an off-grid trek. I have had one connected (a Renogy 1000 watt/2000watt surge pure sine wave inverter) to the battery in the back for over a year via 4 gauge wire using an Anderson connector. The connector end comes out through the little cover by the taillights when I need it. Very quick and easy to use and very useful here in SW Florida. But, since reading the many posts on adding an inverter, I came across some comments that say the "best" place to connect the inverter is under the hood in the fuse box where the jump point is. Reason being that it is the shortest route with heaviest wire from the car DC to DC inverter. I do say that my connection works and will power my fridge and some fans when needed (I did a 24 hour test last year), but I don't mind changing the connection point if it is better for my car and for the added inverter.
    If under the hood IS better, please tell me why and show me where on my 2015 Prius that the connection should be made. I know the basics of this, but wow! the technical knowledge of some forum members absolutely floors me! And, that they generously and kindly (for the most part) contribute that info to us less than tech-savvy members is greatly appreciated! If where I have it now is fine, I will be content to leave it there. That way I don't have to worry about where to place the inverter under the hood during a storm event. Thanks so much for your help!
     
  2. ChapmanF

    ChapmanF Senior Member

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    Mine is in the back, with its positive connection taken from the cable side of the 140 amp fuse in the positive battery clamp.

    That means my connection point is protected from current dumps from the battery, by that 140 amp fuse, and from current dumps from the DC/DC converter, by the 125 amp fuse buried in the front fusebox.

    There is nothing on the path from the DC/DC converter except for that 125 amp fuse and the wire to the back of the car (and my own added fuse for the inverter, because mine is only 1kW). If it were attached right at the battery post, it would also have that 140 amp fuse in the way of the supply from the converter (and my connections would be unprotected from the battery).

    If you attached at the jump point up front, yes, you'd eliminate the wire to the back of the car, and you'd still be on the right side of the buried 125 amp fuse. (If you attached where the converter wire attaches up front, you'd be on the wrong side of it.)

    If you're curious how much difference it would make to eliminate that wire, you could measure its resistance, or estimate its gauge and length and look it up in a resistivity table, and just do the math to find out the exact voltage drop and power loss you would be avoiding (and then ask yourself whether you even care). That's exactly all the magic there is to the question.

    I would pay more attention to the underhood environment just being a hotter and more hostile environment for your inverter to live, compared to a nice dry climate-controlled hatch. That nice location for an inverter is something I've always liked about gen 1 to 3, and why I'm sad gen 4 put the battery under the hood again.
     
  3. Hybrid Hound

    Hybrid Hound Junior Member

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    2015 Prius
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    III
    Once again you have come to my rescue! (Knowing it was the BLUE wire to the brake lights was a BIG help, and the brake controller is working fine.) I think I am following you on which is the correct side of the battery in the back to mount the inverter to, but if possible, a pic or diagram would be much appreciated. Just the thought of connecting the inverter up front and subjecting it to the heat when the engine feels the need to run, or raising the hood a little so it could get cool fresh air and then a rainstorm comes and with high winds soaks the engine compartment, has stopped me from trying out the front connection. Now, your reasoning on the pros and cons has helped me to see that where I have it is not too bad, as long as the connection is made properly. I had NO idea that it would matter, not knowing what other circuit protections would be there if I do it that way. My connection now IS at that battery bolt that sticks up by the post. Again, just coach me and if I am not following I don't mind admitting it. This is the reason I would likely never chance connecting a bigger power inverter to the HV battery, even if I could afford to do so. My setup now on the Prius is adequate, but not overly powerful. (A little off-topic here). I also have a solar powered golf cart with 3-12 volt SLA batteries and a 36 volt DC to 120 volt AC inverter. That inverter is 1500 watt/3000 surge. That can be my backup to my Prius since it is recharged by the abundant SW Fla sunshine. I can run my little camper on it for several hours even with the AC going and it hardly drops in voltage. Might be needed one day if the power goes out for several days due to a storm. Back to the original topic...Thanks again for your (and many others here) technical expertise. Keeps us non-techies humble in case we get to thinking we know how the Prius operates!
     
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