12 v plus solar charging possible

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by erik ahlqvist, Oct 1, 2021.

  1. erik ahlqvist

    erik ahlqvist New Member

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    Solar connected to prius 12 v battery via mppt, 12 volt connected to inverter, inverter connected charging cable, charging cable obviously connected to Prius.

    Is this possible?
     
  2. LeviSmith

    LeviSmith Junior Member

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    Ok... If I'm following correctly...

    You're saying to connect the solar to the 12v, then connect an external inverter to the 12v to generate 120v to power the EVSE?

    Interesting... Let's walk through...
    At standard settings you're going to need like a constant 1500W of solar... Maybe you can change the settings and get to any I half that...

    Let's pretend that's even flow...And you've got a good enough inverter to handle it...
    I *think* that should work in theory...

    The big questions are... What happens when the EVSE doesn't need all that power(Like when it finishes)... Seems like you're going to fry your 12V at that point... Maybe a charge controller on the Solar could take care of that?

    And what happens when a cloud comes over and you don't have enough output from solar? I believe your 12V will be drained quite quickly...
    Although that already seems like something is going to be unhappy since you're then in a loop of the 12V trying to power the EVSE and the EVSE trying to charge the 12V...

    I think the only way to really make it feasible would be lots of solar power with a big charge controller and enough battery capacity to cover your charging demands in case the sun goes dim... Even then while it seems like it *should* work, it still sounds pretty sketchy electrically looping and what not, so I can't say I'd really think it a good idea...

    Well... really there's no point to it in that way... If you've already got charge controlled battery supplied 12V to inverted power... Just plug the EVSE into that power and don't hook into the Prius 12V at all in the first place... :)
     
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  3. bisco

    bisco cookie crumbler

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    no. but you can keep the 12v topped up with enough sunlight and a large enough panel.
     
  4. erik ahlqvist

    erik ahlqvist New Member

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    Damn it, I lost everything I had typed.

    Some short thoughts:

    I've seen campers hook up pretty heavy loads like cooking devices to the 12v battery so I think pretty much power can circulate between the two batteries without any components being fryed.

    The mppt protects the 12 v battery from the solar.

    But I dont know if the car must be in Ready to have current floating between the batteries and you probably cant have the car in Ready when charging from evse.
     
  5. erik ahlqvist

    erik ahlqvist New Member

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    Only the Prius 12 v battery would be used. Not two
     
  6. erik ahlqvist

    erik ahlqvist New Member

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    This would require more solar than I'd like to buy and also there's the problem with relays opening and closing more than they are designed for.

    Sorry for missunderstanding what you meant about this before.
     
    #6 erik ahlqvist, Oct 2, 2021
    Last edited by a moderator: Oct 2, 2021
  7. sam spade 2

    sam spade 2 Senior Member

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    I'm no expert in the charging equipment for "plug in hybrids" but based on extensive general electronics experience..............
    I think the only practical way to charge from solar is to get a system that has 120/240 VAC output and plug it into the charging port.
    Modifications to the systems internal to the car likely are NOT a good idea. Might be dangerous to you AND to the car.
     
  8. ChapmanF

    ChapmanF Senior Member

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    The car has to be READY in order for the high-voltage system to supply charge to the 12 volt battery. When in READY, that supply to the 12 volt system comes via the car's DC/DC converter, which has a maximum rated capacity (120 amps at the 12 volt output side in Gen 3). It isn't bidirectional; the DC/DC converter under the hood never takes power from the 12 volt system to charge the traction battery.

    Whatever you set up to charge the traction battery would be up to you to design and set the rules. But LeviSmith is probably coming at it from the right angle: what sort of traction battery charge rate would you want? Rates in the kilowatts aren't unreasonable there, and that's some big solar panels. And it wouldn't make much sense to have that kind of power, on its way to the traction battery, get detoured through some 12 volt side streets.
     
  9. erik ahlqvist

    erik ahlqvist New Member

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    The sidestreets would contribute with a necessary high and smooth power to keep the relays closed even when using a smaller solar set up. Sure a gigantic solar installation would give sufficient power even when shadows pass by.
    Now Im planning to have the panels stored in my car when traveling and it just wouldn't be practical.
    The things is I dont want purshase
     
  10. ChapmanF

    ChapmanF Senior Member

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    Even a gigantic solar installation won't give you power when shadows pass by, unless you mean gigantic as in utility-scale, covering an area of ground that's bigger than the cloud shadows. I agree that wouldn't be practical to store in the car.

    You might be well served to step back and do a couple of things:

    • Work on learning more about how the stock system in the car already works. Your posts have included some jargon like "relays opening and closing", but sound rather like you are trying to derive the car from first principles, rather than reading the manuals and learning how the real car works.
    • Sharpen some pencils and start doing actual math. It takes a lot of power to move the car. Car recharging systems are rated in kilowatts for a reason. You can make a system as small as you want, but at some point there are two questions to face: what do you want to accomplish? and, what size system will accomplish it? That's what the math is for.
     
  11. sam spade 2

    sam spade 2 Senior Member

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    Why bother when you have nice people on the Internet who will do it for you.
    Or who have already done it and will tell you the results.
    :)
     
  12. Mendel Leisk

    Mendel Leisk Sand Pounder

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  13. erik ahlqvist

    erik ahlqvist New Member

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    Thanks for your reply. How ever the manual is not made for dealing with projects like this.
     
  14. ChapmanF

    ChapmanF Senior Member

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    The manuals are made for the kind of person who prepares for a project by learning how the system goes together and works first.

    And that kind of person is the kind that is made for dealing with projects like this.
     
  15. james nancy

    james nancy Junior Member

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    It's just an idea, if it is possible to charge the traction battery with solar panels, it may be a huge project.
    The power per unit area of the photovoltaic cell is about 127w/m2. The upper cover and engine cover of the prius are about 3m2 (this is a rough calculation), and the power is about 380w for charging. If it is backlit in the parking lot for 10 hours, it can generate 3.8kwh of electricity, which can maintain the prius short-distance driving without starting the engine.
    To complete this task may need to do a lot of things, you may need to invade the prius traction battery management system, so that it knows that the battery has been charged, the charged capacity, and then decide whether to start the engine to charge, to cope with the 3.8kwh energy, may need to be replaced The original Ni-MH battery, I think it is very difficult to write, unless Prius open the code to facilitate programming.
    But if solar charging is achieved, it will have a significant impact on the mpg of short-distance travel. I think I can experience the charm of pure electric vehicles within a travel range of 10 miles.
     
  16. erik ahlqvist

    erik ahlqvist New Member

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    I know the DC/DC converter only works one way (HV to 12v, and there is also a second connection between the batteries also HV to 12v). The plan is to charge the traction battery the traditional way, by using the j1772/EVSE-port. But having the schuko end connected to the 12v battery via an inverter.

    Now the 12v is capable of running a microwave oven for example.
     
  17. erik ahlqvist

    erik ahlqvist New Member

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    Thanks for sharing your knowledge!
    Here's some info about charging:
    PRIUS PLUG-IN HYBRID
     
  18. bisco

    bisco cookie crumbler

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    keep in mind that the evse port goes to an internal charger. so you would have to supply the minimum requirement
     
  19. erik ahlqvist

    erik ahlqvist New Member

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    After reading other threads on the Priuschat I now understand, what I earlier suspected, that the charging from outlet wont work in READY. So no charging is possible the way I had hoped when starting this thread.

    Thanks for all input.
     
  20. james nancy

    james nancy Junior Member

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    Sorry for my ignorance, and just noticed that this is a plugin forum. I am still amazed by the rich and superb design capabilities of Toyota designers, who can do what I can think of.
     
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