Prius as a Generator Revisited

Discussion in 'Gen 2 Prius Accessories & Modifications' started by georgekessel, Nov 12, 2007.

  1. essaunders

    essaunders Member

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    I don't think the Prius, as currently programmed, will charge itsself back to 80%. I expect the cycle to be the previously suggested 45% to 50% (based on my observations at drive-in movies).

    I see a 1kw 12v-fed inverter as nice option to keep the house from freezing. Run the Prius for a bit to power the furnace until the house is warm, then power down until it gets chilly. The biggest advantage would be avoiding having to fuss with and store a dedicated generator.
     
  2. daley

    daley New Member

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    I have been reading about this topic and think it would be useful for me to have as a power option. I live in a converted school bus with solar and battery bank and also have a Prius, so this as a back up would be great.

    I have a question. I have a good deal possibility on a UPS smart3000 without any batteries. Will this work to get useful power from Prius either for direct use, or to use to charge the battery pack on my bus?

    Many thanks for any input.
     
  3. ChapmanF

    ChapmanF Senior Member

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    All depends on the voltage it was designed for in its battery bank. Is it in the ballpark of the Prius battery voltage?
     
  4. T1 Terry

    T1 Terry Member

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    I'll admit I haven't read through this thread so hopefully I'm not treading on toes and repeating what others have already posted.
    There is an inverter/charger MPPT solar regulator that can handle between 120vdc and 430vdc on the solar input side and can supply pure sine wave 230vac (and probably there is a 120vac model) without requiring a battery in between. It is designed to run from a 48vdc battery for a UPS style set up, but it doesn't have to have the battery on the 48vdc side to create the PSW AC power.
    The traction battery is anywhere between 180vdc and 240vdc so could be connected to the solar input side to power the inverter. It can recharge a 48v battery at up to 80 amps and supply up to 5,000va and 5,000w, yes, it has a power factor of 1, so a pretty trick bit of gear.
    They aren't insanely expensive and I think t would be an ideal mix for someone fully off grid or have an off grid back up power supply set up in place of a generator.
    My thoughts are, wire in a current suited Anderson plug to the motor side of the contactors so it can be easily turned on/off and wire a mating Anderson plug to the solar input side of the inverter. This way the ICE driving the motor to recharge the traction battery would supply the inverter power as well, any excess would bring the traction battery capacity back up. This could be used to both power the house AC requirements up to the 5,000w/va level the inverter can supply, plus recharge the 48vdc battery if it needs topping up due to bad solar weather.
    Anyone see holes in this plan?

    T1 Terry
     
  5. ChapmanF

    ChapmanF Senior Member

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    This seems like it must have a magical part I'm not seeing: what does it do to hold up the output during moments when the solar input is less than the load demand, if the battery is absent?

    Does it just cleanly drop the load if it can't keep up? Or does the output quality get bad?
     
  6. RobH

    RobH Senior Member

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    I don't know about the mentioned inverter, but modern SMA grid tie inverters have a mode that can output 1500+ watts so long as there is sufficient solar power. It shuts down if there is too much load, and certainly during nighttime. It's enough to run a TV or even a refrigerator during sunlight. Could probably top off all your USB charged devices during overcast.
     
  7. T1 Terry

    T1 Terry Member

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    No idea just how it works if the solar and output are close to equal and the clouds start to travel through. Maybe you only get the AC when there is enough DC available. The gizmo inside boosts the solar input voltage before feeding it into the AC inverter part rather than the traditional buck converter that drops the solar to battery voltage and then that goes to the AC inverter part and boosts it back up to the AC voltage.
    These things can be linked in parallel to boost a single phase and also in a 3 phase output, but I'd reckon they'd need the battery back up to keep that stable as each inverter must have its own solar array, they can't share that part.
    Maybe a traction pack on each solar array input with that wired to output what ever the upper voltage limit is, 250vdc or 270vdc. Then the Prius could be wired up to either recharge the traction pack from the solar or supply current to the inverter when the solar is poor with the ICE firing up as needed to maintain the supply. It would need 3 Priuses if you wanted to generate 3 phase though :lol:

    T1 Terry
     
  8. T1 Terry

    T1 Terry Member

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    Not sure about how they operate in the states, but here in Australia the grid tie inverter must see a grid supply before they will turn on at all. They rely on the grid line voltage and frequency to drive the gizmo, unlike a stand along inverter that can control its own frequency and voltage.

    T1 Terry
     
  9. RobH

    RobH Senior Member

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    That's how the SMA inverters work normally. But when the grid goes out, you flip a switch and that activates a dedicated AC output. It remains in that mode until you flip the switch OFF, even if the grid recovers. The smallest SMA with this feature is at least 3000 watts, so they've got a lot of working space.
     
  10. T1 Terry

    T1 Terry Member

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    Thanks Rob, I'll have a look and see if they are allowed to be connected to the grid over here. If throwing the switch isolated the inverter from the grid then I guess it should be ok to connect to the grid here and it also means it must have its own wave, frequency and voltage control internally .... that would make it quite a bit more expensive than the grid tie inverters usually installed over here.
    Don't know if it is the same over in the states, but here in Aust there a quite few mobs offering 6.6kW solar and a 5kW inverter, fitted and commissioned for crazy cheap prices. You'd have to be sus about the quality of the equipment they provided, just the solar along without labour or the inverter and wiring etc comes out at under 50 cent / watt.

    T1 Terry
     
  11. RobH

    RobH Senior Member

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    The grid down function is called "Secure Power Supply" and can output up to 2000 watts with the latest inverters. I couldn't find out if the Australian products have it with the grid-only versions. There are versions that support "up to 3" batteries, but they may be more expensive.

    Here's a short video of the older 1500 watt version available in the US:

     
  12. richmke

    richmke Junior Member

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    I would think that a lot of people in the San Francisco area are looking to turn their hybrid cars into backup power. 5000w off-grid inverter seems ideal.
     
  13. T1 Terry

    T1 Terry Member

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    These are the inverters, (MG) 5000w Solar inverter 48v 230vac MPPT solar charger 80A 450Vdc PV | eBay
    Best to know and understand the risks involved when working with high DC voltage and how to isolate both energy sources before getting tangled up between the + & - output from the battery or solar. If your wife heads inside to check if your life insurance is up-to-date, read that as a sign you should get someone with better qualifications to do the wiring up part. It might not kill you dead, but it might make you some what useless to the wife and that never ends well :lol:

    T1 Terry
     
  14. daley

    daley New Member

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    I’ve just been looking at those very things for my solar panels installation on my bus, I was wondering if it could work off of the Prius. The kicker is that I would need to use a step down transformer as I’m in the USA and need 110v output. Is that right? Let me know if I’m misunderstanding.
     
  15. T1 Terry

    T1 Terry Member

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    I think the same seller/supplier has 110vac units as well, worth asking anyway. You would need to isolate the traction battery negative from the body/chassis but I expect this is already the case with all EV's that use 3 phase motors and an inverter as part of the normal drive system. This is so no feed back from the PIP5048MG inverter via the solar input is apparent on the vehicle chassis via the battery negative. I'm not sure if there is a filter built into the MG inverter to block this feed back but if the Prius control system sensed a voltage on the chassis it would assume there was a battery fault and shut down the system. Not what you want if you need to run the ICE in the Prius to top up the battery after a while, the traction battery is only around 6.5Ah @ 240v nom. I believe, so only around 1.5kWh of capacity.

    T1 Terry
     
  16. priusrust

    priusrust Member

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  17. bisco

    bisco cookie crumbler

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    i think that pretty much covers it
     
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  18. T1 Terry

    T1 Terry Member

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    I think the strain it puts on the traction pack to 12v inverter should be considered as well as the fact there is nothing recharging the traction pack. Add to that the short cycle life of a 12v starter battery when used for deep cycle use would become quite expensive after a while. Remember, once you kill the 12v battery you can't restart the Prius to recharge the traction battery, so th whole set up could fall over when you least expected it.
    The interconnection of a solar array with an open circuit voltage of 270vdc to the Prius battery pack and the PIP5048MG inverter means the solar would recharge the traction pack and power the house load during the day while the traction pack powered the house over night. The Prius could be started and run to top up the traction pack if needed by adding a low voltage alarm on the inverter input side.

    T1 Terry
     
  19. dolj

    dolj Senior Member

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    The car is in READY while running this rig, so the ICE runs as required to keep the HV battery charged. In addition, while the car is READY the 12 V battery is receiving power from the DC/DC converter as long as the load from the aux inverter is able to be supplied by it. And if it isn't this setup will not be successful. The 12 V battery will still act as a buffer to smooth out small and infrequent spikes. Given that the article talks about a constant draw of 575 W, it should be ok.
     
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  20. T1 Terry

    T1 Terry Member

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    Fair enough, for 600w the draw wouldn't be too horrific, 5kW might be a bit different though :lol:

    T1 Terry
     
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