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Capturing and using more energy through regenerative braking

Discussion in 'Gen 2 Prius Accessories & Modifications' started by 777Tom, May 7, 2016.

  1. 777Tom

    777Tom New Member

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    I am looking at buying a gen 2 prius and I have an idea that I would appreciate your advice on.

    On a daily basis I have to climb a long gradual hill (over 2 miles long) out of our village and descend the same hill when returning home. As I understand it a prius could, as I was coming down the hill, use regenerative braking to charge its HV battery.

    However when the HV battery is full - as it would likely become quite quickly due to the amount of downhill travel involved in this daily journey - the prius will then spin the ICE to burn off excess energy.

    I am wondering if it would be possible to increase the battery capacity that is available for the storage of regenerated energy by swapping battery packs as the car is travelling downhill - having a second oem hv battery, and all of its connections (HV, BMS etc) changed over using relays / contactors.

    When using the captured energy, one pack would be depleted, then change over to the second pack.

    Has anyone tried anything like this?

    Do you think it would work?

    I am a qualified engineer with plenty of experience working with electrical and electronic components, including industrial 3 phase 415v, so I am familiar with the precautions that are necessary when designing and building an installation like this.
     
    #1 777Tom, May 7, 2016
    Last edited: May 7, 2016
  2. fotomoto

    fotomoto Senior Member

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    Yes, there were a few third-party companies like Hymotion and Engineer who supplied larger, secondary batteries and just as importantly the BMS (battery management systems) for these kits. They had the added benefit of plugging in and working all the time (not just downhill in your scenario). Search threads about them. They are pretty much defunct but the occasional used kit pops up on the market. You may be able to build something similar or go the easier route and get a more capable factory solution plug-in like most folks have done.
     
    #2 fotomoto, May 7, 2016
  3. bisco

    bisco cookie crumbler

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    welcome! agree with f/m above, but you have to be an electrical/electronic genius to make it work. no one is trying it anymore, too many issues. all the best!(y)
     
    #3 bisco, May 7, 2016
  4. 777Tom

    777Tom New Member

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    Thankyou for your replies, perhaps I should have said in my original post that I have been browsing old forum posts and elsewhere on the internet. I am familiar with the aftermarket kits you mention and the associated issues with trying to add extra battery capacity - soc spoofing etc, and the lady who had several oem packs used in conjunction with a new bms but they exploded whilst charging.

    I have not yet found anyone who has tried the design that I outlined above
     
    #4 777Tom, May 7, 2016
  5. bisco

    bisco cookie crumbler

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    correct, and you won't. not that i recall seeing anyway. i guess that makes you a pioneer, which probably won't be anymore difficult than trying to redesign someone else's problem.

    i do think you're idea will work, but i suspect it may be more complicated than you are thinking. but as this thread develops, the roadblocks will become more obvious. again, it can be done, but at what time and expense is someone willing to go.

    the plug in prius has really put the kibosh on aftermarket development, because it is so inexpensive. at least over here.
     
    #5 bisco, May 7, 2016
  6. LamboGuy

    LamboGuy Junior Member

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    The biggest issue is that the batteries are extremely more expensive when you buy them as an individual than when you buy them as a manufacturer. A Nissan Leaf (which is horrible to look at in my book) can be found used with low mileage for $8k. For you to buy the same amount of battery capacity will cost you $15k - that just a battery not a second whole car with wheels, headlights interior and many times still left over warranty. So you will really need to like torturing yourself to go ahead buy these batteries for $15k, install them, make sure you don't overcharge them and drive a frankenstein vehicle that doesn't have warranty and is in danger of being denied from your insurance policy in case of an accident (extreme situation but just saying).
    I would love to do it but unfortunately it will only make sense if you manage to get hold of a very affordable battery pack.

    Also the battery regeneration and usage is a good idea but we are still losing a large portion of the energy. You are honestly better off following the old trick of accelerating a bit more in the straight line and keep your throttle steady allows by the car to gradually slow down while it's going uphill.


    iPhone ?
     
    #6 LamboGuy, May 15, 2016
    Last edited: May 16, 2016
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