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PHEV Recuperation Calculator

Discussion in 'Prius PHEV Plug-In Modifications' started by cproaudio, Mar 25, 2011.

  1. cproaudio

    cproaudio Speedlock Overrider

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    Edit: New version on post 13

    Many hybrid owners think that they can recuperate the cost of PHEV kit. The reality is that you can't. People convert because they want to own a plugin hybrid, not so that they can recupe the cost. It's the same logic as people mod cars to go fast or raise 4WDs. They don't race everyone at every light or go off roading every day. They did it for the sound and the looks. Anyways, this is my PHEV Conversion Kit Recuperation Calculator. This gives you some idea how long it takes to recuperate the cost of the kit. Even if you don't have PHEV kit, you can still use it to calculate cost and mileage of none converted vehicle. If you find any flaws to any formulas, please let me know. Have fun using it.
    [​IMG]
    Notes from the calculator
    1 Current configuration is based on a Gen III Prius with Enginer 4KW kit purchased from an authorized dealer.
    2 Price per KW varies greatly based on type of plan, time of use and total usage per month. Input the amount per kw you think you're paying on average
    3 Price per gallon of gasoline is based on US gallon. If you're using liter or Imperial gallon, input consistent unit of measure throughout this calculator. Do not mix US gallon and Imperial gallon and liter
    4A You can input the total amount you paid for the kit or itemize each charges. Please use the same currency throughout this calculator.
    4B You can input the total amount in rebates you're expecting to receive from the government. Please use the same currency throughout this calculator. 5 Input your calculated MPG before the conversion. I realize that many of you use l/km. You can use the link below to convert l/km to MPG
    l/100km to MPG / Litre / MPG / MPG to l/100km / Liter / Convert fuel efficiency - eForecourt.com
    6 Input your actual or estimated MPG after the conversion that you think you can achieve. If you don't know, use 170% of your stock MPG.
    7 This is the estimated mileage driven on electricity without using gas. It is the improvement the PHEV kit has made on your vehicle per gallon.
    8 This number is hard to calculate. This is your estimation on how much electricity it takes to drive your vehicle 1 mile. The lower the wattage the more efficient the car is. For reference, Leaf takes 340 watts to drive 1 mile, while Volt takes 360 watts per mile.
    9 Enter your PHEV's battery capacity.
    10 Enter the estimated miles you drive per day. If it varies, enter a number to reflect your weekly miles, monthly miles or annual miles. Enter only the daily miles you drive. If your miles vary, enter any miles that reflects your actual weekly, monthly or annual mileage.
    11 Battery packs degrade over time. Enter a percentage that will reflect the actual blended miles driven when your pack has been depleted. This will give you a good estimation of how much usable KW your battery can take and also gives you an estimated EV range. EV WattsPerMile will change this.
    12 Due to conversion loss, there's no charger on the market that's 100% efficient. You can ask the manufacturer for the charger's efficiency rating.
    13 This estimates how much power going into your battery pack and how much power actually made it due to conversion loss. Even though you have a 4KW pack, it may not deliver 4KW of power. BMS high voltage cutoff can prevent rest of the pack from fully charged if 1 cell triggered the HVC. LVC can prevent your kit from working if 1 cell has depleted while other cells still have power. Balancing also removes power from each cell.
    14 To achieve the high MPG, your batteries may be depleted before you've reached your destination. This estimation is to show how many charges you must make in order to drive the miles you want and achieve the mileage you want. You have to round this number up. 1.1 charge = 2 charges
    15 This shows approximately how many EV miles and how many miles of blended driving your kit is capable based on the capacity of your battery pack.
    16 This shows approximately the energy usage based on the stock MPG and the PHEV improvements has made.
    17 This shows approximately how many miles traveled on EV and on gasoline. This is based on the improvements the PHEV kit has made over stock.
    18 This is how much gasoline you've used before you converted to PHEV
    19 This is how much you've spent on gas before you converted to Plugin Hybrid
    20 This is how much gasoline you're using after you've converted to PHEV
    21 This is how much you've spent on gas alone after you converted to Plugin Hybrid
    22 This is how much gasoline you've saved after you've converted to PHEV
    23 This is how much money you've saved on gas after you've converted to Plugin Hybrid
    24 This shows approximately how many kw used from the wall to charger to battery pack based on the EV miles driven and the EV wattage used per mile.
    25 This shows much you've paid on electricity based on the kw used. The cost has been adjusted to offset the charger's efficiency.
    26 This is the total cost when combining the cost of electricity and gasoline. This is how much you pay in energy after PHEV conversion
    27 This is the bottom-line total savings after PHEV conversion
    28 This is how long it takes to recupe the cost of the PHEV conversion kit


    Edit: updated with Version 2. Now includes charger information and charge time.
     

    Attached Files:

    10 people like this.
  2. Flaninacupboard

    Flaninacupboard Senior Member

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    Good calculator. I get about 4 years, depending on whether i think petrol is going to get more or less expensive. i'm keeping this car until 2020 so that's fine by me.
     
  3. cproaudio

    cproaudio Speedlock Overrider

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    How much do you pay for electricity?
     
  4. sub3marathonman

    sub3marathonman Active Member

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    That is a great analysis that cproaudio came up with. The only thing I would want to check is the watts/mile. I think the enginer kit will supply much less than 250 watts/mile driving blended 57% gasoline /43% electric. From the Hymotion kit, I have found it takes about 235 watts/mile going purely electric, and less than 200 watts/mile driving "blended." That is only the figures that I have seen.
     
  5. cproaudio

    cproaudio Speedlock Overrider

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    did you download the calculator? you can change that number to cater your driving style. for my driving style I I've estimated that a mile takes 250 watts.
     
  6. SageBrush

    SageBrush Senior Member

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    Per EPA charging has about 20% energy conversion losses in both the LEAF and the Volt.

    The SS looks like a lot of work, I admit to being lazy and think of it this way:
    A kwh is optimistically good for 4 miles of driving. If I buy a 4 kwh pack for $4000 and recharge once every day for 10 years, my electric miles cap cost in pennies is 400000/(16*365*10) = 6.85 cents/mile. Electricity cost brings me up to 10 cents/mile, so breakeven with petrol assuming 50 mpg is $5/gallon.

    A little more accurate would be to assume only 80% of the pack charge is used, so breakeven jumps to $5/.8 = $6.25 a gallon petrol.

    As an aside cpraudio, if you put your SS on the web as a google doc changes will be much simpler for you and your fans will not have deprecated versions.
     
  7. cproaudio

    cproaudio Speedlock Overrider

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    I totally forgot about the cost per mile. I'll put it in the next version.
     
  8. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    I have recently learned and confirmed that some states (like my own) offer extreme rebates for PHEV conversions.

    If I get an engineer kit installed, I will be out $0.
    If I get a Hymotion kit installed, I will be out less than $2000.

    So obvious YMMV for state rebates.
     
  9. SageBrush

    SageBrush Senior Member

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    ^^ Wow. Colorado is also generous, although not Santa :)
     
  10. mrbigh

    mrbigh Prius Absolutum Dominium

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    cpraudio, thank you for making the chart larger and easy to read in your first post
     
  11. Corwyn

    Corwyn Energy Curmudgeon

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    Just a quick question: I am confused by Watt / Mile. How do you figure Power / Mile? It sounds like you want Energy / Mile (or Wh / Mile), yes?

    What about inflation rates for the respective fuels?
     
  12. cproaudio

    cproaudio Speedlock Overrider

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    Yes it's how many watthours it takes to drive the vehicle 1 mile.
    To truly calculate the actual recupe rate, You'd have to keep a detail fill up / charge up mileage per tank record, then enter those numbers into the calculator to get the result for each tank then record those results and add it up. This is a quick calculator shows the recupe rate based on the current cost of fuel and electricity. I will update with version 3 with more information in the next couple of days. Distance per tank based on full capacity and based on your typical fill up, MPG % improvements over stock, a more defined wh/mile calculation. I may need your inputs on how to calculate this.
     
  13. cproaudio

    cproaudio Speedlock Overrider

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    Version 4 adds a few more info such as how many miles you have to drive to recupe the cost of the kit, how many trips to the gas station and how many trips saved, cost per mile, distance per tank, annual trips to the gas station, how many days a tank will last, and last but not least cost and fuel of a stock hybrid vs PHEV vs a gasoline car. Also fixed electricity cost formula. Have fun. If you find any formulas that don't add up right or if you want me to add something, let me know.
    [​IMG]
     

    Attached Files:

  14. tfrain

    tfrain Prius Rookie

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    Thanks so much for doing this spreadsheet!! My recuperation is 4.138 years, according to the chart - BUT that is with my wife driving 70 miles a day (school next year will be quite a drive for her to take the kids there back/there back) - which leads to a question. The enginer kit, as an example, would not last all 70 miles. So unless we recharge between the long trips, does this chart take into account the fact that the enginer kit wouldn't help after say - 35 to 40 miles? Thanks again!
     
  15. seilerts

    seilerts Battery Curmudgeon

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    I don't know what other guys charge for kits, but right now I am installing Enginer kits for $3295. $4490 is a gross over-estimation of the kit cost, imho.
     
  16. ericbecky

    ericbecky Hybrid Battery Hero

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    Seilerts,
    Is $3,295 for a 4kwh kit?
    Does that include free follow up for when parts need to be replaced under the two-year Enginer warranty?
     
  17. mrbigh

    mrbigh Prius Absolutum Dominium

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    These are the hidden cost of doing business that some people forget about it...........:confused:
     
  18. cproaudio

    cproaudio Speedlock Overrider

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    No, but it calculates how many times you have to recharge each day to to drive the distance you need per day. The reason why I chose this instead of having the user input how many times they can charge per day is because like you said, some kits have limited range, user will input the wrong information and get the wrong result. You can't drive a 4kw kit 70 miles a day and get 90mpg by charging it only once a day. This calculator will tell you to charge your kit how many times a day base on the distance you drive, and actual battery capacity.

    If you haven't had the conversion done, then you can input the information base on "IF". If I get 70mpg with the conversion kit, then how long will it take to recupe.

    If you have the conversion kit, then you can input the information after you have finished 1 tank and 1 fill up. Once you start using your PHEV kit everyday, you'll know your kit's performance such as how many KW it takes to charge the battery when it's depleted. How many miles you can drive per charge.
    $3295 for an Enginer 4kw kit including installation sounds too good to be true. If you're doing it for that price, then you'll make a lot of customers happy.
     
  19. seilerts

    seilerts Battery Curmudgeon

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    Yes, free followup included for the first two years. Not too good to be true at the moment, but the price that I am willing to offer is subject to change, depending on the long term pricing structure that Enginer will commit to, which is still evolving. I can do this because I am not planning on making a living at kit installs. I'm much busier with Honda traction battery repairs.
     
  20. Jordan11685

    Jordan11685 Junior Member

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    Do you know anyone that does this in the Philadelphia or Baltimore area?