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Enginer PHEV best battery use to 70% to 80%

Discussion in 'Prius PHEV Plug-In Modifications' started by whk.wang, Sep 9, 2009.

  1. whk.wang

    whk.wang New Member

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    I have not yet added the Enginer Kit, and am waiting for it to arrive.

    Question comes to mind. I am looking to extend the life of the battery as long as possible. I can take the battery down to empty or Beeping. But I really want to take it down the 70% SOC or 80% SOC.

    So I am geting the 4Kwh system.
    So I am trying to figure out how low to take that will be that level of SOC?

    I was trying to figure out the math to calculate the time the Kit can be on.

    I have a scan gauge that can help me keep track, if not exactly, but it can help to show me the time on for this trip.

    So 3000W used from batteries.
    The batteries are 40AH batteries at 48V.


    I almost have all the pieces to do the calculation for minutes I can have the battery pack on before the Enginer kit runs to the desired SOC?

    So the question is how much time with the pack last?
    What will the Battery Voltange be for 70% SOC?
    What will the Battery Voltange be for 80% SOC?

    I am geting the 4Kw system.

    Is this right?
    3000W / 48 V = 62.5amps.


    40 AH / 62.5 Amps * 60 minutes * 70 % = 26.88 minutes.
    40 AH / 62.5 Amps * 60 minutes * 80 % = 30.72 minutes.

    What am I missing...
    So
    Based on the addition by krousdb:
    2500W / 51.2V = 48.828A Which is about the middle of what krousedb is predicting and absolute max.


    80 AH / 48.828 Amps * 60 * 70% = 68.8 minutes
    80 AH / 48.828 Amps * 60 * 80% = 78.6 minutes
     
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  2. krousdb

    krousdb NX-74205

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    You are missing two things. First, 3000W is the maximum output. The average output for me is about 2000W. The second missing item is the efficiency of the converter, which is about 90%. To have an output of 2000W, you need an input of 2200W. The nominal voltage of the pack is 51.2. So...

    2200W/51.2V = 41.0A

    But a 4kWh kit, you have two strings of 40Ah cells, 80Ah total. With a 70% DoD, you have 56Ah. With a 80% DoD, you have 64Ah to use. So...

    64Ah/41A = 1.56h
    56Ah/41A = 1.37h
     
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  3. karaoke-rockstar

    karaoke-rockstar New Member

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    Many of us are waiting to hear from you after installation and the real world data you can provide us with. I'm hopeful, but a little skeptical of Enginers claims. I hope to be proved wrong so please keep us informed on the actual ev range that can be expected.
    Thanks Gene
     
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  4. whk.wang

    whk.wang New Member

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    So interesting a run with only 10 minutes difference to use up 10% more power from the batteries to go from 70% to 80% of charge.

    So even more interesting if I drive 32 miles my commute which takes about 35 - 50 minutes so most of the time my travel will be easily under 70% discharge.

    And the plan is to be able to recharge at work and at home.

    I bet I could be a candidate for 8kw and the 2 converters. Or even 6kw and 2 converters. And still not abuse the batteries.

     
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  5. whk.wang

    whk.wang New Member

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    I am not looking to over expect. I am expecting to save between 10% and 20% which is 10-20 MPG. But I do expect to get a little more EV range. Which should equate from what I used to get of 1 mile or less, to 3-5 miles with stop lights, and that may get me to the grocery store and home all electric. Which can be a great thing on savings for the short trips.

    I expect to post what I end up with in the other thread, but am trying to do the calculations here since I have nothing better to do while waiting for my kit to arrive. :whistle:
     
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  6. MJFrog

    MJFrog Active Member

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    With only a single converter, I was not able to get more than about 1 1/4 miles in EV mode on a cold engine before dropping out. The fact is, the Enginer pack cannot keep the Prius pack charged quickly enough to run pure EV mode for any distance. Two converters would have a better chance, but I don't have a second one.

    The idea of using it as a NEV is a no-go with just one converter.
     
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  7. whk.wang

    whk.wang New Member

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    I understand that, but if you cruz, and have stoplights, the enginer kit does recharge at each light and yes, it is a falling proposition, that the Enginer kit with one converter can't keep up. But it should get me farther then before. Also if I can already almost get all the way to the store now or even get to the store, I just can't get all the way home all electric also. So this will be helpful. The pain of having too many stoplights and too many stop signs but I do see a light at the end of the tunnel for EV mode now...


     
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  8. miscrms

    miscrms Plug Envious Member

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    It might be a good idea to look into some of the battery monitor products marketed toward EV builders. Here is one example:

    Electric Vehicle e-meter, monitor, volts meter, amps meter, battery monitor

    This one is pretty slick looking, but I believe there are simpler ones out there that don't need a screen. They would likely just give you an Ah or Wh reading on an lcd display, but that would give you a much better idea of how much of your battery you have actually used. Here is another one I have always liked the looks of, although from the website I am not 100% sure if they calculate SOC solely based off voltage or it they integrate the current data.

    PakTrakr Multi Battery Monitor Battery Pack Monitor

    This is one of the areas of concern I do still have with this kit, I don't feel like enough is done to prevent over discharge of the pack which could result in a much shorter than expected lifespan. It doesn't seem like it should be that tricky or expensive to make it better in this regard.

    Rob
     
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  9. atfsi

    atfsi New Member

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  10. mrbigh

    mrbigh Prius Absolutum Dominium

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    Sorry but the "Blue window" is a dedicated EV instrumentation and almost a waste to use in an Hybrid vehicle like a Prius
    -First it requires and NTSC resolution monitor, like the old type Video display, and really looks cheesy.
    -The total voltage readout need to be programed by the factory at time of sale. (Field upgradeable with an extra up loader kit, + $$$)
    -For Amp count it need an external "Shunt" in line for Coulomb arithmetics .
    This instrument doesn't read CAN information through OBDII connections, so for RPM counting you need to install a Hall effect sensor to a rotating shaft somewhere (is it really necessary on a Prius?) and if you want temperature ??????
    The next item of the same shortcut page, the XANTREX X10 (formely E-meter), doesn't work with the Prius neither, I tried it 5 years ago and it's sitting in a shelf somewhere in the work shop.
    The Pak-trakr could be adecuated only for battery monitoring factors but you need a display unit for each 48V strings.

    and still we are coming back to the beginning of the circle, this equipment is based on a working old design by other pioneers and reflects the "LOWER PRICE" that everyone is expending; that it can be improved and made with more reliable merchandise, 100% correct. But at what cost.............
    I bet you that Jack, the Enginer.co rep never had in account the large quantity of failed returned merchandise and the expenses involved to today days.
    Of course, it is still in beta testing or...... it is "delta" testing now????
     
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  11. miscrms

    miscrms Plug Envious Member

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    I agree, neither of the units I posted are really appropriate. Just trying to come up with a few quick examples of the sort of thing folks might want to look for. The one atsfi posted seems much more appropriate in terms of functionality and cost, not sure if its going to be quite strong enough though. You'd probably want the larger capacity "Doc Wattson" version for starters, as I think the 4kWh kit battery is ~80Ah. Keep in mind that the converter is putting out ~12A @ 240V or about 2.9kW. At ~48V, the pack is having to put out the same amount of power, resulting in ~60A plus a bit for conversion efficiency. These currents may also be sustained, as I believe the 12A output is pretty much constant under load conditions. Of course with more than one converter these currents would be 2-3X higher. The spec sheet says you can use this unit up to 100A, but also notes that the max continuous current is 50A. It seems like the unit must use an internal shunt or current sensor. Thats too bad, if it was external you'd have a decent chance of being able to swap it out with something beefier. It also limits your mounting options. It would be really nice to be able to mount this in the cockpit so you could monitor the pack as you're driving, but you really don't want to have to run your 60A battery current up through the cabin.

    This unit may not be quite the thing, but there must be something similar that would do the trick.
     
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  12. miscrms

    miscrms Plug Envious Member

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  13. atfsi

    atfsi New Member

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    There doesn't appear to be any problem using an external shunt...that would make it easy to take care of the 50A continuous dissipation limit.

    I'm going to stick w/ the 65Ah discharge scale as a "practical" fuel indicator as opposed to the 80Ah full discharge...just for longevity.

    The stock shunt is 0.001 ohms (1 milliohm). At 50A continuous, that's only 2.5 watts.....I'll probably use a 10W 0.001 ohm resistor to get a 100A continuous rating.
     
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  14. miscrms

    miscrms Plug Envious Member

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    Sounds pretty good, look forward to seeing your results!
     
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  15. linuxpenguin

    linuxpenguin Active Member

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    MJFrog, if you're primarily interested in longer EV-mode distances I would suggest a more powerful conversion like the PluginConversions (pluginconversions . com) 25 mile package. It is a full OEM battery replacement so there is no DC/DC converter at all so it allows for the full 21 kw at all times from the electric motor.

    It's more expensive yes, but it's worth it if you just want something that works.

    It comes bundled with the Hybrid Energy Manager modification from Ewert Energy (the 70 MPH in EV-mode modification) which would help you avoid running the ICE at higher speeds and it utilizes the electric motor completely before it uses the gasoline engine during normal driving.

    Andrew


     
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  16. MJFrog

    MJFrog Active Member

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    Thanks for your concern, but remember...I'm based in Michigan, not California. Rather long trip for installation (not sure of any closer locations... Plus I don't have the $12500 to spare anyway. The Enginer price fits my budget.

    My main desire for EV-mode is for usage as a NEV for about 3-5 miles max round trip. It would save all the hassle associated with short trips on a cold engine.

    For my daily commute, the Enginer pack does what it says it is designed to do...assist the engine by charging up the OEM pack. The main issues I've seen are the inability of the Enginer pack to recharge the OEM pack quick enough to stop the ICE from jumping in and doing the recharge itself, and the result that the charge in the Enginer pack isn't fully used...at least in the distance I travel: 38 miles round trip.
     
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  17. linuxpenguin

    linuxpenguin Active Member

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    Hi MJFrog,

    The cost is a bit steep for the PICC conversion, but it's worth it for those who can afford it since it just works...They also have installers around the country so you don't need to worry about driving to California for an install.

    If all you are looking for is a few miles in EV-mode you may be able to pull that off with the Enginer conversion if you have a very light foot and are OK with accelerating slow (slower than normal EV).

    The trick is going to be in the winter when the OEM battery prohibits EV-mode due to cold temperatures. At best, a DC/DC converter based conversion will see around 45 to 60 MPG in the winter (cold midwestern style winter) since you have to run the ICE all the time pretty much.

    Andrew
     
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