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Conversions in Florida part 2

Discussion in 'Electric Conversions' started by dimitri, Jun 8, 2009.

  1. dimitri

    dimitri Member

    Joined:
    May 15, 2009
    Messages:
    13
    Location:
    Tampa FL
    Hello everyone,

    I am a regular at DYI EV forum, but new here. I followed Daniel's unfortunate experience with EV Conversion and decided to post my own thread here. I have done 2 EV conversions for myself and enjoyed the process and results so much that I decided to offer conversion service to other people. I created my Web site to share the info at Clean Power Auto - Home.

    Like many here I have been fascinated by electric propulsion for many years, but only when lithium batteries became available I decided its time to stop waiting for auto industry and take the matter in my own hands.

    I have a degree in electronics and computer systems, I have been designing and managing large distributed networks for past 10 years, have excellent project management skills but also enjoy manual labor :smile: .

    It turns out I have a knack for taking apart ICE cars and putting in electric drive train, at least that is what people tell me when they see my EVs.

    My first EV was 2001 Mazda Miata, which I sold to a guy from New Jersey, he seems to enjoy it very much, or so he tells me :smile:

    My 2nd EV is 2002 Mazda Protege5, which uses LiFePo4 battery, Warp9 motor and brand new EVNetics controller, designed and produced by local company here in Tampa. I learned a lot about LiFePo4 batteries and even designed and produced my own BMS system, which monitors and balances each cell in the pack.

    This EV also has automatic transmission, which is a challenge that most conversions stay away from, but I found it fascinating to figure out and adapt to EV. It turned out very successfully, I managed to control shift pattern in my transmission to perfectly match it with Warp9 RPM curve, so I get best efficiency from my motor and enjoy the benefits of automatic transmission.

    Anyway, the purpose of this thread is not self promotion as much as trying to show that EV conversions have their place in EV market, side by side with Teslas and Zebras and whatever else new and exciting post GM market will bring :smile:

    I would be happy to answer any conversion related questions, thanks for having me here :biggrin:
     
  2. WarpedOne

    WarpedOne Supreme Premier

    Joined:
    Aug 17, 2006
    Messages:
    2,660
    Location:
    Slovenia, Europe
    Dimitri, welcome :biggrin:

    As you kindly offered your expertise, would you mind commenting on my dream design? It is not a conversion as there is nothing similar out there yet, but it is intended to be driven by pure electrons. :biggrin:

    What about my drive-train components choice?
    Any suggestion for a charger or DC/DC converter?
    How far off is my 140A max current estimation?
    Is 14A max to much for a 3200mAh LiFePo cell that is advertised as 12A / 28A?
    Any suggestion on how to easily combine single cells in parallel modules of 10 cells?

    I know, I'm asking too much :)
     
  3. dimitri

    dimitri Member

    Joined:
    May 15, 2009
    Messages:
    13
    Location:
    Tampa FL
    The only alternative to Azure AC24 that I am aware of is this one
    Motor, AC Motor & Controller Assembly

    Its supposed to be good for smaller vehicles, and has less voltage, so you can have larger cells but smaller string.

    I am not a fan of small cylindrical cells, unless its for a motorcycle. For 1000 Lb trike you could look at SkyEnergy SE cells, they pack 4C continuous and very easy to install compared to cylindrical cells and dealing with 10P configuration. There is a guy on DIY forum who makes custom packs from cylindrical cells, but still its much more expensive than SkyEnergy cells. In the EV design, rates higher than 3C or 4C are not important, unless its for racing. You want max stored power for range, not fastest way to deplete it :smile:

    If you can fit 30 of these puppies for 96V pack, you'd get your 10kWh
    http://www.evcomponents.com/ProductDetails.asp?ProductCode=SE100AHA

    or you can try to fit 100 of these for 320V pack if you stick to Azure system
    http://www.evcomponents.com/ProductDetails.asp?ProductCode=SE40AHA

    When dealing with cylindrical cells, its all about proper connections between 10 parallel cells, to ensure good balanced discharge, I have no experience in this area, but I have read about others doing it well. I am not sure how much you win in weight and volume when doing this vs. SkyEnergy, you'd have to run some numbers and compare.

    Direct drive with AC is fine for top speeds, but you have to pay attention to acceleration, make sure there is enough torque to get going and merge into traffic. Also pay attention to current levels at low RPMs since it will stress the battery and shorten the range.

    Hope this helps, if I think of anything else , I'll post here.
     
  4. WarpedOne

    WarpedOne Supreme Premier

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    Location:
    Slovenia, Europe
    Thank you for your thoughts.

    That motor/controller pack does look nice (and cheaper!) unfortunately it only does up to 6500 rpm. For 80mph max I'd need about 5:1 gear ratio meaning quite slow acceleration. So, Azure it is.

    If I'm not mistaken, all prismatic cells need external compression harness to see some lifetime? Those 40Ah cells do look small enough that they might even fit. They are much cheaper than cylindrics. I'll look into it.
     
  5. dimitri

    dimitri Member

    Joined:
    May 15, 2009
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    Location:
    Tampa FL
    Prismatic cells should be strapped, but it applies more to larger cells since they have more surface area on the side walls, and also it applies more when you charge them over 4.0V. Smaller cells like 40Ah should not need any serious strapping, and most people don't go over 3.8V with proper BMS and balancing, so swelling is highly unlikely. When you install them in the car, you tend to strap them or box them anyway, so they don't move around, this is sufficient enough to avoid swelling as well. These cells are very easy to work with, and I was told by the vendor that you can mount SkyEnergy cells horizontally as well as vertically. It was believed that Thundersky LFP cells cannot be mounted horizontally because of long term corrosion under the terminal posts, but it might have applied to early production batches and since then was addressed.
     

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