Got a PIS phev kit, advice with using Nissan Leaf cells with it.

Discussion in 'Prius PHEV Plug-In Modifications' started by glyndwr, Apr 27, 2015.

  1. glyndwr

    glyndwr Member

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    Hi all,

    I was very fortunate last week to pick up a complete Nissan Leaf battery pack, the pack was from a gen2 leaf with only 135 miles on the clock, so the pack is virtually new. I have removed the cells from the battery compartment, now deciding what to do with them as I have a few options.

    I already have a pis phev kit running in the gen2 Prius, it's a 76 cell 33ah lifepo4 battery, with my parameters it's got about a 5.5 kWh usage. Each battery cell is made up of 11 26650 batteries in parallel. They have been working really well to be honest for over 20 months since install. I get about an 18 mile range here in the UK in a quite a hilly area of South Wales.

    Now, the Nissan Leaf cells have a different nominal voltage, somewhere around 3.8v during use from what I have researched so far. Parameters for these cells are charge to 4.1v and discharge to 3v.

    I can fit as many as 34 cells in the car quite easily, this would give me close to 16kwh of capacity. I have upgraded the rear springs on the car already. The weight of the 34 cells would be approx 200kg or 2 average sized men. My current pack weighs about 90kg.

    With the Pis kit, what target voltage would you recommend to aim for with the leaf cells to determine how many cells in series I should use.
    With the current set up, my 76 cells when fully charged and sitting at approx 3.33v is 253v, during operation around 240v, and when empty close to 230v.

    As the leaf cells have a higher discharge rate and a higher ah capacity, I am hopeful that they won't sag as much therefore may not need as many cells in series to reduce the voltage.

    I currently use 76 cells as the batteries do sag abit during use.

    Any help or advice would be greatly appreciated.

    Thanks.
     
  2. z704w40

    z704w40 Junior Member

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    Nice find. One nissan cell pack contains 4 nissan cells in a 2P2S configuration. That means you have to deal with about 7.8 volts at 58 AH. So divide 253/7.8 = 32,4 you need to use 32 cell packs.
    What kind of BMS are you going to use?
     
  3. glyndwr

    glyndwr Member

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    thanks for the reply,

    I currently don't run with a bms, I just use cell loggers to monitor each cell, and use the alarm port out to trigger th charger cut off when the cell target voltage has been reached. It's very simple and basic, but it does work well.
    I don't think I'll bottom balance the pack either as they should be well matched and balanced after being in the car.
    They are the latest generation of leaf cells too as they have cooling slots in the cell canister to allow air movement, those packs I must say were built very well, the buss bar cabling is excellent, no finger touch points anywhere, it's all enclosed, very well designed and very safe.
     
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