LiPo Battery LTspice model

Discussion in 'The Projects Forum' started by dprickett, Oct 8, 2015.

  1. dprickett

    Thread Starter New Member

    Oct 8, 2015
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    Does anyone have a simplified spice model for a LiPo battery?
    I saw one out there for about $400. I was hoping for free.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    How elaborate a model do you need?
    Normally it's simulated by a voltage source with a series resistor.
     
  3. dprickett

    Thread Starter New Member

    Oct 8, 2015
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    I need to show it as a load off of a LT3650 charger. I originally put a cap as a load but I don't think that's right. I did see an example representation (attached) but I don't know how to Spice it.
     
    Last edited: Oct 8, 2015
  4. dprickett

    Thread Starter New Member

    Oct 8, 2015
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    The sense resistor should keep the current around 250mA but I see 2A spikes when I run the simulations. I'm not sure if it's because I use a big cap to represent my battery or it's just my Spice ineptness.
     
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    For simulating large (automotive) Lead-Acid batteries, I just use a huge capacitor (100s to 1000s of Farads, not uF) in series with a few hundred mΩ for the impedance. I use a .IC V(bat) = 12.6 V directive as an initial voltage to get the sim started. Beyond that point, the battery is either charging, or discharging as the simulation progresses...

    Example here
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
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    I do similar to Mike, but tend to use a lower capacitance (say 1 Farad or less) so that the sim shows some change in 'battery' voltage in a manageable time. BTW, don't fall into the trap that I did and set the value as '1F'. Spice reads that as 1 femtoFarad !
     
  7. eetech00

    Active Member

    Jun 8, 2013
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    try LTspice users group at groups.yahoo.com
     
  8. dprickett

    Thread Starter New Member

    Oct 8, 2015
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    Thanks everyone.
     
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