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9517Re: [solectria_ev] Charger with Li and BMS

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  • paul dove
    Nov 24, 2013
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      What's a compression end plate?


      From: Charles Bliss <cbliss@...>
      To: solectria_ev@yahoogroups.com
      Sent: Saturday, November 23, 2013 10:50 AM
      Subject: Re: [solectria_ev] Charger with Li and BMS

       
      The NG3 Zivan can be reprogrammed by the 'factory service' people in Sacramento, CA.  That costs $75.  For a 144 volt pack, I would recommend 46 cells and for a 156v pack, 49 to 52.
      The algorithm for Lithium is a little different than PbA.  Before sending the charger to Zivan for reprogramming, you will need to know how many cells you are using, otherwise, you might end up sending them another $75.  Have it programmed for 'safety' and let the BMS handle the charging.  By safety, it should not allow the batteries to exceed the battery chemistry max.  The BMS should cycle / balance below that.  I think mine is programmed to 3.8 / cell but the BMS is programmed to 3.65 max and balances to 3.45.  It might be a little lower, I don't remember the exact numbers.

      You will want a reliable BMS that can control the charger.  Make sure that you mount the Solid State relay on a heat sink, as the current will cause it to warm up enough that it can melt things, like the Solid State relay.  (I have replaced a number of them for others). 

      I have a Zivan NG3 with a solid state relay mounted on a heat sink with convection cooling and it gets hot when charging for hours.

      Don't forget to put compression end plates on the cell sets.  Some people suggest they aren't necessary.  I have replaced cells for those people.  Expensive mistake.

      On 11/23/2013 8:02 AM, William S wrote:
       
      I will be converting from Pb to Li with a BMS. The question is whether the charger (NG3-Zivan) needs to be re-programmed for Li. The BMS will cut off 110 v power thru a solid state relay. I suppose the answer has to do with what the Pb algorithm does at the end of charge. Compared to the cut off voltage for the Li pack. I have seen the cell count range from 49-56. Comments?




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