Tuesday, January 10, 2012

Our BMS has arrived!

Our BMS arrived last Friday and needless to say, we are overwhelmed.  The MR2 has to be totally rewired top to bottom to accomodate the new component.  The BMS will monitor all cells during charge and under driving conditions, giving us real time analysis of the Lithium batteries.  This technology will help preserve the lifespan batteries and help to keep them a balanced set.  The performance of the MR2 should be more consistent and we will have the opportunity to data  log our charge and discharge cycles.  Two students are working on a program that will create an interface that incorporates both the Synkromotive controller and the BMS parameters on the same in dash display.
  Today, we began removing all of the Thundersky batteries so we can top balance the entire set in parallel.  By doing this, we will have a balanced pack, and the BMS will have an easier job for the initial few charge cycles.

5 comments:

  1. Would love to know why this new BMS requires you to re-wire everything. I am considering using that BMS in my build which hasn't been wired yet. Just trying to look ahead to see what problems I can avoid.

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  2. Did you check to see how balanced the pack really was before taking it out? When the charger is at the end of the charge cycle you should have plenty of time to measure all the cell voltages to see how close they really. Maybe I'm not remembering correctly but I thought you top balanced them before. My cells don't drift out of balance and I have the same ones you do.

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  3. Peter, we just have to reconfigure where the most negative and most positive pack terminals are which will require us to physically rotate the batteries, then we will have to relocate the fuse and kill switch in the battery string. We will have three banks.
    Gizmo, we did check the cell voltages and found they were not too close under end charge. We had anywhere from 3.41 to 3.8 under charge. We never did a top or bottom balance...I think we may have done more damage by drawing too much current from our batteries and also the Zivan charger floats the charge at the end for a period of time and we didi not know that was a bad thing with lithiums. The BMS is going to be used as a teaching tool for data collection as well. Hopefully we have not damaged too many cells. We will find out.

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