Accumulator Update!

My primary work on the Engineering 89/90 team responsible for the electric powertrain of the 2016 DFR car has been on the accumulator — the electrical energy storage device for the vehicle.  I’ve spent a lot of time looking for the right battery cell.  Even though I had prior experience with battery cells, it’s been a very difficult task!  Balancing the energy density with the power density of a cell demands a keen understanding of the overall strategy for the electric powertrain…are we willing to accept more weight in order to gain more power output from the accumulator?  Design risks (i.e., risks to functionality and timeline) are were a major factor in the battery pack design.  How difficult is it to weld together many small cylindrical cells?  How can we circumvent the significant design challenge that is building a battery pack with mechanically unprotected pouch cells?  All these considerations, in conjunction with the significant challenge of sourcing viable lithium ion cells from non-OEM suppliers, slowed the process of cell selection (and battery architecture choice), but then, just in the nick of time, we found a prismatic li-ion cell that is perfect for our car!

The cell we’ve chosen is highly power-dense and reasonably energy dense (extremely energy dense in comparison to other prismatic cells, at 104 Wh/kg) and comes from a Florida supplier called Lithionics.  We are extremely excited by the level of safety and stability (especially when we are talking about lithium ion chemistry) that the cell affords us.  That high level of safety is right in line with the “professionally constructed” component of our team’s 2016 vision.  The cells are en route and pack design iterations are underway, and right after Christmas, the mad rush to construct the battery pack will begin!  Wish us luck, because without a battery, we cannot store the electricity we need to spin our motor and drive this car (hopefully down Victory Lane come May 2016).

Ben Parker ’16
Primary Accumulator Designer


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