Lithium Ion Battery Swap

Spiers New Technology has a ‘Tennant’ mobile floor cleaner with a dysfunctional lead acid battery, I designed a stack of Lithium Ion battery cells to replace the old battery. This was done knowing the maximum voltage of the fully charged lead acid battery and the voltage limit of the electronics on board. A stack of Lithium Ion cells were combined into 5 series groups with 4 parallel modules each group for higher current handling and longer life. Once the design and implementation of the pack was decided bus bars had to be fabricated to allow the connection of the cells. As is, the battery runs blind with no management. In the future, a battery management system would be outfitted to allow for the cell to be balanced improving the overall life expectancy of the pack. Once the pack was built and connected together it was dropped into the ‘Tennant’ floor cleaner and connected to the existing wiring. The end product will clean the floors for roughly 6 hours of constant use. The pack is rated at 410 AH. The factory replacement battery is rated at 510 AH and costs $5200 and is more than double the weight of the lithium ion pack. The new pack should last roughly the same amount of cleaning time because the energy densities roughly equal. This project both enabling SNT to be able to use the cleaner and to repurpose Lithium Ion Cells that were not able to be deployed into the field.