Leo Motors’ Battery Management System Achieves 0.01 Volt Cell Balancing in Test
18 June 2010
In testing by the Korea Electric Technology Institute. run by the South Korean government, Leo Motor’s (earlier post) battery management system (BMS) maintained a voltage balance between cells of less than 0.01 volts among 13 cells in the 1.9kW Lithium Polymer power pack that will be used in Leo’s electric scooters and other electric vehicles.
The BMS controls the flow of electricity charging and discharging the battery pack, keeps the battery temperature stable, and maintains the battery cell balance to ensure the Lithium Polymer battery cells are maintained at the optimal combination of efficiency and safety.
Leo fully integrates its BMS into its other systems in its EVs, so that the BMS can adjust to various power requirements in different driving situations. Information from the battery is incorporated into the on-board power management program, so that the driver can check the full detail of the battery’s status and more effectively manage the battery.
We are very delighted with the official test results because the results are superior to any of the self claims made by other BMS brands that we have seen. There are many performance claims for BMS, but most of them can only claim a balance of less than 0.05 volts, and seldom do manufacturers get the official tests.
—Dr. Robert Kang, CEO of Leo Motors
In addition to integrating its BMS into its own line of EVs, Leo plans to market its newly developed BMS to EV and car manufacturers as well as to the manufacturers of other energy storage products that use lithium batteries.
Question: Wouldn't an overly sensitive cell balance system have a tendency to overload weaker cells and under-load better cells? Wouldn't this damage good inherently weaker cells?
Posted by: HarveyD | 18 June 2010 at 05:39 PM
I think you got it backwards. It's all good. Prevents early demise of weaker cells, which kills overall performance.
Posted by: GdB | 18 June 2010 at 05:52 PM
The BMS keeps the voltage across all cells equal, which they should be, and would all be, in their free state.
Without the BMS all cells carry the same current but weaker cells will then have a higher (during charging) or lower (during discharge) voltage - not good.
Is this significant to the success of EVs? - probably not; It's good for Leo.
I suspect that 0.05v is fine.
Posted by: ToppaTom | 18 June 2010 at 07:57 PM
0.01V is good if you plan to cycle the cells to 99%.. and you are never going to do that because it overheats the cells and shortens their life. Hopefully its cheap.
Posted by: Herm Perez | 19 June 2010 at 08:27 PM