Dan-Tech Energy Ltd. Israel. Dan-Tech Energy GmbH, Berlin Germany. System Technik Limited Hong Kong

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2 Dan-Tech Energy Ltd. Israel Development of battery packs, BMS, protection circuits and chargers, prototyping and mid size production in Tel-Aviv. Dan-Tech Energy GmbH, Berlin Germany Development of battery packs, BMS, protection circuits and chargers, prototyping and mid size production in Berlin. Setup of emobility center in Adlershof Science Park System Technik Limited Hong Kong R&D, Custom Production, BMS and PCM design and production.

3 BMS Battery Management System and cell Balancing methods in Li-FePO4 Batteries

4 LiFePO4 Technology in LEV Main advantages of LiFePO4 (LFP) Cycles to Lower cost for the user Lower maintenance costs Operating temperature range -20 to 60 C No additional measures for outdoor applications High discharge current up to 10C

5 LiFePO4 Technology in LEV Main advantages of LiFePO4 (LFP) (continue) High charge current 1C Shorter charge time higher availability High energy density vs SLA Smaller housing Smaller weight No heavy metals in the battery Green battery

6 LiFePO4 Technology in LEV Cell-balancing techniques The impact of cell imbalance on run-time performance and battery life in applications using series-connected cells is certainly undesirable. To avoid cells imbalance and to obtain good performance we need BMS with reliable and efficient balancing system

7 LiFePO4 Technology in LEV Cell balancing is usually categorized into two types passive and active Passive cell-balancing method, also known as resistor bleeding balancing, is simple and straightforward: Cells that need balancing are discharged through a resistance bypass route. This bypass can be either integrated or external to the controlling IC. Such approach is favorable in low-cost system applications. The fact that 100% of the excess energy from a higher energy cell is dissipated as heat makes the passive method less preferable to use during discharge because of the obvious impact on battery run time.

8 LiFePO4 Technology Active cell-balancing method, utilizes capacitive or inductive charge shuttling to transfer charge between battery cells. Active cell balancing overcomes the energy loss of the passive method by using capacitive or inductive charge storage and shuttling to deliver energy to where it is needed most, and with little loss. It is preferable for efficiency-conscious designs and for applications where delivering maximum run time is top priority. The trade-off for this improved efficiency is the need for additional components at higher cost.

9 Case Study escooter Customer: Motion Innovation Holland Project started: 2009 Battery pack: LiFePO4 24V/12Ah (8S1P) BMS: Standard BMS with Bleeding Balancing We faced the following disadvantages: We couldn t achieve real balance we succeeded to reduce the voltage of the higher cell ONLY! Cells with lower voltage remained LOW! Battery cycle life decreased significantly. We couldn t scope the battery state as cycle life and failure logs. End user didn t get the actual remaining runtime.

10 Case Study escooter Solutions: 2011 completed the development of BMS with Active Balancing Implementation of real time fuel gauging Added SMBus protocol Added Bluetooth transceiver Added Remote control service (through Android)

11 Conclusions: Case Study escooter One of the emerging technologies for enhancing battery safety and extending battery life is advanced cell balancing. Since new cell balancing technologies track the amount of balancing needed by individual cells, the usable life of battery packs is increased, and overall battery safety is enhanced. In active balancing, battery run time can also be maximized by balancing at high efficiency at the end of discharge in every cycle.

12 Case Study escooter Adding communication features to the BMS provided: More data for the user as remaining capacity, cycle count, remaining run time and actual capacity. More data for the service center either by wired or wireless readout. Higher customer satisfaction

13 Bluetooth Connectivity Speed State of Charge Remaining Capacity Power Consumption GPS Location