24V16Ah Battery Pack for Hybrid System

1. Basic Parameters of 24V16Ah

2. Capacity Test

We charge the battery pack with 1C(16A) constant current under 20℃±2℃ and then turn to constant-voltage charging as soon as the voltage reaches 29.4V(or single cell reaches 4.25V). Charging stops when the charging current lower down to 0.1C(1.6A).

After storing for 1 hour, we discharge the battery pack with 1C(16A) till the voltage reaches 21V(or single cell reaches 2.8V).

The capacity tested was 16.3Ah, please refer to the curve below.

3. Hybrid Pulse Power Characteristic

3.1 HPPC Testing Steps

1. Charge the battery pack to 100% SOC

2. Discharge it with 1C current until the SOC remains 80%

3. Start Pulse test. First discharge the battery pack with 6C current for 10s

4. Rest for 30s

5. Charge it with 6C for 10s

6. Discharge it with 1C current to consume 10% SOC

7. Repeat step3 to step 6 until the SOC remains 20%

8. Discharge it with 1C current until the SOC remains 0%.

3.2 Voltage Curve generated by above HPPC Test, it shows that the battery pack can bear 6C charging and discharging very well in the range of SOC 20% to 80%.

3.3 Power Curve

According to the calculation method of power input&output in hybrid vehicle stated in Freedom Car, the battery pack's 10s pulse power under different SOC is clearly showed in the curve below. As we can see that the battery pack have more than 5000W input or output power between SOC30% to SOC70%, which means the battery pack is fully capable of powering the hybrid vehicle.

4. Cycling Life Test

In hybrid system, the battery system bears high Charge&Discharge current, and the working SOC range is from 20% to 65%, the average current is 6C, so we test the battery pack's cycle life under this common working condition.

4.1 Testing Steps

（1） Conduct the Capacity Test and HPPC test as above

（2） 1C（16A）constant charge to SOC65%

（3） 6C（96A）constant discharge to 20%

（4） 6C（96A）constant charge to SOC 65％

（5） Repeat Step3 to Step 4 for 1,000 times.

（6） Repeat Step 1 to Step 5.

（7） Count the total cycles.

4.2 Test Result

4.2.1 Capacity Remaining Ability(CRA)

After 20000 cycles DOD45% （equals to 9000 cycles DOD100%）, the remaining capacity is still above 80％ of rated capacity；

4.2.2 DCR Changing Curve

The below curve shows relationship between DCR and Cycles discharging at 6C for 10s under SOC50% , Due to the tiny different of testing conditions(temperature changes for example), the DCR vibrated a little. But based on the entire tendency, after 8,000cycles the resistance of the battery pack increased about 10%, which means that the battery's power remains a high capability even after long time cycling.

4.2.4 Consistency

Battery's consistency is a very very important characteristic for EV. The below format shows voltages of each cells in 24V16Ah battery pack. After comparing the initial voltages at SOC50% and voltages after 8,000 cycles, we can see that the voltage difference of single cells is till lower than 20mV which means that the batteries have great consistency.

5. Working Test

We cycled the battery pack under 42℃ for 8h, and the single cell's temperature raised no more than 5℃, meanwhile the temperature difference between each cell is lower than

3℃.

This test showed that the battery pack's structure is scientific and reliable which has very good capability of heat dissipation and helps maintain good consistency of all cells in long time working.

6. Customized Hybrid Systems are available exactly according to your requirements, just contact us and let us know.