DIY assemble 72V100AH two-wheeled electric vehicle lithium battery pack with Ningde era ternary lithium-aluminum shell large monomer

On March 15, 2020, it took one week to assemble a 12-parallel 20-series battery pack with 240 East Magnetic 18650 ternary lithium batteries, because the original lead-acid battery controller was used, the undervoltage value was high, and the battery pack voltage 68V, when the monomer voltage reaches 3.3V, the electric car feels powerless when running, but there is still a lot of battery power left. The total battery power is 33AH, and the actual available power is 25AH. However, this also has an advantage, that is, the battery will not be frequently discharged to the protection voltage of the single 2.8V, and the shallow charge and shallow discharge is beneficial to prolong the battery life. After many tests, the group of 18650 lithium battery packs can be used for about 100 kilometers for about 2 and a half hours under the condition of good road conditions in the wild. But on urban roads, my driving habit is often full of high-speed driving, and make an emergency stop. Although I can drive quite far after the speed is lower than 35 per hour, I generally can't bear such a slow speed and don't want to drive. For me, the actual range is only about 60 kilometers. In order to continue to increase battery life, reduce mileage worries, drive without scruples regardless of the distance, and reduce the charge-discharge rate to extend battery life, I decided to refit the car in early December 2020 and replace lead-acid batteries with lead-acid batteries. The battery pack was replaced with a lithium battery pack and used in parallel with the 18650 battery pack made in the first half of the year.