Instead of a single battery, Tesla uses thousands of small batteries

Tesla is the only new energy vehicle in the world selling thousands of batteries as power cells. The Tesla battery pack USES a Panasonic 18650 (18*65mm) ternary lithium battery (NCA nickel-cobalt aluminum). It adopts the mode that 74 batteries are connected in parallel and 100 in series to reach the rated voltage of 400 volts. At present, the new energy vehicles sold in China basically adopt the battery pack form of battery monomer in series, without parallel structure.

First of all, let's not talk about the research and development cost of single batteries. In terms of practical use, thousands of small batteries also have more advantages than single batteries. This is mainly reflected in the following aspects:

I. maintenance cost

We all know that new energy vehicles have their own BATTERYMANAGEMENTSYSTEM, or BMS as we know it. If there is any problem in the process of use, the maintenance cost of a single battery must be higher than that of thousands of small batteries. Moreover, since single batteries account for a large proportion of the overall power source, it may break down if the fault is serious. However, the battery pack composed of thousands of small batteries has its own advantages in this aspect. If a single small battery has problems, the BMS system will cut off the connection of the battery and prevent the fault from spreading, so that even if several single small batteries have problems, the vehicle will not be affected.

Second, heat dissipation

In the process of using new energy vehicles, both charging and discharging will generate heat. However, due to the large volume of single batteries, the heat dissipation has not been well handled. By contrast, a battery pack made up of a single small battery can easily solve this problem. Pipes with coolant are shuttled between each battery module, so that each battery can contact the water pipe and take away the heat emitted by it, so that the temperature difference can be controlled within a certain range.

Safety

As we all know, lithium battery technology has developed so far, but it is still far from very safe and mature. Spontaneous combustion and self-explosion of lithium battery occur frequently. If a whole single battery is used, the consequence of deflagration accident will be unimaginable. However, the existing split-type battery pack with a single cell has a small capacity and buffer time in case of accidents. Although it is still impossible to avoid danger, the buffer time at least leaves more time for passengers to escape.

Fourth, single battery management is difficult

Electric vehicle is the most critical system BMS (battery management system), is responsible for the system to monitor battery status, management power output, and the heat coming from the battery in the workplace is one of its most important data, large monomer battery thermal management would be a very tough, not between each batteries as existing battery pack assumes that the cooling system.

Short battery life

With the current technology, a large area of the chip with a small number of defects will be rapidly deteriorated after a certain number of charges and discharges, leading to a rapid decline in battery life, and the shortening of battery life is certainly not what every consumer wants to see.

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