How to Choose the Right JK BMS Model for Your DIY LiFePO4 Battery System

JK BMS is currently the best DIY LiFePO4 battery management system due to its active balancing feature and reasonable price.

With a long list of JK BMS models available, it may be challenging to select the appropriate one for your battery system.

In this article, we will discuss the factors to consider when selecting a BMS and the naming rules for JK BMS models to help you find the right one.

Factors to Consider When Choosing a BMS

1, Battery Chemistry

Ensure that the BMS supports the chemistry of your battery pack.

2, Supported Cell Count

Make sure that the BMS can support the number of cells in your battery pack.

3, Maximum Current Rating

This is a critical factor that determines whether the BMS can meet the needs of your system. The maximum current supported by the BMS should be at least 20% higher than the maximum current of your system to avoid triggering the BMS overcurrent protection due to current fluctuations.

4, Peak Current Rating

Some loads in your system may produce a large surge current when starting up, such as a microwave or an electric stove, which typically generate a surge current twice their rated current. These surges are usually short-lived (a few seconds to a few tens of seconds), but if they exceed the BMS’s maximum surge current rating, they can damage the BMS.

JK BMS Naming Rule

JK BMS has a great naming rule that allows you to identify its maximum current, number of supported battery cells, and active balancing current quickly.

Typically, JK BMS models are named in the format of JK-B2A8S20P. In this naming convention, three letters, A, S, and P, are used to represent the active balancing current, the maximum number of supported battery cells, and the maximum current, respectively.

Balancing Current

If the number before A is 1 or 2, it indicates an active balancing current of 1A or 2A. If the active balancing current is less than 1A, it is represented by DXA, such as D4A for a current of 0.4A and D6A for 0.6A.

Maximum Supported Cell Series

The letter S and the preceding number indicate the maximum number of battery cells that the BMS can support. For example, 17S means the BMS supports 8-17 cells, 20S supports 8-20 cells, and 24S supports 8-24 cells. The minimum supported cells are 4-8 cells for 8S.

Maximum Current Rating

The number preceding P represents the maximum continuous current rating supported. 8P represents a maximum continuous current rating of 80A. 15P represents a maximum continuous current rating of 150A. 20P represents a maximum continuous current rating of 200A.

By using the above naming conventions, we can quickly find the corresponding JK BMS model based on the specific parameters of our system.

We can also determine the primary electrical performance of a new JK BMS by following these rules.

For ease of reference, we have compiled a list of JK BMS models and their main features for DIY LiFePO4 battery pack as below.

Model	Max Current	Active Current	Cells Supported
JK-BD6A20S10P	100A	0.6A	8S-20S
JK-B1A20S15P	150A	1A	8S-20S
JK-B2A24S15P	150A	2A	8S-24S
JK-B2A24S20P	200A	2A	8S-24S
JK-B1A8S20P	200A	1A	4S-8S
JK-B2A8S20P	200A	2A	4S-8S