Batteries are used to store electricity. From a functional point of view, it can be said that all lithium batteries are energy storage batteries.
In order to distinguish applications, it is divided into 3 categories: consumer batteries, power batteries and energy storage batteries.
① Consumer battery applications are in consumer products such as mobile phones and notebook computers;
② Power batteries are used in electric vehicles;
③ Energy storage batteries are mainly used in energy storage power stations.
This blog mainly discusses the difference between the BMS of energy storage batteries and the BMS of electric vehicles.
·Electric vehicle battery
Power batteries are mainly used in electric vehicles. Due to the volume and weight limitations of vehicles and the requirements for starting acceleration, power batteries have higher performance requirements than ordinary energy storage batteries. For example, the energy density should be as high as possible, and the charging speed of the battery should be fast. The discharge current must be large. First of all, as a mobile power source, the power lithium battery has as high a requirement as possible for the volume (and mass) energy density under the premise of safety, so as to achieve a more durable battery life. At the same time, users also hope that electric vehicles can be safely and quickly charged, so power lithium batteries have high requirements for energy density and power density, but because of safety considerations, energy-type batteries with a charge and discharge capacity of about 1C are generally used at present.
·Energy storage battery
Energy storage lithium batteries are mainly used in areas such as peak-shaving and frequency-regulating power auxiliary services, renewable energy grid integration, and micro-grids. The vast majority of energy storage devices do not need to be moved, so energy storage lithium batteries do not have direct requirements for energy density. As for power density, different energy storage scenarios have different requirements. Compared with power lithium batteries, energy storage lithium batteries have higher requirements for service life. The lifespan of new energy vehicles is generally 5-8 years, while the lifespan of energy storage projects is generally expected to be longer than 10 years. The cycle life of the power lithium battery is 1000-2000 times, while the cycle life of the energy storage lithium battery is generally required to be greater than 3500 times.
There are some differences between the power lithium battery and the energy storage lithium battery, but from the point of view of the battery cell, they are all the same. Both can use lithium iron phosphate battery and ternary lithium battery. The main difference lies in the BMS battery management system and the power response speed of the battery. And power characteristics, SOC estimation accuracy, charge and discharge characteristics, etc., can all be realized on the BMS.
This blog will analyze the differences between the 2 (CN) standards of energy storage BMS and electric vehicle BMS corresponding to the application scenarios of the two industries.
"GB/T 34131-2023 Battery Management System for Electric Energy Storage"
"GB/T 38661-2020 Technical Specifications for Battery Management System for Electric Vehicles"
The data presented below are from the above two documents
1. Use environment requirements
The BMS operating environment requirements for electric vehicles are as shown in the figure below, specifically including the requirements for temperature, humidity, and power supply. The power supply requirements are clearly divided into two intervals. Passenger cars are basically in the range of 9V~16V.
The requirements for energy storage BMS are as shown in the figure below, which includes requirements for temperature, humidity, altitude, and salt spray; electric vehicles also have application altitude requirements for BMS, but they are generally placed in the needs of OEMs; as for salt spray, electric vehicles BMS generally do not make requirements; for energy storage BMS, the standard does not define power supply requirements here, and we actually know that there are two power supplies of 12V and 24V, but there is no definition of the use of these two power supplies, so some suppliers will use energy storage The BMS is compatible with both 12V and 24V power supplies.
2. Basic functional requirements
The basic functions of electric vehicle BMS are as follows, covering monitoring, collection, interaction, calculation, alarm, charging, etc.
The basic functions of energy storage BMS are as follows. Through comparison, it is found that the functional requirements of 2 type of BMSs are actually similar. Energy storage BMS has no special charging management requirements. As for data collection objects (such as single voltage, temperature, total voltage, current, insulation resistance, etc.) are the same.
3. Detection Accuracy requirements
The detection accuracy requirements of the two BMS are as follows. From the comparison of this standard alone, it can be seen that there are differences in the accuracy requirements between the two BMSs; the electric vehicle BMS has higher requirements for the SOC detection accuracy, while the energy storage BMS has higher requirements for the SOE detection accuracy.
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Functional items |
Electric Vehicle BMS Performance Requirements |
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Total voltage detection |
±1%FS |
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Total current detection |
±2%FS |
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Single voltage detection |
±0.5%FS, The absolute value of the maximum error <10mV |
|
Single temperature detection |
±2℃@-20℃≤T≤65℃; ±3℃@-40℃<T<-20℃; ±3℃@65℃<T<125℃ |
|
Insulation detection |
±20%@V>400V; ±30%@V≤400V; ±10KΩ@R≤50K |
|
SOC estimation |
≤±5% |
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|
|
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Functional items |
Energy Storage BMS Performance Requirements |
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Total voltage detection |
±5V@<500V; ±1%@≥500V |
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Total current detection |
±2A@<200A; ±1%@≥200A |
|
Single voltage detection |
±5mV@<5V |
|
Single temperature detection |
±1℃@-20℃≤T≤65℃; ±2℃@-40℃<T<-20℃; ±3℃@65℃<T<125℃ |
|
Insulation detection |
±30%@60V<V<400V; ±15KΩ@R≤50KΩ... |
|
SOE estimation |
≤±5% |
4. Test Performance Requirements
The two types of BMSs are divided into test items according to the aspects of electrical, mechanical, environmental, EMC and insulation performance. Next, we will compare several key items.
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Insulation properties
Insulation properties specifically include insulation test and withstand voltage test.
The specific requirements of electric vehicle BMS are as follows:
|
Functional items |
Electric Vehicle BMS Performance Requirements |
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Insulation requirements |
When BMS is not working, RISO≥ 10MQ, the test time is 60s; when BMS is working, RISO≥ 100Q/N*Umax;
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Withstand voltage |
There can be no breakdown or flash-over, the leakage current can be negotiated, the duration is 60s, and the test voltage refers to "GB 18384 - 2020"; |
The requirements for energy storage BMS are as follows: withstand voltage test is called dielectric strength test here, because the platform voltage of energy storage may be higher, so a higher test voltage is specified here.
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Functional items |
Energy Storage BMS Performance Requirements |
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Insulation requirements |
When BMS is not working, RISO≥ 10MQ, the test time is 60s;
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Dielectric strength |
Test when the BMS is not charged, there can be no breakdown or flash-over, the leakage current is < 10mA, and the duration is 60s;
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BMS operating life
Lifespan and MTBF are defined in the energy storage BMS; the BMS of electric vehicles also has requirements, which are generally released by the OEM, and the BMS itself must match the requirements of the entire vehicle.
4. Summary
Due to the different requirements for the use conditions of energy storage systems and electric vehicles, they have the following differences in terms of BMS:
(1) The BMS of the energy storage system requires higher safety performance, because they generally require longer life and higher reliability, while the BMS of the electric vehicle pays more attention to the power density and dynamic response speed.
(2) The BMS design of the energy storage system pays more attention to battery aging and damage, and protects the system from overcharge, overdischarge and short circuit. The BMS of electric vehicles pays more attention to the energy efficiency and stability of the battery.
(3) The BMS of the energy storage system usually requires more safety measures and monitoring functions to ensure the overall stability and safety of the system, while the electric vehicle BMS usually requires more monitoring and control functions, such as real-time calculation of the feasible mileage of the vehicle and battery health status information.
MAXKGO BMS can be widely used in the fields of power batteries and energy storage batteries, and can effectively manage and protect 4S-95S（16V-400V） battery packs.
MAXKGO BMS boards have 5 to 18 cell levels monitoring per board which can achieve 1.2mV accuracy, and operate in -40 to 120℃ environment.
It can provide management and protection for the battery under the current: 500A (continuous); 2500 (peak value).
MKBMS battery management system implements the following functions:
1. Current and voltage protection: protect the battery pack from overcharge and overdischarge, thereby extending the cycle life.
2. Battery health monitoring: monitor the internal resistance of a single battery and the monitoring capacity of the battery pack.
3. Thermal management: Overheating and under-temperature protection.
4. Support batteries: Li-Ion, Li-Polymer, Li-Phosphate
5. Intelligent battery balance: passive balance
6. Field programmable
7. Current limit calculation
8. Fully programmable CANBUS interface, programmable structure of all CAN messages
9. Drift state of charge
10. Reliability, speed and accuracy
11. Integration with other devices
12. Multiple BMS units connected in series
13. Current sensor support
14. Isolation from fault detection
15. Automotive grade design, automotive grade locking connector
16. Software for data logging and programming
You are welcome to contact us via social media or email: info@maxkgo.com, our staff will match the scheme and make the corresponding wiring diagram according to your needs.
We look forward to hearing from you.
Thank you for your patience in reading, see you in the next blog.
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