New Energy Lithium Battery Pressure Switch Selection Mistakes: 5 Errors to Avoid

In new energy lithium battery production, pressure switches act as "invisible guardians" for ensuring liquid injection accuracy, formation efficiency, and battery safety—from electrolyte pressure control during cell liquid injection to cooling water circuit monitoring in PACK thermal management systems. Abnormal pressure in any link can lead to cell swelling, batch scrapping, or even safety accidents. According to the 2025 New Energy Lithium Battery Equipment Maintenance Report, 42% of lithium battery production line shutdowns stem from pressure switch selection errors, with an average single-fault loss exceeding 150,000 RMB (approximately $21,000). However, most lithium battery factories fall into the traps of "parameter stacking" and "experience-based selection" during the selection process, ignoring the unique working conditions of the lithium battery industry. Combining Chengdi Tech’s practical experience serving over 300 lithium battery clients, this article breaks down 5 high-frequency selection errors and provides scientific solutions.

Mistake 1: Ignoring Electrolyte Compatibility, Using "General Materials" to Deal with Corrosion Risks

Error Manifestation

To control costs, ordinary 304 stainless steel pressure switches are used, which come into direct contact with fluorine-containing and lithium-containing electrolytes (e.g., LiPF6-based electrolytes).

Hazards in Lithium Battery Scenarios

Fluoride ions in the electrolyte accelerate pitting corrosion of 304 stainless steel, leading to probe leakage within 1–3 months. This causes electrolyte contamination of the pressure chamber, requiring switch replacement (increasing individual unit costs by 800 RMB) and potentially affecting cell purity due to electrolyte leakage, resulting in grade degradation of the entire batch.

Correct Approach

1. Mandatorily select SUS316L corrosion-resistant material: SUS316L contains 2%–3% molybdenum, offering corrosion resistance to fluoride ions 5 times that of 304 stainless steel. It is suitable for all lithium battery processes (liquid injection, formation, water washing). Chengdi’s MKV-L series pressure switches come standard with SUS316L probes and can provide material test reports;

2. Simultaneously upgrade seals: Use electrolyte-resistant PTFE (polytetrafluoroethylene) gaskets to prevent nitrile rubber, silicone, and other materials from swelling due to electrolyte exposure. Chengdi’s custom models can optimize seal formulas based on electrolyte composition;

3. Supplement regional compliance requirements: For lithium battery production lines exported to Europe and the US, ensure materials meet RoHS 2.0 (EU) and CPSIA (US) environmental standards to avoid heavy metal non-compliance affecting product market access.

Mistake 2: "Just Matching" the Pressure Range, Ignoring Pressure Fluctuations in Lithium Battery Working Conditions

Error Manifestation

Selection is based on "rated working pressure"—for example, a 0–0.3MPa range pressure switch is chosen for a liquid injection process with a rated pressure of 0.3MPa.

Hazards in Lithium Battery Scenarios

"Instantaneous pressure peaks" occur during lithium battery liquid injection—when the cell liquid injection port is blocked, pressure can surge to 0.5MPa. Switches exceeding their range will trigger overload protection, causing liquid injection interruptions; if switches lack overload protection (such as the 1.5x pressure resistance design of Chengdi products), shell cracking may even occur, leading to electrolyte splashing.

Correct Approach

1. Reserve 1.5–2x margin for the pressure range: Select based on "maximum instantaneous pressure"—choose 0–0.6MPa for liquid injection (rated 0.3MPa) and 0–0.2MPa for formation (rated 0.1MPa). Chengdi supports custom ranges of 0.1–1.0MPa while maintaining an accuracy of ±0.5%F.S.;

2. Prioritize models with overload protection: For example, Chengdi’s MS31-L series has a pressure resistance of 1.5x the range (0.9MPa pressure resistance for a 0.6MPa range) and built-in pressure overload alarms to avoid hard damage;

3. Adapt to low-power requirements of new energy lithium batteries: Select low-power models with ≤45mA (no load) to prevent insufficient backup power life in battery-powered scenarios of PACK workshops due to excessive switch power consumption.

Mistake 3: Underestimating Explosion-Proof Ratings, Ignoring Flammable and Explosive Environments in Lithium Battery Workshops

Error Manifestation

In explosion-proof areas (hazardous areas Zone 1/Zone 2) such as cell drying and electrolyte filling, ordinary pressure switches without explosion-proof certification are used.

Hazards in Lithium Battery Scenarios

Electrolyte vapors (e.g., dimethyl carbonate, ethyl carbonate) in lithium battery workshops are flammable and explosive gases. Electrical sparks from ordinary switches may ignite the vapors, causing local explosions. This violates GB 50160 Code for Fire Protection Design of Petrochemical Enterprises and may result in penalties from safety supervision authorities.

Correct Approach

1. Select corresponding explosion-proof ratings based on areas:

1. Liquid injection workshops (Zone 1): Choose ATEX II 2G Ex d IIC T6 (EU) or IECEx Ex d IIC T6 (globally universal) to ensure the flameproof enclosure blocks sparks;

2. Drying workshops (Zone 2): ATEX II 3G Ex nA IIC T6 can be used to balance safety and cost. All of Chengdi’s explosion-proof models are certified by the National Explosion-Proof Electrical Product Quality Supervision and Inspection Center;

2. Explosion-proof treatment for communication interfaces: RS485 communication cables must be equipped with explosion-proof cable glands (e.g., M20×1.5 thread) to prevent static electricity introduced by cables from igniting gases. Chengdi provides explosion-proof accessory kits;

3. Additional attention to UL certification for the North American market: For lithium battery production lines exported to the US, select models with UL Class I, Division 1, Group C&D certification. Chengdi can quickly match certified inventory.

Mistake 4: Incompatible Communication Protocols, Inability to Connect to Lithium Battery MES Systems

Error Manifestation

Pressure switches supporting only analog output (4–20mA) are selected, making it difficult to connect to lithium battery factory MES systems (e.g., SAP, UFIDA U9) and unable to achieve real-time traceability of pressure data.

Hazards in Lithium Battery Scenarios

Analog signals have short transmission distances (≤100m) and are susceptible to high-frequency interference in formation workshops, leading to pressure data deviations; historical data cannot be automatically recorded, making it difficult to trace pressure abnormal nodes when cell quality issues occur, increasing fault diagnosis time (averaging 4 hours longer per incident).

Correct Approach

1. Prioritize RS485 communication pressure switches: Supporting Modbus RTU protocol, they can be directly connected to lithium battery MES systems with a transmission distance of up to 1000m and a data sampling rate of 4 times/second, meeting real-time monitoring needs. All of Chengdi’s lithium battery-specific series support this protocol;

2. Select Profinet protocol for two-way control: If remote adjustment of pressure thresholds via MES systems is required (e.g., switching liquid injection pressure for different cell models), Profinet protocol models can be selected. Chengdi provides protocol customization;

3. Adapt to data storage needs: Choose models with local cache functions (e.g., Chengdi’s MS32-L series, which can store 7 days of historical data) to avoid data loss when MES systems are disconnected.

Mistake 5: Ignoring Temperature Impact, Failing to Consider Temperature and Humidity Fluctuations in Lithium Battery Workshops

Error Manifestation

In high-temperature formation workshops (40–60℃) and low-temperature material storage rooms (-10–0℃), pressure switches with narrow operating temperature ranges are used.

Hazards in Lithium Battery Scenarios

When temperatures exceed the switch’s operating range, "temperature drift" occurs—high temperatures can expand accuracy deviations from ±0.5%F.S. to ±2%F.S., leading to inaccurate liquid injection volumes (deviations exceeding 5%) and poor cell capacity consistency; low temperatures may cause the switch’s LCD display to fail, making it impossible to intuitively judge pressure status.

Correct Approach

1. Select models with wide operating temperature ranges: Covering -20–80℃ (e.g., Chengdi’s MKV-L series), with custom -40–120℃ models available for high-temperature formation workshops. Built-in temperature compensation chips control temperature drift to ±0.02%F.S./℃;

2. Adapt LCD displays to low temperatures: Choose 3-color LCD screens (red/green/orange) with low-temperature wake-up functions, which can still display normally at -20℃. Green indicates normal status, and red indicates over-limit, facilitating quick identification by on-site workers;

3. Add moisture-proof treatment for humid environments: Lithium battery factories in southern China (e.g., Guangdong, Fujian) need to select IP67 protection class to prevent moist air from entering the switch interior and causing short circuits. Chengdi’s enclosures adopt an integrated molding process to meet protection class requirements.

Ultimate Checklist for New Energy Lithium Battery Pressure Switch Selection

✅ Material: SUS316L probe + PTFE seal, suitable for electrolyte corrosion

✅ Pressure Range: Select based on maximum instantaneous pressure ×1.5, with pressure resistance ≥1.5x the range

✅ Explosion-Proof: Choose Ex d IIC T6 for Zone 1, Ex nA IIC T6 for Zone 2; CE/UL certification for exports to Europe/US

✅ Communication: RS485 Modbus RTU protocol, supporting MES system connection

✅ Temperature: Operating temperature covering -20–80℃, with temperature compensation

✅ Power Consumption: ≤45mA (no load), suitable for battery-powered scenarios

Chengdi Tech has focused on the new energy lithium battery field for 6 years and provides OEM sensor solutions—customizable pressure switches based on cell sizes (e.g., 18650, 21700, prismatic aluminum cases) and production processes (dry/wet methods). Lithium battery-specific models are in stock in warehouses in Germany, India, and Vietnam, with a delivery cycle of ≤7 days. Click to consult and get an exclusive selection plan!

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