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ANSI C22.2 No. 339-18 (2019): Safety Requirements for Battery Chargers
Ensuring Safety and Reliability in Stationary and Mobile Charging Applications
1. Scope and General Requirements
ANSI C22.2 No. 339-18 (2019) is a Canadian safety standard (also recognized as an American National Standard) that specifies safety requirements for battery chargers intended for commercial and household use. The standard covers chargers with a rated input voltage not exceeding 600 V AC and a rated output voltage not exceeding 50 V DC (subject to exceptions for higher voltages in industrial applications). It applies to chargers used with lead‑acid, nickel‑cadmium, lithium‑ion, and other battery chemistries in stationary and mobile applications.
Key equipment within the scope includes:
- Automatic and manual battery chargers
- Chargers with integrated battery management systems
- Portable and stationary charging units
- Multi‑output and multi‑chemistry chargers
The standard does not apply to chargers for electric vehicles (covered by CSA C22.2 No. 280) or to chargers designed for industrial trucks.
Tip: When designing a charger for a new battery chemistry, verify that the charging algorithm and protective features fall within the parameters allowed by the standard to simplify certification.
2. Technical Requirements
Electrical Ratings and Insulation
The standard mandates minimum clearances, creepage distances, and dielectric withstand levels between primary and secondary circuits. For chargers with basic insulation, a dielectric test at 1000 V + 2 × rated input voltage (minimum 1500 V) is required. Double or reinforced insulation doubles the requirement.
Protection Features
Each charger must incorporate the following protective functions:
- Overcurrent protection – both input and output circuits
- Short circuit protection – the charger must be self‑reacting or provided with a device that interrupts current within a defined time
- Reverse polarity protection – either electronic or mechanical means must prevent damage under reverse battery connection
- Over‑temperature protection – internal thermal sensors must limit component and enclosure temperatures
Environmental and Enclosure Requirements
Chargers must be rated for the intended environment (indoor or outdoor, pollution degree 2 or 3). Enclosures shall meet at least IP2X for indoor use and IP54 for outdoor use. The standard also specifies minimum ingress protection for battery terminals.
| Parameter | Lead‑Acid Charger | Lithium‑Ion Charger |
|---|---|---|
| Maximum output voltage (V DC) | 14.4 (12 V nominal) | 21.0 (18 V nominal) |
| Output current regulation accuracy | ±5% | ±3% |
| Minimum isolation voltage (input to output) | 1500 V AC | 1500 V AC |
| Overcurrent trip time at 150% | < 2 s | < 1 s |
| Enclosure temperature rise (steady state) | ≤ 40 °C | ≤ 30 °C |
Caution: For lithium‑ion chargers, an OCP (overcharge protection) function must activate within 0.5 seconds to prevent cell damage and thermal runaway. Always test this function with a simulated battery failure.
3. Implementation Highlights
Design Considerations
To meet C22.2 No. 339‑18, designers should prioritize galvanic isolation using transformers meeting Class B or Class F insulation. Printed circuit board creepage distances should follow Table 9 of the standard; for a 250 V working voltage, minimum 3 mm between circuits. Use of optocouplers or digital isolators rated for reinforced isolation is recommended for feedback circuits.
Testing and Validation
Compliance testing includes dielectric strength, temperature rise under normal and abnormal operations, and endurance cycling. For chargers with microprocessor control, fault injection is required to ensure all safety functions remain operational. The standard also requires that the charger be tested with both a fully charged battery and a deeply discharged battery to verify that the charging algorithm remains within safe voltage and current limits.
Success: Many manufacturers reduce certification time by performing a pre‑compliance check using the test sequences described in Annex A of the standard, which provides a systematic test matrix.
4. Compliance Notes
Marking and Documentation
Each charger must be permanently marked with the manufacturer’s name or trademark, model number, rated input voltage and current, output voltage/current, and the applicable standard number (C22.2 No. 339‑18). Instructions must include warnings about battery type compatibility, use of fuses, and disconnection requirements.
Certification
Certification is typically performed by a recognized testing laboratory (e.g., CSA, UL). The final product must bear the mark of the certification body. For field‑modifiable or programmable chargers, the standard requires that any change in charging parameters automatically validates the protective functions.
Mandatory: Any charger that does not include reverse polarity protection as per Clause 6.10 will be considered non‑compliant and cannot be certified. This protection must be verified at both 25 °C and 50 °C ambient.
Frequently Asked Questions
Q: Does ANSI C22.2 No. 339‑18 apply to USB‑C chargers for mobile phones?
A: It applies only if the charger is designed primarily for battery charging (i.e., the output is a constant‑voltage or constant‑current profile). Standard USB chargers that only supply 5 V are typically covered by other standards such as CSA C22.2 No. 60335‑2‑29. Check the scope carefully.
A: It applies only if the charger is designed primarily for battery charging (i.e., the output is a constant‑voltage or constant‑current profile). Standard USB chargers that only supply 5 V are typically covered by other standards such as CSA C22.2 No. 60335‑2‑29. Check the scope carefully.
Q: How often must a compliant charger be re‑tested for certification?
A: Re‑certification is required when there is a change in the circuitry, transformer, or protective components that could affect safety. Routine follow‑up inspections (e.g., quarterly) are carried out by the certification body to ensure ongoing compliance.
A: Re‑certification is required when there is a change in the circuitry, transformer, or protective components that could affect safety. Routine follow‑up inspections (e.g., quarterly) are carried out by the certification body to ensure ongoing compliance.
Q: Can a charger certified to IEC 60335‑2‑29 also comply with C22.2 No. 339‑18?
A: Not automatically. While many requirements are similar, C22.2 No. 339‑18 contains specific provisions for North American line voltages (120 V/240 V) and ambient temperature testing at 40 °C and 50 °C. A separate evaluation against the Canadian standard is needed.
A: Not automatically. While many requirements are similar, C22.2 No. 339‑18 contains specific provisions for North American line voltages (120 V/240 V) and ambient temperature testing at 40 °C and 50 °C. A separate evaluation against the Canadian standard is needed.
Last updated March 2026