Can Unapproved Batteries Be Used in Intrinsic Safe Circuits?

When designing new products for hazardous environments, all the components used should ideally be already pre-approved. But does that mean that if one or more of the components is not, the product will automatically be non-compliant with its applicable safety requirements?

As a Certification Body, we often come across Intrinsic Safe (IS) circuits that are using unapproved batteries, and the common question we get from the manufacturer is:  will this cause a problem when it comes to testing?

The answer is no, which is good news. For context, intrinsic safety relies on preventing sparks or heat that could ignite flammable atmospheres. While pre-certified batteries reduce risk, uncertified ones may qualify through additional evaluations. Learn more about battery safety in our guide to HazLoc Certification. If the batteries are not pre-approved components, they can still be tested and accepted based on the following testing requirements.

Testing Requirements for Unapproved Batteries Visual Diagram

Testing Requirements for Unapproved Batteries

  1. General Testing
  • Testing of batteries and/or cells to ensure in case of short circuit or reverse charging they will not explode.

Note: Cells used in Batteries that meet requirements of UL1642 or IEC 62133 battery standards are sufficient to meet this requirement. For uncertified batteries, testing verifies their failure modes align with IS principles.

  1. Electrolyte Leakage Test for Cells and Batteries:
  • Method: 10 samples of the battery are put through the worst-case scenario from one of the below:
  • Pass Criteria: Short circuit until discharged (this is skipped if the level of protection is “ic” or Zone 2/22 or Category 3)
  • Input/charging current, applied within the manufacturer’s recommendations
  • Battery is charged, as per manufacturer’s recommendations, with one fully discharged cell or experiencing polarity reversal.

Samples are then kept on blotting paper for 12 hours and if there is no electrolyte leakage from the samples, the test is considered a “pass”.

Note: If this test was conducted on rechargeable batteries, they shall be put through a fully charged and discharged cycle at least twice. Also, if batteries are encapsulated in the product, they can be tested with encapsulation for a leakage test.

For further insights into battery durability, see our article on Lithium Battery Testing.

  1. Spark Ignition & Thermal Ignition Testing: Batteries and/or cells can be either evaluated for spark assessment or tested with spark ignition tester. For Thermal Ignition, they shall be tested for surface temperature requirements with both normal and abnormal conditions for “ia” and “ib”. For “ic”, it is only tested in normal conditions.

So, although using pre-approved components, when designing your Intrinsic Safe circuit, is always the best way to go, there is no need to despair if they’re not already approved. At the end of the day, the key goal is for your system to meet the applicable safety requirements for the intended market and if needed, the goal can still be achieved with just a few additional tests.

Key Takeaway

While pre-approved batteries streamline certification, unapproved ones can still comply through targeted testing. The priority is demonstrating that the entire system meets safety standards for its intended use.

For questions about Intrinsic Safety or other Hazardous Locations equipment requirements, please contact LabTest Certification at info@labtestcert.com.