Safe Battery UsageBattery Recycling and DisposalStatistics About BatteriesAbout Car BatteriesAbout BAJ

Important Notice About the Safety of Mercury-Free Alkaline Button Batteries
For Equipment Manufacturers Using Imported Batteries

February 17, 2017
Battery Association of Japan

Alkaline button batteries are widely used in a variety of application. Along with the recent popularization of mercury-free button batteries, some batteries have been found inadequate in terms of safety, especially those made by foreign manufacturers.
The Battery Association of Japan (hereafter called BAJ) independently conducted safety tests and examined the assessment method with a view to the safety of customers.

Overview of the Assessment:

Assessment was conducted in order to develop an assessment method for identifying poor quality mercury-free alkaline button batteries, as follows.

  • Application under test: emergency buzzer(3 or 4 batteries in series) and LED flashlight (3 or 4 batteries in series)
  • Battery type under test: LR44 (mercury-free) as representative type

  • Test method: Over-discharge with heavy load
  • Assessment method: Measure deformation dimensions and observe rupturing of batteries left to stand after the test.

Specific Test Conditions:

After the following tests were conducted simulating equipment under test, the batteries were removed and deformation and rupturing observed (battery: mercury-free LR44).
(1) Simulating a emergency buzzer:
36Ω load x 24-hour discharge with four batteries in series, and 24-hour discharge with a real device using four batteries in series.
In each case, batteries were removed after discharging for 24 hours and their states observed.
(2) Simulating an LED flashlight:
50Ω load x 24-hour discharge with three batteries in series, and 24-hour discharge with a real device using four batteries in series.
In each case, the batteries were removed after discharging for 24 hours and their states observed.Generally available batteries were used (two Japanese manufacturers, three foreign manufacturers).

Specific example of discharge test

Three or four alkaline button batteries are inserted in series into a commercially available N cell battery (LR1 / R1) holder. The space is filled up to the contact with a conductive member. A 36Ω or 50Ω resistor is solder-mounted across the terminals of the battery holder in advance. The holder is left to stand for 24 hours, and the batteries are removed after the test.
[Warning]
This test must be conducted by a person with expertise due to the risk of rupturing, etc. Additionally, this test must be conducted in a metal can, etc. Care must be taken to avoid injury or fire due to the content violently exiting as a result of rupturing.

Assessment Results:

1) Partial rupturing of the batteries made by foreign manufacturers was observed in the assessment using a real device.
*Ruptured after being left to stand for 20 days after the test (real device - emergency buzzer)
2) Since we observed similar deformation and rupturing in Test Conditions ⑴ and ⑵ simulating a real device, we believe these test conditions are satisfactory for simulating real devices. When designing equipment with alkaline button batteries, application of tests ⑴ and/or ⑵ is recommended depending on the application.
(1) Ruptured after being left to stand for 20 and 30 days after the test
(2) Ruptured after being left to stand for 7 and 30 days after the test

[Safety Test Results]

Test Results

No. of ruptures /No. of tests
Manufacturer Foreign
Manufacturer
A
Foreign
Manufacturer
B
Foreign
Manufacturer
C
Japanese
Manufacturer
1
Japanese
Manufacturer
2
Mercury
Content
Mercury-Free Mercury-Free Mercury-Free Mercury-Free Mercury-Free
Heavy load discharge with 4 batteries in series 0/2 0/2 2/2 0/2 0/3
Load discharge with 3 batteries in series 0/2 0/2 2/2 0/2 0/3
Real device – emergency buzzer 0/1 1/1
Real device – flashlight 0/1

Test Conditions

Test Item Test Conditions
Heavy load discharge with 4 batteries in series 4 batteries in series simulating a personal alarm, 36Ω load x 24-hour discharge (4 batteries per test)
Load discharge with 3 batteries in series 3 batteries in series simulating an LED flashlight, 50Ω load x 24-hour discharge (3 batteries per test)
Real device - emergency buzzer Petit Alarm 2 (PAW-20) water-resistant, ultra-high sound type emergency buzzer (button released after 24 hrs) (4 batteries per test)
Real device - flashlight LED LENSER K2L (OPT-8202L) compact key flashlight (button released after 24 hrs) (4 batteries per test)