Jody Leber, Global Battery Manager, SGS
The Bureau of Indian Standards (BIS) recently gave smartphone manufacturers who want to ship batteries to India a little more breathing room. But just a little. In June 2016, the BIS released new norms that for the first time requires handset vendors to test smartphone batteries separately. In September, the BIS pushed the original deadline out to August 2017. Despite the extension, the timeframe remains tight. Let’s examine what manufacturers of smartphones, and any other battery-powered devices, can do today to avoid creating costly go-to-market delays.
The new requirements and deadline for smartphone manufacturers are just the latest wrinkles to the BIS’s original 2014 decision to add portable batteries to the list of mandatory goods that fall under the Compulsory Registration Scheme (CRS). The CRS demands that every new smartphone model launched in India must have its battery, the cells inside the battery, the adapter and the mobile handset tested and registered separately.
For now, BIS allows two battery certification norms to run simultaneously, one that was issued in 2012, and the other from 2015. But after August 31, 2017:
“Manufacturers who have models as per 2012 and 2015 versions fail to changeover completely to the revised version by August 31, 2017, existing models as per 2012 version shall be processed for deletion (will not be allowed to use in phones).” (Source: BGR)
August 2017 is months away, but there are a few factors that should create a sense of urgency for handset manufacturers. First, all testing must be done at approved laboratories in India. But there are fewer than 15 approved facilities in-country. Combine that fact with the sheer volume of products, and significant delays are inevitable. The Indian Cellular Association reports there are approximately 850 models launched in India every year, and this number is estimated to grow. But the country has only 12 to 13 BIS-certified laboratories, which are inadequate to meet the growing demand for testing in a time bound manner. (Source: The Economic Times)
Timing is not the only challenge. The BIS is forcing manufacturers to transition away from the common practice of assembling phones locally and importing batteries as a separate component. By August 2017, both the device and battery will require separate certifications; they cannot be tested and certified as one complete unit.
The consequences to the unprepared manufacturer are production delays that will result in loss of go-to-market lead time, a critical tool in a very competitive market. That’s why the best advice is to begin the testing process now to avoid those delays.
Testing Processes and Timetable
The applicable test standard is IS 16046. It’s based on IEC 62133, which calls for simulating the conditions a portable battery may be exposed to during intended use and reasonably foreseeable misuse. Cells must be approved or tested concurrent with the battery, and vary depending on its composition.
The testing requirements for nickel batteries are:
- Continuous Low-Charging: Requires that a continuous low-rate charge shall not cause fire or explosion. The test is subjecting fully charged cells to a charge as specified by the manufacturer for 28 days to prove it will not catch fire or explode.
- Vibration: Requires that vibrations encountered during transportation shall not cause leakage, fire or explosion. Fully charged cells or batteries are vibration-tested under the following test conditions. A simple harmonic motion is applied to the cells or batteries with an amplitude of 0,76 mm, and a total maximum excursion of 1,52 mm. The frequency is varied at the rate of 1 Hz/min between the limits of 10 Hz and 55 Hz. The entire range of frequencies (10 Hz to 55 Hz) and return (55 Hz to 10 Hz) is traversed in 90 min ± 5 min for each mounting position (direction of vibration). The vibration is applied in each of three mutually perpendicular directions.
- Molded Case Stress at High Ambient Temperature: Demands that internal components of batteries are not exposed during use at high temperature. Fully charged batteries are exposed to a moderately high temperature to evaluate case integrity. The battery is placed in an air circulating oven at a temperature of 70°C ± 2°C. The batteries remain in the oven for 7 hours, after which they are removed and allowed to return to room temperature.
- Temperature Cycling: Designed to ensure that the battery will not catch fire or explode because of repeated exposure to high and low temperatures. Fully charged cells or batteries are subjected to temperature cycling (–20°C, 75°C), in forced draught chambers, per the following procedure:
- Place the cells or batteries in an ambient temperature of 75°C ± 2°C for 4 hours.
- Change the ambient temperature to 20°C ± 5°C within 30 minutes and maintain at this temperature for a minimum of 2 hours.
- Change the ambient temperature to –20°C ± 2°C within 30 minutes and maintain at this temperature for 4 hours.
- Change the ambient temperature to 20°C ± 5°C within 30 minutes and maintain at this temperature for a minimum of 2 hours.
- Repeat steps 1 to 4 for a further four cycles.
- After the fifth cycle, store the cells or batteries and check after a rest period of at least 24 hours.
- Incorrect Installation: Fully charged cells are evaluated under conditions in which one of the cells is incorrectly installed. Four fully charged single cells of the same brand, type, size and age are connected in series with one of the four cells reversed. The resultant assembly is connected across a resistor of 1 Ω until the vent opens or until the temperature of the reversed cell returns to ambient temperature. Alternatively, a stabilized d.c. power supply can be used to simulate the conditions imposed on the reversed cell.
- External short circuit: Two sets of fully charged cells or batteries are stored in an ambient temperature of 20°C ± 5°C and +55°C ± 5°C respectively. Each cell or battery is then short-circuited by connecting the positive and negative terminals with a total external resistance of 80 mΩ ± 20 mΩ. The cells or batteries remain on test for 24 hours or until the case temperature declines by 20 percent of the maximum temperature rise, whichever is the sooner.
- Free Fall: Demonstrate that dropping a cell or battery (for example, from a bench top) shall not cause fire or explosion. Each fully charged cell or battery is dropped three times from a height of 1,0 m onto a concrete floor. The cells or batteries are dropped so as to obtain impacts in random orientations. After the test, the sample shall be put on rest for a minimum of one hour and then a visual inspection shall be performed.
- Mechanical Shock: The fully charged cell or battery is secured to the testing machine by means of a rigid mount which will support all mounting surfaces of the cell or battery. The cell or battery is subjected to a total of three shocks of equal magnitude. The shocks are applied in each of three mutually perpendicular directions. At least one of them shall be perpendicular to a flat face. For each shock the cell or battery is accelerated in such a manner that during the initial 3 ms the minimum average acceleration is 75 gn. The peak acceleration shall be between 125 gn and 175 gn. Cells or batteries are tested in an ambient temperature of 20°C ± 5°C. After the test, the sample shall be put on rest for a minimum of one hour and then a visual inspection shall be performed.
- Thermal Abuse: Each fully charged cell, stabilized at room temperature, is placed in a gravity or circulating air-convection oven. The oven temperature is raised at a rate of 5°C/min ± 2°C/min to a temperature of 130°C ± 2°C. The cell remains at this temperature for 10 minutes before the test is discontinued.
- Crushing of Cells: Each fully charged cell is crushed between two flat surfaces. The force for the crushing is applied by a hydraulic ram exerting a force of 13 kN ± 1 kN. The crushing is performed in a manner that will cause the most adverse result. Once the maximum force has been applied, or an abrupt voltage drop of one-third of the original voltage has been obtained, the force is released. A cylindrical or prismatic cell is crushed with its longitudinal axis parallel to the flat surfaces of the crushing apparatus. To test both wide and narrow sides of prismatic cells, a second set of cells is tested, rotated 90° around their longitudinal axes compared to the first set.
- Low Pressure: For example, during transportation in an aircraft cargo hold, shall not cause fire or explosion. Each fully charged cell is placed in a vacuum chamber, in an ambient temperature of 20°C ± 5°C. Once the chamber has been sealed, its internal pressure is gradually reduced to a pressure equal to or less than 11,6 kPa (this simulates an altitude of 15 240 m) held at that value for 6 hours.
- Overcharge: Examines whether charging for longer periods and at a higher rate than specified by the manufacturer shall not cause fire or explosion. A discharged cell or battery is subjected to a high-rate charge of 2,5 times the recommended charging current for a time that produces a 250 percent charge input (250 percent of rated capacity).
- Forced Discharge: Requires that a cell in a multi-cell application shall withstand polarity reversal. A discharged cell is subjected to a reverse charge at 1 It A for 90 minutes.
The tests for lithium batteries are similar, with the exception that when it comes to testing continuous charging, lithium batteries are charged at constant voltage for seven days to a charge as specified by the manufacturer.
Recommendations
For most manufacturers, this is not a DIY project because they lack the in-house expertise and equipment to conduct this multitude of tests. Even if they do have the necessary resources and personnel, chances are their laboratories are not based in India. That’s where partnering with an independent laboratory with facilities in India that can immediately begin helping the manufacturer incorporate BIS testing requirements in the product design process. Whatever you do, don’t wait until after the assembly lines start up to begin testing!
