How thorough are India’s EV battery-testing standards?

Arguably the most vital aspect of AIS-156, the fire resistance test is carried out in four different phases involving pre-heating, direct heating and two stages of indirect heating. In all stages, the battery or REESS is placed on a steel grating table with a pan placed underneath, containing commercial fuel which is then ignited. In the indirect heating stage, a screen is placed between the pan and the testing-device. Following this the battery is then observed for another three hours while it returns to ambient temperatures.

Vibration Test

Given the road conditions that battery and battery management systems have to endure specifically in India, vibrations tests are an essential part of AIS testing procedure. The vehicle is subject to shocks ranging from 7Hz to 200Hz and back to 7Hz in the span of 15 minutes. The process is then repeated 12 times over, followed by a period of observation.

Mechanical Shock and Drop Test

For vehicles with non-removable batteries, a proper mechanical shock test has been devised. According to a brief prepared by the MoRTH, the testing device is subject to mechanical shock with peak acceleration of 1500 m/s 2. The testing-device is then subject to these shocks 18 times in varying angles and positions. This test, like others, has been borrowed, nearly verbatim from the UN R136 standard.

For removable batteries, a mechanical drop test has been devised, wherein, mimicking real life conditions, the battery is dropped from a height of 1 metre onto a hard floor, usually made of concrete. This is done six times from angles determined by the testing agency. However, the manufacturer does have the option of using a different battery for each drop.

Thermal Shock and Cycling

According to the paper published by MoRTH, the purpose of this test is to subject the battery to rapidly changing temperatures. For six hours straight, the battery is subjected to a temperature of 60 degree celsius (higher if the manufacturer insists) followed by six consecutive hours of being kept in -40 degree celsius. The maximum time interval between these two stages is 30 minutes only. These test cycles are repeated for five times after which the battery is under observation for 24 hours, under ambient temperature.

However, thermal testing is one of the key areas which highlight why the AIS-156 test may be more suited to European conditions. In a country where certain regions have ambient temperatures running up to 50 degree celsius, the thermal load on a battery is considerable.

Are these tests sufficient?

Much like the UN certified R136 standard adopted internationally (including Japan and several European nations), the AIS-156 standard also places strong emphasis on testing shock protection measures, how a battery performs under overcharging and over-discharging (as both extremes are detrimental to a battery’s overall health). However, the tests do not account for how well a battery and its management systems fare over time. For that, brands themselves must set-up a system which exceeds the stringency and rigour of these tests in every single way. Ather Energy, also includes a nail test, which isn’t part of the AIS-156. At least not in its current form. “Regulatory standards are the minimum. They form a small layer” says Tarun Mehta, the brand’s co-founder and CMO. “Before we launched the first vehicle I think we’d cycled 200 battery packs over four years”.

Vivekanand Hallekere, co-founder and CEO of Bounce echoes Mehta’s thoughts. “The biggest challenge is that batteries, by themselves, deteriorate over a period of time. So how these batteries respond to testing in the beginning, does not account for how it will handle its life cycle.” Hallekere adds that the government alone cannot provide a solution. “What would help is having independent agencies, which evaluate more than the testing standards based on data that companies are voluntarily sharing and then assign a particular rating. It’s better if a private, reputed agency does this because assigning this task to the Government can take time and that can create a bottleneck for manufacturers who cannot introduce new technology”

As for the standards themselves, they seem very comprehensive, but do have one glaring flaw. They only test one battery. According to Chetan Maini “Both the AIS standards are very good standards as they undergo a fire test. These are very stringent standards at a global level. These however certify one battery pack.” says the co-founder and president of SUN Mobility. I think when you see these one-off issues, it’s because something has gone wrong in one area of manufacturing – something which may not be detectable. So I’m not sure if the current standards would detect that. So as far as certification processes go, it’s at a fairly good level.”