Battery Safety


How to make the best out of your e-bike battery?

The battery is an integral part of your e-bike, the battery's performance deteriorates gradually over its life time. However, if it is well maintained, the life can be extended to last longer The life of a battery is calculated based on the energy throughput. For simplicity and ease of understanding it can also be described in charge cycles i.e. how many times you can charge your battery from 0% to 100%. The charge cycle varies from battery to battery. There are certain factors like temperature, type of battery, and charging process that impact the life of your electric bike battery.

What are the most common types of e-bike batteries?

There are multiple types of e-bike batteries available in the market.

1) Lead-Acid Batteries:

They are inexpensive and easy to produce and recycle. They have 100-300 charge cycles.

2) Nickel Cadmium Batteries and Nickel -Metal Hydride Batteries

They are light and offer high storage density at a low price. These batteries can last anywhere between 300-500 charge cycles.

3) Lithium-ion Batteries:

Today, modern electric bikes contain lithium-ion batteries. They are lightweight and can last over a thousand charge cycles.

What is the role of battery management system in modern Lithium-ion batteries?

Lithium-ion batteries have a Battery Management System (BMS) inside their case: a sophisticated electronic device that monitors key parameters like temperature, current and voltage of the cells in the battery pack. A BMS is responsible for maintaining the performance and efficiency of the battery. It is also responsible for the safety, performance, longevity, and efficient charging of lithium-ion batteries.

Does the size of your battery matter?

Yes, the size of batteries matters, and we calculate it in Watt-hours of energy. A battery with more watt-hours of capacity can run for a longer duration. For example, if a battery capacity is mentioned as 1.5 KWH. It means that in one hour of discharging, the battery can deliver 1500 watts of power.

How to get the most out of your e-bike battery?

1) Store it in a cool & dry place

Temperature affects the lifespan of your battery. Both high and low temperatures can be detrimental to the life of your battery. Always store your battery in a coolplace; an ideal temperature for the battery is preferably around 25°C.

2) Use your battery regularly

The health of the battery is at its best when you use it regularly. If you stop using yourbattery regularly, the cells will deteriorate and affect its performance. To ensure the battery performance remains consistent, you need to use it regularly.

4) Charge only with approved chargers

A battery must be charged only with chargers approved by the battery manufacturer. Charging with unauthorized chargers may affect battery life and in some cases may also be a safety risk if the battery is not compatible with the charger. Charging with higher currents will charge the battery faster, but may affect the life of the battery if the charging currents are higher than approved by the battery manufacturer.

How to clean your battery?

The best way to clean your battery is to use a damp cloth and give it a swipe. However, care must be exercised to not touch the terminals with metal or wet objects, to avoid any chances of an electrical shock. Though the batteries are designed to be water proof or water resistant, it is recommended to not submerge the battery in water.

However, do note that in rare case of a fire emergency with the battery, the best way to bring the emergency under control is to completely submerge the battery in water!

Things to avoid!

  1. 1) Do not instantly plug in your charger after you come from a ride. Allow the battery to cool down for some time. Typically, atleast 30 minutes on hot summer days.
  2. 2) Avoid draining your battery completely. If after your ride, the battery is drained, charge it within the same day. Leaving a battery discharged for long durations can adversely affect the battery life. The battery will go into an under voltage protection mode and it will not be possible to charge it anymore with the charger. It will need intervention from the dealership to revive the battery
  3. 3) Avoid tampering. E.g. Opening the battery casing, connecting unauthorized chargers etc

Conclusion

Your e-bike battery can last for several years if you maintain it well. The batteries are generally safe when handled as per the OEM guidelines. When the batteries reach its end of life make sure you dispose of it in a responsible manner. You can go to a local battery dealer or electronics recycler, who will take care to dismantle and recycle it in an environmentally sustainable manner.


Battery handling guidelines for EV OEM’s

The following guidelines are meant as a best practice sharing for establishing safe storage, inspection and dispatch of batteries

It is important that the batteries from battery supplier is 100% tested before dispatch to the vehicle manufacturing plant. Batteries have to be at ~30% charged during transit. It is not safe to transport batteries which are fully charged.

Once the batteries arrive at the plant, a thorough incoming quality inspection is necessary to check for transit damages if any and also to check the basic performance and safe operation of battery.

  • Safe unloading and segregation for incoming batch
    • Recommended to keep storage area separate from main production hangar
    • All storage guidelines of battery manufacturer to be followed
    • Fire-safety measures to be in place. (Equipment, trained personnel etc.)
  • Incoming Quality Check (IQC) - 100%
    • Check for any signs of physical damages (dents, bulging etc.)
    • Verification of technical specifications as per product data sheet
    • Energy test – 100% charge / discharge test. One cycle
    • If any abnormalities found – the parts to be quarantined
    • If IQC – OK, then batteries to be stored safely as per battery manufacturer instructions
    • Traceability to be ensured for all batteries and their IQC test results
  • FIFO system to be ensured for dispatching batteries for production to ensure
  • In case battery needs to be stored for long in inventory, then regular checks to be done to confirm that battery does not go into under-voltage condition
  • Safe handling during assembly
    • Clear instructions to be available on shopfloor for battery handling
    • Only trained personnel to handle battery operations
  • Pre-Departure Check
    • After vehicle assembly, vehicle to be checked (all electrical operations)
    • Basic short drive test to confirm that all systems are working OK
    • Battery to be charged between 30- 40% before dispatch to dealership

Battery handling guidelines for EV Dealerships

Batteries are the fuel source for electric vehicles. It is important to handle it with the same care as done for all inflammable materials.

It is essential that all dealerships are well equipped with fire-safety mechanisms which are well maintained. All employees to be well trained in handling any fire-safety

After receipt of battery or vehicle at dealership from transporter, the battery has to be handled as follows

  • Battery to be safely stored on metal racks and no combustible or corrosive material to be stored nearby (at least 10 feet distance)
  • Ensure 40% -50% charge
  • Do-not Stack the Battery pack one above the other
  • If you find battery casing is damaged or there is water intrusion in the battery pack, immediately isolate the battery and store it separately and inform the OEM. Do not use the damaged battery
  • Storage temperature should be 5⁰C to 35⁰C
  • Conduct periodic check for battery Voltages & temperatures once in a week
  • For prolonged storage periods (> 15 Days), charge the battery pack once in 15 days
  • If you find that the battery has become hot, odour, deformation, or other abnormal phenomenon during using, please stop further operations immediately isolate and store separately, and inform the service personnel of the OEM.

Battery checks during Vehicle servicing

  • Vehicles need to be serviced as per the OEM service guidelines at regular intervals as defined by the OEM
  • During serving, it is essential that the service center understands from the customer about the battery usage behavior of the user.
    • Customer must be reminded of the general safety guidelines of handling batteries as mentioned in the vehicle user-manual.
    • Service personnel must try to understand whether customer has understood all the “do’s and don’t” and must reiterate the need to follow all the safe practices
  • After ascertaining from the customer that there have been no adverse situations (e.g. battery falling, or vehicle accident etc.) service center to perform basic battery health check
    • One cycle charge- discharge check with appropriate Battery Tester tool
    • Observe for any abnormal temperature increases / overheating
    • Time taken for charging
    • Check the battery capacity (AH) and confirm that it is within acceptable deviation based on the battery usage
  • In case any abnormal behavior found in battery
    • The OEM must be informed immediately and necessary actions must be defined jointly.
    • Opening of battery and any re-work at dealerships / service centers is not allowed
    • If battery needs to be sent to OEM for analysis or for warranty claims, appropriate packaging must be followed as per the OEM instructions

Schematic Diagram of Battery Safety Alarm

Working Principle: When the temperature rises, the thermistor value decreases, lowering the voltage at its terminals and causing the voltage at the non-inverting terminal to be less than voltage at inverting terminal. This situation causes the comparator output to go low (Zero), saturate the transistor and activate the relay, which, in turn gives the alarm signal. This signal can then be connected to a buzzer that sounds an alarm



R1, R2: Resistors

P1: Potentiometer (To set the temperature at which the alarm should be started)
NTC1: Thermistor with Negative Temperature coefficient (i.e. Resistance decrease when temperature increases)
Comparator: Compares voltages on the inverting and non inverting inputs (Opamp)
D1: Diode

The device can be operated on a coin cell 3.3V or on a 12V power supply. The values of R1,R2, P1 and NTC1 can be chosen appropriately, keeping in mind the power required to operate the buzzer

The Battery safety alarm can easily be attached to any existing Battery / Battery Box using conductive adhesive