ELECTRIC STORAGE – RTN asia

Indian Space Research Organization could soon help Indian e-bikes overcome their biggest drawbacks -- low mileage per charge and limited speed. Costing between Rs 35,000-50,000, most of these bikes have a top speed of 25 km per hour and a range of 30 to 50 km per charge. That could change soon, thanks to the incorporation of space technology from ISRO. IT'S ALL IN THE BATTERY The primary reason for the limited speed and range of electric two-wheelers in India is poor battery capacity. Most of these bikes come with 1000 watt-hour batteries. That means the bike's motor can consume 1,000 watts for one hour before the battery is completely drained. However, to achieve a speed of 50-60 km/hour -- which is required to flow along with petrol-fueled traffic -- you need a motor that consumes about 1,650-2,500 watts -- depending on the weight of the bike. However, if the motor consumed 2.5 kW, the battery will be exhausted in 24 minutes. So even if you are traveling at 60 km per hour, you would have traveled only 24 km by the time the battery runs out. In practice, due to braking, inclines and speed variations, the effective range will be about 20 km on highways, which is too less for most users. As such, manufactures do not put 2.5 kW motors on such e-bikes. Instead, they go with much smaller motors in the 250 to 500 watt range -- which have only one-tenth to one-fifth of the required power need to travel at a speed of 60 km per hour. While this helps in regulating power consumption and improving the range slightly, the maximum speed drops to 20-30 km per hour because of the weak motor. BIGGER BATTERY The obvious solution to this problem is to increase the battery capacity, but this creates a different problem. With the widely used lead-acid batteries, each 50 watt-hour of battery capacity adds 1 kg to the weight of the battery. So, if you want a 2,500 watt-hour battery which would power a 2,500 watt motor for 1 hour and give you a top-speed of 60 kmph and a range of 60 km, you end up with a battery that weighs 50 kg. This is a significant problem for the industry as the electric scooter itself weighs only around 50 kg and putting a battery weighing 50 kg on such a vehicle creates various structural problems. Besides, the speed and the range of the vehicle will be noticeably impacted by the weight of the battery. ISRO TO THE RESCUE This is where ISRO is pitching its in-house battery technology. Since the weight of the battery has to be kept minimum for space applications such as rockets and satellites, India's space agency has spent considerable amount of time thinking about ways to reduce the weight of power units. It has developed its own light-weight batteries -- based in lithium-ion technology -- that deliver far more capacity compared to the lead-acid batteries in use today. To demonstrate, the agency, along with Automobile Research Association of India, has created a test bike with a 2,400 watt-hour battery inside it. While a lead-acid battery of this capacity would have weighed about 48 kg, ISRO uses lithium-ion technology to keep the weight down to about 12 kg. The bike is powered by a motor of around 1,500 watts and can achieve top speed of 50 km per hour. Instead of the usual maximum range of 30-50 km per charge, the test vehicle delivers a range (mileage) of 98 km under optimum conditions. Both the speed and the range can be improved with further optimization. The closest competitor to the test vehicle is Hero MotorCorp's Photon. It also comes with 1,500 watt motor, but can achieve a top speed of only 45 km/hour because of the heavy lead-acid battery inside it. It is powered by a 1,584 watt-hour battery, which alone should weigh close to 32 kg, going by the traditional weight to capacity ratio. Due to the heavy battery, the Photon travels only 31.57 meters for each watt-hour capacity contained in its battery. In comparison, ISRO's bike travels 40.83 meters for each watt-hour capacity inside its battery. In other words, if it was ISRO's battery inside the bike, chances are that the bike would have a range of 65 km instead of 50 km and the top speed too would have been 5-10 km/h more than 45 km/hour. PRICE IMPEDIMENT However, ISRO's technology alone may not be enough to enable companies like Hero MotoCorp to make the switch from lead-acid batteries to lithium ion. While ISRO can license its manufacturing technology for very low rates to Indian manufacturers, there is a second factor at play -- the cost of lithium, the key ingredient. At present, due to high prices for the metal, the cost of producing lithium ion batteries is about Rs 11,000 ($165) per 1000 watt-hour -- and that too at a large scale. As such, the 2,400 watt-hour battery found inside ISRO's test bike would cost about Rs 26,000 if made today at a large scale. Assuming that the overall cost of the bike has to remain in the Rs 50,000 bracket, that leaves only Rs 24,000 for the rest of the bike. In comparison, traditional lead acid batteries of the same capacity can be purchased for just Rs 12,000. CHEAPER IN THE LONG TERM Despite this, for regular bike users, a lithium ion unit is still far more economical. A traditional lead-acid battery can only be charged and discharged about 200-250 times, which means they will have to be changed every 10 months or so for daily users. However, lithium ion batteries can be recharged 1,000 to 5,000 times depending on their quality, which means that they can last 5 to 15 times as long as a lead acid battery. As a result, if the vehicle is used for 5-10 years, a lithium ion battery would require a one-time investment of Rs 26,000, while the other one will involve a cost of Rs 60,000 to 1,20,000 for buying 5 to 10 units during the bike's lifetime. Another promising development is the huge investments being made by Tesla Corp and Chinese companies in creating huge factories to bring down the cost of lithium-ion batteries. These firms expect the price to dip to $100 per kWh, which would bring down the price of a 2,400 watt-hour unit to Rs 16,000, comparable to the Rs 12,000 price of lead-acid. However, neither the Indian government nor India companies have any plan to invest in making such batteries on a large scale in India, and the country may have to import the units from China and the USA.

Tag: ELECTRIC STORAGE

ISRO offers space tech to electric vehicle makers in India