The determinants of the electric bike's cruising range are similar to those of automobiles.
Whether it is a two-wheeled vehicle or a four-wheeled vehicle when choosing an "electric drive vehicle", the focus must always be on the "endurance range". The primary way to analyze the cruising range is to calculate the capacity of the integrated battery pack. However, the conclusions drawn in this way are not true, because the final power consumption is the electric motor, and the driving form is the vehicle! The power to horsepower mass ratio of the machine must be calculated.
1. Capacity standards and concepts
Taking the new national standard "≤48V" two-wheeled vehicle as a reference, assuming that the battery standard is 48V·20Ah after grouping, the theoretical total capacity is 0.96kwh (degree). This is equivalent to a high-standard car starter battery. For example, a 12V-85Ah starter battery will have a capacity of 1.02kwh, which shows that the actual capacity of a battery car is very low.
Key point: The new national standard electric bicycles are required to be equipped with motors of 400 watts (w) or less. In order to ensure that the vehicle performance is qualified, major car companies will choose motors with a peak value of 400 watts. What should the cruising range of this type of vehicle be?
"400w" is the peak output power of the motor. The curb weight of the vehicle must match the relationship between power and speed; to put it bluntly, the vehicle has the highest power output and can drive electric bicycles within the standard weight range at a speed of ≤25km/h. .
The power of the motor can be understood as "power consumption", that is to say, driving with this output standard and speed standard will consume 0.4kw (1kw=1000w) of electricity per hour. Driving for two hours will consume 0.8kwh of electricity, and the mileage has reached 50 kilometers. Although there is still some remaining power, what needs to be done at this time is often to charge instead of continuing to drive.
2. Power battery·Elementary
The power batteries used in two-wheeled electric vehicles (including electric motorcycles) are mostly "lead-acid batteries". This is the low-end option with the lowest mass energy density and the shortest service life among the chemical power sources used in motor vehicles! The average service life is only 350 times of complete charge and discharge, and it basically reaches the scrapped state after reaching the standard.
In the process of use, the battery will also have a linear capacity drop, because the charging and discharging of this battery are chemical reactions with very low efficiency and loss. For example, when discharging, the lead element of the electrode plate and the sulfuric acid solution are used to chemically react, and lead sulfate crystals will be produced in the process of generating electric current. These substances will slowly adhere to the electrode plate and accumulate less and more. This is the so-called electrode plate. vulcanization.
Key point: The vulcanization process of the electrode plate is the process of the formation of lead sulfate. Too many crystals are attached to the electrode plate, which will affect the efficiency during charging and discharging. The result is a decrease in discharge efficiency (increased discharge capacity), resulting in increased energy conversion loss and reduced cruising range.
At the same time, the texture of part of the lead sulfate crystals will be very hard. When the lead sulfate is decomposed in the reverse direction, more and more crystals that cannot be decomposed will appear; as a result, the concentration of the electrolyte will be seriously reduced. . Therefore, two-wheeled vehicles will always experience a rapid decline in mileage, especially vehicles that are charged once a day or more than once a day are afraid that they will not be used for a year.
3. Power battery·Upgrade
The reason why lead-acid batteries are recognized is that everyone generally believes that they are cheap enough. However, it would cost hundreds or even thousands of yuan to replace a battery pack, but the replacement battery pack has a capacitance of more than one degree at best, so why not switch to a lithium iron phosphate battery at such a high cost?
LFP lithium iron phosphate battery is currently the most comprehensive cost-effective option. Its service life will be more than ten times that of lead-acid batteries, and its energy density will be 2 to 3 times higher. The increase in density is actually equal to the decrease in weight. Make the vehicle lighter and have a longer cruising range.
Key point: The manufacturing cost of lithium iron phosphate batteries is already very low, and the low-end options used in ordinary cars can be as low as about 300 yuan 1kwh. Therefore, electric bicycles can be replaced with this kind of battery, and there are indeed some new national standard electric bicycles used.
The cruising range of these vehicles can exceed 100km, and the volume and weight of the vehicles will not exceed the standard. At the same time, they can still match the 400-watt electric motor through series boost and parallel expansion. As for electric motorcycles, there is no need to worry. You must know that the low voltage of the LFP battery pack used in cars can be as high as about 600 volts, and there is no problem in driving hundreds of kilowatts of electric motors.
Summary: Lead-acid power batteries are about to be eliminated. This kind of purchase cost is not low, the replacement cost is not low, and the battery that will produce serious lead pollution is almost worthless. Once there are a large number of lithium iron phosphate battery suppliers facing electric bicycle car companies, scooters will also have three-digit cruising range, and two-wheelers will also become "new energy series" due to battery upgrades.
(Lithium iron phosphate battery and mainstream nickel-cobalt ternary lithium. This type of battery can be used as electric field energy storage power station battery for decades after motor vehicles are eliminated. Accelerating the growth of new energy power generation is defined as a new energy vehicle Core factors)
