The correct expression for a battery pack should be how much V how much AH. And the AH is the ampere hour.
A is the current in amperes and H is the time in hours.
It’s the product of current and time.
For example :48V 10AH battery pack popular understanding method is the voltage of the battery pack working in the case of 48V with 1A current discharge can be put for 10 hours or 10A current discharge can be put for an hour…
If you make this clear, you don’t understand the meaning of the above battery pack representation.
And the mileage standard is how to calculate below make a simple explanation…
Such as 48V 10AH battery pack used in 350W motor above…
There’s a couple of formulas that we’re going to use here.
P=U*A, where P is the power is 350W and U represents the voltage 48V A represents the current. It can be inferred from the above formula that the rated working current of 350W motor is about 7.3a.
The approximate running time of A 10Ah battery pack is 10h/ 7.3a =1.37 hours.
If you multiply it by the constant speed of 30km/h, that’s 30km/h*1.37=41.1km.
For example above, it is not difficult to push the theoretical value of all battery packs.
Now we need to introduce a few parameters…
S is for mileage.H is for time. A is for current.
V stands for speed and P for power.
W is for work done.
U stands for voltage. Assume that the rated power of the motor is constant 350W;
V Assume a constant average speed of 30km/h
S=V*H Formula 1 High school Physics: S=VT
Formula 2 high school Physics: P=UI
W=AH*U Formula 3 High school Physics: W=UIT
It’s easy to see from formula 3 that for example 48V/10Ah is the work that the battery can do, which is “W”.
H is W over P and S is V times W over P
It is not difficult to see from the above mileage formula, such as 48V/12Ah battery pack working on the rated power 350W motor average speed of 30km/h, it is easy to calculate the mileage
S = 30km/h*48V*12Ah/350W = 49.3km
S = 30km/h*60V*12Ah/350W = 61.7km
48 v S = 30 km/h * * 20 ah / 350 w = 82.3 km
Two: Electric car can’t run far
Why: shopkeepers brag about the batteries they use: a 10Ah battery pack that they say can run 50 to 60 kilometers.
Under normal circumstances, A 10Ah battery pack is placed on A 350W motor, and its discharge current is about 7.3a, so its discharge time is 10Ah/ 7.3a =1.37h. Suppose the speed of the 350W motor is 30km/h, so its driving distance is 1.37*30=41.1km.
In this way, consumers will think that the performance of the battery is not good, but it is caused by the seller’s boasting.
1. The load of the car
2. Smoothness of road surface
3. Environment (temperature and humidity)
4. The number of times the user brakes
5. The size of the wheel (the motor power is the same, the same speed, the bigger the wheel, the faster the driving speed, so the farther the run)
6. User control of the trolley speed
7. Battery capacity
8. The size of motor power
9. The size of the controller current affects the discharge
10. The width and tire pressure of the tire affect the driving resistance, which will affect the running current.
11. And the brake system is perfect also affect the driving resistance
Iii. Common anomalies (unbalanced voltage of multiple batteries)
If the following diagram:
In order to prevent the battery overcharge and release safety considerations, in the software and hardware section set to protect the single battery power reaches 100% or less than 0% to stop charging or discharging, so no matter how to charge, how to discharge use, power ratio of the highest battery 20% power is always not used.
The higher the percentage of power, the higher the voltage of the individual battery.
Charging: if the battery is in series, the battery charging current is equal.
Discharge: constant power output. According to Ohm’s law: P = U * A, the lower the battery percentage, the greater the output current of discharge, and the power loss rate is far higher than the battery.
For a long cycle the ratio of the two batteries will get bigger and bigger.
Four: the influence of temperature on lithium battery
Among all environmental factors, temperature has the greatest impact on the charge and discharge performance of lithium batteries. The electrochemical reaction at the electrode/electrolyte interface is related to the ambient temperature. The electrode/electrolyte interface is regarded as the heart of lithium batteries.
If the temperature drops, the reactivity rate of the electrode also drops.
But if the temperature is too high, above 45, the chemical balance in the lithium battery will be destroyed, leading to side reactions.
The discharge efficiency of nickel-cadmium nickel-hydrogen lithium battery will be significantly reduced at low temperature (such as lower than -15), and at -20, the lye reaches the freezing point, and the charging speed of lithium battery will be greatly reduced.
In order to effectively charge, the ambient temperature range should be between 20 and 30. Generally, the charging efficiency will increase with the increase of temperature, but when the temperature rises to more than 45, the performance of lithium battery materials charged at high temperature will degrade, and the cycle life of lithium battery will be greatly shortened.