n order to further alleviate the problems of air pollution and urban traffic congestion, miniaturized short-distance transportation has also attracted people’s attention, mainly including electric bicycles, electric motorcycles, electric scooters, self-balancing electric two-wheeled and unicycles. Among them, the world’s first two-wheeled mobile vehicle which can balance itself, the car body has only two left and right driving wheels. After people stand up, they can achieve self-balancing, if the driver’s body leans forward or back, forward and backward will be achieved.
This kind of car has a wide range of applications, such as police patrols at airports and railway stations.
Battery design requirements for electric unicycles:
Electric unicycles are a new generation of energy-saving, environmentally friendly, and portable transportation tools. The very convenient short-distance walk is realized, which can replace the bus and subway.
The electric unicycle is small in size and easy to carry. It can be put directly into the trunk of the car and carried to the home or office. So how to design as many batteries with larger capacity as possible in the limited space for battery placement to meet customers’ mileage?
To this end, our company adopts a new imported Panasonic NCR18650BD battery cell. This battery has advantages of high energy ratio, lightweight, small size, high cycle life, high safety, and high voltage consistency,etc., which can fully meet the power requirements of the instruments;
The protection circuit uses the protection board designed by our company: the protection board IC all uses chips imported from Japan, high precision, high-temperature resistance, and the protection board has a balanced charging function, which can improve the consistency of the battery and strengthens the battery life; with temperature control Protection, the voltage will be restored automatically after disconnection!
Adopt integrated voltage sampling module, no need to connect through multi-pin cable when using the battery, greatly increasing the stability of the structure and eliminating the hidden danger of short circuit that caused by the wear of the sampling line.
The specific design requirements are as follows:
- Design requirements of Lithium battery pack:
|16S2P 57.6v 67.2v 6A 3000mAh PANASONIC NCR18650BD Lithium Battery Pack|
|Cell model||Panasonic NCR18650BD|
|Cells in total||32 x 18650 cells|
|size||Weight, max.||1.72 kg|
|Length, max.||166.0 cm (approximate)|
|Width, max.||137.0 cm (approximate)|
|Height, max.||42.0 cm (approximate)|
|voltage||Voltage, charge max.||67.2 V|
|Voltage, nominal||59.2 V|
|capacity||Capacity, max.||6.0 Ah|
|current||Max. continuous discharge current||12 A|
|Suitable for use in e-bikes, power tools, UAVs/drones, consumer electronics, and many other applications.|
- Design requirements of Protection Circuit（With overcharge,over-discharge, overcurrent, overtemperature, short circuit and other protection functions, etc.,):
1.Voltage – Charging voltage DC: 67.2V CC/CV
The balanced voltage of a single cell: 4.20±025V
2. Current – Balanced current of single-cell: 84±10mA
Current consumption (self-consumption):≤20μA
3. Overcharge protection (single cell)
Overcharge detection voltage:4.275±0.025V
Overcharge detection delay time:0.5S—2.0S
Overcharge recovery voltage:4.175±0.025V
4. Over-discharge protection (single cell)
Over-discharge detection voltage:2.50±0.05V
Over-discharge detection delay time:10mS—200mS
Over-discharge recovery voltage:2.40±0.05V
5. Over-current protection
Over-current detection voltage:0.10±0.015V
Over-current detection current:35±5A
Over-current detection delay time:5ms—20ms
Recovery status – Disconnect the load and recover automatically
6. Short circuit protection
Detection status – External short circuit
Detection delay time:200-500us
Recovery status – Disconnect the load and recover automatically 7、Internal resistance
7. Protection Circuit（MOSFET）≤30mΩ
8. Temperature control
Over-temperature protection range:65±5℃
9. Operating temperature
Range of operating temperature:-20～60℃
Design requirements for battery charging :
Need a special charger for lithium battery, constant current, and constant voltage.
2、Charging voltage:67.2V CC/CV
4) Design requirements for battery discharge :
1、Output with three-core aviation plug charging and two output lines（Charge and discharge plugs can be customized）
2、Maximum instantaneous current:≤30A
3、Maximum working current:≤12A
The design requirements of the dimension for the battery appearance:max 166*137*42mm