Custom 72V Lithium Battery Pack

A 72V lithium battery is a rechargeable battery pack designed to provide a nominal voltage of approximately 72 volts for electric vehicles, golf carts, industrial equipment, and energy storage applications.

The actual cell configuration depends on the battery chemistry.
For LiFePO4 batteries, a typical 72V battery pack uses 24 cells connected in series (24S), providing 76.8V nominal voltage and 87.6V full charge voltage.

For lithium-ion NMC batteries, a 72V pack is commonly configured with 20 cells in series (20S), depending on the selected cell voltage and application requirements.

A: VTCBATT doesn’t suggest DIY building of lithium ion 72 volt batteries. Only a skilled technician can make it. You need to use the cells in great consistency and place the cells in the cell holder. Then use the nickel strip to solder each cell together, wiring cell,s and assemble the BMS.
After the assembly, the 72-volt battery should be provided with an external enclosure to prevent physical damage. Finally, use the professional equipment to test the battery voltage, internal resistance, and whether it can be charged and discharged normally.

A: For a 72V lithium ion battery consisting of 20S cells, the minimum cutoff voltage is 60V with 3.0V per cell.
For 72V LiFePO4 ( lithium iron phosphate) battery, the cell cutoff voltage is 2.5V per cell. 23S cells lifepo4 battery pack has 57.5V minimum cutoff voltage.22S cells lifepo4 battery pack has minimum cutoff voltage is 55V. 24S cells lifepo4 battery has minimum 60V cutoff voltage.

A: First, you need to identify the 72 volt lithium battery technology, whether it is a lithium ion battery or a Lifepo4(lithium iron phosphate) battery.

For lithium-ion battery technology, it typically consists of 20S cells in series, with a full charge voltage of 84V, corresponding to 4.2V per cell.

For Lifepo4 battery technology, it is normally 22S-24S cells in series, and its full charge voltage is 79.2V-86.4V with 3.6V per cell.

A: The differences mainly exist in configuration, application, and cycle life.
(1)Configuration difference
72V lithium-ion batteries consist of 20S lithium ion 18650,21700 standard cells with 3V minimum cutoff voltage per cell and 4.2V maximum charge voltage per cell.

72V Lifepo4 batteries consist of 22S-24S Lifepo4 prismatic or cylindrical cells with a 2.5V minimum cutoff voltage per cell and a 3.6V maximum charge voltage per cell.

72V lithium polymer batteries consist of 20S lithium polymer battery cells in any flexible size with a 3V minimum cutoff voltage per cell and a 4.2V maximum charge voltage per cell.

(2) Application difference

72V lithium-ion battery packs are widely used in e-bikes, motorcycles, scooters, and AGVs.

72V Lifepo4 battery pack is widely used in energy storage, EV, golf carts, AGV, forklifts, UPS, Heavy-duty robotics, etc.

72V lithium polymer battery pack is widely used in drones, eVTOL, and racing vehicles for any applications in need of burst current and lightweight.

(3)  Cycle life
72 volt lifepo4 battery pack has 6000+ cycle life with a designed 10-year shelf life.

72 volt lithium ion battery pack has 500-1000 times cycle life with 3-5 year designed life.

72 volt lithium polymer batteries has 300-500 times cycle life with 2-3 year designed life due to continuous burst current, which reduces the battery cycle life.

A: For Lithium ion battery 72 volt, the cycle life is about 500-1000 cycles. For high discharge current applications of motorcycles and scooters, the cycle life is shorter with 500-700 cycles.
For a lifepo4 battery pack 72 volt, the cycle life is about 2000-6000 cycles. For solar applications, the cycle life is typically longer for shadow charge and discharge.
For golf carts, AGV, or forklift applications,the cycle life is reduced about 2000-5000 cycles due to higher discharge current.

A: First, you need to understand the battery technology of the 72V lithium pack.
For a lithium ion 72 volt battery, it is a 20S 72V battery pack with 84V charger voltage, and the recommended charge current is 0.2C-0.5C for safety.
For lifepo4 72 volt battery, it is a 22S-24S 72V battery pack with a 3.6V charge voltage per cell. The recommended charge current is 0.2C-0.5C for safe charging.

A: Choose a specific 72 volt lithium battery charger matched with the 72v battery in battery technology and battery series.
Make sure to use the charger with balance charge functions, which can balance each cell voltage during charging. Some intelligent 72v battery chargers can even support a communication protocol with the battery to identify the charge phase in CC-CV charge and cell balance charge.

Integrated in the 72 volt lithium battery packs, the smart BMS not only provides basic protections against overcharge,overdischarge, overcurrent, over overtemperature, but also provides cell balance function and cell monitoring to ensure safe operation of the battery pack.

For big 72V lithium battery packs, it is better to choose the charger and BMS both have cell balance functions.

A: For a standard 72V battery pack, it is suggested with a 0.2C-1C continuous discharge current. But for some special applications, such as drones, golf carts, forklifts, AGVs, a normally max 3C discharge rate is suggested. The higher discharge rate will reduce the battery cycle life.

A: There are five most common signs for the degradation of 72V lithium battery packs.
(1). Shorter runtime
If you found the runtime is shorter than before, it is a typical sign of capacity decay.
(2). Incomplete charging
The charger indicator turns green faster than before, and it can’t reach 100% fully charged.
It means that the battery capacity is reduced and takes a shorter time to charge.
(3).Heat
The 72 volt lithium battery packs become hotter than before usage, which means that the battery pack internal resistance has increased due to degradation.

(4). Cell imbalance
It’s very common that the cell voltage is imbalanced due to battery pack degradation.
Some cell voltages increase very fast during charging, and some cell voltages decrease very fast during discharging, which will make the battery have shorter runtime and quicker charge time.

( 5). Voltage Sage under load
Lithium battery 72 volt has a fully charged voltage of 80V. But the battery pack voltage drops from 80V to 65V, making the scooter/e-bikes cut off at high throttle.

A: Temperature greatly affects the charging and performance of the 72 volt lithium batteries.
Charging performance
The 72 volt lithium batteries are only allowed to charge under 0°C-45°C. It’s extremely dangerous to charge the 72 volt lithium batteries under 0°C, which may cause an explosion and fire.

A lower temperature range of 0°C-10°C will make the charge slow. Thus small charge current of 0.1C-0.2C is recommended for safe consideration.
A temperature of 10°C-45°C is the optimal range for safe charging, accepting 0.5C-1C fast charging.

Discharge performance
Low temperature under zero will increase the internal resistance of the 72 volt lithium battery and make 20%-50% capacity usable.

Under a temperature range of 0°C–25°C, the battery pack performance is normal.

Under 25–40°C, the battery pack has slight improvement in high current performance.
For high temperatures 45°C-60°C, the 72 volt lithium battery packs age faster and have a risk of thermal runaway.

A: Besides the basic safety protections of 72V battery BMS, the 72 volt lithium ion battery packs provide temperature protection, communication, and fault logging, SOC and SOH estimation, which facilitate people to know the battery information.

VTCBATT can customize 72V e-mobility battery packs around the vehicle platform. Common 72V series options include 40Ah, 50Ah, 58Ah, 73Ah and 117Ah packs. The final capacity, enclosure size, connector and discharge current should be selected according to motor power, controller current, installation space and required driving range.

Yes. High-current 72V lithium battery packs can be designed for electric dirt bikes, off-road motorcycles and Surron-style platforms. The pack design should confirm the controller peak current, continuous discharge current, cell model, BMS rating, heat dissipation, enclosure strength and connector specification before production.

Yes. The charger must match the battery chemistry and series configuration. A 20S lithium-ion 72V pack typically uses an 84V charger, while LiFePO4 72V packs use a charger voltage based on the exact 22S, 23S or 24S configuration. VTCBATT can provide the matching charger and connector for the battery pack.