18650 Battery Voltage Safe Range

The 18650 battery voltage is usually determined by the material, and there are usually two types of 18650 batteries, NMC and LFP. Although the nominal voltage of LFP batteries is slightly lower than that of NMC batteries, the high safety of LFP makes LFP batteries gradually replace NMC batteries in the market.

  • 18650 NMC battery, nominal voltage of 3.6 or 3.7 volts, maximum voltage is 4.2V, minimum voltage is 2.5V,
  • 18650 LFP battery has a nominal voltage of 3.2V, maximum voltage of 3.7V, and a minimum voltage of 2V.

What is the voltage range of the NMC 18650 battery?

NMC (Lithium nickel manganese Cobalt oxide) is the most common 18650 battery on the market. Usually can be discharged to the minimum voltage of 2.5v, the maximum voltage is 4.2v, in 2.5v~4.2v. Overdischarge or overcharge will damage the battery, for safety reasons, the battery discharge voltage should not be lower than 3.0v, usually the battery pack will use BMS to set the charge and discharge cut-off voltage to avoid damage to the battery.

18650 battery voltage

What happens if the 18650 NMC battery overcharges more than 4.2v?

You can use 4.2v voltage to 3.7v lithium-ion battery for constant voltage charging, battery full voltage reached 4.2v to stop charging, at this time the battery has been fully charged.

If the 18650 NMC battery continues to charge after the voltage reaches 4.2v, it will lead to internal overreaction. If it continues to charge after fully completing the charge, it will lead to irreversible chemical reaction of the battery, which will lead to electrolyte decomposition and gas precipitation. Excessive heat will cause the battery to bulge, and the negative electrode will continuously generate metal lithium and Pierce the diaphragm, resulting in short circuit. There could even be an explosion or a fire. Even if the overcharge is stopped before the battery is damaged, the battery capacity is greatly lost, and the battery is attenuated in advance and cannot be recovered.

What happens if the 18650 NMC battery over discharge to below 2.5v?

When the 18650 MNC battery voltage drops to 3.0v, it can be considered that the battery is out of power and should be charged in time. If there is no BMS protection, the 18650 NMC battery has been discharged to below 2.5v, and for a long time below 2.5v, the battery will also damage the lithium coating and cannot be repaired.

The storage of lithium requires the storage of a certain amount of electricity, without overdischarge, a small amount of self-discharge for a long time may also lead to less than 2.5v.

Can the 18650 LFP battery be overcharged or overcharged?

Both NMC batteries and LFP batteries are lithium compounds, and similar chemical reactions make them overcharged or overdischarged, which will also cause irreversible damage.

It is worth noting that although the voltage range of the 18650 LFP battery is 3.65v to 2.5v, which is slightly lower than that of the NMC battery, the LFP chemical is more heat resistant.

18650 battery voltage

What is the best storage voltage for an 18650 battery?

The storage voltage should not exceed the nominal voltage, and the power margin of 40% to 60% is the best storage state. If it is not used for a long time, it must be placed in a cool and dry room temperature.

Before long-term storage of the battery is required, the 18650 battery should be charged using a special lithium-ion battery. Keep the cycle check and charge, self-discharge although slow, when the same will make the voltage continuously reduced until overdischarge.

Does the 18650 battery automatically prevent overcharge and overdischarge?

No, some 18650 batteries have miniature BMS overcharge and overdischarge protection circuits, only suitable for small electronic devices, and do not support series, series discharge current is too large, miniature BMS can not protect the battery. Large energy storage systems still require professional circuit design and separate configuration of BMS.

When is the cycle life of a battery considered to be over?

Cycle life refers to the degree of capacity attenuation of the battery, for example, the new 18650 battery capacity is 6000mAh, cyclic charge and discharge after a period of time, the full charge capacity is only 5400mAh, that is, 90% of the original capacity. When this percentage drops to 80%, the battery’s cycle life is over.

18650 battery voltage

The NPP cell is used in a normal environment with a cycle life of up to 3,000 times before the capacity drops to 80%. For more than a decade, NPP New Energy has been a leader in rechargeable battery energy storage. Please refer to our lithium battery product series, feel free to contact us to make suggestions or seek cooperation.

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