# what does the c stand for when charging li ion batters ie Max. Discharge rate: 2C (6.8A)

looking to charge a 4 pack of li-ion battery but dont understand what the 2c means know the rest. i.e. Max. Discharge rate: 2C (6.8A)

• There is a paragraph in this answer which explains the C notation. Mar 13, 2017 at 23:13

C in this context means the battery capacity in Ampere-Hours but divided by hours. If battery's capacity is 3.4 Ah, then C would be 3.4A, and 2C would be 6.8.

Charge and discharge rates of a battery are governed by C-rates. The capacity of a battery is commonly rated at 1C, meaning that a fully charged battery rated at 1Ah should provide 1A for one hour. The same battery discharging at 0.5C should provide 500mA for two hours, and at 2C it delivers 2A for 30 minutes. Losses at fast discharges reduce the discharge time and these losses also affect charge times.

A C-rate of 1C is also known as a one-hour discharge; 0.5C or C/2 is a two-hour discharge and 0.2C or C/5 is a 5-hour discharge. Some high-performance batteries can be charged and discharged above 1C with moderate stress. Table 1 illustrates typical times at various C-rates

"C" is the ampere-hour rating of the battery.

This would mean 2C discharge rating for the battery is 6.8 Amp, the battery would be rated at 3.4 Ampere-hours.

A battery has a capacity rating usually in mA hours or Amp Hours.

The C or C-Rate is the C harge and dis C harge rate, expressed as a ratio of the battery capacity.

A 1Ah battery should provide 1A for one hour. If it is powering something that is draining 2 Amps that is a 2C discharge rate.

The rate is used when the specifics of the battery such as voltage and capacity are not an issue. It is a generalize term applying to all batteries or the type of battery being addressed. For example: Li-Ion batteries are recommend to be charged at an 0.8C rate. This means the 1Ah battery should be charged at 800mA. A 2Ah battery would be charged at 1.6 Amp.

The C rate can be applied to any battery regardless of it capacity or voltage.