Insights & Tips

C-Rate Charge Programming

Battery Circuit Charge Parameter: C-Rate

C-Rate factor calculations for charging or discharging the battery. (Reference the application chart.)

Battery manufacturers will use different Cxx rates depending on the market or application at which their batteries are targeted. Typical rates used are C8 in UPS, C10 in telecommunication and C20.  The most common C10 factor settings are 10% recharge based on the capacity of the battery as programmed using AHr ratings.  The default setting 0.100C10 will program the controller to check the battery AHr setting and calculate the 10% size recharge current limit.  The actual current measurement is taken inside the power system with a shunt placed in series circuit design, just before the connection to the battery (output) connection block.

System current limit will be active when one of two thresholds is met:

• the current reading relative to the programmed percent battery size or
• the 105% capacity of a rectifier(s).

Either limit reached will be the current limit of the system. Use a setting equal to 1 for maximum output with no limitation based on the battery size and current limit algorithm in the software.

Sample Calculation using C10 default setting

Battery in Amp Hour      =          100

System value                =          0.10                  (Screen View –“Limit: 0.100C10” )

Calculated Limit(amp)  =          10

By example                  :           100(0.10) = 10 amps

Table: C-Factor Sample Settings

Battery Manufacturer’s instructions should be readily available at the installation when programming and adjusting any rectifier/charger system connected to a battery.  Battery damage will occur if voltage, current or temperature conditions are allowed to exceed the battery design intent.  It is recommended that the user fully understand the interaction of the rectifier system, battery and supported loads.