Discharge Rating (C” Rating)

Apr 21, 2016 by admin Category: RC Battery 0 comments Tags: Discharge Rating (C” Rating)

Almost all Lithium Polymer batteries you buy today will come with a ‘C’ rating. The ‘C’ in C rating stands for Capacity. The C rating is the maximum, safe, continuous discharge rate of a pack as specified by the manufacturer, so when you see 20C printed on your label, it means it can be discharged at 20 times the pack’s capacity,”continuously”. Capacity is usually measured in mAh and a popular cell size is 2200mAh. Therefore, so by way of example:

2200mAh 20C Cell = 2.2A x 20 = 44A continuous discharge

Along with the continuous discharge rate, some batteries display ‘burst’ discharge rate. This is typically twice the continuous discharge rate. It usually means the battery is capable of allowing twice the current, but only for a few seconds at a time.

Lithium Polymer batteries come partially charged and are significantly more volatile than the alkaline, Ni-Cd or Ni-MH batteries used in RC applications. Here are some guidelines for using Lipo Batteries.

Before the First Charge

Make a visual and physical inspection of the battery. Look for any damaged or loose leads or connectors, broken shrink tubing or other irregularities which may cause a short circuit and eventual fire.

Check for proper polarity of the factory installed leads and connectors. Use a digital voltmeter to ensure that the polarities are correct.

Check the voltage of the battery using a digital voltmeter or the E-flite Power Meter (EFLA110). The voltage of the cells within the battery should be between 3.5V and 3.9V each.

The voltage of a new 2S (7.4V nominal) battery should be between 7.0V and 7.8V

The voltage of a new 3S (11.1V nominal) battery should be between 10.5V and 11.7V

The voltage of a new 4S (14.8V nominal) battery should be between 14.0V and 15.6V

The voltage of a new 5S (18.5V nominal) battery should be between 17.5V and 19.5V

The voltage of a new 6S (22.2V nominal) battery should be between 21.0V and 23.4V

Charging Guidelines and Warnings

  1. You MUST use a charger specifically designed to charge Li-Po batteries ONLY. The charger must be capable of constant current / constant voltage” charging. Failure to use the proper charger may result in a fire causing personal injury and/or property damage. DO NOT use an Ni-Cd or Ni-MH charger at any time.
  2. The battery should always be charged in an open area away from, and not placed on, any flammable materials. The battery should never be charged inside of the model or a full-size vehicle. It is also suggested that an ABC” type fire extinguisher be readily accessible in the charging area in case any issues resulting in fire are experienced.
  3. Never charge the battery charging the battery, you should always remain in constant observation to monitor the charging process and react to potential problems that may occur.

 

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