Whenever you are using batteries, you might have seen it mentioned as mAh, Ah, or Wh. What are these? milli-amp Hours, Amp-Hour, and Watt-Hour all denote the battery capacity. But how does it is differentiated?
- Ah – How much Capacity does a battery hold (Amps x Hour)
- Wh – How much Energy Capacity does a battery pack hold that includes the voltage. (Volt x Amp x Hour)
- C-Rating – How powerful you can charge or discharge a battery.
What is AH in a Battery?
Ah is also known as Amp-Hours. For a smaller capacity battery, it can be mentioned as mAh (milliamp Hours) 1 Ah = 1000mAh. The Ah in the battery denotes how much charge it can hold (Capacity). It is a unit to mention the capacity of the battery. The discharge can be 1Amp/1 Hour or 5Amp/ 1 Hour or anything as per the load. Remember that, when a battery is mentioned 2Ah, it doesn’t mean it delivers 2 Amps directly, the consumption is based on the load needs.
For example: A Mobile Phone backup life. A 5000mAh capacity battery of your mobile phone can be drained even in 4 hours when gaming or can withstand 2 Days when it is not used.
Consider when gaming your mobile consumes 1.25 Amps (Load). We will calculate how many hours you can play the game with 5000mAh (5Ah) Battery.
To find Capacity (Amp Hours) the formula is
Capacity (Ah) = Load x Battery Life (i.e Discharge Time)
Deriving equation to find Discharge time, the equation becomes
Battery Life = Capacity (Ah) / Load
Battery Life = 5Ah / 1.25 Amps (Load)
Battery Life (Discharge Time) = 4 Hours ( Play Time possible with a 5Ah Battery)
What is Watt Hour in Battery?
What Hour is a more precise way of mentioning a battery capacity along with the Voltage. Below are the three different battery packs 1 Cell, 2 Cell and 3 Cell, but if you look at the mAh all are same. If we multiply Voltage and Amp-Hours we will get Watt Hour of a battery. Both Amp-Hour and Watt-Hour are useful in their respective places.
What is C-Rating in battery?
C Rating is used to denote how safely you can charge/discharge a battery without damaging it. The best example of a C-Rating is a car jump starter and drone batteries.
A Jump Starter is a device used to start a car when its battery is drained. The jump starter act as a temporary battery to start a car. It is mostly handy on road trips and forest camps. If we compare a Lead acid battery with Jump Starter, the Lead Acid battery is 15 times more larger and heavier than the Jump Starter. But the lithium-powered Jump Starter has the power to start the engine safely without heating itself that too in a compact size. The jump starters will have a extra special circuit to cut off the battery to protect it from over-discharge above the rated capacity.
The C Rating can be mentioned for both Charging as well as Discharging.
Charge Rate: If 1C is mentioned for Charge Rate of a 2200mAh battery, then it can be charged at 2.2 Amps Safely. If it is mentioned as 3C, then it can be charged at a 3 x 2.2 Amps = 6.6 A (Charging Current). A Higher C Rating in Charge Rate is ultimately useful for fast charging.
Discharge Rate: For drone batteries, you might have seen the C ratings as 40C of a 2200mAh Battery. This means 40 Times x 2.2Ah = 88Ah. Hence the jump starters have enough juice to start with the small footprint. It can provide that much of current until the car starts. A Higher C Rate for Discharge is useful for heavy loads, but the backup time will reduce according to the current consumed.
Note that, some companies also mention max. burst discharge along with C Rating like 40C (Actual C Rating) /80C (Max. Burst Discharge). Some Simple C Rate and it’s backup time,
- 3C = 15 Minutes
- 2C = 30 Minutes
- 1C = 1 Hour (Actual Capacity as mentioned on Battery)
- 0.5C = 2 Hours
- 0.2C = 5 Hours
These are the basic battery units that are used in a battery.
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