How do you measure a battery’s capability?

Usually, when people ask about a battery’s capability, they want to know two big things:

  1. The amount of energy stored in the battery’s cells. (How far can I go?)
  2. At what rate the cells discharge electricity. (How much power and speed?)

Amp Hours are the most common way to describe the amount of electricity in the cells – and all that talk about Էatt hoursԠis really the same thing, times the voltage (Volts x Amp-hours = Watt Hours). The capacity of one cell in Amp Hours is also the capacity of the entire battery in Amp Hours. One 7 amp cell is 7 AH at 1.2 volts. If you need 30 of them to get your required voltage, you still only have 7 Ah in usable energy – at that voltage.

To put this another way: More Amp Hours means you can go farther, at higher speeds, and up to bigger hills. But more Amp Hours usually cost more money and weigh more. Also in our experience you rarely get the Amp Hours stated out of the cheaper batteries. In fact you hardly ever get close.

 

More Amp Hours means you can go farther, at higher speeds, and up to bigger hills.

 

Max current means essentially Ԉow fast can the cell discharge energy? Think of it as a can full of water. The can is the cell, the water is the electricity – the larger the cell, the larger the amount of water – and the water flows out of a hole in the can. The larger the hole, the faster the water can come out. In terms of a battery, if the discharge (the hole) is not big enough, then the motor may not be able to get enough energy (the water) to function at Max performance.

You could also think of the Max current as Ԩow big the fuel line is”.

Some people will describe Max current in terms of Max amperage that the cell can endure and for how long. Another way is what rate can the battery be discharged for one hour = 1C. An example is: If a battery can be discharged at a 10 amp draw and will last for one hour, then it is a 10Ah battery at 1C.

 

Other posts in this series:

Electric bike buying guide (part 1/20)
Electric bike buying guide (part 2/20)
Electric bike buying guide (part 3/20)
Electric bike buying guide (part 4/20)
Electric bike buying guide (part 5/20)
Electric bike buying guide (part 6/20)
Electric bike buying guide (part 7/20)
Electric bike buying guide (part 8/20)
Electric bike buying guide (part 9/20)
Electric bike buying guide (part 10/20)
Electric bike buying guide (part 11/20)
Electric bike buying guide (part 12/20)
Electric bike buying guide (part 13/20)
Electric bike buying guide (part 14/20)
Electric bike buying guide (part 15/20)
Electric bike buying guide (part 16/20)
Electric bike buying guide (part 17/20)
Electric bike buying guide (part 18/20)
Electric bike buying guide (part 19/20)
Electric bike buying guide (part 20/20)

 

 

 

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