Ah vs Wh in E-Bike Battery

Most if not All of the Electric Bicycle sold here in Singapore, would have the AH reading of their battery publicised. As a result, buyers would only look out for the AH reading of an E-Bike Battery to jump into conclusion that the bigger the AH reading, the better the E-Bike is in terms of battery life.

Well, what if we told you that you have been lied to all these while? What if we told you that a big AH does not necessarily mean it’s better?

Before that, let’s all go back to basics about the E-Bike battery and use an analogy to make you understand better. 

Water Flowing Through A Pipe

If we think of electricity as water flowing through a pipe it can help us understand amps, volts and watts. 

  • Amps:  Volume of water flowing through the pipe.
  • Voltage: Water pressure
  • Watts: Power (Amps x Voltage) the water could provide 

With this analogy in mind the definitions below for amp, volt and watt should be easier to understand.

Amps: Used to describe the number of electrons moving

Volts: Used to describe how fast electrons move, more voltage = more speed !

Watt: The combination of Volts and Amps ( Volts x Amps = Watts )

Ampere-Hour (Ah): It is the unit of a battery capacity that measures the amount of charge that can be available in a fully charged battery. This amount of charge is what determines the amount of current that can be discharged from the battery and its discharge time.

  • For example, if a 12V battery is rated 48Ah, it theoretically means the fully charged battery can discharge 48A for one hour or 12A for 4hours and so on. Thus, Ampere hour (Ah) is about the current(A) discharged by the battery and its discharge time(h)

Watt-Hour (Wh): It is referred to as the energy capacity of a battery as it more accurately determines the energy that can be stored in a battery. Wh = Volts x Ah

Watt-hour (Wh) gives a more accurate capacity of batteries because it includes the Voltage (V) and the Ampere-hour (Ah). It also determines how far you might go on a full charge.

As much as amp-hour determines how much charge is in a battery, you can’t compare batteries by just using it. You have to consider both the amp-hour and voltage.

Here’s an example:

Volts Ampere/Hour Watt/ hour
E-Bike A 48 V 8 Ah 48V x 8Ah = 384 Wh
E-Bike B 36 V 10 Ah 36V x 10Ah = 360 Wh

With this example, You can clearly see that E-Bike A produces a LARGER Watt-hour (Wh) even though it’s Ampere-hour (Ah) rating is SMALLER than E-Bike B. 

Conclusion

Key Takeaways for you to bring back:

  1. Bigger Ah does not mean it’s Better
  2. The correct Unit to look out for is Watt-hour (Wh) because it includes the Voltage (V) and the Ampere-hour (Ah)

We hope this gives you a better understanding as to what to look out for when you are getting an E-Bike. If you do still have any burning questions to ask, feel free to drop us a DM on Facebook and our team will get to you as soon as possible!  

Leave a Comment

Your email address will not be published. Required fields are marked *