There are many units that are present in equipment, devices, or gadgets that we use on a daily basis. For energy consumption we have watts, for electricity pressure we have voltage, but the problem is how are they different from each other? What do they tell you about how the equipment uses electricity? Since covering all of possible candidates in one blog will make this article quite lengthy and might bore readers, I have decided to instead make a blog the aims to give a general differentiation between two of the most common units used in battery specifications, Watt-hour and Ampere hours.
Watt-hour is commonly used in household electric meters, or watt-hour meter, as we know it - This is what distribution utilities use to compute for your electric bills, along with some other miscellaneous of course(VAT, system loss, etc.) But before discussing what watt-hour is, let’s start with the its root unit, Watt, watt mathematically is just the product of the voltage and the current passing through a load, generally we can refer to it as the power being drawn by that particular load, we use this to describe how much power that a load needs in order for it to work. Just a brief review, (to make this a little bit more detailed), voltage is the value of electrical pressure and current is the flow of electron in a conducting material. But, the powerful watt-hour isn’t only present in our electric bills, we can also observe it on our battery packs, powerful right?
Before we can discuss the battery version of watt-hour, let me explain first the more common battery specification we might have already heard after purchasing our very first power bank, the Ampere-hour(Ah), or for smaller capacity batteries, milliampere-hour(mAh). Wh and Ah are just basically the same, they represent the capacity of the battery, or in a more generic term, how long can a battery last given a load. Their only difference is that Wh considers the voltage of the battery, while on the other hand, Ah or mAh does not. Ah assumes that the voltage remains constant throughout it whole cycle, and yes, technology have already minimized voltage drop of batteries to a negligible level. Manufacturers use Ah instead of Wh for convenience, but either way, they still give the same impression on a battery. Now how can we use this values to compute for operating time of a battery. Assuming that you are using the prescribed battery of the load you wish to energize(this will neglect battery Average drain requirements) we can easily compute for the operating time of the battery, Say you have 10000mAh battery used in a 1000mA flashlight, you can directly divide the capacity by the amperage of the load, so you get around 10hrs of operating time. This is also true when computing for operating time using Wh, assuming that your batteries voltage conforms with that of the load, you can directly divide the battery capacity with the wattage of the load.
-Paul Custan is an Electrical Engineer who have worked as a software engineer and as a digital platform specialist before becoming a full-time FNX Solar employee. FNX Solar Power Solutions Inc. is a business based in Canada. We develop and sell portable power stations and related accessories.