Scientists are using new tools to better understand the electrical and chemical processes in batteries to produce a new generation of highly efficient, electrical energy storage.
Like any other battery, the more energy it can store, the more stuff you can usually power with. Of course, there are other factors (like power rating and chemistry), but as a general rule of thumb, more capacity means more devices powered for longer periods.
How are batteries rated?
Batteries are rated for two different capacity metrics: total and usable. Because usable capacity is most relevant to the amount of energy you'll get from a battery, we like to use usable capacity as the main "capacity" metric to compare storage products. Also, from our energy storage glossary, see how the two terms differ below:
Tesla battery cells have different energy storage capacities. The 18650 cells hold about 10 watt hours (36,000 joules). In contrast, the 2170 cells, used in most current Tesla models, store around 15 watt hours (54,000 joules). Energy storage varies depending on the specific model and configuration of the battery.
How important is battery capacity?
Battery capacity is very important, but perhaps more importantly, a single battery's capacity isn't necessarily the capacity you'll install. For example, you can install multiple Tesla Powerwall batteries together to create a much larger system than an individual battery.
Eguana, Electriq Power, and sonnen currently make the home batteries with the most capacity. Battery capacity can be a misleading metric: in many cases, you can stack multiple batteries together to make a larger system. Compare solar-plus-storage quotes from local installers on EnergySage. What is battery capacity? How is it measured?
Why is battery power so important?
It's as important as motor power and torque because the car's range depends on the size of its battery, and how efficiently the car uses that energy. Energy capacity is measured in kilowatt-hours, or the ability of a battery to deliver a set power output (in kilowatts) over a period of time (in hours).