It can be difficult, given the increasing number of battery options, to determine the best type of battery for your application. Some important considerations are energy density, power density, cost, cycle life durability, voltage, and safety.
These considerations generally involve trade-offs. Ideally a battery would possess high energy and power density, and good durability — at a low price. In reality, consumers have had to pay a premium for batteries with greater energy density. But that is changing.
Research organization BloombergNEF reported that the volume-weighted average lithium-ion battery pack price (which includes the cell and the pack) fell 85% from 2010-18, reaching an average of $176/kWh. BloombergNEF further projects that prices will fall to $94/kWh by 2024 and $62/kWh by 2030. That would reflect a 95% price decline over the course of 20 years. In comparison, lead-acid battery packs are still around $150/kWh, and that’s 160 years after the lead-acid battery was invented.
Thus, it may not be long before the most energy dense battery is also the cheapest battery. That has enormous implications for the future of lead-acid batteries.
Another important consideration is a battery’s capacity. The capacity defines the run-time of the battery, which reflects the discharge current the battery can provide until it needs recharging.
The energy content of a battery is obtained by multiplying the battery capacity in ampere hours (Ah) by the voltage to obtain watt-hours (Wh). Two batteries can have the same Ah capacity, but if one has a higher voltage it will have more energy.
These are important concepts to understand if you are trying to decide on a battery to power a flashlight versus one to power a forklift.
The power density defines the maximum rate of discharge of the battery. Some batteries require a low rate of discharge, but those used to provide bursts of power will need greater power density.