1: Charge fully…
A battery life is measured by the number of charge and discharge cycles it can survive rather than, say, the total time for which it has been used. So it therefore makes sense to maximise the usefulness of each of those cycles by charging you battery all the way to full whenever you charge it.
2: …but avoid charging once full!
We’ve just explained that it makes sense to charge you battery fully to get the most out of its limited number of charge and discharge cycles. However, if you leave your battery charging once full, it will discharge a little, then charge back to full, then discharge a little, then charge again… and so on through countless little charge and discharge cycles. So avoid damaging your battery by avoiding these unnecessary cycles once it’s fully charged.
3: Avoid “Deep Discharge”
Though it’s good practice to charge your battery fully, the opposite, discharging it completely, sadly isn’t. Continuing to use your battery until it is almost (or completely) empty, referred to as “deep discharge”, is in fact one of the most common ways to damage your battery. Although batteries have clever internal management systems designed to avoid a really deep discharge, it’s still best to avoid draining the battery too low. Instead, when the battery gets down to around 10-20% charge (one bar left on the display) then it’s time to ease off the throttle and charge up the battery.
In summary, the best way to use your battery is to:
1.Charge it to 100%
2.Remove it from charging promptly once full
3.Use it until the charge reaches 10-20%
Other Useful Tips
Unfortunately, lithium-ion batteries age over time. This means that even if you haven’t put your battery through that many charge and discharge cycles, it will start to lose charge after about 3 years. You should therefore aim to get the most out of your battery during that time. A good 200-300 charges each year, following the best practice above, will make sure you get your money’s worth!
Knowing how much charge is left in a battery can actually be rather tricky. Generally, as a battery discharges, its voltage decreases. As long as the voltage decreases predictably, as it does for lithium-ion batteries, then the battery’s charge state (i.e. full, empty, or somewhere in between) can be estimated. However, the problem is that not every battery is identical so these predictions, and the reported charge state, can only ever be approximate. Incidentally, the voltage of LifePo4 batteries, another popular battery type, doesn’t change anywhere near as much as the battery discharges. It’s therefore even harder to predict the charge state of these batteries and any meter designed for one battery type will tell you lies if hooked up to the wrong battery.
Finally, it’s worth knowing that lithium-ion batteries can recover after heavy use. So if it looks like your battery is running low, make sure to ease off the throttle and see if the voltage bounces back a little, giving you a more accurate reading as to the amount of charge left.