batteries and battery-powered devices like you do dairy
products. Buy the freshest one whenever given the choice.
A slightly older product is fine - particularly if you're
offered an outstanding discount - but expect it to expire
sooner.St eer clear of anything with questionable origin.
And avoid buying something that you only expect to use
a long time from now.
Here are a few things you can do to make your lithium-ion
(Li-ion) batteries last longer, whether they be used in
an electric car, a large home installation - such as Tesla's
newly announced Powerwall - or in your portable device,
such as a smartphone or laptop. These tips will focus primarily
on extending the lifespan of Li-ion batteries, so they don't
need to be replaced as often. But if you are looking to
maximise running time just for this very moment, possibly
at the expense of having to replace the battery earlier,
there are some added tips at the end.
The most important influence on battery life is temperature.
Li-ion batteries are typically happiest at around room temperature
of 20 to 25°C. In warmer temperatures, a protective
layer inside the batteries breaks and needs to be reconstituted,
which sucks up some of the energy capacity the battery has
to offer. And in colder temperatures the chemical reactions
inside the battery slow down. However cold is usually less
harmful than heat. So if you have the choice between placing
your phone in the sun or the shade, the latter is probably
IT OR LOSE IT
degrade not only during use, but also when sitting idly
on a shelf. This is one reason why most manufacturers specify
not only a cycle life but also a calendar life for their
batteries. So a good approach to take is to treat batteries
and battery-powered devices like you do dairy products.
Buy the freshest one whenever given the choice. A slightly
older product is fine - particularly if you're offered an
outstanding discount - but expect it to expire sooner.
One of the more widely known aspects about battery life
is the "memory effect". In older rechargeable
battery chemistries, such as nickel cadmium, partial charging
and discharging significantly decreases the energy capacity.
What is less known is that the memory effect in lithium-ion
batteries, if it exists, tends to be very small. Instead,
they have quite nuanced characteristics. When not in use,
batteries degrade most when fully charged. So if left for
several days or weeks without use, they should ideally be
kept at a relatively low charging state, e.g around 20 per
cent charged. Conversely, when being charged and discharged
a lot, it is best to keep the batteries as close to the
50 per cent mark as possible. So if you are only charging
and discharging batteries a bit at a time, it is much better
to do this between 45-55 per cent than between 90-100 per
Li-ion is not a single chemistry, but a range of chemistries.
The above is intended as rough guide for iron-phosphate
or cobalt-based cathode chemistries, which tend to be the
most widely used. However, there are others including manganese-spinel
which have slightly different characteristics. If in any
doubt, ask the battery manufacturer for guidance.