How to choose Electric bike batteries
Common e-bike Battery Types
batteries are light and efficient
When buying an ebike today,there are only two types of battery
chemistry you are likely to encounter. Lead acid, which is the older, heavier,
dirtier and cheaper option; and lithium ion, which is the newer, lighter, far
longer lasting and efficient, and more expensive option. The vast majority of
new electric bicycles are equipped with lithium ion batteries, and I would
suggest staying away from lead acid chemistry unless you absolutely need to
save a bit of money. Lead acid batteries typically fail after 100 to 300
charges, and during this time their max capacity falls very quickly.
Lithium ion cells last far longer on the other hand, usually lasting
to between 700 to over 1000 charges before dropping below 50% capacity. They
have next to no “memory effect”, meaning that you can partially charge them
without issue and their natural discharge over time doesn’t create the problems
which are experienced with older chemistry types such as lead acid. They are
extremely light in comparison to other batteries which is ideal for electric
bikes, and they also carry a large charge so you can travel further on a single
charge. The biggest drawback with the technology is that it is expensive and is
likely the most costly component of any ebike.
When choosing your electric bike battery or browsing the battery
capacity on an ebike you’re thinking of purchasing, there are generally two
figures provided which describe the capacity; Voltage (V), and Amp hours (Ah).
Both of these contribute to the overall capacity of the battery, so higher
voltage or a greater number of amp hours, translates to larger capacity and a
greater distance you can travel on a single charge. In fact the best way for
you to get a “feel” for the capacity of a battery is to multiply the two
numbers together which will give you the Watt hours (Wh). For example:
Battery A: 24V * 10Ah = 240Wh
Battery B: 36V * 8Ah = 288Wh
So Battery B has a total of 288 watt hours, providing it with a
larger capacity that will take you further on a single charge than Battery A.
It’s impossible to exactly say what distance a battery’s full charge will
actually cover, there’s too many variables such as hill conditions, amount of
pedaling, outside temperature, total weight, wind etc. As a very rough guide, a
36V 10Ah battery powering a 250W motor and ridden under standard conditions
will cover 50-60km. That includes light pedaling and few hills. In tough and
hilly conditions that distance can easily half.
Ebike battery capacity is not the only important aspect, it’s also
worth paying attention to voltage options.
Sticking with our no-nonsense explanation, voltage can be thought of
as the ability for the battery to provide energy over the shortest period of
time possible. Basically, it affects the max power which the battery is capable
of providing. Batteries and motors work their hardest during hill climbs, and
an electric bike with a 24V battery may not climb as fast or as well as an
identical electric bike with a 36V battery. What is crucial here is to match the battery to the motor. A
powerful electric motor will require a relatively higher voltage battery to
perform at its best, while on the flip side a weak electric motor with a high
voltage, high capacity battery, is not getting any performance advantage from
the higher voltage (although the capacity is obviously better).