Batteries and Electric Bikes
All electric bikes come with a battery and a charger. However, the battery and its capacity doesn’t indicate how powerful the bike is. The power of the bike lies in the size of motor. Battery just provides the motor with the electricity it needs to be powered.

Battery Types
Most commonly used batteries today are Lithium based batteries, these are the ones you'll find in cell phones, laptops, portable electronic devices and such. Before Lithium batteries became widely available, there were Nickel based batteries and before Nickel, there were Lead Acid based batteries. Lead Acid based are the oldest batteries and they're also heaviest. Many gas powered traditional cars still use Lead Acid based batteries to start the ignition. Some of our first electric bikes that we sold in early 2000s: Merida Power Cycles, Currie US Pro Drive, Giant's LaFree were all powered by Lead Acid batteries. Later on Giant switched to Nickel Metal Hydride batteries, which were newer and lighter batteries than Lead Acid. Eventually Lithium batteries became available and replaced all the others. Lithium based batteries today are the lightest and with some exceptions safest and most reliable batteries available for mass production.
 

Battery Specifications
There are two basic specifications that you need to know about batteries: the power output, measured in Volts and the current the battery can deliver in an hour - measured in Ampere/Hours. Usually, these numbers will be printed on the battery with letters V - for voltage and Ah - for Amp/Hours. For example, typical Bosch 400 pack battery will have the numbers printed on back of the battery that reads 36V, 11Ah. Multiplying these two numbers gives us the total capacity of the battery: 36 x 11 = 396, measured in Watt/Hours and spelled “Wh”. Hence 36V battery with 11Ah, has the capacity of 396Wh. Bosch rounds this number to 400 and that’s why they call it 400 pack battery.

Capacity and Range
The capacity of a battery is the number that tells you how far you can go on one charge. However, the range of the electric bike depends on many variables. Generally when manufacturer says that an electric bike model can have a certain range, this normally means the bike can go up to a certain range in moderate or near perfect conditions - on flat terrain, with minimal load, no head wind, lower power assist levels, warm weather and etc. Because of these variables it is extremely hard to accurately estimate range. Bosch has very useful tool built in their website called “Range Calculator”, where you can fill in all the specifications of your bike - type of bike, type of motor, size of battery, terrain, season, rider weight etc. And it tells you how far you can go with an average speed you indicate.

In general 500Wh is the average size of electric bike battery. Voltage of the battery may vary, but 36V is very common power output for electric bike batteries. Let's say all we know about the battery is that it's 500Wh and it's output is 36V, but we don't know the Ah number. With the same formula, just like by multiplying Volts and Amp/Hours we get the Watt/Hours, we can also divide Watt/Hours by Voltage and get the Amp/Hour number. So 500Wh battery with 36V output would be 13.88Ah battery, because 500Wh divided by 36V equals to 13.88Ah. We can round this up to 14Ah. So a typical 500Wh, 36V electric bike battery size spelled in Volts and Amp/Hours would be 36V, 14Ah.

Battery Care
Most electric bikes today have Lithium batteries. Lithium batteries in general last for 3 to 5 years with good care. After 3 to 5 years they slowly start to decay. To get most out of your battery, you’ll need to take good care of it. Lithium batteries don’t like extreme temperatures. They also shouldn’t be discharged below certain threshold. It’s a good practice to recharge your battery once it reached 20% or 15% and not drain it down completely. If the Lithium battery charge drops below certain threshold, the cells in the battery will start to get damaged and eventually the whole battery will die. Generally all batteries discharge naturally at very slow rate, whether you’re using them or not. Low temperatures noticeably accelerate the natural discharge.

If you’re not using your battery and decided to put it away, it’s best to store it in the room temperature, away from direct sun and keep it charged. Don’t let the charge drop below 60%-50%. Also, it’s not recommended to leave your charger plugged in all the time. Not only can you damage your charger, but in most cases it won’t even charge the battery more than once. Most chargers will only do one cycle of charge and even if the battery starts to naturally discharge, the charger will not recognize that drop in charge and will not reset itself. You will have to unplug the charger and plug it back in to start the charging again. Lithium batteries also do not like extreme heat, do not store them in extreme heat and direct sun, because some Lithium batteries may become damaged in extreme heat.

Battery Chargers
Most electric bikes that we sell have unique chargers. There are some electric bikes that have more generic chargers. If you lose the charger or if it stops working, it's always highly recommended to get the replacement charger made for your particular bike by the bike brand you have. There are aftermarket chargers that might work in certain cases, but major specifications of the battery and the charger should match - the Voltage of a battery should match the voltage output of a charger and the polarity of a charger's connector should match the polarity of a battery's charging port. Different battery chemistry types we talked about above will have their own unique chargers too. Nickel based battery chargers won't work with Lithium batteries and vice versa. Lead Acid battery chargers won't work with Lithium or Nickel based batteries and vice versa. If you have Lithium battery you must charge it with Lithium charger and normally it will be printed on the charger if it's a Lithium battery charger.