Electric Bike Batteries
Picking an e-bike battery can be a real “charge” of a decision! It’s the heart of your electric bicycle and the key to unlocking all the power and range that you crave. With so many options available, it can be tough to choose the right one. Do you need a 48V or 52V battery? How many amp-hours? How expensive does it need to be? But fear not, my e-biking friends! I’m here to help you navigate the world of batteries, so you can build the e-bike of your dreams.
The voltage of an e-bike battery determines the level of power that is available to the motor. And let’s be real, who doesn’t love more power?
A standard voltage for e-bikes is 48V, which is great for most riders. It provides enough power to ride with speed and tackle hilly terrain, but for those who crave a little extra excitement, a 52V battery might just be the ticket.
With a 52V battery, you get a small boost of power, resulting in faster acceleration and higher top speeds. In our 48V vs 52V battery comparison, we wanted to find the difference in top speed between a 48V and 52V battery. Using a Bafang BBSHD motor, keeping all other parameters the same (rider, bike, etc), we reached a top speed of 30mph with a 48V battery and 32mph with a 52V battery, a modest advantage. The extra bit of voltage can slightly increase your speed and potentially power you through slightly steeper inclines and slightly rougher terrain. 52V is not a requirement to have a powerful e-bike, but for those who want as much as they can get, 52V is the way to go.
We should also mention that there are other voltage options for batteries, most commonly 36V and 72V. If you are looking to ride on flat pavement, a 36V battery can get you going at modest speeds while 72V batteries are usually used for electric dirt bikes, small 4-wheeled EVs, or custom e-bike builds (like this speed demon). In general, more voltage means you can go faster and carry more weight. If you are working on a custom project, reach out to our support team and we can give you some tips for selecting the right battery.
The amp-hours (Ah) of an e-bike battery determine its capacity or the amount of energy it can store. Having your battery die while you are out riding is not a good experience, especially for medium to long-distance commuters! The higher the Ah rating, the longer the range of your e-bike. For example, a 13Ah battery may give a typical e-bike and rider a range of around 32 miles, while an 18Ah battery may provide a range of around 45 miles. In theory, the ratio of Ah to e-bike range is constant, so doubling the Ah of your battery will (almost) double the range of your e-bike. It’s important to know, however, that the actual range is heavily dependent on the bike and rider’s weight, the terrain, and how much throttle or pedal assist you are using.
Technically, the energy stored by the battery is actually given the battery’s Watt-hours, calculated by Voltage x Amp-hours. For example a 48V 18Ah battery stores 48V x 18Ah = 864Wh (Watt-hours) of power. This means that your battery could potentially supply 864W (watts) of power for one hour, or equivalently, 1728W for two hours. This is a more accurate measure to help you calculate battery range practically. If you know how many watts your ebike will consume on average, you can calculate the time it will take before your battery dies! Riding your e-bike at higher powers to carry bigger loads or go faster will require the battery to supply more watts, meaning it will last less time according to the Watt-hours spec.
The maximum power (watts) your battery can continuously supply is directly related to the continuous current (amps) spec. This is often confused with the amp-hours spec which has to do with the battery capacity and not the current it outputs. To calculate the continuous power output (watts) that a battery is capable of, multiply its voltage by its continuous current. This number will determine the most you can get out of your motor in terms of power. For example, a 52V battery with 30A continuous current can output 1560W continuously, making it powerful enough to run a BBSHD motor to its max. Many cheaper batteries will have lower continuous current ratings so the power output isn’t high enough for 1000+ watt motors. So look out for this battery spec (and voltage) because it’s what really matters when you need power!
Most e-bike batteries these days are Lithium Ion (Li-ion) batteries because of their amazing power output. There are a few other Lithium batteries such as LiFePO4 batteries which are also great options. It’s best to stay away from Lead Acid batteries because they are heavy and can’t output enough power for a fast and responsive e-bike.
As a quick note, buying cheap batteries from China is almost always a bad idea. The BMS (battery management system) on these batteries are very poorly made and the battery cells are bad quality. These batteries often don’t accept regen current from the motor which could lead to it damaging the motor controller. Moreover, the continuous current is never as good as a high-quality battery, so you won’t get the same power output from a cheap battery. In the best case, the battery won’t give you as much power or range as you hoped for, and won’t last as long as it should. In the worst case, your battery might damage your motor controller, or the battery might even catch fire. It’s just not worth the risk.
Your battery decision will ultimately depend on the riding conditions and experience that you want out of your bike, and the e-bike that you are using. If you are a mountain biker running a Bafang or CYC motor on a 52V battery, you’ll enjoy faster acceleration and higher top speeds, allowing you to tackle even the steepest hills with ease. If you are looking to maximize your motor’s potential, 52V is the way to go. If you plan on riding your bike for hours on end, you’ll want a battery with a high amp-hour rating, although it will add some weight to your bike.
On the other hand, if you’re looking for a leisurely ride with some pedal assist, a 48V battery with a high Ah rating would be the way to go. It provides enough power for a comfortable ride with a longer range, making it ideal for recreational riders and commuters.
It’s important to remember that the right battery choice will depend on a variety of factors, such as your weight, the type of terrain you’ll be riding on, and whether you prefer throttle-only or pedal-assist modes. So, before you make your final decision, be sure to consider all of these factors to ensure that you choose the battery that’s right for you.