An e-bike battery is the heart and the energy source of the bike and logically also the most expensive component of the entire vehicle.
And not without reason, after all, the battery has a lot to perform and must in turn be able to take a lot! No matter what the weather, the load or the gradient – the battery must always provide enough energy to get us and our passengers from A to B relaxed and sweat-free. The journey is often the destination and we like to take the longer way home.
The requirements for this high-tech construct of lithium-ion cells are complex:
Simply put, the capacity of a battery describes its "size" and thus allows a possible range to be derived. The unit of capacity is given in ampere-hours (Ah), which in turn can be converted into the more common household quantity of watt-hours (Wh) by means of the voltage in volts (V):
Capacity (Ah) x Voltage (V) = Energy Unit (Wh)
14.25Ah x 48V = 684Wh or 20.4Ah x 48V = 979,2Wh so almost 1kWh!
We currently offer the following battery types & capacity models, which are limited to two different package standards (Silverfish & Hailong) and one soft pack variant:
The battery sticker tells you more about the characteristics of your battery.
A battery's range depends very much on vehicle type/weight, terrain, load, tire pressure & type, wind and road conditions as well as other factors and can therefore vary greatly.
Especially in wintertime with low outside temperatures, the capacity/range of the battery can be noticeably affected, but this is normal for lithium-ion batteries and returns to normal when temperatures rise.
Likewise, riding style plays a decisive role in the possible range. Anticipatory riding to avoid unnecessary braking actions and to minimize start & stop maneuvers (e.g. in city traffic) or smart riding allow a higher range – varying the pedal assist level (e.g. when going downhill), extensive use of the mechanical gear shift to relieve the load on the electric drive train and other actions have a decisive influence on the range.
Our range figures are based on ideal conditions, i.e. low payload, low assistance level, no start & stop traffic, level asphalt surface, adequate tire pressure to minimize rolling friction, outside temperature of 24°C, adequate addition of muscle power, no thumb throttle, max. speed of 25km/h.
The range record with the 20.4Ah battery is 155km!
Finally, two short rules of thumb for rough orientation:
In principle, the battery charging time can be calculated as follows (completely empty battery or one full charging cycle):
h = hours | Ah = ampere hours | A = ampere
Charging time (h) = capacity of the battery (Ah) / charging current (A) * 1.3 (electr. work)
14.25Ah / 2A * 1,3 = ca. 9h 15min
20,4Ah / 2A * 1,3 = ca. 13h
20,4Ah / 5A * 1,3 = ca. 5h 20min
In the case of the battery, we do not talk about a range limit until "the juice runs out", but about the total number of so-called charging cycles that it has undergone.
A charging cycle describes a charging process of a completely empty battery (0%) up to the completely full charge level (100%) including its complete discharge.
A half-full battery that is charged and discharged again has consequently only used "half" a charge cycle, a 75% full battery logically only a quarter of a charge cycle, etc. - here we speak of partial cycles.
If you have 20% of the full battery volume available and charge the battery to 70%, use the battery again to 20%, and do exactly the same again, a complete charge cycle is reached and a new one begins.
It is therefore the total number of charges or full charge cycles that add up with each additional charge.The battery manufacturer specifies a number of 800 to 1000 charging cycles until the battery has a remaining capacity of 80%. This means that the battery is still usable and provides up to 80% of its original capacity and range. If you map this to a period of normal, regular battery use, you're looking at about 2-3 years of life. In addition to common wear and tear, batteries age over time (cell aging), regardless of use and care. Unused as well as regularly charged and well maintained batteries lose about 4% of their storage capacity per year.
Deep discharge is caused by excessive current consumption and manifests itself in the almost complete exhaustion of the battery charge capacity, which falls below a certain voltage level. This can be harmful to the battery and should therefore be avoided as a matter of urgency or prevented in advance. To detect such a deep discharge, the output voltage must be measured using a volt/multimeter.
A deep discharge is when the charge level of the battery falls below 20% of its capacity, i.e. below the final discharge voltage or the minimum voltage limit. This can result in various damages. For example, if cells are connected in series, they can even be reversed in polarity due to a deep discharge. The damage can occur after just one deep discharge. If a battery is not used for a longer period of time, the cells can self-discharge – a whole 0.5% to 1.0% of the battery's capacity per month.
Common protective measures or circuits installed in rechargeable (lithium-ion) batteries are so-called Battery Management Systems (BMS), whose task is to monitor and control the balanced charging and discharging of the cells or cell packs and thus prevent overcharging. These systems, in the form of circuit boards, store important data such as the number of charging cycles to date, the current charge level and the expected remaining service life, and can be read out by the manufacturer or a specialist using appropriate analysis tools.
What is the best way to store my battery, e.g. during the winter break?
We have already learned that the battery loses capacity not only during use, but also during storage - in the form of the previously mentioned self-discharge.
How you store the battery unit will also affect the discharge rate. Even short-term storage at high or very low temperatures can already damage the battery irreparably, so avoid temperatures below -10 °C and above 40 °C whenever possible. Some manufacturers already warn that even 4 hours at temperatures between 40 °C and 60 °C can have a negative effect on battery life and such temperatures are reached faster than expected – in the trunk of your car, in the winter garden or even in direct sunlight. At the other end of the scale, 20 hours at temperatures of -20 °C can cause equally irreversible damage. Your battery should be stored at a temperature between 0 °C and 20 °C in a completely dry place, but away from flammable materials. All manufacturers agree that the optimal storage temperature is a constant 10°C, as this slows down degradation processes and reduces the aging rate of the battery.
How do I bring the battery back from hibernation to use it?
Even after extended storage, for example in winter, it is possible to simply plug the battery into the bike and ride without recharging. Modern lithium-ion cells have no classic memory effect, so lithium-ion batteries can be charged at any point in their state of charge without causing damage or reducing capacity - regardless of interruptions and charging time. To gently wake the battery from hibernation, it's best to fully charge it once and then run it down again. Only then should you fully charge it again. This procedure helps the battery management system to calibrate and calculate the battery capacity.
We hope that this article gives you a helpful insight into the battery topic of e-bikes as well as a better general understanding of lithium-ion batteries.
We welcome feedback and are always available for questions and suggestions.