E-bike Battery

Discover everything you need to know about e-bike batteries

What components make up an E-Bike battery?


The housing is the casing for the battery components and connects the battery to the bike. The housing protects the cells and electrical components from the elements.

BMS = Battery Management System

The BMS is the internal management system that serves to manage and protect the battery pack’s cells. It distributes and balances the loads between cells and manages incoming and outgoing currents to maximize the battery’s potential capacity and lifespan. Besides managing the charging and discharging of the battery pack, the BMS also monitors the total voltage in the system and cuts power when the battery is fully charged.
The BMS also protects the cells from deeply discharging which can permanently damage cells. When the battery’s voltage drops below a certain value it cuts power to the bike to prevent deep discharge cycles.

Battery Cells

Battery cells are the proverbial heart of the battery pack and are what effectively stores the charge. The industry standard 18650 cells are used in the Li-ion packs in a QWIC battery. These can be arranged in either series or parallel circuits to achieve the desired voltages for our bikes.


The QWIC battery packs have a nominal voltage of 36V. In case your battery needs to be replaced and you are purchasing a new one, please ensure the voltage is equal to your original Battery pack. In the case of QWIC E-bikes this will always be 36V.


A battery’s rated capacity indicated how much power it can theoretically store. The capacity of your battery can be directly linked to your actionable range; the larger the pack’s capacity, the larger your cycling distance. With our E-bikes we represent the capcity in Watt-hours (Wh). For more information on the available capacities available from QWIC click through to “QWIC Batteries & Prices”

The position of the battery pack

Battery packs from QWIC can come in a couple of different form factors and positions on the bikes. In most bikes on the market the battery pack is located either underneath the rear-carrier or mounted in or to the frame. At QWIC we use removable battery packs that are mounted to either the rear-carrier or the frame’s downtube to maintain our signature sleek lines and urban style.


In some models the battery pack is neatly integrated into the rear-carrier. Here it is protected by the frame of the carrier and can be protected even more by mounting bike bags. This battery pack slides out of the rear of the carrier frame.

The Frame/downtube

When the battery is integrated into the downtube as it is in QWIC Performance and Urban models, the center of gravity shifts lower to the ground. This contributes to comfortable riding characteristics and a stylish look.

Charging the battery

The way in which the charger is used can influence the lifespan of the battery. When the battery needs to be charged please follow these steps:

Step 1: Connect the battery to the charger
Step 2: Plug the battery into a wall outlet
Step 3: The light on the charger turns red
Step 4: When the light om the charger turns to green it has finished charging
Step 5: Unplug the charger from the wall outlet
Step 6: Disconnect the battery from the charger

Keeping a battery always connected to a power source can damage the cells. That is why you should never keep a battery connected to the charger for longer than necessary to charge it. Li-ion batteries have better lifespans if they are not charged higher than 95% and so do not reach their peak voltage. This reduces the wear-and-tear on batteries per charge and discharge cycle making them last longer.

Extra: Only ever use the designated charger for your battery, provided with your bike. Using chargers that were not designed for your battery can damage your battery pack and shorten their lifespan.

When and How often do you need to charge your battery?

Regular Charge and discharge cycles

When you are taking short trips that do not require a full charge of your battery, we recommend using your battery until it has almost completely emptied, and then charge it. Spacing out charges between every 2-3 trips can improve your battery’s lifespan.

Always try to prevent Deep-discharges

It is very important that after every ride where you discharge the battery pack fully or to below 20% to subsequently charge it soon after. Batteries naturally lose charge over time, and so if they are stored for any period of time with very low voltages they can then self-discharge to dangerously low levels. Deep discharging batteries can damage the cells and will either reduce their lifespan, or render your battery pack entirely unusable.

The QWIC Battery packs contain a self-protecting BMS that helps to prevent deep-discharges. When the BMS recognizes that the pack’s voltage has dropped below a pre-determined value, it will simply cut power to the bike’s motor. The lights will continue to work for a period of time, to ensure the safety of our users.

The Importance of re-charging the battery after depletion

Battery cells naturally lose charge over time and will discharge during long periods of storage. The BMS cannot prevent this, so it is necessary that the Battery will be charged again before it is placed into storage.

The Effects of temperature on a battery pack

Environmental temperature can have a big impact on both the lifespan and the capacity of your bike’s battery pack. Higher temperatures can negatively impact your battery’s lifespan, however cold can impact the voltage output of battery cells and shorten the battery’s capacity and range. It is therefore recommended to store your batteries at room temperature, approximately 20°C.

Capacity  – The colder it is, the smaller your capacity will be

The Wh rating of your battery is based on a room temperature measurement of 20°C. When the temperature drops the voltage from the cells lowers, even if they are fully charged. This effectively lowers the total capacity of the battery.

Example: at 0°C the change in capacity can be approximated to 20%. This means that whereas normally your bike has an effective range of 50km at 20°C, when the temperature hits 0 your effective range will be more like 40km.

These effects from temperature are temporary, and once brought back up to room temperature will also return to their previous capacity.
Rule of thumb: for every degree below 20°C, your battery’s approximate capacity can drop by 1%. There is little effect to your effective capacity and range above 20°C.

The Lifespan of your battery at higher temperatures

Extremely high temperatures can negatively impact the lifespan of a battery, so on extremely hot and sunny days we recommend to park your bike in the shade when possible.

The Actionable Range of an E-bike

The actionable range gives an approximation of the distance you can ride with a fully charged battery. It is not possible to give precise values for this, because this dependent on a number of variables that change per rider and use case.

Contributing factors from the rider and the bike on the actionable radius:
  • Total weight – The combined weight of the rider and the bike
  • Motor – Some motors work more efficiently than others
  • Battery pack – The Capacity and age of the battery
    → With a larger battery you can cycle longer distances
    → As with all batteries like your smartphone or laptop, the capacity of your battery pack will decline with age
  • Tire pressure – When your tires are inflated to the optimal pressure, the rolling resistance will be lower and therefore improve your range.
  • Individual riding styles – shifting and speed
    → Start in your lowest gear and only shift up when the you have reached the right pedaling cadence. This helps the motor work more efficiently.
    → When cycling faster the motor will draw more power

External influencing factors affecting Range:
  • Terrain – Your environment also determines your range. Flat terrain will demand less power than up-hill segments. This is also applicable to smoother vs. Rougher roads.
  • City or rural environments – In urban areas, constantly stopping and accelerating in traffic and at lights will demand more power of your bike.
  • The weather – A strong headwind can also mean your motor needs to draw more power to keep you up to speed.
  • TemperatureTemperatures beneath 20°C will decrease  the capacity of your battery and therefore also the actionable range

5 tips to improve your Actionable range

Tip 1: Efficient use of the motor

Try not to excessively use your motor, but rather extend your range by balancing your own power output with the motor. Set the support level lower or even turn it all the way off to maximize your range. This is best done when you have a tailwind, or are riding downhill!

Tip 2: Starting from stop – use light or no support

When you start moving from a complete stop there is a lot of energy necessary to start moving. If you are in an advantageous position when beginning to move, you can lower the support to improve your range but still be able to accelerate smoothly and easily.

Tip 3: Lower gears at traffic lights and hills.

You should see the gears on your bike as similar to those on your car. Use lower gears when starting from a complete stop or when ascending hills to reduce the amount of strain on your motor. Of course in between lights and hills you can shift back up to comfortable gears.

Tip 4: Take your charger with you!

For longer rides it can be useful to have your charger with you. You are likely to find e-bike charging points, so if you bring something to eat and drink you can picnic while you wait!

Tip 5: Buy an extra battery

When you want to take your bike for long-distance rides it can be conducive to have an extra battery. Though it is often unnecessary, it can be helpful in a pinch or should you find yourself stranded in “the middle of nowhere”.

How do you safely store an e-bike battery?

When you correctly store and care for your battery you can contribute to extending your battery’s lifespan. Store your battery at room temperature, both for long-term storage as well as when charging. It is best not to store or charge your battery in a cold space, like a backyard shed.

Choose a safe place to store your battery

We would like to emphasize that all batteries naturally discharge over time if they are not used for extended periods of time. Don’t leave your battery in your bike as this will make it discharge faster. An e-bike with a battery still in it is also a likelier target for theft.

How do I safely care for my battery?

The safety of our users and our products is very important to us, so QWIC feels it is necessary to address this issue. It has happened in the past that Li-ion batteries in consumer products like smartphones have malfunctioned and started fires.

The electric bikes from QWIC are  provided with the highest available quality of 18650 cells, however just like all battery products these are not immune to abuse and damage. The value in the battery-packs lies in their high energy density and discharge characteristics, however excessive heat can cause them to malfunction and in some fringe cases catch fire.

The most common causes are:

→ During charging
→ Through use of incorrect or inappropriate chargers
→ during over-charging
→ damage to the battery pack (falls, crashes, etc.)

A Battery pack can catch fire when it is least expected, although there are some early warning signals to watch for:
  • (Excessive) heat
  • Strong odors
  • Smoke
  • Sparks
  • Inflation/expansion of battery housing

If you suspect that your battery is defective or in danger of catching fire we recommend you do the following:
  • Immediately disconnect the battery from the charger or bike.
  • If you can safely do so, bring the battery outside and way from flammable materials.
  • Call the emergency number if you see smoke or sparks.

It is difficult to prevent your battery from ever catching fire because it mostly happens when users are not present. Always be sure to:
  • Read the provided manual thoroughly and completely
  • Let the battery cool down after extensive or intensive use.
  • Unplug the charger when the battery is fully charged.
  • Do not leave the battery in direct sunlight, especially while charging.
  • Use exclusively the original charger. Keep an eye on your battery during charging, don’t leave it to charge overnight!
  • Have you dropped your battery? Have it examined for potential defects, cracks or any other damage by an experienced professional. If you have any doubts, don’t use the battery until you have had it checked!

Does your Battery pack need to be replaced?

A Battery pack will on average last you three to five years, so taking good care of your battery can mean years of extra enjoyment. The wear you experience in your battery is a normal process and will depend heavily on usage, charge cycles and care.

Batteries therefore do not last nearly as long as your bike does. There is a high chance you will need to replace it after a few years. There are two options available to you: You can have your battery revised, or buy a new pack.


When somebody chooses to have their battery pack revised, the 18650 cells will get replaced with fresh ones. This restores the capacity to it’s original capacity or in some cases even higher!

The Advantages of revision:
  • Cheaper
  • Restores your pack to it’s original or even higher capacity
  • Eco-friendly – Reusing the casing and controller creates less waste

QWIC recommends against doing this repair yourself and does not provide this service. It is necessary to contact a professional service to have this service done. In contrast, some repairs are simple and can be done by your dealer. Small things like cracked cases, burnt fuses, bent contacts and broken charging plugs can all be replaced.

Purchasing a new Battery pack

The battery is one of the most expensive components of the E-bike, but it is significantly cheaper than purchasing an entire new bike. To purchase a new battery it is best to contact a local dealer who can advise you on types and capacities. They can subsequently order the original QWIC parts for you.

Please look at the “QWIC Batteries & Prices” to determine which capacity is best suited to your needs.