August 27

Batteries For E-Bikes Explained

0  comments

A decent quality lithium-ion battery pack may cost you more than all the other components in an e-bike kit. This is why you must get the right battery for your bike when you decide to go shopping for one. In this post, you’ll find all the information you need when selecting a battery for the best e biking experience! When I first developed an interest in e-bikes and e-bike conversion kits, it was way back in the ’90s.

What I discovered is that a lead-acid electric bike battery pack sold online for $250 whereas an NIMH pack, which is the gold standard of e-bike batteries, sold for $1200! This is almost tenfold the price of a lead-acid pack…just to get double the range? I know what you’re thinking…is it really worth it?

How Do You Get the Most Value Out of the Battery You Buy?

To do this, you want must understand the fundamentals of electric bike batteries before determining what you require. There is nothing more devastating than having your electric bike battery dying when you are miles away from home. This is because e-bikes are meant to take away the strain out of regular riding.

They allow you to ride further and longer without getting easily fatigued and ensure that you get home without feeling stressed out. It is no surprise that more and more people are integrating e-biking into their daily life schedules. 

Range- How Long Can Your Ride on a Full Charge?

The range estimate is one of the first aspects you want to look at in electric bike batteries. Typically, this is something that almost every other e-bike battery company or salesperson you come across struggles with. While many of them want to provide you with the best-case scenarios, the sales pitch usually seems too good to be true! 

The truth is that you will typically get around 20 miles of range from a 6-8lb lithium battery when it is fully charged. Don’t always believe what you see on the manufacturer's website…some statements are simply exaggerations! 

 Li-Ion battery weight  -  6-8lbs

 Range (miles)  -  20mi (32km)

Until the technology powering e-bike batteries improves, the general rule of thumb is that the lighter the battery, the shorter the range. For a 6-8lb battery, you can expect a no-pedal range of 20 miles at a speed of 20mph. Therefore, you want to determine the actual weight of the battery and base the range on this when shopping for electric bike batteries.

Some vendors will tell you that their lithium batteries can deliver a 100-mile range on a single charge, which is not realistic on a 6-8lb pack, unless if they want you to turn on the power for the first 20 miles then pedal the rest of the journey…! However, some e-bike models don’t have handlebar throttles, and instead, use a pedal sensor that requires you to pedal to engage the power.

In such a case, the quoted range estimates may be true, especially at low-power settings. But considering that the rider has to provide human effort by pedaling the bike, this cannot be said to be a no-pedal range, which is a different issue altogether. 

An e-bike that comes equipped with a handlebar throttle allows the motor to engage without you pedaling, and makes for greater power consumption. Therefore, you must understand how your e bike works. For instance, a 500w bike doesn’t necessarily use 500w all the time. If you decide to pedal without motor assistance, your e-bike battery will remain at full capacity until you begin using the power.

It is, therefore, possible to spend the whole day riding your bike on a single charge…as long as you use the battery power sparingly. However, in ordinary circumstances, you’ll find many people riding their electric bikes with the throttle pinned to “max”. In this case, you can only expect to cover 20 miles on an e-bike with a 6 to 8lbs battery. 

bike battery

Definition of Terms

What is a Battery Pack?

This is basically a pack of batteries comprising of a couple of smaller battery cells that have been stacked in such a way to deliver the power required by your e-bike system to function. To get the best performance out of your bike, it means that you should choose the appropriate pack for your bike’s application.  

Volts and Amps

In simple terms, Voltage is what pushes the flow of electric energy whereas Amps refers to a measure of force. Generally, an e-bike with a high voltage rating will go faster while higher Amps will necessitate larger and more powerful e bike batteries. A combination of Amps and Volts gives you Watts. 

While shopping for an e-bike battery unit, you’ll notice a list of various parameters printed on the items packaging. This is very important information that you need to examine when searching for the appropriate battery pack for your bike. They include:

Amps- This is the measure of volume of the electrons i.e. it describes how wide the road is…how many cars (electrons) can pass side by side at the same time 

Volts- Describes how fast the electrons move…the more the voltage, the higher the speed

Watts- A combination of Amps and Volts …Volts * Amps = Watts

Amp Hours- This is normally abbreviated as “Ah” on the battery unit. It is a measure of the fixed number of Amps that a battery can sustain for one hour. 

Watt-Hours- This provides you with a more accurate way to know the amount of usable energy stored in the battery and is abbreviated as ‘Wh”. This figure, when available on the electric bike battery, can be translated into how many watts can be sustained for 1 hour. For example, a 500Wh battery delivers 500w for 1 hour or 250w for 2 hours. 

One thing to note is that most electric bikes don’t use power continuously at an exact level, meaning, the Wh figure doesn’t necessarily translate to ride time. However, you’ll notice that a larger battery with greater capacity can deliver lower levels of power over a long period and have a longer-lasting charge. 

Battery energy

Watt Hours

 500 wh

 500 wh

 500 wh

Load

250w

500w

1000w

 Run Time (hours)

2 hours

1 hour

30 minutes

Something you want to watch out for; some battery vendors tend to overstate the facts when it comes to the range estimates. As such, some due diligence will come in handy before you decide to buy. Be sure to ask the right questions to figure out whether the range promised matches the bike's weight and its intended use. 

Ah vs Wh

Although it can be confusing, you must understand the difference between Amp and Watt Hours. Ah only becomes significant when you factor in the voltage. On the other hand, Wh is more important since it factors in the voltage, as well as the Amp Hours to determine how far you can ride on a full charge cycle.  

Wh Example: 36v 10ah = 360wh and 48v 10ah = 480wh

Consider a bicycle that can be powered by both a 36v and 48v battery. This means the bike will run faster on the 48v battery when you engage a full throttle. However, you’ll need more energy to move at this higher speed. Therefore, a 48v battery will not always offer you more range than the 36v pack. 

The bottom line is, with the right information, you can make a more informed decision when buying an e-bike battery. 


What is the Best Electric Bike Battery?

Joyisi Ebike Battery - Best Small to Medium Size option

The Joyisi is an electric bike battery with a compact and seamless design that won’t add too much weight to your bike. This 48V 10Ah lithium battery offers a range of practical features to ensure high performance during your ride. Its high-quality electric cells have been fitted with a 30A BMS plate that serves to prevent overcharge, over current, and short-circuiting, ensuring that you get a long life from the battery.

Joyisi Ebike Battery

The battery is encased in a rugged plastic shell for protection and LED battery level lights have been integrated so that the rider is aware of the battery level at all times. The light turns red when the battery is charging and green to inform you that the battery is fully charged. In the package, you'll also find a 54.6v 2A charger that will take at least 8 hours to fully power the battery.  

A USB port on the battery lets you charge your phone or other devices on the go and there is a key to safely lock it when not in use. Finally, you get a 1-year warranty when you buy the Joyisi e-bike lithium ion battery.


UnitPackPower Triangle

UnitPackPower Triangle - Best for Larger Engines, longer range

If you’re looking for a high-capacity battery unit that will pair well with your large e-bike motor, the UnitPackPower Triangle is a great choice to consider. This 52V 20Ah lithium battery was built for high-speed, extended range rides and will be suitable for 500W-1100W bike engines. 

The UnitPackPower boasts an exclusive patent design that features a newly-added power switch, as well as a USB port that can charge a phone, tablet, or even speaker during your ride. There is also a battery level light that indicates how much charge is remaining. 

To ensure maximum protection from impact and elements, the battery is covered with a private mold hard-plastic case. The high-quality cells inside the pack are also protected with a built-in 30A BMS plate that prevents overcharging, short-circuiting, over-discharging, etc. to make for extended shelf life. The manufacturer further provides a 1-year warranty. 


Weight, Size, and Shape- Things to Consider When Shopping for the Right Battery Pack

The right battery for an electric bike needs to not only be lightweight enough but also look good when installed. Unfortunately, you may not find everything you looking for in one battery pack, although some features prove to be more important than others. 

A common mistake that many e-bike owners make is that they look for the largest battery they can find. The problem comes when you want to mount the battery on your bike and it gets even worse when you need to hang it on a bike rack or carry it upstairs for storage.

Generally speaking, the key to the perfect setup for bikes is to find the smallest and lightest battery unit possible that will get the job done. To be on the safe side, look for a pack that delivers twice the energy so that you don’t run the risk of the battery running out of power on those extended adventures. 

When searching for the ideal battery, the first step should be to determine your needs. Most people can barely ride for more than 15 miles at a time without taking a break. Instead, they often opt for multiple short rides in a day, taking breaks between them. It is a good idea to charge the battery for a quick boost of power every time you return home from running an errand in town. 

This is possible as a smaller and lighter battery unit can be charged quickly and the brief windows of time you get between trips can go a long way to improve the battery capacity. It allows for more than enough range for every trip you make during the day. 

However, if you use your bike for more functional purposes such as taking your kids to school or pull a trailer/shopping cart of groceries ; it will require you to prioritize size. It means that you'll need to get a bigger battery and a stronger motor. There are larger capacity batteries out there that will get the job done in such a case.

More often than not, a lightweight electric bike tends to be the perfect fit for most people. When riding such a bicycle on a fairly flat trail, with little to no headwind, and on the right tire pressure, expect an average burn rate of 10wh/km. This is true for riders weighing 200lbs or less. While there are factors that may come into play, the 10wh/km burn rate is very realistic.

For the above, you should Consider a 36v 10ah battery pack. This will give you a 360wh of battery (i.e. 36v multiplied by 10ah). In theory, this battery should provide a range of 36km on a full charge. However, very few people manage to realize this as they lack the tools to accurately calculate the capacity of a battery. This is something some vendors might take advantage of. 

Voltage (v)

 36v

Capacity (ah)

10ah

Energy (watt hours)

360-watt hours

Range (mi)

22mi (36km)

Voltage

Most electric bike kits are usually rated for a specific voltage range. For instance, a typical 36v e-bicycle will need a battery that offers a capacity of between 42v and 30v. At 42v, a 36v battery pack is fully charged and storing as much energy as possible but at 30v, it should automatically shut down and seize producing power before it can experience permanent damage. The “36v” you commonly see on most batteries is simply an average operating voltage, also known as nominal voltage

According to Electric-Find.com"Nominal Voltage is a nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (e.g., 120/240 volts, 480Y/277 volts, 600 volts). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment. May 28, 2009"

Some electric bicycle kits may have a wider operating range, such as 36v to 48v. This is something you should note when choosing a battery pack. Most e-bikes are fitted with a display to show you the level of charge using a series of LED lights which will only work at the stated voltage. 

Voltage is what powers the motor’s peak rotations per minute (RPM). When you increase the voltage, the speed of the bicycle also increases. With that said, electric motors are designed to rotate at a specific RPM for a certain application and this is determined by its construction. In short, a 36v e-bike will run faster with a 48v battery pack (but the electronics between the battery and motor have to be compatible).

bike Battery

Amps

To choose the appropriate battery pack, you need to know the nature of your e-bicycle controller. This is a small gadget that you’ll find on every e-bicycle and is used to control the power between the motor and battery by pulsing on or off very quickly, i.e. PMW/ Pulse With Modulation.

If your bicycle is completely stationary and you try to turn the throttle to full, the controller is what will step in to set the limit of the number of amps that can flow from the battery to the motor. But why is this important when it comes to choosing the ideal battery pack? Well, this is because you need to have a battery powerful enough to produce the required number of amps without overheating, blowing a fuse, or shutting down. 

Generally, a 10ah rated battery pairs well with a controller of 20Amp or less. This is something you can work out even if you don’t have all the specs, as long as the data provided is true and accurate. Some controllers will come with “Watt ratings” whereas others will have “Max Amps”, which can be a little bit confusing for some people.

When you find a controller rated for Watts, you should note that this is “Maximum watts” (“Continuous watts” with a higher peak. Your battery should be able to safely handle the Max or Peak whenever needed.

Quality

The quality of a battery pack is only as good as the weakest cell inside of it, as well as the durability of the casing. Back in the day, it was quite rare to find a long-lasting battery pack. You’d be lucky to find a pack that can survive 6 months of sitting idly on a bench without self-discharging to death. This is to say that the battery technology available today has come a long way. 

We’ve come to the point where reliability and quality is the number one priority for lithium batteries manufacturers. A lot of attention is given to the finer details and all you need to do is buy from a reputable manufacturer to get the best quality. There is a quick turnover of stock, meaning that only the recently produced batteries are found in the stock and you still get a warranty to back your investment. 

Battery Monitoring System and Chargers

Lithium batteries are durable and lightweight, but they should be used within the specified limit for the best performance. To ensure a long life for your battery pack, it should have a BMS (Battery Monitoring System). This stands between the lithium ion batteries and power wires, monitoring the voltage of the cells within, as well as the number of amps flowing through. 

In case the limits are reached, the BMS steps in to cut off the power and ensure the safety of the lithium batteries. In the ideal circumstances, the BMS will just sit there and have nothing to do but once you’ve used up all the power available in the battery from continuous riding, it will shut down the e-bicycle to prevent damage to the battery cells. 

The same is true when it comes to the functioning of the charger. The BMS will only allow the charger to charge if the battery cells are within their limits. In this case, you can’t overlook the importance of a quality charger. The wrong type of charger will easily damage the lithium ion batteries!

Mounting Your Battery Pack

Installing the li ion batteries on your e-bicycle can prove to be a daunting task, and this will depend on the nature of the pack. For the best distribution of weight and riding comfort, the front frame triangle is the ideal mounting location for the battery pack. Meanwhile, the rear rack is a convenient and easy location, although it may interfere with your handling. 

Batteries that are sealed in aluminum cases make it easy for you to mount, it also protect the cells inside from impact. However, this adds weight and bulkiness to the load, and it will cost more. The cheaper option would be a pack with a simple shrink wrap but its fragility dictates that you should take great care to keep it from crushing as a result of vibration during riding or impact when the bicycle tips over.

Too Small?

This is a problem that may arise! A battery that can power your e-bicycle for about an hour under the worst-case scenario is normally sized appropriately. Larger capacity batteries won’t have to work as hard as their smaller counterparts. For instance, a 20ah battery pack producing 500w continuously can run for twice the time it takes a 10ah battery. Nevertheless, there are more factors to consider, such as the Internal Cell Resistance of cells inside the battery unit and C rate (C-rate refers to the rate at which a battery is being discharged). 

Converting Your Regular Bicycle into an E-bicycle

It is possible to convert your regular road bicycle into an e-bicycle if you want to avoid the high cost of acquiring a new battery-powered bicycle. All you need is an e-bicycle conversion kit, which you can easily access via a quick search on the internet. The best e-bicycle conversion kits typically come with components like a motor, controller, thumb-operated throttle, brake levers with kill switches, on/off switch, as well as a battery in the package. 

Installing the various electrical components is straight-forward, as long as you have basic knowledge of bicycle mechanics. Once you’ve finished fitting the motor, switches, and battery, it will only be a matter of time before you start enjoying some motor-assistance on your once regular bicycle. 

fixing the bike

If you’re not sure about the best way to convert your bicycle, we provide guides on practical conversion kits out there, as well as the best e-bicycle motors to use with your chosen battery for electric bike. The best thing about e-bicycle conversion kits is their price; even the most expensive ones will cost just a few hundred dollars to acquire. 

Caring for Your Battery

Appropriate care has to be taken to ensure that your e-bicycle battery pack lasts as long as possible. Even with a BMS plate to safeguard the battery, it’s always important to charge it and never allow the power to drain all the way. This is true for all battery types you may be using. If you live in a cold region, don’t make the mistake of charging a cold or frozen battery pack. Instead, get it to a warmer place first and give it time to warm up before charging. 

You can wrap it with a rug or any other relevant piece of fabric to get it warm. Riding your bicycle in cold conditions doesn’t harm the electric battery , but you may notice that its range has dropped. Remember to allow the battery pack to warm up before you start charging it.

Opportunity Charging

Opportunity charging is the kind of charging that you had not planned for. For instance, you decide to stop for a cup of coffee in the middle of your bicycle trip and plug in the charger for a boost of power. This can be of significant help and although it may not bring your battery to full capacity, it will surely extend your range. 

Legal Shipping

Legal shipping of your battery pack can be a very controversial subject, especially when you consider the amount of energy held inside the different battery types. The shipping is guided by various regulations that make for a proper and safe way of packaging and handling them. Reputable and established vendors usually advertise about legal shipping or “UN Certified”.

Unfortunately, this is an expensive affair that may require you to dig deep into your pockets. Smaller vendors won’t ship the “UN Certified” way and resort to illegal shipping. This makes it impossible for you to return the e bike batteries in case of a warranty violation. 

Energy Density

Energy density refers to the amount of energy that a battery pack can store for a particular volume (Liter/Wh), which is unlike ordinary liquids where one gallon occupies a certain space. Two e bike batteries of the same size can contain varying amounts of usable energy. For instance, a typical 18650 lithium battery from back in the day would hold around 1000mah while the same 18650 cells today can store as much as 3500mah, if not more.

Notice that the two batteries measure practically the same in size but the current one can deliver triple the range that the one from 10 years ago could deliver. This simply points to the difference in energy density.

Lead Acid Batteries vs Lithium ion Batteries

Lead is less expensive of the two options and if you can’t afford a decent lithium battery unit, lead is the alternative available to get you on the road. For perspective, a 6lb lithium battery can go as far as a 30lb lead-acid pack of equal voltage rating. 

  Battery Chemistry

Lead-Acid

Lithium Ion

Capacity

15ah*

9ah

Weight

30lbs

6lbs

Range (mi)

20mi (32km)

20mi (32km)

The table above considers a 15ah lead acid battery against a 9ah lithium-ionbattery because the usable capacity of the lead-acid battery is just about 66%(9ah), which puts them at the same range. 


FAQ

How to Make an E-bike Battery

To do this, you’ll need enough 18650 cells for the DIY e-bicycle battery, as well as a suitable BMS. This can be calculated based on the desired voltage, capacity, and the BMS current ratings will determine the amount of power your battery can safely supply. If your bicycle has a 1000W 48V motor, you’ll need to run at least 25A continuous. 

So, get a BMS with at least 25A continuous rating and 13 series cells to be able to run at 48V. Finally, you’ll need to get an enclosure for the battery. You can either build your own using a bicycle bag or go for a pre-made enclosure to protect your battery from the elements. 

How Much do E-bike Batteries Cost?

Usually, a new and high-quality e-bicycle battery will cost you anything in the region of $500 to $900, depending on its capacity and the brand you buy . You can expect the capacity to be between 400wh to 700wh. Another thing to note is that name brand batteries will typically be notably more expensive when you consider the cost per Wh of capacity than high-grade off-brand batteries. 

What Battery Do I Need for a 48v 1000w Motor?

Technically, there is no one ideal battery! You have to consider how far you want to ride and the nature of the terrain you’re going to ride on. Having said that, an 800Wh+ battery pack will allow you to ride as you please for 20 miles, assuming the trail you’re riding on has no hills. This should be enough time to enjoy your ride. 


Final Thoughts

From the post above, it is clear that there is so much to know when it comes to batteries that power e-bikes. Generally the most important considerations to note when shopping for a decent battery is aspects such as range, watt hours and weight. It is furthermore important to care for the battery in order to maximise the battery life.

Last update on 2020-10-28 / Affiliate links / Images from Amazon Product Advertising API


About the author

Emma was born and raised in the UK, studied in Amsterdam (where she discovered her passion for biking), and is currently living in Ohio. Her main passion is cycling, that's why she is always looking for an amazing new e-bike to make her journey even more unforgettable!


You may also like

Will an Electric Bike Charge as You Pedal?

Solar Power- E-Bike Charging: The Possibilities

{"email":"Email address invalid","url":"Website address invalid","required":"Required field missing"}