March 25

Batteries For E-Bikes Explained

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A decent-quality lithium-ion battery tends to be really pricey, sometimes more than all the other components in an e-bike kit. This is why you must buy the appropriate battery for your bike when you embark on the shopping journey. In this post, you can go through all the information needed when selecting a battery meant for your best e-biking experience! Back when I developed an interest in e-bikes and e-bike conversion kits, way back in the ’90s, I noticed a trend in battery prices. 

What I discovered was that an average lead-acid electric bike budget battery pack retails for $250. On the other hand, a NIMH pack, which is the gold standard of e-bike batteries, can be sold for up to $1200! This is almost tenfold the before mentioned price of a lead-acid pack…And what do you get? Double the range? I know what is going through your mind…Is it really worth it?

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

In order to do this, you want must understand the fundamentals of e-bike batteries before deciding what your requirements are. There is nothing more devastating than having your battery die when you are miles away from home. E-bikes are essentially meant to take away the physical 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 - What Can A Full Charge Provide?

The range estimate is one of the first aspects to look into when discussing batteries used in electric bikes. It's not uncommon to see that e-bike companies or your chosen salesperson struggle with the terminology. While many of them want to pitch you the best version of events, it's often clear that the situation is not realistic, it's a little bit sugarcoated.

Realistically, you get around 20-ish miles of range from a 6 to 8 pound lithium battery when it is completely charged. Don’t always believe what you see on the manufacturer's website…Some statements are simply exaggerations! 

 Li-Ion battery weight  -  6 to 8 pounds

 Range (miles)  -  20mi (32km)

Until the technology powering e-bike batteries advances further, the general rule of thumb is that lighter batteries provide a shorter range. A battery that weighs between six to eight pounds gives about 20 miles at a speed of 20 mph. Therefore, you shoud aim to determine the actual weight of the source and then calculate the range with that in mind - that is one of the most important numbers to keep in check when you go shopping for e-bike batteries.

Some salesmen will tell you their lithium batteries provide the rider with a range of 100 miles on a single charge, but know that this is not realistic at all, especially for those who don't want to pedal 99% of the time. However, some e-bike models don’t have handlebar throttles, and instead, they have a pedal sensor that has you pedalling in order to engage with power. 

In such a case, the quoted range estimates may be true, especially at power-saving settings. But considering that the rider has to provide human effort by pedaling the bike, which means we are no longer in the "no-pedal range", which is a different issue altogether. 

An e-bike equipped with a handlebar throttle makes the motor engage even when you are not engaging yourself - this will naturally use up more battery power and the consumption will thus be higher. Therefore, you must get to get to know the principles of e-bikes. For instance, a 500w bike doesn’t necessarily use all of its power at all times. If you decide to bike without any motor assistance, your e-bike battery will stand at full capacity until you begin using it as help.

In that case, you can surely bike all day on a single charge, but this is not what e-bikes are for. You need to use the battery power sparingly, but you should be confident in the battery capacity you have. In ordinary circumstances, you’ll see many people riding their electric bikes with as much help and guidance as they can - the throttle is usually set to “max” in those cases. That is when you can only expect to cover 20 miles on an e-bike accompanied by a 6-8lbs battery. 

bike battery

Definition of Terms

What Are Battery Packs?

A battery pack is essentially a set of batteries comprising of a few smaller sources stacked in a combination that gives you optimal power - the amount that your e-bike system runs on. To achieve the best results when biking, you should choose the appropriate battery set for your bike’s application.  

Volts and Amps

In simple terms, Voltage is what controls the flow of electric energy whereas Amps refer to a measure of force. Generally, an e-bike with a high voltage rating has better speed, while higher Amps usually bring you more power. Combining these Amps and Volts gives you Watts, which is another important measure.

While shopping for an e-bike battery unit, you’ll begin to notice a lot of info on the packaging - there are many parameters to take into account. This is relevant information that needs to be examined when searching for the appropriate battery pack for your bike. They include:

Amps - They measure volume of the electrons. Methaporically, this measure describes how wide "the flow road" is…And you can understand how many cars (electrons) pass at once.

Volts - Describes the velocity of the electron movement… More voltage definitely results in more speed.

Watts - It is a measure dictated by the previous two measurements…Volts * Amps = Watts. It's general physics.

Amp Hours - Although most of the time there are reffered to as "Ah", you might see different notations elsewhere. In the end, it's all about the measure of Amps that one battery can work through in an 60 minutes.

Watt-Hours - This measurement talks about how much usable energy one battery has, and the abbreviation is ‘Wh”. This figure, if you manage to find it on the info sheet of a bike battery, can be used to find out how many watts you can get from the battery in an hour.

For example, a 500Wh battery has the ability to deliver 500w for 1 hour or 250w for 2 hours. This is where you make a choice.

One thing to note is that most of the electric bikes on the market don’t use power continuously at an exact level, meaning, the Wh figure doesn’t necessarily translate to ride time because there are too many factors to keep in mind.

However, you’ll notice that a physically bigger battery with greater capacity can give you smaller amounts 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 salesmen tend to overstate the facts when discussing range estimates. As such, some due diligence will come in handy before deciding to buy. Make sure to ask questions to find out whether the range promised matches the weight of the bike, and the way it is supposed to be used. 

Amper Hours vs Watt Hours

Although it can be confusing, you must try your best to differ the Amp Hours and the Watt Hours. Ah only become significant when you take into account the voltage as well. Wh and Ah can be quite relevant as parameters too (more than voltage for sure) when determining how far you can go when using one charge, so pay more attention to them.

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

Consider a bicycle that has the ability to run multiple batteries - let's compare the 36v and 48v batteries. The bike will surely run faster when powered by the 48v battery if you decide to engage a full throttle. However, you’ll need probably have to put in more energy to move at this higher speed. Therefore, a 48v battery will not always provide a better range - the 36v pack might do the same. 

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, practical and seamless design that won’t add too much weight to your pre-existing luggage. This is a 48V 10Ah lithium battery offering a range good enough to ensure high performance during your ride. Its carefully produced cells have been fitted with a 30A BMS plate that serves to prevent overcharge, as well as to protect a possible short circuit, making sure that you get a the best possible lifetime for your battery.

Joyisi Ebike Battery

The battery itself is encased in a rugged plastic shell that protects it and it also has integrated LED battery level lights so that the rider is aware of the battery level at all times. When in the process of charging, the battery glows in a red hue, while the green color lets you know that it is fully charged. In the package, you'll also find a 54.6v 2 Amps charger that will usually take about 8 hours to fully charge your battery. 

The USB port on the battery helps when your devices are drained - you can easily charge your phone, but also use a safety lock to protect the battery when you're not using it. Finally, you can rest assured that all possible issues will be fixed as the 1-year warranty is in the deal as well...


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 and possible short circuits, as well as accidental discharging, and more. The manufacturer further provides a 1-year warranty.


Weight and Size - Things To Check Out When Looking For The Perfect 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 a battery pack that all of the features that you are looking into - you might want to look into those that prioritize the functions important to you. 

A mistake that occurs quite often with many e-bike owners is that they always search for the largest battery they can find. The problem is that you might want to mount the battery on your bike in a sturdy way, and it won't be possible. Even hanging it on the rack or moving it around gets quite complicated.

Generally speaking, if you want to make sure you have the perfect setup, you need to find the smallest unit that will be sufficient for your needs.If you want to be really safe and make sure that everything turns out just the way you want to, try to look for a pack that will deliver twice as much energy when compared to what you need - this will make sure you have what you need on your adventures.

When searching for the ideal battery, the first step should be to figure out what your need are. Most people can't do more than 15 miles at a time without having some time off. That is why they are often taking breaks between the multiple rides they embark on daily. It is always smart to have your battery charged as you might need a quick boost when you go for an errand.

Since smaller, lighter batteries charge much quicker and in brief windows of time, you can go on your errands more relaxed. This will give you more than enough range for every trip you make during your daily commitments.

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

When looking for electric bike kits, it's useful to find out which voltage range works for the bike you'e buying. As an example, a typical 36 V e-bicycle will require a battery that offers a capacity lingering between 30 V and 42 V. At 42 V,  a 36 V battery pack is actually storing as much energy as it can possibly hold, but at 30 V, it has to shut down as soon as possible, and seize producing power before it gets damaged in a non-reversible way. The “36 V” mark is one you'll often see on batteries, and it is simply the average voltage that particular battery operates on - in books, this is called the 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 provide a better operating range, one between 36 V and 48 V. This is very important as a parameter, so make sure you check the voltage when choosing a battery pack. Most e-bikes are fitted with a display to show you the charge percentage or level using LED lights, but this will only work on the stated voltage. 

Voltage is the value that gives power - it regulates how many rotation a motor can do in a minute. When you deal with more voltage, you can experience greater speed. With that said, keep in mind that electric motors rotate at a specific RPM and this is determined by its construction, amongst many other things. The application has to be taken in mind as well. To conclude, a 36 V e-bike will befaster if it is powered by a 48 V battery pack. Keep in mind, the battery and the motor itself must be compatible.

bike Battery

Amps

To choose the appropriate battery pack, it's important to be familiar with the nature of your e-bicycle's controller. This small gadget can be found on pretty much every e-bicycle - you use it to control the energy exchange between the motor and the battery. This controller regulates something called PMW or Pulse With Modulation.

If your bicycle is completely stationary and you try to turn the throttle to the max, the controller is crucial for you - it will limit the current that your battery provides to the motor and make sure you don't use it up really quick. If you are wondering why this is so important when choosing the perfect battery pack for you, it's because it prevents a lot of issues. You need a battery strong enough to produce the needed number of Amps without any overheating, blowing a fuse, or shutting down. 

Generally, a 10 Ah battery does well when combined with a controller working on 20 Amps or even a little bit less. As long as the information provided about the controllers is true and accurate, you will be able to find what you are looking for. Keep in mind that some controllers come with “Watt ratings”, whereas others have information on “Max Amps” - this confuses people, but it's actually not that complicated.

When you find a controller with information in Watts, you should note that this measure means “Maximum watts” or “Continuous watts”, but there is a higher peak. This means that your battery has the ability to safely handle the Max (the so-called peak) whenever needed.

Quality

When determining the quality of a battery pack, keep in mind that you have to discuss the weakest cell inside of it, as well as the durability of the whole product. Back in the day, it was quite rare to find a long-lasting battery pack. If you could find a pack that you could use for about half a year, that itself would be really fantastic - most of them couldn't sit without self-discharging to their very death. Thankfully, battery technology has come a long way and we have many more options now.

We’ve come to the point where quality is the number one priority for manufacturers of lithium batteries, as one needs to rely on the product. A lot of attention is given to the small, refined details and buying from a reputable, famous seller is good enough of a guarantee that you're getting a good product. Moreover, as the product became more famous, more restocking has to be done, meaning that you're getting freshly produced batteries, as well as a warranty to back your investment.

Battery Monitoring Systems and Chargers

Lithium batteries seem to be both durable and lightweight, which makes them ideal for everyday use, but you need to keep in mind that there are limits to every type of use. To make sure you are not sabotaging your battery pack's lifetime, you must make sue that you battery has a BMS (Battery Monitoring System). This system connects the lithium ion batteries with the power wires and it monitors the voltage as well as the number of amps flowing through the cells.

If it happens so that any limit is reached, the BMS steps in and it cuts off the power. This ensures safety both for you and the battery, and both are equally important. Ideally, the BMS won't need to regulate what's going on constantly, just once you’ve used up all the power in the battery and you switch from continuous riding to support. After use, it will shut down the whole electric bike to make sure there is no damage to any part, especially the sensitive battery cells. 

The same logic applies to the charger as well,as the BMS will allow charging only if the battery cells are within the proper limits. Overlooking the quality of the charger is probably the number one mistake you can make. The wrong type of charger will easily damage your lithium-ion batteries!

Mounting Your Battery Pack

Installing the Li-ion batteries onto your e-bicycle sometimes seems like a daunting task, but this also depends on the quality and the type of the pack. For your best comfort while biking, you must make sure that the weight is well distributed - the triangle in the front part of the frame is possibly the best mounting location for your battery pack. Meanwhile, the rear rack is more convenient and easy to manage, but it might interfere more with your movement.

Batteries sealed in aluminum cases usually end up being easier to mount, and this type of case also protects the cells inside from impact. Keep in mind that this will add weight and bulkiness to your bike, and it will cost more. The cheaper option, but also the more fragile one, would be a pack covered in simple shrink wrap. It will take care of the vibrations during riding as well as the impact when the bicycle tips over.

Battery Too Small?

It's not uncommon for this problem to arise! A battery that can power your e-bicycle for about an hour in the worst-case scenario is usually sized appropriately. Batteries of larger capacity will obviously have an easier tiime providing energy when compared to their smaller counterparts. For instance, a 20 Ah battery pack producing 500w continuously runs twice as long when compared to the 10 Ah battery. However, there are always multiple factors that you need to keep in mind, and one of them is the Internal Cell Resistance that each battery cell has. The other is the so-called C rate (C-rate refers to the rate at which a battery is dischargiing). 

Converting Your Regular Bicycle into an E-bicycle

It is possible to convert your regular road bicycle into an e-bicycle, and it's something most people do to avoid the high price tag that comes with acquiring a new battery-powered bicycle. You just need an e-bicycle conversion kit, and you can easily access it via a quick search on the internet. The best e-bicycle conversion kits typically come with components like a motor, the previously discussed controller, as well as a thumb-operated throttle, brake levers with kill switches, on/off switch, as well as a battery in the package. 

The installation of these electrical components is straight-forward, as long as you have basic knowledge of bicycle mechanics. Once you’ve finished fitting the motor, switches, and the power source, 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 kits for conversion out there, as well as the best e-bicycle motors to use with the battery you've chosen for your electric bike. The best thing about kits for e-bicycle conversion is their price; even the priciest ones will cost just a few hundred dollars to acquire.

Taking Care of Your Battery

Appropriate care is very important when you're making sure that the lifetime of your e-bicycle battery lasts as long as possible. Even if you have a BMS plate to safeguard the source, it’s very important that you continuously charge it - never allow the power to drain completely, this is not a good idea, and it's a general rule for all types of batteries. Pay extra attention if you live in a cold region, as you don’t want to make the mistake of charging a cold battery pack (even worse if it is frozen). Instead, let it rest at room temperature so it gets warmer, and then charge it after it acclimates.

You can cover it with a rug or any other piece of fabric to get it warm. Riding your bicycle in cold conditions isn't harmful to the electric battery, but the range might drop slightly, so keep that in mind. To conclude, it is essential you let your battery pack to warm up and reach room temperature before you charge it. 

Opportunity Charging

Opportunity charging is a term that describes all charging session that you have not planned in particular. You might decide to take a break somewhere in town and grab a cup of coffee in the middle of your bicycle trip. In that case, you can charge it for a boost while you take a break and get your caffeine boost! This can be of significant help and although it may not fully charge the battery, it will impact the range greatly. 

Legal Shipping

Legal shipping is something that needs to be taken in mind when it comes to battery packs - it can be a controversial subject too. When you take into account the amount of energy that is held inside the different battery types, it becomes clear that more regulations are needed. 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 could force you to dig a little bit deeper into your pockets. Smaller vendors won’t ship your battery taking the “UN Certified” approach and they resort to illegal shipping. This makes things quite difficult when it comes to returns, as well as replacements due to personal preferences or warranty violation.

Energy Density

Energy density refers to the quantity of energy one battery stores at a particular volume (Liter/Wh), which is unlike ordinary liquids where one gallon occupies a certain space. That means that two different e-bike batteries, although they are the same size, carry a different amount of usable energy. Let's go through an example! A classic 18650 lithium battery that has been used a lot in the past decades holds 1000mah, while the exact same 18650 cells store as much as 3500mah with today's improved technoloogy. Sometimes, they even store more.

It's worth noting that the two batteries have the same dimensions, and they are practically the same when it comes to size, but the advanced technology the new one has implemented delivers triple the range that the one from 10 years ago could deliver. Energy density is what plays the major role here.

Lead Acid Batteries or Lithium ion Batteries?

Lead is the more price-friendly option when you compare the two, so if a decent lithium battery is out of your price range, you might want to get a lead alternative with somewhat similar parameters. For perspective, a 6lb lithium battery does the same job a 30lb lead-acid pack would do in the same conditions (voltage). 

  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 to get enough of 18650 cells so that you can DIY the whole e-bicycle battery, alongside a BMS that is suitable. You can easily calculate how much you need by taking into account the voltage, capacity, and the BMS current ratings that you want. This will give you a good idea about how much power your battery can supply to your bike safely. If your bicycle is supplied by a 1000 W 48V motor, you have to expect about 25A of continuous current.

Moving on, getting a BMS that has at least 25 Amps when it comes to continuous rating, as well as 13 cells, will help your battery run at about 48V. Finally, an enclosure for the battery is needed. You can either makeyour 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 2021-08-02 / 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!


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