Everything you need to know about e-bike batteries from a battery engineer…

OVERHEATING AN E-BIKE CAN BE A BUZZ KILL, LITERALLY

Too much load on an e-bike motor can get it hot enough to trigger an error code that will usually trigger a fail safe mode. It’s one of the most common problems people find with budget brands. Truthfully, the majority of the bikes that can experience this issue are hub drive systems. Simply knowing what the realistic capabilities of a hub-drive are will help you know if one is right for you.

Dealers are getting a taste of a momentum in sales they’ve never experienced as the e-bike segment rapidly expands. Therefore, the more informed you are the better chance you’ll make the right purchase for your style of riding. Getting most dealers to tell you what they have isn’t right for you is a long shot.

On one hand you have the consumer’s responsibility to be honest about where they live or ride the bike. For example, if a heavier rider lives on a steep hill, they may need a different e-bike than a 90 pound 4th grader. Then again selling e-bikes is a business like any other. Ultimately, the more informed you are, the better chance you’ll have to get the right bike.

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POINTING THE FINGER AT HUB-DRIVES

Electric motors similarly to combustion engines struggle to dissipate heat as more load is applied. Load, in the case of electric bikes, comes almost exclusively in the form of hills. Steep hills can be too much effort for the average 250 Watt hub-drive to handle without any assistance from the rider. Some bikes do have more powerful motors, even up to 750 Watt in many cases. However, they’re mostly used in heavier bikes which somewhat offsets the gain in power.

250 Watts is enough power to comfortably propel a 50-75 pound bike and its rider on flat ground until the battery runs out. Hills are a different story though and in extreme cases hub-drives can only handle a couple minutes before an overheating error can stop you. Most companies use a fail safe error code that will put you in a limp mode or just cut power till it cools down.

If you bring your bike to the point of an error too many times, you run the risk of wearing the motor and other components out much faster. Usually the insulation around the copper coils that make up the bulk of an electric motor is the first thing to breakdown. As more load is applied at lower speeds, the more the other components start to breakdown. Sections of the copper windings will also start to char after a while.

DON’T EXPECT A FISH TO CLIMB A TREE

Hub-drive systems used on cheaper e-bikes do not utilize advanced technology that is available. Often, basic electric motor and sensor technology used doesn’t lend itself to the demands of steep hills. The basic technology we’re referring to is sold in the majority of e-bikes ranging from about 1000-2000.

You can usually look at the rear hub of one of the bikes in that price range and see a Bafang stamp on it. Bafang is a Chinese company that produces a massive amount of electric motors for the majority of hub-drive bikes. They’re more impressive than you may think though, and we’ve even heard of Bafang motors with over 30,000 miles on them. So, how they’re treated is the key factor.

The number of mid-drives that have overheated are almost unmentionable in comparison to hub-drives. Mid-drive e-bikes are known for being able to hold their own on rides with massive elevation gains. It doesn’t mean they don’t get really hot though. If you’ve ridden a mid-drive bike, you’ve probably felt how hot it can get at the top of a long climb. However, with the newer generation motors we’ve heard of only a handful of overheating errors in the past few years. In just about every case it was an extremely long climb on turbo mode just trying to let the motor do all the work and often a heavier rider.

TIPS FOR KEEPING IT COOL

Often hub-drive bikes have a throttle which is overused in general, but particularly on steep hills. It doesn’t take long for error codes to present themselves when used in that way. Spending 2000 on an e-bike doesn’t make it a motorcycle. Therefore, actually putting more effort into pedaling up hills will be the best error code prevention. Not to mention add some life to the system overall.

Shifting knowledge is one of the most crucial things to know when it comes to riding hills. Many people are getting back into riding with the help of e-bikes. If you’re one of those riders, you may not even be familiar with modern shifters and how they work. You absolutely must understand how to use them via your dealership, friends, or YouTube because it will change your riding experience for the better.

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Being in a gear that allows your legs to spin at a relatively high cadence will give you the best chance of helping the bike get up hills. Cycling science tells us that it is easy to put more power out at a higher cadence. In other words, try to spin your legs a little faster as opposed to a little harder. As much as you can, try to feel a bit of resistance on your legs when climbing. If you are getting too tired or sweating more, then take a break.

Like we said it doesn’t take long for most hub-drives to get warm on steep hills but they do cool down quickly. A 2-5 minute break is a fair amount of time to let it get back to proper operating temperature. If you start to get errors on flat ground with minimal load you may have a separate problem which you should consult a shop about.

FINAL THOUGHTS

Usually companies don’t tell the whole story when it comes to the potential of their bikes overheating. One company we won’t name says that it’s possible to overheat your bike in extreme conditions like, “the peak of summer heat”. Sure it’s the truth, but not the whole truth. In reality we hear of this happening to people on a weekly basis. Many people figure it out and quickly adapt their riding, while others are left angry that their machine doesn’t do what they thought it would.

Hub-drive e-bikes are sold in mass quantities and this article isn’t about throwing shade on them. Truthfully, their benefits outweigh this one weak point, but it’s important to know about before buying one. All e-bikes whether mid or hub-drive come in many different styles, quality, capability and price ranges. Do the research and take your time in deciding which bike is best for you.

Everything you need to know about e-bike batteries [from a battery engineer]

Would you be the person taking the stairs or the escalator?

I’ll be honest. barring the one-off day that I’m feeling particularly sprightly, I would just hop on the escalator with those 30 people on the right. And I’m willing to guess that most of you would too.

What we can gauge from this picture is that most people would rather do as little work as possible to get from point A to point B. This is especially true when it comes to commuting on a bike. The picture above is analogous to the difference between a regular bike and an e-bike.

Even if we address all the concerns when it comes to biking in a city (like safe biking infrastructure), we can’t expect to change fundamental human behavior. when given the option between less work or more work to achieve the same outcome, people will more likely choose to do less work.

Since getting my e-bike, I can comfortably bike from my home in Somerville to the Seaport district in Boston. a roughly 5-mile trip. in just about 20-minutes. All of a sudden, biking 5-miles is a piece of cake. I also don’t have to spend time sitting in traffic, waiting for public transit, or worry about showing up to a meeting looking like I swam across the Charles river to get there.

The beauty of an e-bike is that it makes cycling an inclusive mode of transportation because it doesn’t discriminate by age or physical ability.

When it comes to purchasing an e-bike though, there are a plethora of options for both the bike and battery. So how do you decide which one is best for your needs? As a battery engineer who has built hundreds of batteries and logged way too many hours soldering battery packs, here are my thoughts on the most commonly asked questions when it comes to e-bike batteries.

If you’re new to battery terminology, you might want to start here: Battery terms that every e-bike owner should know.

In this post, we’ll cover the following questions:

What is the best e-bike battery?

This is one of the hardest questions to answer. There are so many variables that go into what makes a good battery and what’s best for you, may not be the best for me. Even then, a good battery can perform poorly if it’s not cared for properly.

Battery packs are made up of individual battery cells. Cells are classified into cylindrical cells (like your AA and AAA) and prismatic cells (like the one in your phone). Each class of battery is manufactured in a variety of form-factors (in the battery world we use this term to mean size). The most commonly used form-factor of cells in an e-bike battery pack is the 18650.

A battery pack is only as good as it’s weakest cell.

When it comes to batteries, in my experience, there is a strong correlation between price and quality. I don’t follow this rule when it comes to most things like for example, box wine (I’m just saying, there are plenty of really good box wine options these days!). When it comes to batteries though, you really don’t want to be compromising on quality because you’ll eventually end up having to pay the price.

Here are some things to keep in mind when purchasing an e-bike:

Cell Manufacturers: Panasonic, LG, and Samsung have a good reputation in the battery industry for their high quality cells, so paying a premium for these cells is certainly worth it. If the e-bike you’re trying to buy doesn’t have or provide cell manufacturer information, they’re likely not going to be a reliable source anyway.

Cell Chemistry: Lithium-ion (li-ion) batteries are the best option for e-bikes. Although lead-acid batteries are significantly cheaper, they’re three times as heavy as their li-ion equivalents.

Li-ion has several variants of cell chemistry. The most popular ones for e-bikes are Nickel Manganese Cobalt (NMC), Lithium Cobalt Oxide (LCO), and Lithium Iron Phosphate (LFP). The metrics to look for when selecting a cell chemistry are:

  • Specific Energy: has an impact on the range of your battery.
  • Specific Power: how the battery handles high load scenarios like going up
  • a hill.
  • Safety: does the chemistry have a history of high in-field failures.

There are trade-offs when choosing one chemistry over another, but as we’ve shown in the image below, NMC and LFP are both great options that both offer the best value in terms of performance, price, and safety.

Picking the right battery chemistry has to do with figuring out what matters most to you. Do you want a battery that has a longer range (higher specific energy) but doesn’t have as much power? Or do you want a battery that has a more power (higher specific power) but may not last as long?

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In my opinion, the best e-bike batteries are likely going to be made from cells manufactured by Panasonic, LG, or Samsung with either LFP or NMC cell chemistry.

What is the range of an e-bike battery?

The range of a battery pack depends on the amount of energy packed inside of it and is measured in Watt-Hours (Wh). Watt?

Watt-hours are calculated by multiplying the battery capacity, in Amp-hours, by the battery Voltage, in Volts.

Let’s assume that, on average, 1-mile requires about 25Wh of energy. So a 14Ah, 36V battery should get you about 25-miles per charge.

Keep in mind that the weight of the rider, outside temperature conditions, and the amount of pedaling will make a significant difference in range.

A word of caution: the range that e-bike manufacturers provide should be taken with a grain of salt. That number is generated from tests that are run in perfectly tailored lab conditions. Do you charge any of your electronics in an incubation chamber set at 28° C with a lab-grade charger that applies the perfect current while charging? Yeah, I don’t either. And so, We should assume that the manufacture-specified range is delivered only if the battery is charged and discharged under ideal conditions i.e. not real world conditions.

For a more realistic estimate, shave off 15% of the manufacturer specified range and assume this padded number to be your real range.

If you’re looking for a longer range, choose a battery that has higher capacity (Ah). If you’re looking for more power, choose a battery that has higher voltage (V). Learn more why voltage and capacity matter.

What is the lifespan of an e-bike battery?

There are several factors that affect the lifetime of a battery such as:

  • environmental conditions: temperature during charging discharging
  • charging rate: how fast or slow your battery is charged
  • charging voltage: what voltage the battery is charged to
  • depth of discharge (DoD): what voltage the battery is discharged to

The list above isn’t exhaustive but, in general, batteries decay as a function of time in the charged state. Period.

Day 1: You get your new e-bike and charge it up to 100% and go on a bike ride. When you come home, you charge the bike back up to 100% and you’re excited to ride it again soon.

Day 2. 364: Life get’s in the way and you still haven’t been out on your bike since that first ride.

Day 365: One year later, it’s the perfect day for a bike ride and you finally have some time on your hands. You head to your basement, unlock your bike, and excitedly turn it on. 80% charge. What? You clearly remember charging your bike to 100% last year before moving it to the basement!

The truth is, we can’t beat thermodynamics. I’ll say it again: batteries decay as a function of time in the charged state.

Now, because you left your battery at 100% for a whole year in a basement with no temperature control, you inadvertently caused your battery to lose a certain amount of irreversible capacity. Your range will be ~20% lower and you’ll likely have to replace your battery sooner than you expected. The table below shows you how much recoverable capacity exists in a battery after storing it at different temperatures and different charge states for 1-year.

This is why a lot of electronics come with batteries that are only partially charged. to help slow down this decay. That being said, it’s hard to track how long e-bikes and their batteries have been sitting in warehouses before being delivered to your door so you could get a battery that has been decaying for a year or two.

Manufacturers also tend to overrate their batteries and will make claims about certain batteries having a lifetime of at least 1,000 cycles. Show.me.the.data.

The lifetime of a lithium-ion battery is described as the number of cycles until the capacity (Ah) drops below 80% of it’s initial capacity. In general, this is roughly 250-400 cycles (depending on battery chemistry and other factors) which amounts to roughly 1.5 to 2 years if you charge discharge daily and care for your battery properly.

How to charge your e-bike battery to make it last longer

  • The thing that will kill your battery faster than anything else is leaving it charged at elevated temperatures. If it’s 80 degrees outside and you have your e-bike fully charged, move it indoors where it’s cooler and try to drain the battery as soon as possible.
  • Charge your battery at room temperature as often as possible.
  • When sourcing an e-bike battery charger, the slower the charge rate the better. For example, if you have a 2-Amp charger, and your battery is a 14 Ah battery pack, you are charging at 14 Ah / 2-Amps = 7-hours. This is a nice, slow charge which will certainly improve the longevity of your battery pack. Avoid charging at rates that are faster than 2-hours for a full charge.

There’s a lot that goes into choosing the best battery for you e-bike, and there certainly isn’t a one-size-fits-all approach. But if I were buying an e-bike battery today, here’s what I’d do: LFP or NMC, slow charge, avoid storing or charging in hotter temperatures, and leave the battery at around 30% charge if you don’t plan on using it for a while.

Have questions? We’d love to help. You can get in touch using the contact form or find us on @somerville_ev

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What You Need to Know About E-bike Battery Safety

It’s no secret that here at Liv we’re huge fans of electric bikes. Just the mere mention of our women’s E-bike range breaks us out in a big smile.

But. we’ll also put on our serious face and discuss electric bike battery safety with you. Because we know that E-bikes, with their high-tech batteries, can sometimes feel complex.

That’s why we’ve broken it down in this article. So read on to discover :

  • What’s inside an electric bike battery (the techy stuff)
  • How we ensure the highest battery safety standards on our Liv E-bikes
  • The 13 must-know best practices for ultimate E-bike battery safety

The techy stuff: What’s inside an E-bike battery?

E-bike battery packs consist of individual battery cells containing lithium-ions. These battery cells store the energy to power the motor.

E-bike batteries are made with either cylindrical, prismatic, or pouch-shaped cells. The shape of these cells is really important. High-quality E-bike battery suppliers like Panasonic, Shimano, and Bosch use cylindrical cells because they handle higher temperatures without deforming.

Aside from the individual battery cells, a critical component inside an E-bike battery is the battery management system (BMS).

The BMS is hugely important as it regulates the individual performance of each battery cell. Regulation is important because even when they’re installed at the same time all the individual batteries don’t drain, deteriorate or perform at the same rate. Some cells last longer than others, some cells will drain slower than others and some will glitch out and cause more problems than others.

Left to their own devices, with so many cells acting independently, you’d encounter performance and safety issues with your E-bike.

So the BMS helps to provide your E-bike battery with long-term consistent performance.

We like to think of the BMS as the competent ride leader overseeing a group of different riding abilities and working to keep everyone together on the trails.

How we ensure the highest battery safety standards in our Liv E-bikes

At Liv, we take your safety VERY seriously. That’s why our E-bike batteries have been co-developed in partnership with the biggest and best battery manufacturer available – Panasonic.

Although other brands may purchase Panasonic batteries Liv has gone the extra mile. or two.

Firstly, we work closely with Panasonic to co-develop our batteries. The output is an e-bike battery that’s completely proprietary to us and designed to the highest safety standards.

Secondly, not only does Panasonic manufacture the cells and the battery management system on our E-bikes but they also assemble and test them for us.

So by investing in a Liv E-bike you can feel totally confident you’re getting a safe, reliable, and high-performing battery that’s developed, assembled, and tested by industry leaders. You won’t find our e-bike battery on any other e-bike on the market.

Liv’s EnergyPak E-bike battery is also distinct from other brands because it has individual separators (rooms) inside. This helps prevent heat from spreading from one cell to another.

Our BMS – aka the capable ride leader – monitors the battery pack and individual cells to make sure each cell is regulated for maximum efficiency and to prevent overheating.

While your Liv E-bike is charging, Liv’s Smart Charger continuously communicates with the battery to ensure individual cells are charged at the optimum rate. Also, in extremely hot or cold weather conditions the Smart Charger will adjust the charging voltage for optimal battery efficiency.

simple do’s and don’ts for ultimate E-bike battery safety

E-bike battery safety: The Do’s

  • Do purchase your E-bike from a reputable e-bike brand.
  • Do always use the battery and charger that originally came with your E-bike.
  • Do go to an authorized dealer if your battery is damaged so they can check it before your next ride.
  • Do remove your battery when transporting your e-bike to protect it from damage.
  • Do store the battery at room temperature in a moisture-free environment to avoid unnecessary damage to the cells.
  • Do keep the battery away from children and pets.
  • Do stop the charging procedure immediately if you feel concerned.

E-bike battery safety: The Don’ts

  • Don’t modify your E-bike or let your ‘helpful’ friend tinker with it either. For maintenance, always go to an authorized dealer for your E-bike brand.
  • Don’t charge your E-bike around flammable materials.
  • Don’t store your E-bike battery in a damp place.
  • Don’t subject the battery or charger to high-impact eg. by dropping them
  • Don’t cover the battery or charger or place objects on top of it.
  • Don’t leave your battery at full charge if you’re storing it for a month or more. It is also best to remove the battery from the bike and store it at 60% of its capacity. You can make use of Liv’s Smart Charger which has a useful 60% charge function to ensure safe storage.

Now let’s look at the bikes.

OK. Battery tech talk–done. Serious face–gone. Now for the fun stuff because it’s time for you to start drooling over our awesome range of women’s E-bikes.

Understanding the Shimano STEPS System

As you may have already noticed, electric bikes can be complicated. Between thinking about pedal assistance and throttle systems, hub and mid-drive motors, and the rest. it can be pretty confusing. We decided to provide the basics on one of the motor systems featured on select bike models: Shimano STEPS. This information was found through Shimano’s STEPS training program and the system’s user manual. As always, we are always happy to chat with you about questions regarding this system.

Understanding the Shimano STEPS System

What is Shimano STEPS?

Shimano STEPS, an acronym for Shimano Total Electric Power System, is a pedal-assist system for electric bikes.

What makes bikes with Shimano STEPS different?

Bike companies have sourced parts for their electric bicycles from many different manufacturers for a long time. The bicycle could have a motor from one company and cranks from another.

Shimano STEPS bikes are the first to use motorized drive systems entirely from the same company. That means that every component is optimized for electric assistance. For example, the power from the motor is carried through a Shimano-approved chain that is specifically designed for increased assistance provided by electric bikes. Electric bikes are designed specifically for Shimano STEPS. Manufacturers craft the bike around the system, not the other way around.

In some cases, having a bike that is tuned properly to one system makes servicing easier and more streamlined.

Shimano STEPS Mid-Drive

Bicycles with Shimano STEPS are mid-drive systems, meaning that the motor is located near the pedals and not in a wheel hub. The motor is seven pounds and is incredibly compact, giving you a more balanced ride.

Shimano STEPS bikes have a torque sensor, which senses the amount of power you are putting onto the pedals. This allows the motor to assist you as much or little as you need.

Speed Longevity

All bikes with Shimano STEPS have a top speed of 20 miles per hour, making it a motor for Class 1 electric bikes.

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At the highest level of assistance, you can expect up to 30 miles on a battery’s charge. As with other drive systems, riding at a lower assistance can elongate your battery’s life. On ECO mode, you can expect about 50 miles on a single charge.

Batteries on Shimano STEPS bikes take about four hours to fully charge and can last up to 1,000 charges before having significant power loss.

Shimano STEPS Batteries

You are able to charge a Shimano STEPS battery either on or off the bike. Batteries have an adapter included to charge off the bike. If you charge your battery on the bike, you can plug in to the port. Just like any other bike, you can use your charger on any standard wall outlet.

As with all batteries, you will need to charge them within a specific temperature range. Luckily, any errors in charging the battery will be shown by a blinking LED light.

Additional Features

Many bikes are beginning to introduce Walk Assist on electric bikes, and the Shimano STEPS system is no different. Walk Assist is great for walking a bike around or guiding it up a ramp to a rack. To activate this feature, turn off the motor’s assistance and press the down button. You’ll start to feel your bike moving at two miles per hour.

Using a Bike With Shimano STEPS

You may believe that all electric bikes are the same. just turn on the battery and go! Shimano STEPS systems are similar with one difference. When turning on your bike (which can be done by pressing the power button on the display or battery), you want to make sure you don’t have your feel on the pedals.

It sounds crazy, we know. The added pressure on the pedals or chain at start-up can affect the torque sensor. When this happens, the display shows an error code (either E012 or W013), and you won’t be able to use the motor.

If this happens, simply turn off the bike, take your feet off the pedals, make sure the bike is upright and stationary, and turn the system on.

Technical Aspects

Understanding STEPS Status Display

(A) Battery level indicator

(B) Maintenance alert: Indicates that maintenance is required. Contact your place of purchase or a bicycle dealer if this icon is displayed.

(C) Gear position display

Start mode gear position1

This notifies you of the recommended timing at which to shift based on the bicycle’s riding conditions

(D) Travel data display

(E) Gear shifting mode13: Displays current gear shifting mode as [Auto] or [Manual]

(F) Assist gauge: Displays assistance level

(G) Current assist mode

(H) Current speed4

(I) Current time

(J) Light icon: Indicates that the light connected to the drive unit is lit.

(K) Bluetooth LE icon: Display when connected over Bluetooth LE.

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