A Deeper Dive into Running Out of Charge on Bosch Batteries. Bosch battery charger ebike

A Deeper Dive into Running Out of Charge on Bosch Batteries

We’ve touched on battery topics a few times like special considerations for cold weather. and how to extend your range with dual battery setups. best practices for Bosch battery care can be found in the updated Battery Guide 2021.

A question we’ve gotten a lot lately though, is:

What actually happens when you run out of battery while riding your e-bike?

First, when you hit “no bars” on your battery indicator, the system will remain on but the assistance mode will switch off. The bike offers no pedal assistance to you even though the system is still on.

Why? The battery holds reserve power to run the lights for at least two hours. The amount of power held on reserve this way is dependent on the power required for the lights. If your system is configured for brighter lights, the system knows to save more power to keep them powered. If you have a Kiox or Nyon display, you might have noticed that this is around 2 or 3% on the battery indicator.

If your bicycle additionally has integrated e-shift, it also holds reserve power to power through at least 50 more shifts.

Then, If you keep riding the battery all the way down to 0% on the indicator, the entire bike will shut off. If this happens, it is important to reconnect your battery to a charger as soon as you have completed your ride and get it at least partially charged. Otherwise, your battery can reach what is called “deep discharge” where it will no longer take a charge and must be replaced. Lithium ion batteries, unlike lead acid batteries found in cars, cannot be “jumped” or re-awaken from this state. According to Bosch, fully discharging a battery into deep discharge is considered misuse and is not covered under warranty.

How does this deep discharge scenario actually happen?

The answer is complicated, and to be honest, I do not fully understand. Battery experts, drop me a line, I would love to hear! My understanding is basically that the battery is holding a teeny bit of charge left even when it is telling you it has no more power to give. That amount of charge is required for its internal processes, including the Battery Management System. Batteries very slowly lose charge over time even without use (commonly referred to as “trickle discharge”), so if you run your battery all the way down to its last teeny reserve, it will then trickle discharge that power, and there will be nothing left and become unusable. I reached out to Bosch and they summarised it,

“All modern lithium ion battery cells, whether they’re in a Bosch PowerPack or some other device, contain a protection circuit that, for safety reasons, renders the cell unusable if over-discharged.”

I also asked Bosch about exactly how bad for the battery it is to run it down to system power-down,

“I would definitely avoid doing this if possible. It’s not the worst thing for the battery, but it’s not great either. I recommend not making a habit of it, but also not worrying too much if it happens on occasion”

I would agree with trying to avoid running the battery down to system power-down if possible, but the important thing is to charge the battery as soon as possible after doing so. If you are regularly running out of battery on your route, consider checking out if there is a way to set your bicycle up for dual battery.

How fast does it trickle discharge?

The battery will lose charge slowly over time, but how slowly though? This is an important consideration for fair-weather riders who might be putting their bike away for nine months of the year.

According to Bosch, high-quality Lithium ion batteries lose charge at approximately 0.5%/month. This means if your battery had only 4% charge when you put it away, it would be into deep discharge by the time summer rolled around next year. Lithium ion batteries are also sensitive to temperature, so storage below 32 F (0 C) or above 86 F (30 C) can increase the rate of trickle discharge. This scenario should be avoided by bringing your battery up to a medium charge level before putting in storage.

So how should I store my batteries?

Bosch batteries (or any high quality Lithium ion e-bike batteries) should ideally be stored between 32 and 68 degrees F (0-20 C) and between 30 and 60% charge level. Avoid leaving the battery plugged in for a long time, and avoid leaving it for long storage at full charge.

So when winter comes and you’re putting your bike away for the season, charge the batteries up to 60%, put the bike somewhere at room temperature, and let it sit. If the bike lives somewhere that might be the outside temperature like a shed or uninsulated garage, consider removing your batteries and bringing them in the house for secure room-temperature storage during the winter.

If the whole summer passes by without a ride, while you theoretically have many years before it trickles out of the ideal range, we still recommend taking a moment to check the charge level again before starting another year of storage.

Bosch makes a special Battery Capacity Tester tool, that among other things, can be used to set the charge level to 60% when putting the battery into storage. Bosch recommends doing this if planning to leave the battery unused for three or more months. We are thrilled to say we now have one of these cool tools! Give us a call and we can arrange to do this for your batteries in advance of your planned storage.

What if my battery suddenly won’t respond?

Another consequence of trickle discharge and deep discharge being considered user fault is that if you are having a warranty issue on your battery that it suddenly becomes wholly unresponsive, the battery will continue to trickle discharge. This is especially a concern if it was at low charge before it finally died all the way. If the battery trickles all the way into deep discharge, we won’t be able to determine that it was a warranty.

So if your battery has suddenly become unresponsive, especially within the two year warranty timeline after purchase, please reach out to us right away so we can see if it can be revived, or if we can pull the error codes to make the warranty claim smoother.

What is the normal lifespan of the battery?

In a battery that does not experience a warranty shut-down or deep discharge, what life span can you expect from it? There is no single answer as it depends on use and storage conditions. Like our cell phone, as the battery ages, its capacity decreases over time, meaning we get less power per charge. Bosch cites that after 500 charge cycles (over 10,000 miles), the user can still expect the battery to have 60-70% of the original capacity.

The basic diagnostic report we run during tune-ups will show how many charge cycles your battery has been through. But the Battery Capacity Testing tool can also be used to assess the current capacity of your battery – you can request this extra diagnostic as well when your bike is in for service. It takes several hours to run so this is a service that must be done by appointment.

When your battery has reached its end of life, whether by unresponsiveness or the capacity having decreased to unusably low, we are an e-bike battery recycling collective site. Bosch batteries cannot be refurbished, but we can get them properly disposed of for you. on that coming in a future post.

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Available in Fast, Standard and Compact, the Official Bosch battery chargers ensure that your battery is charged correctly every time. These are compatible with all of the present series of batteries, as well as some older models with a secondary adapter.

Fast Charger (6A):

Delivering the maximum amount of charge your pack can accept safely #, the 6A Fast Charger is the ideal companion for Bosch’s largest battery packs and riders keen to top-up as quickly as possible.

You can recharge most packs in about the time it takes to rest-up for a good lunch, then be back on the trails for more!

deeper, dive, running, charge

Standard Charger (4A):

The 4A Standard Charger is the same model as many Bosch eBikes come with when they are new. They provide a good balance between recharge time, volume and weight.

Compact Charger (2A):

The 2A Compact Charger is perfect for riders who like to carry a charger to top-up ‘on the go’. It is lightweight and 40% smaller than the Standard Charger, returning a battery to a 100% charge level within 5-7.5 hours (timeframe depends on the PowerPack).

Fast, Standard and Compact Charger are available


Active Line Plus (BDU3XX) Active Line (BDU3XX) Performance Line Speed(BDU4XX) Performance Line (BDU3XX) Cargo Line / Speed (BDU4XX)

Modelyear 2011 / 2012, with secondary adapter Active Line (BDU2XX) Classic Line Performance Line CX (BDU2XX) Performance Line (BDU2XX)

# Charging for PowerPack 300 and Classic Line batteries is limited to 4A.

We include a standard British plug and cable with all Bosch Chargers.

Bosch e-bike charger (BCS220)

Due to the high level of returns on Bosch products and as Bosch products are ordered in specially to fulfil orders, any item returned will incurr a re-stocking charge of 10-15% to cover our costs.

deeper, dive, running, charge

Please makre sure you order the correct part.

Express Shipping, on orders over £25, see shipping policy for more details

Have a Question?

Be the first to ask a question about this.

As an authorised Bosch e-bike dealer we’re able to supply official Bosch parts. If you need help or have the part number then get in touch and we’ll be able to quote.

All parts are ordered in, we only take payment once we know if Bosch have stock and an order is placed with them.


️ Access to extensive spares️ Cytech trained mechanics️ Workshop facilities️ UK backed warranty

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If you’re local to us (Hare Hatch, Berkshire) then why not get in touch to arrange a visit?

Fully charged battery in three hours

Stuttgart/Reutlingen – People who make long, frequent journeys with their eBike need a suitable charger. For model year 2019, Bosch eBike Systems is now introducing the Fast Charger, which at 6 A charging current, is the fastest charger from any provider on the market. With this new development, it is possible to fully charge a Bosch PowerPack 500 in three hours.

Charging speed is an important purchasing criterion

Quick charging times are of prime importance for eBikers: 61% of prospective eBike customers in the Bosch eBike market study indicated that charging speed is important or very important to them. Bosch eBike Systems acknowledges this fact with the development of the Fast Charger. The Fast Charger needs about 1.2 hours to charge a PowerPack 500 or a PowerTube 500 halfway and three hours to charge them fully. The fast refuelling times allow eBikers to experience riding enjoyment more intensively – with longer rides and shorter stopovers. For example, it takes a midday break of around an hour to recharge the battery by 40 percent.

Fast charging times are also an important prerequisite for a trendsetting infrastructure. With the Fast Charger, hire stations in cities, districts and tourist destinations can now offer an optimal service to eBikers. This allows Bosch not only to meet individual needs but also to contribute to the establishment of an eBike-friendly infrastructure, says Claus Fleischer, CEO of Bosch eBike Systems.

Weighing only 20% more and adopting a size that is only slightly bigger than the Standard Charger, the Fast Charger is compatible with all Bosch product lines. The Fast Charger is available in Europe, Australia and New Zealand. The charger can often be selected when purchasing an eBike. The Fast Charger will be available to specialist retailers as of autumn 2018.

Bosch eBike battery chargers

With the Fast Charger, Bosch eBike Systems now has an expanded portfolio of three chargers which are optimised for a variety of applications. While the Standard Charger is mostly used in stationary applications, the Compact Charger, weighing less than 600 grams and with 40% less volume in comparison, fits in many saddle bags and is therefore the perfect tool to take with you when riding. In addition, the Compact Charger works at all supply voltages (110 to 230 V). Both the Standard and the Compact Charger are compatible with all Bosch product lines.

Five tips for charging eBike batteries

1. How often and how long should I charge a battery? Bosch batteries with lithium-ion cells can be charged quickly at any time irrespective of their charge level. The integrated Bosch battery management system in conjunction with a Bosch charger protects the battery from overload. Interrupting the charging process does not harm the battery. Even after 500 full charges, about 70% of the original battery capacity is still available.

2. Can any charger be used for any battery?Any of the three chargers can be used for any Bosch eBike battery. In principle, the following applies: Bosch eBike batteries may only be charged with original Bosch chargers. Otherwise, irreparable damage may appear and warranty or warranty claims are forfeited.

3. How long does it take to charge a battery?The charging time depends on the capacity of the battery: With the Fast Charger, the PowerPack 500 needs about 1.2 hours for half a charge, while the DualBattery 1000 needs about 2.4 hours. A completely empty PowerPack 500 is fully charged in three hours, whereas the Dualbattery 1000 needs six hours to be fully charged.

4. What is the perfect charge status?The perfect charge status in case of long-term storage is between approximately 30% and 60%, or two to three illuminated diodes on the battery display.

5. At what temperature should I charge a battery?To charge an eBike battery under optimal conditions, it is recommended that charging be done at room temperature and in a dry environment.

Contact for press enquiries:Robert Bosch GmbH Tamara WinogradDirector Marketing and Communications Bosch eBike SystemsPhone 49 (0)7121 35-394 64Tamara.Winograd@de.Bosch.com

Basic information

Bosch eBike Systems is shaping the future of eBike mobility with innovative products and digital services ranging from highly efficient drive systems to the first production-ready ABS for eBikes and Connected Biking solutions. On the daily routes through the city, on leisurely rides through the countryside or for sporting adventures in the mountains: Bosch eBike Systems offers eBikers the right drive system (drive unit, battery, display, and app) for every requirement and every area of use, ensuring a unique riding sensation. Today, more than 100 of the world’s leading bicycle brands trust the perfectly coordinated, modular product portfolio. As an independent division within the Bosch Group, Bosch eBike Systems also makes use of the Group’s technology and manufacturing expertise. For healthy, safe and sustainable mobility that is fun.

For more information please visit www.Bosch-ebike.de

The Bosch Group is a leading global supplier of technology and services. It employs roughly 421,000 associates worldwide (as of December 31, 2022). The company generated sales of 88.2 billion euros in 2022. Its operations are divided into four business sectors: Mobility, Industrial Technology, Consumer Goods, and Energy and Building Technology. As a leading IoT provider, Bosch offers innovative solutions for Smart homes, Industry 4.0, and connected mobility. Bosch is pursuing a vision of mobility that is sustainable, safe, and exciting. It uses its expertise in sensor technology, software, and services, as well as its own IoT Cloud, to offer its customers connected, cross-domain solutions from a single source. The Bosch Group’s strategic objective is to facilitate connected living with products and solutions that either contain artificial intelligence (AI) or have been developed or manufactured with its help. Bosch improves quality of life worldwide with products and services that are innovative and spark enthusiasm. In short, Bosch creates technology that is “Invented for life.” The Bosch Group comprises Robert Bosch GmbH and its roughly 470 subsidiary and regional companies in over 60 countries. Including sales and service partners, Bosch’s global manufacturing, engineering, and sales network covers nearly every country in the world. With its more than 400 locations worldwide, the Bosch Group has been carbon neutral since the first quarter of 2020. The basis for the company’s future growth is its innovative strength. At 136 locations across the globe, Bosch employs some 85,500 associates in research and development, of which nearly 44,000 are software engineers.

How to Charge an E-Bike for Maximum Battery Life

From safe charging to the longest possible lifespan, here’s everything you need to know about your electric bike’s power source.

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If you bought a bike in the last couple years, chances are good it’s an e-bike. Electric bicycles are the fastest-growing type of bike in the U.S. today; in 2021 they surpassed road bikes as the third biggest category of bikes overall and in 2022 e-bike sales were over 800 million. E-bikes still outsell electric cars, and for good reason. The lightweight electric motor on an e-bike gives a powerful boost to all kinds of riding, especially utility cycling like commuting and errands. (Plus, there is a nice tax incentive for some e-bike riders.)

At the heart of that system is a powerful lithium-based battery. Taking proper care of that battery and knowing how to properly charge it is key to safely getting the best range and long-term battery life. Here’s what you need to know about charging your e-bike battery.

Safe charging basics

You should charge your battery inside, on the proper charger, and with the motor system powered off, says Kunal Kapoor, senior manager for quality and compliance at Bosch, a leading supplier of e-bike motor systems. While e-bike motors, batteries, and wiring are weather-resistant, “chargers aren’t intended for outdoor use,” he notes.

Using the proper charger is primarily a safety issue. With a modern lithium battery, Kapoor continues, when the battery signals it’s ready to accept a charge, “the battery monitoring system in the charger makes sure that the temperatures inside the battery are optimum to receive the charge,” and shuts off if needed. An off-brand charger—even rated to the same output—doesn’t have all the features of that battery management system, so current can flow to the battery even if temperatures rise, which is a fire risk.

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The risk of battery fires is low, but Kapoor recommends people not leave batteries unattended while charging. You can leave the battery on the bike to charge or take it off, as long as it’s not sitting on or near flammable stuff (like the spare gas can in the garage, for example). If you’re looking at lower-priced e-bikes with house-brand or unbranded motor and battery systems, make sure the battery and charger carry a UL 2849 certification stamp from Underwriters Laboratories. This is the industry-wide standard for safe electric systems and battery charging for e-bikes. Some bike shops won’t work on e-bikes with motor and battery systems that lack this stamp, citing fire risk when left overnight in the store.

How to optimize battery range and lifespan

Let’s start with some definitions. Range is essentially runtime: how long a battery will last on a single charge, expressed in miles of riding. Range, even on the same bike, will vary; a flat commute to the office with just a light backpack will see better range than a fully loaded uphill ride home from Costco. Most e-bikes today get between 25-75 miles of range, depending on these factors.

Lifespan is how many times a battery can be discharged and recharged before it starts to lose significant capacity. When capacity starts to dip, you won’t notice less power while riding, but you will see range start to shrink. A common lifespan benchmark for e-bike batteries is 500 “full” discharge/re-charge cycles (if you use half the battery capacity and recharge, that’s half a cycle), which works out to about three to five years of normal use before capacity begins to drop noticeably.

Even though battery range and lifespan aren’t the same thing, they are linked, and actions that reduce range will also, over time, shorten lifespan. A big culprit, Kapoor says, is running the motor hard, like leaving it in Boost or Turbo mode all the time, which means a ride of a given distance relies progressively more on motor power than at lower assist levels. You’ll run the battery through charging cycles more quickly, which will shorten its life.

A less-obvious factor that strains motors and batteries is pedal cadence. Most e-bike motors are optimized for efficiency around a 70-90 rpm pedaling cadence. You can lower efficiency by pedaling too fast (Bosch motors, for instance, max out at 100-120 rpm depending on the system). common is sub-optimal efficiency from pedaling too slowly in a large gear. This is the same as “lugging the engine” in a car; whether gas or electric, the motor works harder. “Choose your gears wisely,” says Kapoor, to stay in that 70-90 rpm sweet spot.

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Mistakes that kill your battery

When you buy a new e-bike, you should charge the battery to full before riding it because it’s likely been inactive for a while. But lithium batteries do not have “memory;” that is, they do not need to be fully discharged and fully recharged every time to hold their full capacity. In fact, it’s best if you don’t run a battery to zero, says Kapoor. “If you let the battery deplete completely, that may permanently damage it,” he says, and it will never recharge to its full original capacity.

If you’ll go a few weeks or more without riding the bike, store it (or at least the battery) in a dry, room-temperature space with the battery between 30-60 percent of full charge, says Kapoor. That’s the most stable level for long-term storage, and will lower the chance of a deep discharge that would damage your battery. Don’t leave your battery plugged in to the charger for long periods. It’s not necessary, and can create a short discharge/recharge cycle that will eventually reduce capacity. If you go long periods without riding the bike, check the battery charge monthly and partly recharge when it drops below 30 percent.

Lithium batteries are less affected by cold weather than other types of battery and you shouldn’t see reduced range while riding unless the temperatures are truly arctic. But researchers at the Department of Energy recently found storing lithium batteries below freezing for longer periods can damage part of the battery’s cathode, which will reduce its capacity. Lithium batteries also won’t charge effectively in cold temperatures. If you store your bike outside or in an unheated space and live in an area with sub-freezing temps, says Kapoor, bring the battery inside when not in use.

Also, keep your battery protected from extreme heat, like sitting next to a sunny window or a hot car. Excess heat can raise battery temperature enough to damage its components; in an extreme situation, it can contribute to what’s called thermal runaway, where a battery enters an unstable, uncontrollable self-heating state that can result in fire.

You don’t need to recharge after every ride. Topping off your battery sounds Smart, but over time it will reduce capacity more quickly. If you get 50 miles of range from a charge and ride 10 miles a day, you only need to recharge every three to four days.

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When it’s time to replace

Even if you take great care of a battery, over time it will lose capacity. You’ll notice this on your bike’s range estimate on the controller unit. Capacity is a primary indicator of the health of a battery, so if you notice your range dropping to 70 percent or less of what it was when your bike was new, that’s a sign to start planning a replacement. If your battery is less than two years old and is well under original capacity, it might be a warranty claim (terms vary by manufacturer).

If it’s not a warranty issue, the decision on when to replace is personal preference, says Kapoor. “If you got 50 miles (of range) out of the battery originally and let’s say now you get 40, I wouldn’t classify it as ‘end of life’ if you can live with that 40-mile range,” he says. A battery with reduced capacity should still be safe, Kapoor adds.

Always purchase a name-brand replacement for your battery. Just as batteries and chargers should be paired, batteries and motors are designed to work together. And, says Kapoor, never try to repair a damaged battery or let someone else do it. Despite guides that claim you can, this is not just corporate greed or legal butt-covering by manufacturers. While e-bike batteries are almost always made from standard 18650 cells that are widely used in various products (even electric cars), those cells have a variety of different chemistries, capacities, and amperages, and that’s before we even get into connecting a string of them and repackaging the battery in the housing. The slightest mistake in any of that increases fire risk. If you need a new battery, just buy one.

Dealers that sell your brand of bike can order you a direct replacement for that bike or motor brand. Costs vary depending on battery size and brand, but plan on spending 400-800 for a new unit.

A dealer can also recycle your old one. A new program from Call 2 Recycle offers free e-bike battery recycling (paid for by bike and motor brands) through partner shops in almost every major city and many smaller ones. No participating dealers near you? Request an easy DIY shipping kit online.

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Why recycle? Even a spent battery contains raw materials that can be re-made into fresh ones, at moderately less energy cost and less environmental damage than producing from virgin materials. Spent lithium batteries also have a fire risk in landfills and can leach toxic metals and other chemicals into the soil and air.

In case of fire

Though rare, battery fires do happen. If your battery gets hot to the touch while charging, unplug the charger from the wall immediately. If you can, put the battery in a metal container like a bucket (better yet, one filled with sand) away from anything flammable.

But if it’s not safe to handle, call 911 right away and tell the dispatcher that you have a lithium battery fire, which requires different firefighting methods than conventional fires. Don’t pour water on a battery fire; water and lithium react to produce hydrogen, which is highly flammable. A standard fire extinguisher may help, but in the event of a fire, special tools may be needed.

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