bosch charger

How to Care for Your Bosch E-Bike Battery

The Bosch battery is a vital (and costly!) component of your Bosch electric bike from Tern. Naturally, you would want to give your battery the proper TLC so that it remains in good working condition for as long as possible. 

Here’s how to keep your Bosch e-bike battery happy, healthy, and long-lasting. 

Table of Contents

NBD battery

How should I handle my Bosch e-bike battery?

Our Bosch e-bikes are equipped with batteries that are easily detachable for swapping and recharging, but lock onto the bike frame securely. Simply insert and turn the key to unlock the battery, and carefully remove the battery from the battery mount. It is important to take extra caution when handling the battery, as impacts from dropping the battery can damage and potentially destroy it.

  • Your battery should snap in securely but still be easily removable. Never use the battery or battery mount as a handle for your e-bike. 

Do not open the battery. Doing so means tampering with battery conditions approved by Bosch, which introduces safety-related risks. Opening the battery will void any and all warranty claims against Bosch.

How do I charge my Bosch e-bike battery?

Bosch chargers are designed exclusively for Bosch e-bike systems and components. To ensure your Bosch battery suffers as little loss of capacity as possible from repeated charging, only use an e-bike charger certified by Bosch for your battery type. 

For the safest way to charge, connect the charger to the battery first, before plugging the charger into the electrical outlet. This ensures proper connection before the electricity starts flowing. 

The battery can remain mounted on your e-bike while charging, but make sure your e-bike is parked in a dry, covered location with an ambient temperature of around 20°C (68°F), such as in a garage, where a smoke detector is installed. Just insert the charging plug on the charger into the charging socket of the battery mount, and connect the power plug to the wall outlet.
You can also conveniently remove the battery from the e-bike to charge. The battery should be charged at room temperature (roughly 20°C, or 68°F), on a flat surface, in a dry, clutter-free location where a smoke detector is installed. Charging must be done without the presence of flammable materials or heat sources nearby, and out of reach of children and pets. No items should be placed over the charging battery, including the battery cover, which should be removed before charging. 

bosch charger

Is it OK to charge my battery overnight?

Bosch batteries feature an intelligent Battery Management System that prevents overcharging by knowing when to cut off the electrical current. In general, it is safe to leave your Bosch battery to charge overnight before a long ride without reducing its service life, provided that the charging is done correctly and the battery and charger are undamaged and properly cared for. However, as Bosch batteries feature rapid charging, you may find that overnight charging may not be necessary at all. Also, there are better ways to charge the battery that can help prolong the battery lifespan, as we will get into next.

How should I charge my battery to maximize battery life?

It is recommended to fully charge your Bosch battery to 100% before you ride your e-bike for the first time. After that, there’s no need to top off your battery to 100% after each ride, especially if you frequently take short trips. In fact, unless you are going on a more demanding ride and need the full battery range, you can get the longest lifespan possible out of your battery by maintaining the charge at 80-90%. 

This doesn’t mean you need to charge your battery once it drops to 80%. Depending on how much range you need for the next ride, you can wait until the charge falls below 30-40% before charging your Bosch battery back up to the 80-90% ballpark. This is easy to determine if you regularly take the same routes for commuting–just pay attention to how much charge you use per ride, and make sure you have sufficient charge remaining for the next ride. For a more detailed estimate of the range for your next ride according to your e-bike setup and riding conditions, visit Bosch’s handy e-bike range calculator.

Batteries will self-discharge over time even when not in use. For those who only ride occasionally, it is fine to keep the charge at around 40-70% so that the battery doesn’t discharge completely when not in use.

Regularly riding your e-bike until the battery is completely drained will compromise the battery’s ability to hold charge and decrease its efficiency and service life. The best way to avoid this is to check your battery before each ride to make sure there’s enough charge remaining.

To help you determine the charge, each LED bar of the battery charge indicator roughly represents a 20% charge. For instance, when 4 out of the 5 bars are lit, the battery has approximately 80% charge. When all 5 bars are lit, the battery is fully charged. 

  • Disconnect the battery and charger from the power supply after charging.

How should I charge my battery during winter?

Batteries that are “cold” have greater internal resistance that hampers the charging and discharging process. If you cannot store your e-bike indoors, remove the Bosch battery from the e-bike and bring it indoors to charge during the winter, particularly when the temperature dips below 0°C (32°F). Having your battery indoors at room temperature until just before riding will also help keep it warm during winter rides. 

What if I have more than one battery?

E-bikes such as the Tern GSD e-cargo bike feature Bosch’s dual-battery system, meaning it is wired to accommodate two DualBattery-compatible Bosch batteries (like the PowerPack 400 and 500, in the case of the GSD). The smart dual-battery system switches between the batteries during charging and discharging when it detects a certain charge difference to ensure the batteries are evenly charged and discharged, thereby reducing the frequency of either one being overly drained and prolonging their service life. Riders also have the option to only install one battery, and it can be mounted on either one of the battery mounts. 

The dual batteries can be directly charged on the e-bike, or removed from the e-bike and charged at a separate location. However, it is only possible to simultaneously charge both batteries with one charger when they are mounted on the bike. If you only have one charger, the batteries must be charged individually when they are removed from the bike. 

How do I find out the status of my battery?

This is a simple one–to find out the status (or number of charge cycles) of your e-bike battery, simply bring your Bosch battery to a certified Bosch e-bike dealer or service center. There, an expert can run diagnostics on your battery to help you understand the health of your battery and how well it is functioning. Bosch diagnostic reports are also particularly useful if you are looking into buying a used e-bike, since the battery’s health is a major factor determining whether or not a used e-bike is worth buying.

bosch diagnostics report

Bosch diagnostics report

How should I store my Bosch e-bike battery?

If you won’t be riding your e-bike for an extended period of time, remove the battery from the e-bike and store the battery properly by taking the following steps:

  • Charge the battery until approximately 30-60% before storing it (2 to 3 LED bars on the battery charge indicator). Prolonged storage at a fully charged or fully discharged state can shorten the battery lifespan. 
  • Store the battery in a dry, ventilated location that’s away from heat sources or flammable materials, and out of reach of children and pets. 
  • Keep the battery away from small metal objects such as keys, nails, screws, and coins, which could make a connection from one terminal to another and cause short-circuit damage.
  • The optimum storage temperature for the battery is approximately 20°C (68°F). Do not store the battery at temperatures below 0°C (32°F) or above 40°C (104°F). 
  • If you have more than one battery, store them separately to prevent them from reacting with each other.
  • Do not store the battery connected to the charger.
  • Regularly check on the stored battery, and charge it back up to the 30-60% range if necessary (set your calendar reminders!)

How should I transport my Bosch e-bike battery when traveling?

By car

If you are transporting your e-bike by car on a bicycle rack, remove the battery before loading the bike and store the battery safely in the passenger cabin. Do not leave the battery inside the car when the weather is hot, since the temperature inside the car can quickly reach dangerous levels that can damage your battery or cause it to catch fire.

By public transport

If you wish to bring your e-bike onto public transport such as trains, buses, and light rail services, plan ahead and check with the relevant transport authority before traveling. There may be operator-specific fees and requirements for bringing an e-bike onboard. Some transport services will require the e-bike battery to remain installed for the entire duration of the journey, while others may allow you to remove the battery and keep it by your side if you are not seated near your e-bike. Charging the battery may also be prohibited. In some cases, it is only possible to take your e-bike on certain routes.

By plane

Bosch e-bike batteries are lithium-ion batteries, which are subject to strict airport and airline regulations. In general, lithium-ion batteries are limited to a battery capacity of no more than 100 Wh to be allowed onboard a plane. As Bosch e-bike batteries start at 300 Wh, it is unlikely you would be able to transport your Bosch battery by passenger planes, whether as checked baggage or carry on. To be certain, you should always check with your airline in advance.

dirty e-bike

Your e-bike battery needs cleaning, too! Photo courtesy of Muc-Off.

How do I clean my Bosch e-bike battery? 

You should regularly clean your Bosch battery to ensure it’s free from dust, dirt, and road chemicals such as salt, which may disrupt connection and corrode components. Remove the battery from the e-bike, and use a damp cloth or sponge to clean the battery. Avoid having water or cleaning products enter the battery port. The battery terminals should occasionally be cleaned as well, and lightly greased with terminal grease to protect against corrosion and wear. If you’re unsure about how to do this or what product to use, your e-bike dealer will be happy to help! 

  • The cloth or sponge shouldn’t be drenched in water, but just wet enough to wipe the dirt off. 

To protect electrical components, the battery must not be submerged in water, or cleaned with a direct jet of water or high pressure hose.

If water gets into the battery mount, simply let it drain off. The battery mount is designed so that water can drain off and the contacts can dry. However, this only works if the mount and plug area are kept clean, so check regularly to see if they need cleaning. 

Got any additional tips for me?

Park your e-bike in the shade or in a cool location, and avoid leaving it in direct sunlight. If you must leave your e-bike outdoors, use a cover to protect it from the elements.

After each ride, your battery will benefit from a “resting period” before you plug it in to charge. The resting period allows the battery to cool down from a state of constant discharge. Around 30 minutes will do–in the meantime, freshen up and grab a drink! You can set a reminder on your phone or other smart devices to go back and charge the battery once you (and your battery) have had some time to rest.

Lastly, check the weather report for the outside temperature. Avoid riding your e-bike in extreme heat or cold, as it will harm your battery. If riding during the winter, it is a good idea to use a thermal protective cover to keep the battery warm.

For more helpful information on Bosch e-bike batteries, download the official Bosch eBike Battery Guide.