Tips for charging your e-bike battery

How you charge your e-bike battery decides how long it lasts and how well your e-bike performs. Customers often ask us: "How do I charge my new e-bike battery?", "How long does charging take?", "How should I charge my battery after a cell replacement (re-celling)?" and "How long will my battery last?" Fair questions, because an e-bike battery is vulnerable and needs specific care. We also hear: "Can I overcharge my e-bike battery?" and "Do I have to run the battery completely flat before I charge it again?" You will find the answers on this page.

Basic steps for charging an e-bike battery

1. Take the battery out: Remove the battery from the bike and put it on a stable, dry surface.
2. Connect: Plug the charger into the wall socket first, then connect the charger to the battery.
3. Charging indicator: A light on the charger shows the charging status. Red means the battery is charging; green means the battery is fully charged.

Charging tips

• First charge: With a new e-bike battery, we recommend charging it fully the first time.
• Charge regularly: Charge the battery regularly, even when it is not completely empty. That helps it last longer.
• No need to fill it every time: You can use the battery before it is completely full. Before a long ride, charging to 100% is fine; just do not leave it standing full for weeks.
• The right conditions: Charge the battery in a dry, well-ventilated room and avoid extreme temperatures.

The right order for charging an e-bike battery is simple: plug the charger into the wall socket first, and only then into the battery. That way you connect the battery to a stable power supply and avoid unnecessary spikes as you plug in. Do it the other way round and the voltage difference between battery and charger can be too high, which causes sparking.

You may have wondered why your charger gets warm in use. That is quite normal. It comes from the electric current that flows through the charger to charge your battery. A little warmth is to be expected. But if your charger gets very hot, so hot that you can no longer hold it comfortably, something may be wrong. In that case, do something about it before it becomes a risk. If you suspect a problem with your charger or battery, we recommend having it inspected by our specialists.

The charging port of your e-bike battery gets a lot of use: over its life a battery is charged countless times. You need the right charger, and both the charger and the charging port in your battery have to work properly. If the plug of your charger is pushed in too hard, or does not fit the charging port of your battery properly, it can damage the port. The charger can then no longer deliver the current the battery needs.

From experience we know that some battery brands use chargers that are too powerful. That can shorten the life of your battery pack. If that is the case, we replace the charging port straight away during an e-bike battery cell replacement and supply you with a new charger.

The charging port and the plug have to match for charging to work properly. The plug on your charger and the voltage together determine which type of charging port is needed. That ranges from RCA and 3, 4 or 5-pin connectors to a DC plug connection.

Some brands even have their own proprietary connectors, often with communication built in. Bosch chargers and Flyer battery chargers, for example, use communication between the battery and the charger. Charging only starts once the signal is right, which makes charging safer and more efficient.

At KWS Seuren we know how much your e-bike battery depends on a charger and a charging port that work properly. Our knowledge and our wide range of chargers and accessories are there for you to use, so you can ride without worrying about charging.

Charging the battery is part of using an e-bike. How long it takes varies a great deal, depending on the battery and the type of charger you use.

Factors that affect charging time

1. Battery capacity: Larger batteries with a higher capacity naturally need more time to charge fully than smaller batteries.
2. Type of charger: Standard chargers and fast chargers charge at different speeds. A fast charger can cut the charging time considerably.
3. Condition of the battery: Older batteries can take longer to charge because they have become less efficient.

Standard charging times

• Large battery: About 6 to 8 hours with a standard charger.
• Small battery: About 3 to 5 hours with a standard charger.
• With a fast charger: Almost twice as fast as with a standard charger.

Charging indicators and safety tips

• Charging indicators: Most chargers have an indicator light that changes from red to green when the battery is fully charged.
• Avoid overcharging: Do not leave the battery on the charger for longer than necessary. Overcharging can harm the life and the quality of the battery.

Battery management systems (BMS)

• Preventing overcharging: Many modern e-bike batteries are fitted with a BMS that prevents overcharging automatically.
• Getting more out of the battery: A smart BMS also makes the battery work more efficiently, which gives you a longer range.
• Preventing deep discharge: Charge your e-bike battery regularly to prevent deep discharge, which can lead to irreparable damage.

Charging time table

This table gives a general overview of the charging times you can expect for different kinds of battery, with both standard and fast chargers.

Charging times to 50% and to 100%:

These times are based on the Bosch 4A Standard Charger. With the Fast Charger the charging time is shorter.

When and how you charge the battery of your e-bike has a direct effect on how long it lasts and how well it performs. Here you can read when and how best to charge it.

Charge a new e-bike battery fully first

When you buy a new e-bike, the battery is usually only partly charged, because that is the safest state for storage and transport. So make sure you charge the battery fully before you use it for the first time. The same goes for a battery that has just been re-celled.

Avoid running the battery completely flat

We advise against riding the battery completely empty. Ideally, you keep the battery between 15% and 90% charged at all times. That keeps the battery in good condition and prevents damage from deep discharge.

Use the range as a guide

Some e-bikes show the range in kilometres. That is a handy guide to when it is time to charge the battery. If your bike has a maximum range of 100 km, for example, it is sensible to charge the battery once the remaining range drops to about 15 km.

Charge level

Most e-bike batteries have indicator lights that show the charge level. If only one light is still on, for example, it is time to charge the battery. Keep an eye on these indicators to see when your battery needs charging.

How often should I charge the battery?

How often you need to charge your e-bike battery depends on several things: how much pedal assistance you use, your body weight, the wind and the type of terrain you ride on.

Modern lithium-ion batteries

With a modern e-bike that has a lithium battery, you do not need to worry about the right moment to charge. You can top these batteries up at any time, whether they are 40%, 60% or 80% full. You can also charge them to 100% before a long ride, as long as the battery does not then stand full for weeks. Unlike the older nickel-metal hydride batteries, which did lose charge when left standing, lithium batteries hold their charge better.

Summary

• Charge batteries fully before first use.
• Avoid running the battery completely flat; keep it between 15% and 90%.
• Use the range and the charge level indicators as a guide to when to charge.
• You can top up a modern lithium battery at any time.

Follow these guidelines and your e-bike battery stays in good condition, which means a longer life and better performance from your e-bike.

Choosing the right moment to charge the Bosch battery of your e-bike can extend its life. A few tips:

1. Not permanently on the charger: As soon as the Bosch battery of your e-bike has finished charging, take it off the charger.

2. Charging during long periods of standstill: In winter, make sure you charge your Bosch e-bike battery at least once a month, and store it at room temperature.

3. Check the manual: For specific instructions on charging a Bosch e-bike battery, check the manual of your e-bike. Follow these tips and your battery keeps performing well and lasts longer.

If you are a keen cyclist who likes long rides, you need to know how to charge the battery of your e-bike along the way. Whether you are riding through the Dutch countryside or finding your way around town, it helps to be prepared for the moment your e-bike battery needs charging.

Public charging points

There are many public charging points across the Netherlands. You often find them in tourist areas, at cycling cafés, in nature reserves and even at some shopping centres. These charging points suit a short stop: your e-bike battery charges while you take a rest yourself and have a look around.

Portable chargers

A practical solution is to take a travel charger with you. These chargers are compact and fit easily in a pannier. The pannier gives your charger a place and also protects it from rain and other weather. Picture it: you stop at a pleasant little restaurant, plug in your battery and enjoy a good meal while your e-bike battery charges back to full.

A second e-bike battery

For the real long-distance cyclist, a second e-bike battery is a good investment. It means you always have a spare battery to hand for when your main battery is empty. Swapping batteries is quick and easy, so you lose hardly any time and are never left without pedal assistance. That is especially useful in areas where charging points are scarcer.

You can extend the life of lithium-ion batteries by using specialised chargers that do not charge all the way to maximum capacity. Limiting the charging voltage to 4.10 volts instead of the usual 4.20 volts can almost double the life of a battery, and it also reduces the risk of overcharging. So the charger you choose matters for both the efficiency and the safety of the battery.