Charging E-bike Battery – Everything needs to know Before Charging

What is the most crucial part of an electric bike?

Well, the wheels, frame, and groupset together make a bike. But what makes a bike an e-bike? Yes, the motor and the battery.

Both parts are equally essential for an electric bike. So, when one of them is not performing well, the bike won’t remain an electric bike.

Whatever the motor is, riders struggle with the battery most, especially when charging it. Most of us don’t know where and how to charge.

So, today I am gonna answer some of the most common queries about charging an electric bike battery. Let’s check it out. BTW, an important note is left in the ending.

Read till the end to know what is important, waiting for you.

1. How many watts does a ebike charger use?

It depends on the battery you are charging. You will find the capacity (in VOLT-AMPERE) written on it whenever you get a new one. This makes it easier to get a suitable charger. Let me explain with an example.

Basically, you can determine the watt required for a battery by multiplying its voltage with the ampere (voltage X ampere). Assume the battery capacity is 45V-20A. So, you will need 900 watts of power to charge the battery in an hour. (45V X 20A) = 900 watts

Now, you are probably thinking. Oh! Then I need a charger of 900 watts to charge a 45V-20A battery.

No. you don’t! It’s actually a calculation of how much power you need to charge the battery for an hour. Chargers are not designed for charging so fast.

It’s not good for the battery’s health. So, get a charger of one-third of the required power.

If we again take the previous example, you should get a 300 watts charger to charge a 45V-20A battery. Then, it will take more than 3 hours to charge the battery regarding the heat loss.

Anyways, why should you slow charge the battery? I will talk about it later.

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2. How long does it take to charge an electric bike battery?


About 3-5.5 hours. Again it depends on the battery capacity and the charger you are using. But there are a few other factors that also affect the charging time. Let’s know which factors affect the charging time of an electric bike battery.

  • Battery Capacity: Charging is actually creating a voltage difference between the positive and negative poles of the battery. That’s why a battery with a higher voltage takes more time to charge, where a lower volt battery takes less time.
  • Current Supply: If the current supply of your house is inadequate (as per charger requirement), it may slow down charging. However, higher current flow can cause a short circuit. So, you have to maintain an optimum current flow while charging. You must have a safety fuse in your home. Get a suitable multiplug for charging if you want double safety.
  • Charger Power: The charger’s capacity should be compatible with the battery capacity. If the charger has a lower capacity, it will slowly charge the battery. A higher capacity charger can do it faster. But, it can damage the cell if you use a charger that is too fast.
  • Temperature: It may be overlooked most of the time. But, the temperature actually has effects on charging speed. When you charge the battery at a high temperature, a false positive charge appears. Thus, the battery shows full charge when it’s far from 100% in reality. So, while charging, keep the battery at room temperature. Otherwise, it will slowly affect the battery life.

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3. How often should you charge your e-bike battery?

It’s difficult to answer if you ask after how many days or miles I should charge my e-bike battery.

It depends on many factors like your riding frequency and the type of assistance your e-bike provides.

But if you ask when to charge, I would simply say, “When needed.” But how to know when needed? Well, there are 3 ways to determine it.

  • Method-2: If the battery has no battery level indicator, get a Voltmeter to determine the level. For example, if you use a 50V battery, charge it when the meter’s volt shows less than 15V (30%).
  • Method-3: When you are not even using the battery, it discharges, and the standby time decreases. So, you have to charge the battery to keep it charged. But how often should you do it? Well, charging it once in two months is good to keep it on standby.

4. Can I charge my e-bike battery overnight?

Yes, you can! There was a time when batteries got swollen due to overcharging. But, as time passes, technologies evolve.

Now batteries come with Lithium Polymer cells which have less or no influence of overcharge. So, you can charge the battery overnight without worrying about damage.

But, before you set the battery, follow these 3 tips to make it more effective and safe.

  • Tip-1: A slower charger can help better in this case. As the whole night remains, it won’t be a problem for you to be slow. Moreover, a slow charger fills the battery more compactly with charges. Where there a false positive can appear in fast charging.
  • Tip-2: Some people avoid charging overnight as they are afraid of short circuits. Which is fair enough. There is always a risk of an accident when you leave a battery plugged in for a night long. But, you can prevent it with some safety measures, such as using good quality wiring with a safety fuse.
  • Tip-3: When charging the battery overnight, avoid high volt areas like engineering workshops or heavy industries. As there is a massive flow of current, the voltage jump is also high here. Especially when it is bad weather, the risk of short circuits is more in this kind of area.

5. Can you charge an e-bike at a car charging station?

There is too much confusion about it. Some people say, yes, you can, whereas some people are absolutely denying it. Let me make it simple. Can you charge your e-bike from a car charging station or not?

Well, you can’t. Not only car stations, most of the EV charging stations offer a high voltage alternating current. When you plug your bike in it, the battery will charge too fast.

But it will significantly damage the battery. So let the car charging stations for the cars.

Use an inverter, power bank, or solar panel instead. How to use them? I will be explaining in the following sections.

6. Can you charge an electric bike with a portable charger/power bank?

Can you charge an electric bike with a portable charger-power bank

As a power bank or portable charger is easy to carry and convenient to use, you may think of charging the bike with it.

Yes, it is possible to charge an electric bike with a power bank or portable charger. But, there are few things to calculate for knowing if the power bank is suitable for your bike or not.

  • Firstly, know the capacity of your battery. For example, if you are using a 45V-10A, the power in watts is 450 W.
  • Secondly, determine the capacity of the power bank. Assume there is a 55V-10A power bank. So, the capacity is 550 watts here.
  • Lastly, evaluate the charger capacity. Let, it offers 35V-10A output current. So, it will be a charger of 350 watts output capacity.

If the power bank’s capacity is more than the battery capacity, then it’s suitable. Also, the charger’s capacity should be less than 75% of output power.

In the above example, it fulfills all these conditions. So, it’s appropriate to charge the battery with that portable charger.

7. Can you charge an ebike with a solar panel?

Can you charge an ebike with a solar panel

Yes! You can charge an e-bike with a solar panel. Actually, there are already such charging stations where electricity is produced by solar systems.

It’s safe and harmless for the environment. But there are some limitations of solar panels.

  • Firstly, solar panels produce a small amount of power. So, voltage is too low here, which is inadequate for charging an ebike battery. However, you can solve this problem by using an integrated or hybrid module.
  • Secondly, setting a solar panel is a bit costly. If you want your own solar charging station, it won’t be cost-effective at all.
  • Lastly, the solar panel has no use on a dark night. Though you can store the energy and use it later. But, it’s not that efficient.

Although there are limitations, solar panels can rescue in an emergency situation. If you are riding long distances, solar charging stations can help to increase backup.

8. Can I charge my bike battery with an inverter?

Can I charge my bike battery with an inverter

The answer is yes! You can charge your e-bike with an inverter. In my opinion, it’s the best way to charge the e-bike outdoor.

However, an inverter changes direct current to alternating current. Let’s know how to use it.

  • Firstly, get a suitable inverter+charger for the bike battery. For that, check the output capacity of the charging port. Then, make sure it suits your bike battery and charger. For example, if you have a 300W battery and an 85W charger. If you want to transfer energy from a 120V DC source, get a 200W inverter. Remember, the inverter should be more than 125% capacity of the power source. Thus, it will cover the heat loss.
  • Lastly, connect the battery cables. Do it carefully and ensure you don’t swap the positive and negative ends (generally indicated with red and black color). Now, turn the inverter on. If the setting is OK, the LED should show the output voltage. If everything is OK, set the battery in to charge and enjoy.

Anyways, you will get the voltage “controlled” with an inverter. So, it’s safe, efficient, and, what I said, the best way to charge an e-bike battery outdoor.

Last Words

Charging is nothing but a chemical reaction. As a rection demand a specific environment (temperature or pressure) to occur, a battery needs an ideal place and parameters to charge.

You can control the external parameters. But, what you can’t control is the internal system and chemicals used inside the battery.

Why am I telling it?

Because most of us run after cheap options rather than quality products. The same thing happens for the electric bike battery.

When you get a cheap battery, inefficient internal systems and contaminant chemicals are predictable.

Thus, you won’t get the expected performance regardless of where and how you charge the cell. So, get a good quality battery for your e-bike.