Why is my ebike battery draining so fast? (Explained)

Why is my ebike battery draining so fast? (Explained)

Apr 17, 2024创易达

The electric bike battery is one of the most important parts of an electric bike and without it the electric bike will turn into a regular bike.With this importance, everyone is trying to get the best performance from the battery in order to increase his enjoyment of the electric bike.


One of the most frequently asked questions: Why is my ebike battery draining so fast? In fact, this question is an important but somewhat confusing question.The reason for this is that the word FAST cannot be measured, meaning the battery drained fast, i.e. some 15 minutes of riding your ebike.


Or drained fast, meaning if you used to  use  the ebike for 20 miles per one charge, and now you go 15 miles per one charge? That is why in this post we will answer the question Why is my ebike battery draining so fast?  from both sides.We will explain the reasons that lead to abnormal battery consumption and also the reasons that reduce the range of a single charge.

So that you have all the information you need to determine the causes of the battery problem and how to repair it.

Why is my ebike battery draining so fast? (the extreme condition reasons)


As a general rule, the battery drains fast as a result of damage to the internal cells of the battery or a problem with the BMS.


1-Damage Cell or Group of Cells.


The first and main reason why the electric bike battery drains fast is that there is damage to a cell or group of cells inside the battery, and the reason for this is that when there is a damaged battery cell the voltage becomes lower than normal, so the BMS “battery management system” completely shuts down the battery to save the internal cells of the battery.


To understand this point better, let’s take a quick look at how the BMS works.


How the BMS works:


Inside the battery of your electric bike are cells grouped together and each group is connected in series and connected to the BMS.

Through this connection, the BMS measures the voltage coming out of each group.

BMS is programmed to a minimum voltage & when the battery cells reach it, the BMS turns off the full battery completely.


Based on this, if you have only one cell or a group of cells damaged, you will find that the battery drains very fast.

In order to solve this problem, the damaged cell must be identified by measuring the voltage for each group of cells using a voltmeter


2-BMS Problem.


The second reason that may lead to the battery draining quickly is that there is a problem with the BMS unit itself.

The reason for this is that the BMS, as we mentioned, is the controller of the battery, so if there is a problem with the BMS and it is unable to read the battery cell voltage correctly, It will cause the battery to shut down quickly and you will notice that the battery is drained abnormally.


To solve this problem, you can reset the BMS or replace the BMS. You can see this post to learn the correct ways to do REST for BMS

Why is my ebike battery draining so fast? (The reasons for the low mileage)


In this part of the post, we will explain the most important reasons that reduce the miles you travel with your electric bike on a single charge.


1-Using Super Fast Charger.


One of the reasons that reduce the performance of the battery in general and reduce the long term is the use of a very fast charger because this will strain the battery cells and reduce their lifespan.


Based on my personal experience, I have noticed that the number of miles I travel when charging my bike battery with the original charger is more than the miles I travel when I use the fast charger.


Of course, you will need to use a fast charger in some situations, such as you need to charge on the go in case you are away from home,but do not make the fast charger your first option.


You can check out this post to learn how to choose a fast charger that is suitable for your bike battery.


2-Wrong storage habit.


When storing your electric bike battery, you should follow the rules that help maintain the life span of the internal cells and or these rules are to keep the charge rate around 75%.


We wrote this post that explains the best steps that you can take to maintain your bike battery during storage.


3-Using throttle only.


When you rely only on the throttle while riding your ebike, this will lead to the battery draining fast because you are making the bike do all the work.

This will lead to the fact that the motor will need to consume a lot of watts, which will reduce the range of a single charge.


4-Going uphills too much


When you use an electric bike up a steep hill, it takes a lot of the bike motor to give you the right torque to go up the hill.

This will also increase the battery drain and reduce the range of a single charge.

5- Riding in hot weather.


When you ride your electric bike in very hot weather, this will affect the movement of ions inside cells, which makes the chemical processes that occur inside the cell difficult.


This will greatly reduce the duration of a single charge and generally, most high-quality BMS will shut down the battery if the internal temperature of the battery reaches a certain degree.


6-Loading a Lot of staff.


Another reason for the battery depleting quickly is loading many things on the bike or towing a trailer.

This will lead to an increase in pressure on the motor to produce the highest torque, which will increase the battery consumption and thus reduce the battery range.



The reason for fast battery draining  (30 minutes or less) are often due to damage to some battery cells or a malfunction in the battery management system BMS 


On the other hand, there are several reasons that lead to the battery draining faster than normal, including the frequent use of a fast charger that is not commensurate with the capacity of the battery, improper storage of the battery, loading heavy things on the bike, and riding the bike in very hot weather.

Also, the continuous use of throttle only while riding and riding uphills a lot.

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