How to charge traction batteries correctly

15 January 2026

Traction batteries are at the heart of electric equipment, providing the energy needed to power the drive motor. That’s why it's important to care for them properly, starting with correct charging. In this blog, our Energic Plus experts answer some questions about charging traction batteries and share valuable charging tips.

When should a traction battery be charged?

For optimal performance, batteries should be charged immediately after discharge. This means that traction batteries should never be stored in an uncharged state. Additionally, the discharge should never exceed 80% of the battery’s rated capacity. Any deeper discharge causes wear to the active mass, resulting in a lower effective capacity.

How long does it take to charge a traction battery?

The charging time of a traction battery depends on both the charge factor and the type of charger used.

Charge factor
A battery is charged by putting in more energy than was consumed. The charge factor (CF) of a battery is the ratio of the ampere-hours (Ah) charged to the ampere-hours consumed. Most batteries have a charge factor of 1.2. For example, a traction battery with a rated capacity of 1000 Ah has discharged 80% (800 Ah). At a charge factor of 1.2, 1.2 × 800 Ah, or 960 Ah, must be recharged into the battery.

Type of charger
There are different types of battery chargers available. As well as the conventional or low-frequency charger, a common alternative is the high-frequency charger. Although the latter is more expensive to purchase, it charges batteries more quickly and cheaply. Thanks to intelligent charging technology, it also ensures batteries last longer. In short, high-frequency chargers are efficient and prevent premature wear to both the battery and the charger.

What risks are involved in charging a traction battery?

Of course, there are some risks to consider when charging traction batteries.

Heat is naturally generated when charging a battery. However, if too much heat is generated, it could start a fire.
Charging wet batteries produces hydrogen through the electrolysis of the electrolyte. When this hydrogen combines with the oxygen in the air, an explosive mixture called oxyhydrogen can form. As hydrogen is lighter than air, it rises to the highest point, so sufficient ventilation is required during charging.
Sparks may be generated when disconnecting a battery from a charger while it’s still powered. These sparks can cause the formed oxyhydrogen to explode.

What precautions should be taken when charging a traction battery?

Given the risks listed above, take the following precautions into account to ensure safety when charging a traction battery:

Provide a separate charging area.
Ensure that there are no flammable materials in the vicinity of the battery or charger.
Ventilate the charging area thoroughly to prevent the accumulation of oxyhydrogen.
Prohibit smoking, welding or grinding in the charging zone.
Provide an explosion-proof electrical installation, including lighting fixtures, sockets, and other related components.
Prevent short circuits by never placing metal objects on the battery.
If possible, place the charger on a support to prevent dust accumulation and the risk of fire.
Check the charging cables regularly and arrange for them to be repaired immediately if you notice any damage.
Switch off the charger before connecting or disconnecting the battery.
Only allow well-trained personnel to perform these actions when charging.

Find out even more about Energic Plus

Read some of our other blogs to find out more about industrial batteries, chargers, and advanced battery maintenance solutions from Energic Plus:

How to discharge lead-acid batteries
How to choose the right high-quality battery charger
Things you should know before using a battery charger
Why machines should not be used while charging
Why a high-frequency charger is the better choice
How to choose between a built-in and stand-alone charger
Save batteries with the Energic Plus battery regenerator
5 tips to maintain a starter battery
How to maintain lead-acid batteries

Looking for Energic Plus power solutions?

Click here for more info about Energic Plus.
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Please don’t hesitate to contact us if you have any questions.

About the authors

This blog post is brought to you by your Energic Plus team.

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