BATTERY LIFETIME OF AN E-BIKE: HOW LONG DOES AN E-BIKE BATTERY LAST?

From the design and the number of charging cycles to usage – there are many factors that influence the lifetime of an e-bike battery. In an interview, we spoke in detail with FIT e-bike battery expert Lingfei He about the background to the topic of the «lifetime of e-bike batteries».

Lingfei, before we talk about e-bike batteries and their lifetime, let’s talk about you first. What exactly is your job at Biketec GmbH?

Lingfei He: At Biketec, I am responsible for the management of e-bike battery and motor projects. I am also responsible for battery product management and take care of our battery portfolio. Although I am not involved in cell development, I do have an overview of the processes in cell chemistry.

Which e-bike batteries does Biketec currently have in its range? And what are the differences here?

Lingfei He: At the moment, we mainly have 36 V batteries in our portfolio, which differ in terms of capacity and design. These are:

The Ultracore family with 555 Wh, 740 Wh, 925 Wh capacity
TP 500 and TP 630 with 500 Wh and 630 Wh capacity
Supercore with 750 Wh capacity

From fall 2023, we will finally be presenting some 48 V batteries, also with different capacities and designs.

Could we now take a look at the lifetime of an e-bike battery? How long does an average e-bike battery actually last?

Lingfei He: The lifetime of an e-bike battery is defined in charging cycles combined with the resulting state of health (SOH) of the cells. A charging cycle describes the complete discharging and recharging of the cell. The SOH is the current full capacity in relation to the full capacity of the new battery.

The question that always arises here: How many cycles can a cell tolerate? The usual requirement for the cell is that, under ideal conditions, the cell can still provide 80 % of its original capacity after 500 cycles. The emphasis here is on ideal conditions: Because the more you put the cells under pressure, the faster they age. A battery may therefore only have 60 % of its original capacity when subjected to heavy use after 500 cycles.

What are the main factors that can influence this lifetime?

Lingfei He: There are several. The first is the level of charging and discharging current. High discharging currents occur when the charging status is low and/or when the motor is under full pressure, e.g. when driving uphill. The higher the current and the longer the process lasts, the greater the load on the cells. The same applies to driving in very hot or very cold temperatures. The cells can also be affected if the battery is fully charged to 100 % or completely discharged. And last but not least, correct storage also plays a decisive role. In short, the better care you take of your battery, the longer it lasts.

As an e-biker, how do I know how much my e-bike battery has already aged?

Lingfei He: This can be read out by the specialist dealer. The dealer connects the e-bike to the computer and can determine exactly what condition the battery is in. It is also possible to assess whether the battery is simply worn out or whether there is a fault that can perhaps even be corrected.

When should I replace my e-bike battery with a new one?

Lingfei He: That depends entirely on the intended use. Someone who commutes only 10 kilometers to work can still cope well with 60 % capacity. Someone who likes to tackle very long tours on a mountain e-bike, on the other hand, depends on full capacity. It is therefore difficult to issue a time directive. But a good indication is always your own feeling: If the battery has weakened noticeably in a relatively short period of time or is no longer suitable for everyday use, it should be checked by a dealer and replaced if necessary.

You can find more information about this in our blog post:

Repairing an e-bike battery – yes or no?

Lingfei, thank you for the informative interview!

5 quick tips to extend the lifetime of an e-bike battery

Partial charging: Don’t always fully charge the battery, but keep it between 20 and 80 % charge level. This protects the cells and increases the lifetime. By the way: In the case of FIT 2.0 batteries, you can activate the long-life mode. This ensures that the charging process stops automatically at 80 %.
Gentle use: Don’t push your drive system over an extended period of time unless absolutely necessary. Because if you keep the motor running at full load, the battery will age faster.
Optimal storage: Store the battery at room temperature and avoid extreme temperatures and humidity.
Regular care: Clean the battery regularly and make sure the contacts are clean and dry.
Software updates: Keep your e-bike software up to date.

30.08.2023