Stromer battery revision and alternatives.

The goal of this article is to help understand what you can and what you should not expect from a Stromer battery revision with full replacement of Li-ion cells

Every week, Stromer owners contact our service center with the same question: “Can you revise the battery? I need 10–20 km more.” Or “It holds charge less now, I would like it to go like before.” Behind these words is a very understandable and human need: just ride a bit further, feel confident, not worry if there is enough charge to go home, and not charge during the ride.

We wrote this article to try to tell in the most objective and clear way:

What a battery revision is and what it really gives.
When it is really suitable.
In which cases it is disappointing.
What other more effective and cost-effective ways exist to increase range.

If at the end of this article you understand your situation better and can make a calm, reasoned decision — then we wrote it not for nothing.

A situation familiar to almost every Stromer owner

Suppose you ride your Stromer every day 20–25 km one way. Before everything was great, but over time the battery started to hold charge a bit worse. You miss about 5–10 km, but these kilometers are like a gap in the schedule: you have to charge at work, take the charger with you, save energy, reduce support. And sometimes just feel nervous: “Will I get home today?”

One of our clients, for example, said:

“I come back from work in the evening — the battery turns off 5–7 kilometers before home. I have to pedal by myself. I come home tired, like after training, even though I sat all day at the computer.”

This is a very understandable wish. And the first impulse is to revise the battery.

What is a revision, and what to expect from it

A revision is a full replacement of all lithium-ion cells inside the battery. So outside the battery looks the same, but inside — new cells, like in a new Stromer battery. In the end, you get up to 960–983 Wh of capacity — like in the original.

But it is important to clearly understand that in a revision all the old internal energy of the battery — and this is often 70–80–90% of its original capacity — is just thrown away. So you remove not worn-out cells, but energy that still worked and had potential for several more years.

📌 Imagine a car fuel tank with 40 liters of petrol left. You come to a service, and they offer to throw it all away to put 50 liters of new petrol. But the old petrol is still good and could take you far.

Absurd? But that is what happens with batteries during revision: working energy is removed to add only a little more.

From this point of view, if you only want to increase the range a bit, revision is a expensive and not effective solution. So before deciding, you should clearly understand: you lose more than you get.

Important to understand: if your battery now has, say, 80% of its original capacity, then replacing the cells gives an increase of about 15–20%. That is about 150–200 Wh, or around 7–10 km extra range.

💸 The price of revision up to 983 Wh — about 750 euro.

1️⃣ One client shared that before the revision his battery could do about 41 km, and after — about 50. He said: “I thought it would be more. It feels better, but I still have to watch the percentage.” His case is typical: there is improvement, but the problem is not fully solved.

2️⃣ Another client expected that after the revision he could go 20 km more. In reality, he got 9 km more. He said: “I worry less now, but the charge still ends on the last kilometers. Not what I expected.”

Each of these cases shows: expectations from revision must be very realistic.
Revision does not always solve the distance question, if you are missing 20–30 km.
It only restores the original parameters of the battery.

When revision is the right decision

Still, there are cases when revision is really needed and makes sense:

The battery is very degraded, the remaining capacity dropped to 30–50%. The range became much shorter.
Fast capacity loss in a short time. This usually shows a problem in one or more cells.
The battery behaves strangely: charging stops at 80–90%, or drops fast from 30 to 0%, etc. The range is much shorter. This may also show damage in one or more cells.
The battery became unstable: works normally, then suddenly turns off. The bike may turn off under load even if charge level looks good.

📌 Example:

The Stromer stood all winter in the garage. In spring the owner found that the battery did not charge. The check showed critical voltage in the cells and strong imbalance between them. Here revision was the only option — and helped bring the battery back to life.

When revision does not meet expectations

But more often people come with a battery that works, but just misses a little. In these cases, revision is an expensive way to get a small improvement.

📌 Example:

The client had a battery with 82% remaining capacity. Range — about 45 km. After revision — 53 km. But he expected 60+. His comment: “If I knew before, I would have kept the old battery and searched for something extra.”

🔍 Here the revision was technically successful, but not psychologically. Because expectations did not match reality.

Alternatives to revision: how else can you increase the range?

There are not many options, but they exist.

Use economy mode (1–2), reduce speed. Not for everyone, especially if you ride fast or in hilly areas.
Charge in the middle of the route. Works if you can charge at work or with friends.
Buy a second original battery. It is expensive — about 1500 euro, second-hand is also not cheap and not always reliable.
Install Dual Battery System with extra battery. This option allows you to keep and continue using the old battery and add 1100–1450 Wh to it.

💡 We developed the Dual Battery System solution, which allows Stromer to use a removable extra battery together with the main one. More about this solution — here.

Field test — just to show the difference

To better understand the difference, here are the results of a simple test that we did in summer 2025.

Test conditions: Stromer ST-2, 3rd (maximum) support level, average speed 38 km/h (35–40), riding without stops, air temperature 23°C, flat asphalt road, no wind, no bags, well-inflated tires, no charging between.

Test results:

Original Stromer battery after revision with new Samsung Li-ion cells (983 Wh): first ride 48.5 km, after 6 hours rest without charging another 10.5 km (26–0%). Total in 2 rides 59 km.
Same bike model, same conditions:
- Dual Battery System “Compact” 1146 Wh: 56 km + after 6 hours another 12 km. Total 68 km.
- Dual Battery System “Midi” 1188 Wh: 59 km + after 6 hours another 13 km. Total 72 km.
- Dual Battery System “Maxi” 1426 Wh: 72 km + after 6 hours another 15 km. Total 87 km.

These numbers are not “record,” but they are realistic. They simply help compare the gain from revision (up to 7–15 km) and from adding a second battery (up to 70–80 km).

More about Dual Battery System — here.

Conclusion

Before you decide, answer a few questions:

How many kilometers does your battery give now?
How many are you missing?
Is your battery working stable?
What exactly do you want: restore the battery, or seriously increase the range?

If the battery works badly or is unstable — revision may be your way.

If the battery is still okay, but you want to go further — better look at alternatives.

We just share our experience. It is important to us that you understand what revision really gives. So there will be no disappointment. So that your expectations match reality.

And if you want to know other ways to increase range — we are always here. For now — we hope this article was useful.