How long does an e-scooter battery last?

NIU 17 september 2019

NIU for example states for the N series that the batteries have a “lifetime” of 600 charging cycles. Does this mean that the battery is broken after the 600th charge? No, not at all!

1 Charging cycle is a full charge!
The first common misconception is that every charging process – for example the recharging of an 80% charged battery – represents a charging cycle. But that is wrong. 1 charge cycle corresponds to a 100% full charge.

If you charge a battery twice from 50% to 100% charge, this corresponds to a single charge cycle. Or if, for example, you charge a battery five times from 60% to 80%. Then this is also a single charge cycle.

After 600 charging cycles there is still a long way to go!
The second mistake is that a battery is broken after the stated “lifetime” (probably the wrong ratio!). After 600 charging cycles the battery of the N series has only 90% of the original capacity. Or to put it another way: instead of 51 km range, only 45.9 km. Considering that the majority of scooter riders in Europe only cover about 10-15 kilometers per day, this is still a good distance.

So what happens next?

The manufacturer of the battery cells has given the following values:

0 – 600 charging cycles: 90% – 100% of the original capacity

600 – 1,000 charging cycles: 80% – 90% of original capacity

1.000 – 2.000 charging cycles: 70% – 80% of the original capacity

How many kilometres is that?

Here we make simple invoices, which of course are not quite exact. Firstly, our calculation is based on the assumption that the capacity decreases linearly, which it does not do in practice, and secondly, we assume that the homologation shows that the 51 km range corresponds to the actual range. On the other hand we neglect the fact that the capacity decreases at low temperatures and assume an optimal treatment of the battery (no deep discharge, no storage at low temperatures etc.).

For the first 600 charging cycles, the capacity is between 90% and 100% of the original capacity. So we calculate simplified with an average of 95%. 95% of 51 kilometers are 48.45 kilometers. We multiply this by 600, resulting in 29,070 kilometres. After this mileage, the capacity is 90% of 51 kilometers, which would be 45.9 kilometers.

Result 1: After 29,070 kilometres, the range is only 45.9 kilometres.

Between 600 and 1,000 charging cycles, the capacity is then between 80% and 90%, so in simplified terms we expect an average of 85%. 85% of 51 kilometres is 43.35 kilometres. We multiply this by 400 (1,000 minus 600) and arrive at 17,340 kilometres. To these we now add the 29,070 kilometres of result 1 and come to 46,410 kilometres. After this mileage, the capacity is then only 80% of 51 kilometres, i.e. 40.8 kilometres.

Result 2: After 46,410 kilometres the range is only 40.8 kilometres.

Between 1,000 and 2,000 charging cycles, the capacity is then only between 70% and 80%, we calculate again simplified and with an average of 75%. 75% of 51 kilometres is 38.25 kilometres. These are multiplied by 1,000 (2,000 minus 1,000) and we get 38,250 kilometres. We now count them among the 46,410 kilometres of result 2 and get 84,660 kilometres. After this mileage the capacity is then only 70% of 51 kilometres, that is 35.7 kilometres.

Result 3: After 84,660 kilometres the range is only 35.7 kilometres.

If you are a long-distance scooter driver now, that may sound a bit low, but for the majority of scooter drivers it is a lot. Most scooter riders in our latitudes only cover about 10 – 15 kilometres per day. Let us assume that a scooter rider actually drives exactly 15 kilometres all year round on absolutely every day of the year, even on Sundays and public holidays and in rain, snow and ice. Then we just get to 365.25 × 15 = 5,478.75 kilometres.

This means for this driver that after 29,070 / 5,478.75 = 5.31 years he still only has to load every third day (45.9 / 15 = 3.06). After 84,660 / 5,478.75 = 15.45 years it is still enough to load every second day (35.7 / 15 = 2.38). How nice it would be if we only had to charge our smartphones every 2nd day!

As already mentioned, these calculations are not exact and no guarantee or warranty claims can be derived from this example.