Xiaomi Pro 2 Extra battery, foot space, foldable

External Battery Enclosure for Xiaomi Scooter Series

This project is a tested and proven external battery enclosure designed for scooters such as the Xiaomi Mi Electric Scooter Pro 2 and other models from the Xiaomi scooter family. The enclosure was developed through real-world use and multiple iterations to ensure durability and practicality.

During testing the enclosure survived several solid drops without structural failure. It has also been load-tested while mounted on the scooter — I stood directly on the battery pack (90 kg) and the enclosure did not crack or break.

For best results I recommend printing the parts in PCTG, which offers excellent impact resistance and layer adhesion. Successful tests were also performed with PETG, so it remains a viable alternative.

To improve durability and sealing between parts, I recommend bonding the individual layers with automotive gasket silicone. This adds vibration damping and helps keep the assembly rigid during riding.

One particularly useful feature of this design is that the scooter retains its folding capability even with the battery installed. The battery position also allows the rider’s foot to partially slide underneath the pack, which makes it easier to lift the front wheel when hopping curbs or riding over potholes.

The enclosure is not fully waterproof, so avoid prolonged exposure to heavy rain or submersion.

Electrical configuration

The battery pack is designed as 10s4p using 18650 cells (20 cells total).
This mirrors the configuration used in the stock battery of the Xiaomi Mi Electric Scooter Pro 2.

Running two 10s4p batteries in parallel effectively doubles the total capacity, which significantly increases range. In practice the range improvement can be slightly more than double due to load sharing:

• each battery provides only part of the total current
• each individual cell operates at lower current
• voltage sag is reduced
• usable capacity increases

This also improves battery longevity, because both packs operate under lower stress.

With a modified firmware and favorable conditions, my personal maximum recorded range reached about 85 km on a warm summer day.

Important safety note

When connecting the external battery, both batteries must be at the same voltage level.
The easiest way to ensure this is to fully charge both packs before connecting them.

Modular cover system

Several top and bottom cover variants are included.
I own multiple scooters in my family, each equipped with this battery system, so the covers were created to allow mixing and matching different versions depending on preferences or hardware layout.

Technical details

Mounting interface

• Frame ellipse: 52 × 43 mm
• Length: 94 mm

BOM (Bill of Materials)

Battery

• 18650 cells — 20 pcs
  • preferably the highest capacity available
  • very high discharge cells are not required unless running >1 kW power

BMS

• DALY 10S 20A BMS (direct fit)
• or any compatible 10s BMS

Connectors

• XT60E-F connector
• M3×15 countersunk screws — 2 pcs

Bottom bracket

• M4 screws — 6 pcs minimum
• Length range: M4×15 to M4×20
• M4 threaded inserts 6 mm

Back cover

• M3 screws — 11 pcs
• Minimum length: M3×10
• Maximum length: M3×25

Front cover

• M3 screws — 11 pcs
• Minimum length: M3×23

• Maximum length: M3×40

   

Assembly order

From top to bottom, the enclosure is assembled as a layered sandwich:

1. Top cover (choose any version)
2. BMS layer
3. Top spacer
4. Battery core – top
5. Battery core – bottom
6. Bottom cover