# UBTECH Walker S2 Battery Swap

How the Walker S2 humanoid robot swaps one of its two backpack batteries while the other keeps it powered, so it can keep working without stopping\.

By Jeremy Courvalet

Topic: Home & DIY

[Open the interactive Jig](https://ask.jig.com/j/XVTRZs1YbJ7d)

## Transcript

### 1. Meet Walker S2

Walker S2 is a humanoid robot made by UBTECH to work in factories\. It stands 1\.76 metres tall, about as tall as a grown\-up, and weighs 70 kilograms\. Let's watch it change one of its batteries all by itself\.

Drag anywhere to turn the scene and look around\.

### 2. Two batteries in its backpack

On its back, Walker S2 carries two battery packs, one above the other\. A battery stores electrical energy, like a lunchbox of power for its motors\. Either pack on its own can keep the robot running\.

UBTECH calls this a dual\-battery design: the robot can run on two batteries or on just one\.

### 3. The top pack runs low

Five little lights on each pack show how much energy is left\. The top pack is draining, while the bottom pack is still nearly full\. The robot keeps an eye on its own batteries and decides when it is time to swap\.

### 4. Twist and reach

Walker S2 twists at the waist to turn its back to the swap station, while its legs stay put\. Then it reaches behind with both hands, grips the top pack by its sides and slides it out\.

Its waist can turn up to 162 degrees either way\.

### 5. Into the charging slot

The robot pushes the empty pack into an open slot of the station, which is a charger with shelves\. The bottom pack stays in the whole time and keeps the robot powered, so it never switches off\. The slot light turns amber while the pack recharges\.

Changing a battery while a machine stays switched on is called a hot swap\.

### 6. Grab a full pack

Just below waits a pack that is already charged, its slot light glowing green\. Walker S2 slides it out and lifts it up, level with the empty bay on its back\.

### 7. Push it home

The robot pushes the fresh pack into the empty bay until it clicks, then twists back to face forward\. Both packs are full again\. UBTECH says the whole swap takes about three minutes\.

### 8. Back to work, day and night

Because one battery always stays in, the robot never has to stop and wait hours for a recharge\. That is how UBTECH aims for Walker S2 to work around the clock, 24 hours a day, 7 days a week\.