How to Choose a Battery for Wireless Motion Capture Sensors and Data Gloves

Choosing a battery for a wireless motion capture device is not simply a search for the highest capacity that fits. A mocap system may use one central source, independent sensor modules, hand-mounted units, or a combination. Each architecture creates different limits on size, weight, runtime, charging, and serviceability.

Begin with the capture session and measured power profile, then assess installation space, cell format, pack electronics, and validation. This avoids finishing the enclosure and PCB before discovering that the remaining space cannot support the intended workflow.

For the market and product developments behind these requirements, see our companion overview, Motion Capture Industry Trends: How Power Requirements Are Evolving. This guide focuses on the engineering choices.

Step 1: Define the Device and the Capture Session

Before calculating capacity, identify what is being powered and how the user expects it to work. Two devices described as “wireless mocap sensors” may have very different energy needs.

Identify the Device Architecture

A centralized suit connects body sensors to an on-body hub. One source supports sensing, processing, storage, and wireless communication. Charging is simpler, but the pack must support the complete system.

A distributed system puts a battery, processor, and radio in each node. It reduces body wiring, but every node must be maintained. Xsens offers both a body-wired Link architecture and an Awinda architecture with individual wireless trackers, showing why power must follow system design. (Movella)

A data glove places electronics near the wrist or back of the hand. Sensors, radio, processing, and haptics affect consumption, while even a small added mass can influence comfort and movement.

Define the Required Operating Time

Tie runtime to a real task, such as a creator session, laboratory protocol, outdoor test, or robot-data shift. Define both the target and minimum acceptable time.

A short-session sensor may benefit more from low weight and quick charging, while a professional device may favor longer operation or rapid battery exchange.

Decide Whether the Battery Must Be Replaceable

An internal rechargeable battery supports a sealed, integrated product. A replaceable pack can reduce downtime when users work for longer than one charge. MANUS uses interchangeable batteries in its professional gloves and describes continuous operation through battery swaps as part of the workflow. (MANUS)

This affects the enclosure, connector, locking mechanism, spares, and charger, so decide before mechanical design is finalized.

Step 2: Calculate Capacity From the Power Profile

Calculate capacity from measured current under representative conditions. Datasheets help with planning, but firmware, radio settings, sensors, regulators, and storage change the result.

Measure Average and Peak Current

Average current determines approximate energy use. Peak current shows whether the complete power path can maintain voltage during radio transmission, startup, memory writes, haptics, or reconnection.

A normal multimeter may hide short events. Nordic Semiconductor's Power Profiler Kit II can show sleep, active, and peak currents from 200 nA to 1 A at up to 100 kS/s, producing a useful trace for wireless wearables. (Nordic Semiconductor)

Test the intended sampling rate, radio interval, packet size, storage, feedback, and realistic weak-radio conditions.

Estimate the Required Capacity

A useful first calculation is:

Required capacity (mAh) = average current (mA) × target runtime (hours) ÷ usable capacity factor

The usable-capacity factor accounts for cutoff voltage, conversion losses, temperature, aging, and load behavior. Using 0.8 during early planning adds 25% over the ideal current-times-hours result. It is only an assumption and must later be replaced with test data.

Check the Peak Against the Complete Power Path

A battery can have enough capacity and still cause resets during a peak. Check the cell, protection, connector, wiring, and regulator together near empty and at the lowest intended temperature.

Step 3: Determine the Complete Battery Space

Use the available finished-pack envelope, not the largest rectangle visible on a PCB drawing. It must include everything required to connect, protect, and retain the cell.

Define Length, Width, and Thickness

Record maximum values in all three directions. For a body-worn product, also specify maximum weight and preferred center of mass because thickness can create a noticeable pressure point.

Separate Cell Size From Pack Size

Published dimensions normally describe the cell body. The pack may also need tabs, insulation, protection, wires, a connector, adhesive, and retention. Confirm both cell and finished-pack dimensions.

Mark Keep-Out Areas and Sensitive Components

Mark antennas, magnetic sensors, connectors, bosses, heat sources, and components that must remain uncovered. Overall dimensions alone cannot show interference with sensing, radio, or assembly.

Reserve Mechanical Tolerance

Do not continuously compress a pouch cell. Allow production tolerance and protect it from sharp edges, repeated folding, and movement-related loads.

Step 4: Compare the Battery Options

Once the electrical and mechanical boundaries are known, the team can compare formats. Start with the least complex option that meets the product requirement, then consider customization where it creates measurable value.

Start With a Standard Rectangular LiPo

If a standard cell meets runtime, weight, and space requirements, it is the practical starting point. Customize only to solve a real limitation.

Consider Ultra-Thin or Ultra-Narrow Cells

Ultra-thin cells can reduce the profile of clothing-integrated or body-facing modules; ultra-narrow cells can use space beside a PCB or inside a strap. Grepow lists wearable rechargeable lithium-ion options as thin as 0.5 to 0.85 mm. (Grepow Smart Clothing Batteries) Reducing one dimension usually limits capacity, so compare fit against runtime and manufacturing needs.

Use a Custom-Shaped Cell When It Recovers Useful Space

A keep-out area can make a non-rectangular cell more effective than shrinking the entire battery. Quantify the benefit in usable energy, device size, or placement. Grepow lists curved, round, L-, D-, C-, and rectangular pouch formats. (Grepow Shaped Batteries) Custom shapes require accurate drawings and allowance for tabs, seals, tolerances, protection, and the finished pack.

Use a Pre-Curved Battery for a Fixed Curved Housing

A wrist or hand enclosure may follow a stable curve. Grepow specifies customizable curved pouch batteries whose curve and dimensions are evaluated against the device structure. (Grepow Curved Batteries) A pre-curved battery is not dynamically flexible and must not be repeatedly bent unless designed and validated for it.

Evaluate Rechargeable Coin Cells for Low-Power Nodes

A rechargeable coin cell may suit a circular, low-power module, but its capacity, thickness, resistance, peak current, life, and charging requirements must match the real load.

Use Replaceable Packs to Reduce Downtime

A replaceable pack can reduce downtime. Prevent reverse insertion, accidental release, intermittent contact, and terminal damage, and provide a clear charging workflow for spares.

Step 5: Design the Complete Battery Pack

Cell selection is only part of the solution. The finished pack must match the product's electrical, thermal, mechanical, and regulatory requirements.

Match Voltage and Charging Limits

Confirm the device operating range, regulator behavior, nominal cell voltage, and maximum charge voltage. The charger must match the selected cell chemistry and specification. Do not substitute a cell with a different charge limit without reviewing both the charger and the rest of the power path.

Add Protection and Temperature Monitoring

Define responsibility for overcharge, overdischarge, overcurrent, and short-circuit protection. Decide whether the protection circuit and NTC temperature sensor belong in the pack or on the device PCB. Texas Instruments' wearable battery-management reference design combines a single-cell charger, protection, and fuel gauging, illustrating how these functions interact in a compact product. (Texas Instruments)

Plan the Connector and Wire Direction

Connector height, wire bend radius, and exit direction consume space. Specify polarity, pinout, wire length, connector, and direction; for replaceable packs, also define contact life and reliability.

Decide How to Report Remaining Energy

A voltage threshold may suit a simple product, while dynamic loads or strict uptime targets may require a fuel gauge. TI describes gauges that report state of charge and health for lithium-based batteries, including changing loads. (Texas Instruments Battery Fuel Gauges)

For multi-node mocap, use consistent thresholds and show which node needs attention before recording starts.

Step 6: Validate the Battery in the Actual Device

Bench measurements are necessary, but final validation must use the complete wearable device. Test the intended firmware, sensor rates, wireless conditions, enclosure, charging system, and user movements.

The validation plan should cover:

• runtime under representative capture conditions;

• voltage behavior during current peaks and near empty;

• charging temperature and operating temperature;

• connection stability while the user moves;

• drops, vibration, and mechanical loads appropriate to the product;

• simultaneous operation and charging of all nodes;

• runtime and internal-resistance change after cycling;

• behavior when one node reaches a low-battery condition.

Define compliance for the target market and product category. IEC 62133-2 covers safety requirements and tests for portable sealed secondary lithium cells and batteries. (IEC) The UN Manual of Tests and Criteria includes subsection 38.3 requirements for lithium battery transport. (UNECE) The OEM and supplier should agree on responsibilities.

Step 7: Prepare a Complete Battery RFQ

A battery request should support engineering evaluation without exposing unnecessary project details. Include:

• maximum cell and finished-pack dimensions;

• a simplified mechanical drawing with keep-out areas;

• nominal voltage and maximum charge voltage;

• measured average and peak current;

• target and minimum runtime;

• operating and charging temperature ranges;

• protection, NTC, fuel-gauge, wire, and connector requirements;

• fixed, built-in, or replaceable installation;

• expected sample and production quantities;

• destination markets and required certifications.

Public content should omit sensitive customer information and identifiable project data. The supplier needs the engineering envelope, not the confidential product story.

How Grepow Supports Custom Mocap Batteries

Grepow can evaluate standard, thin, narrow, shaped, or curved solutions and integrate protection, temperature sensing, wiring, and connectors as required.

For multi-node systems, discuss battery matching and charging at the system level. Early review of space, measured power, and workflow leaves more room to balance runtime, comfort, and manufacturability.

Conclusion: Select the Battery as a System

The best battery for a motion capture sensor is not automatically the one with the highest capacity or the most unusual shape. It is the option that supports the complete capture session while meeting limits for size, weight, voltage stability, charging, comfort, and maintenance.

Use a consistent selection sequence: define the device, measure average and peak current, calculate the energy target, map the complete pack space, compare battery formats, design the pack, and validate the finished wearable. That process turns battery selection from a late sourcing problem into a controlled part of product development.