1. Product Overview

The Wattnine 3.7V 2600mAh battery pack is a compact rechargeable power source built using one 18650 NMC lithium-ion cell in a 1S1P configuration.

It has a nominal voltage of 3.7V and reaches 4.2V when fully charged. The product label indicates an operating-voltage range of 3.0V to 4.2V and a current rating of 2A.

The pack is enclosed in black heat-shrink insulation and includes an output cable for connection to compatible equipment. The label also indicates that a BMS is fitted inside the pack.

Its compact size makes it suitable for compatible portable electronics and low-current battery-powered equipment requiring a single-cell lithium-ion supply.

2. Technical Specifications

The approximate nominal energy is calculated as:

3.7V × 2.6Ah = 9.62Wh

Exact BMS protection thresholds, cable length, wire size, connector type and cell manufacturer are not specified on the visible label.

3. Battery Configuration

The pack uses a 1S1P configuration:

• 1S means one cell group connected in series.
• 1P means one cell connected in parallel.
• The nominal pack voltage remains approximately 3.7V.
• The pack capacity is approximately 2600mAh.
• The fully charged voltage is 4.2V.

This is a single-cell battery pack and must not be charged using a charger designed for a 2S, 3S or higher-voltage lithium battery.

4. Integrated BMS

The product label indicates that the battery pack is supplied with a BMS.

Depending on the exact internal protection circuit, the BMS may provide:

• Overcharge protection
• Over-discharge protection
• Overcurrent protection
• Short-circuit protection
• Charge and discharge control

The exact cutoff voltages, overcurrent threshold, short-circuit response and recovery method are not printed on the visible label and should be confirmed before use in a critical application.

The BMS is a safety device and does not function as a battery charger.

5. Suitable Applications

This battery pack may be suitable for compatible low-current electronic equipment such as:

• GPS tracking devices
• Portable electronic instruments
• IoT devices
• Wireless sensors
• Data loggers
• Rechargeable LED products
• Small monitoring systems
• Alarm and security equipment
• Handheld electronic devices
• Prototype and development projects
• Backup power for low-current electronics
• Custom single-cell battery replacements

Compatibility must be confirmed using the equipment’s voltage, continuous-current, peak-current, connector and physical-size requirements.

6. Device and Charger Compatibility

Use this battery pack only when:

• The equipment is designed for a single-cell lithium-ion battery.
• The equipment can operate within the battery’s 3.0V–4.2V voltage range.
• The continuous and peak current remain within the verified battery-pack limit.
• The connector and polarity match the equipment.
• The charger is designed specifically for a 1S lithium-ion battery.
• The charger’s maximum output voltage does not exceed 4.2V.
• The charging current is suitable for the battery pack.
• The pack fits securely inside the intended enclosure.

Do not use a 5V power supply directly as a lithium-ion battery charger. A proper CC/CV lithium-ion charging circuit with a maximum output of 4.2V is required.

7. Installation Guidance

• Measure the battery voltage before installation.
• Confirm the positive and negative wire polarity with a multimeter.
• Never identify polarity only by wire colour.
• Confirm that the equipment and connector polarity match the battery pack.
• Insulate all exposed joints and terminals.
• Secure the pack inside the enclosure so it cannot move or vibrate.
• Avoid placing pressure on the cable exit point.
• Do not sharply bend, pull or crush the output wire.
• Keep the pack away from sharp edges and conductive surfaces.
• Use suitable cushioning or battery-safe double-sided foam tape when mounting the pack.
• Do not solder directly to the internal cell.
• Disconnect the pack immediately if it becomes unusually hot during installation or testing.

8. Important Current-Rating Note

The product label states a current rating of 2A. Confirm whether this represents continuous discharge current, maximum discharge current or the BMS current limit before using the pack in equipment that draws close to 2A.

The device’s startup or peak current may be higher than its normal operating current. If the equipment demands more current than the battery or BMS can safely provide, the BMS may disconnect the output or the battery may overheat.

This pack is not intended for high-power motors, power tools, electric vehicles or other heavy-current applications.

9. Safety Information

• Use only a compatible 4.2V lithium-ion charger.
• Do not reverse the battery polarity.
• Do not short the output wires.
• Do not charge above 4.2V.
• Do not intentionally discharge below the verified cutoff voltage.
• Do not exceed the verified current rating.
• Do not puncture, crush, bend or open the battery pack.
• Keep away from fire, water, direct sunlight and excessive heat.
• Do not use the pack if the heat shrink is torn or the wire insulation is damaged.
• Stop using the battery if it becomes swollen, leaks, smells unusual or becomes excessively hot.
• Do not leave the battery charging unattended.
• Store the battery in a cool, dry place away from conductive objects.
• Keep the battery away from children.
• Installation should be performed by someone familiar with lithium-ion battery safety.