DALY 13S 48V 40A Lithium-Ion Battery BMS with NTC and Balance Wiring

1. Product Overview

The DALY 13S 48V 40A BMS is designed for lithium-ion battery packs containing 13 cell groups connected in series.

A completed 13S lithium-ion battery has a nominal voltage of approximately 46.8V–48.1V and reaches 54.6V when fully charged. This configuration is commonly marketed as a 48V lithium-ion battery pack.

The BMS monitors the individual series groups and helps protect the battery against abnormal charging, excessive discharge, overcurrent, short-circuit and temperature-related conditions.

The product label indicates a 40A discharge-current rating and a 40A charging-current rating. Heavy-gauge B− and P− cables are supplied for the main current connections, while the multi-wire harness connects to the individual series groups for voltage monitoring.

2. Technical Specifications

3. Main Connections

This appears to be a common-positive design. The battery, charger and load positive connections are normally joined directly to the pack-positive terminal.

Always confirm the wiring diagram supplied with the exact BMS before installation.

4. Protection Functions

The DALY 13S BMS is intended to provide the following battery-protection functions:

• Individual series-group voltage monitoring
• Overcharge protection
• Over-discharge protection
• Discharge-overcurrent protection
• Charging-current protection
• Short-circuit protection
• Temperature monitoring through the supplied NTC sensor
• Charge and discharge control through internal MOSFETs
• Recovery after eligible protection conditions are removed

Exact trip voltages, delay times, recovery behaviour and temperature thresholds are not visible on the product label and should be confirmed from the datasheet for the exact model.

5. Suitable Applications

This BMS may be suitable for compatible 13S lithium-ion battery packs used in:

• Electric scooters
• E-bikes
• Portable power systems
• Robotics projects
• Battery-powered equipment
• Solar and backup battery systems
• Custom 48V lithium-ion packs
• Battery repair and replacement work
• DIY energy-storage projects
• Low-to-medium-power electric vehicles

The equipment’s continuous current, peak current and starting current must remain within the verified capabilities of the BMS, battery cells, wiring and connectors.

6. Battery and Charger Compatibility

Use this BMS only when:

• The battery contains exactly 13 lithium-ion series groups.
• Each cell has a nominal voltage of 3.6V or 3.7V.
• Each cell has a maximum charging voltage of 4.2V.
• The charger is designed for a 13S lithium-ion battery.
• The charger’s maximum output voltage does not exceed 54.6V.
• The battery cells can safely supply the required current.
• The load’s continuous and peak current remain within verified limits.
• All 13 series groups are at closely matched voltages before connection.

Do not use this BMS with LiFePO₄ cells. A 13S LiFePO₄ battery requires different charging and protection-voltage settings.

7. Installation Guidance

• Measure every series group before installing the BMS.
• Ensure that all groups are at closely matched voltages.
• Connect B− to the battery-pack negative terminal.
• Connect the balance wires sequentially from battery negative towards battery positive.
• Connect P− to the load and charger negative connection.
• Connect the load and charger positive directly to the battery-pack positive terminal unless the supplied wiring diagram specifies otherwise.
• Position the NTC sensor against the cells where it can accurately detect temperature.
• Verify each intermediate voltage with a multimeter before connecting the balance plug.
• Use cables and connectors rated for the expected current.
• Keep soldering or terminal-heating time as short as possible.
• Insulate the BMS and every exposed electrical connection.
• Protect the balance wires from sharp edges, crushing and vibration.
• Mount the BMS where heat can dissipate safely.
• Do not allow the BMS enclosure or terminals to contact conductive parts.

8. Important Current-Rating Note

The 40A BMS rating does not increase the current capability of the battery cells.

The complete battery pack must be designed according to the lowest current rating among:

• BMS
• Battery cells
• Nickel strips or busbars
• Main power cables
• Connectors
• Fuse
• Charger
• Connected equipment

A load with a high starting or surge current may activate BMS overcurrent protection even when its normal operating current is below 40A.

For reliable operation, avoid continuously operating the system at its absolute rated limit unless the BMS specification explicitly permits it and adequate cooling is provided.

9. Package Contents

• 1 × DALY 13S 48V 40A lithium-ion BMS
• 1 × 13S balance/sensing-wire harness
• 1 × NTC temperature sensor
• Attached B− and P− power cables

Package contents should be confirmed against the product photographs before purchase.

10. Safety Information

• Incorrect balance-wire sequencing can permanently damage the BMS.
• Never insert the balance connector before verifying every wire voltage.
• Do not reverse the battery polarity.
• Do not short B−, P− or the battery-positive terminal.
• Use only a compatible 54.6V lithium-ion charger.
• Do not exceed the current rating of the BMS or battery cells.
• Install a correctly rated fuse close to the battery-pack positive terminal.
• Keep the BMS away from water, conductive dust and loose metal objects.
• Do not use a burnt, cracked, corroded or unusually hot BMS.
• Stop using the battery if any cell becomes swollen, damaged or excessively hot.
• Installation should be performed by a person familiar with lithium-battery wiring and safety.