1. Product Overview

The DALY 10S 36V 20A BMS is a battery protection system designed for ten 3.6V or 3.7V lithium-ion cells or parallel cell groups connected in series.

A completed 10S lithium-ion battery pack has a nominal voltage of approximately 36V–37V and reaches 42V when fully charged. These batteries are commonly marketed as 36V lithium-ion battery packs.

The BMS monitors the ten series-connected cell groups and disconnects the battery when unsafe charging, discharging, current or temperature conditions are detected.

The product label specifies a 20A discharge-current rating and a 20A charging-current rating. It also includes an NTC connection for battery-temperature monitoring.

2. Technical Specifications

Protection thresholds, balancing current, recovery delays and other parameters not printed on the product label should be confirmed using the manufacturer’s specification for the exact model.

3. Typical Connection Points

The exact balance-connector pin order must be confirmed using the wiring diagram supplied with the BMS. Never identify the connections only by wire colour or physical position.

4. Protection Functions

The DALY 10S BMS is intended to provide essential protection for compatible lithium-ion battery packs, including:

• Individual cell-group voltage monitoring
• Overcharge protection
• Over-discharge protection
• Discharge-overcurrent protection
• Charging-overcurrent protection
• Short-circuit protection
• Charge and discharge control through internal MOSFETs
• Temperature monitoring through the NTC connection
• Recovery after supported protection events
• Cell balancing only if supported by the exact model

A BMS helps protect a correctly designed battery pack, but it cannot repair damaged, mismatched, internally shorted or deeply discharged cells.

5. Suitable Applications

This BMS may be suitable for compatible 10S lithium-ion battery packs used in:

• Electric bicycles
• Low-power electric scooters
• Portable power equipment
• Robotics and automated equipment
• Battery-powered instruments
• Rechargeable lighting systems
• Small backup-power systems
• DIY electronics projects
• Custom 36V lithium-ion battery packs
• Battery repair and replacement projects

The connected equipment’s continuous operating current and startup or surge current must remain within the verified capability of the BMS, battery cells, wiring and connectors.

6. Battery and Charger Compatibility

Use this BMS only when:

• The battery contains exactly ten series-connected lithium-ion cell groups.
• Each cell group has a nominal voltage of 3.6V or 3.7V.
• Each cell has a maximum charging voltage of 4.2V.
• The complete battery has a maximum charging voltage of 42V.
• The charger is designed specifically for a 10S lithium-ion battery.
• All ten cell groups are at closely matched voltages before installation.
• The battery cells can safely provide the required charge and discharge current.
• The load’s continuous and peak current remain within the verified system limits.

Do not use this BMS with 10S LiFePO₄ cells. LiFePO₄ batteries require different charging and protection-voltage thresholds.

Do not use a lead-acid charger unless its charging profile and maximum voltage have been verified as suitable for a 10S lithium-ion battery pack.

7. Installation Guidance

• Measure all ten cell-group voltages before installation.
• Confirm the balance-connector pin sequence using the supplied wiring diagram.
• Connect B− to the negative terminal of the first cell group.
• Connect the balance wires sequentially to the correct cell-group junctions.
• Connect B+ or the final sensing wire to the battery-pack positive terminal as specified.
• Connect the charger and load negative through P−.
• Connect the charger and load positive directly to the battery-pack positive terminal.
• Install the NTC sensor where it can accurately monitor battery temperature.
• Measure the voltage between every consecutive balance wire before inserting the connector.
• Use correctly sized power cables and connectors for the expected current.
• Install an appropriately rated fuse near the battery’s positive terminal.
• Keep soldering and terminal-heating time as short as possible.
• Insulate all exposed electrical connections.
• Mount the BMS where it cannot contact nickel strips, busbars, metal enclosures or other conductive components.
• Provide adequate heat dissipation when operating at higher current.

Incorrect connection of even one sensing wire can permanently damage the BMS.

8. Important Current-Rating Note

The printed 20A BMS rating does not increase the current capability of the battery cells.

The safe current of the complete battery system is determined by the lowest-rated component, including:

• Battery cells
• BMS
• Nickel strips or busbars
• Power cables
• Connectors
• Fuse
• Charger
• Connected load

Electric motors and other inductive equipment may draw startup or surge currents significantly higher than their normal operating current.

Confirm both the continuous and peak-current requirements before selecting this BMS. Operating margin is recommended instead of continuously running the BMS at its maximum advertised rating.

9. Safety Information

• Use only with a compatible 10S lithium-ion battery pack.
• Use only a charger designed for a 42V 10S lithium-ion battery.
• Never reverse the battery polarity.
• Never short the battery or BMS terminals.
• Do not connect the balance wires in the wrong sequence.
• Do not insert the balance connector until every sensing voltage has been verified.
• Do not exceed the verified charging or discharge-current rating.
• Use a suitable fuse and correctly rated wiring.
• Keep the BMS away from water, conductive dust and loose metal objects.
• Do not use damaged, burnt, corroded or unusually hot components.
• Stop using the battery if any cell becomes swollen, overheated or abnormally unbalanced.
• Installation should be performed by someone familiar with lithium-ion battery wiring and safety.