BMS 2S 3A Protection Board

2S 3A 7.4V Lithium Battery Bms Protection Board
18650 Li Ion Li Po 8.4V Charging Circuit Overcharge Overdischarge Short Circuit Protection

It is a basic rule that you are able to set the charging current with your own external circuit.

     The 2S 3A lithium battery BMS protection board is used for protection in battery packs made up of 2 series-connected 3.7V Li-ion or Li-Po cells, with 7.4V nominal and 8.4V fully charged voltage. It is suitable for 18650 battery packs, small portable electronic devices, hobby circuits, sensor systems and low-current battery applications.

     This product is not a charger. It does not charge the battery on its own, and it does not make 2S battery charging possible with a 5V usb adapter or a random power supply. If a 2S lithium battery pack is to be charged, a suitable 8.4V CC/CV lithium battery charger must be used. The task of the board is to help protect the battery pack against overcharge, over-discharge, overcurrent and short circuit conditions.

     The charge and load connection is made from the P+ and P- terminals. The B+, B- and BM terminals are for the battery connections. The BM terminal is the junction midpoint of the two series batteries, and the board does not work correctly without this connection being made. It is recommended that the series-connected batteries are of the same type, of close capacity, at a similar charge level and in healthy condition.

     Important information about the charging current: The 3A value stated on this board does not mean that the battery has to be charged at 3A. The 3A value is related to the current carrying and protection capacity of the board. The charging current must be selected according to the capacity of the battery used and the charging value permitted by the manufacturer. This board does not set the charging current; the current is determined by the 8.4V CC/CV lithium battery charger used. If the charging current permitted by the battery is not known, a high-current charger should not be preferred.

Features:

• Protection circuit for 2 series lithium batteries.
• Cell count: 2S
• Compatible battery type: Li-ion / Li-Po
• Compatible battery structure: 2 series 3.7V lithium cells
• Nominal pack voltage: 7.4V
• Fully charged pack voltage: 8.4V
• Charger voltage: an 8.4V DC 2S Li-ion / Li-Po CC/CV charger must be used
• Charge connection: made from the P+ and P- terminals
• Board current capacity: 3A  (the 3A value is not the recommended charging current of the battery)
• Instantaneous peak current: 5A
• Overcharge protection: Yes
• Over-discharge protection: Yes
• Overcurrent protection: Yes
• Short circuit protection: Yes
• Overcharge detection voltage: 4.25-4.35V per cell, tolerance 0.05V
• Over-discharge detection voltage: 2.3-3.0V per cell, tolerance 0.05V
• Standby current: below 3uA
• Internal resistance: below 45milliohm
• Operating temperature: -40C to 50C
• Size: 36mm x 6mm x 2mm

Board connections:  Please examine image number 1.

• B+: Positive terminal of the battery pack
• B-: Negative terminal of the battery pack
• BM: Junction midpoint of the two series batteries
• P+: Common positive terminal for charge and load
• P-: Common negative terminal for charge and load

Areas of use:

• 2S 18650 battery packs
• 7.4V lithium battery applications
• Portable electronic devices
• Small hobby circuits
• Low-current robotics applications
• Sensor and control circuits
• Small led lighting systems
• Prototype battery packs

Points To Be Careful About:

• This product is not suitable for 1S, 3S or 4S battery packs.
• It is not suitable for LiFePO4 battery chemistry.
• It is not a charger, voltage booster or voltage reducer.
• With motors, pumps, heating elements, powerful leds, hand drills, electric bicycles and loads drawing high startup current, the 3A limit can be exceeded.
• If the batteries are connected in reverse, the board or the batteries can be damaged.
• It must not be used without the BM connection being made.
• Batteries of different capacity, different brand, mixed old-new or with voltages very different from each other must not be connected in series.

Package contents:

• 1 Piece 2S 3A Lithium Battery BMS Protection Board