CN3791 MPPT 12V Solar Panel 1S Battery Lithium Charging Board

1S 3.7V Lithium Battery MPPT Charging Board CN3791 with 12V Solar Panel

Solar Cell 18650 Lion Lipo Battery Accumulator Charge Deep Battery Charging

     The CN3791 MPPT 12V Solar Panel 1S Lithium Battery Charging Board is a charging board with maximum power point tracking (MPPT) that charges single cell (1S) 3.7V Li-ion and Li-Po batteries with energy from a 12V solar panel. It charges the battery up to 4.2V ±1% charge voltage with about 2A current. Because the board works with 300kHz switching (PWM), it transfers the power taken from the panel to the battery with low loss.

     The board is set for a 12V panel: when sunlight decreases and the panel voltage starts to fall below this set point, the CN3791 reduces the charge current and keeps the panel at its most efficient working voltage. A fully discharged battery is first recovered with low current (pre-charge), then charged with constant current and constant voltage; charging stops when complete and restarts automatically when the battery voltage drops.

     It is easy to use: the board has 2 SOLAR IN and 2 BAT PH2.0 sockets; the panel and battery are plugged in with the cables in the package. With the VIN, GND, GND, BAT pin holes on the edge an additional panel or battery connection can also be made. The CH and OK LEDs show that charging is in progress and complete. The 45mm x 20mm board fits into solar powered cameras, sensors, weather stations and lighting devices.

Key features:

     Most power from the panel with MPPT: When the panel voltage drops to the set point the charge current is reduced; in cloudy weather the panel works at its most efficient point without collapsing.

     Full charge cycle: Pre-charge (trickle), constant current and 4.2V ±1% constant voltage stages; automatic stop at the end of charge and automatic recharge.

     2A charge current: With the 0.05ohm current sense resistor on the board it supplies about 2A charge current; suitable for charging high capacity cells such as 18650 with solar power.

     Socket connection: 2 SOLAR IN and 2 BAT PH2.0 sockets, 2 connection cables and 2.54mm pin holes allow installation without soldering.

     Status LEDs: The CH LED shows that charging is in progress, the OK LED shows that charging is complete.

Features:

• Product type: MPPT solar panel 1S lithium battery charging board
• Chip: CN3791
• Panel input: 12V solar panel (nominal)
• CN3791 input voltage range: 4.5V - 28V
• Battery type: 1S (single cell) 3.7V Li-ion and Li-Po (18650 etc.)
• Charge voltage: 4.2V ±1%
• Charge current: about 2A (fixed by the 0.05ohm current sense resistor on the board; CN3791 calculation 120mV / 0.05ohm = up to 2.4A)
• Charging method: MPPT, pre-charge (trickle) + constant current + constant voltage (CC/CV)
• MPPT method: constant voltage; the CN3791 holds the MPPT pin at 1.205V, the panel working voltage is set for a 12V panel by resistors on the board
• Pre-charge: with 17.5% of full current while the battery voltage is below about 2.8V (66.5% of charge voltage)
• End of charge: charging stops when the charge current falls to 16% of full current
• Automatic recharge: when the battery voltage drops below about 4.0V (95.5% of charge voltage)
• Switching frequency: 300kHz
• Soft start
• Battery over-voltage protection
• Indicators: CH (charging) and OK (charge complete) LEDs
• Connections: 2 SOLAR IN, 2 BAT PH2.0 2 pin sockets; VIN, GND, GND, BAT 2.54mm pin holes
• Operating temperature: -10°C - 60°C
• Color: Blue
• Dimensions: 45mm x 20mm x 9.5mm
• Weight: about 12gr

Usage information:

• Connect the panel to one of the SOLAR IN sockets and the battery to one of the BAT sockets with the PH2.0 cables in the package; following the + and - marks on the board, the red cable is the + side and the black cable is the - side.
• The two SOLAR IN sockets are in parallel; two panels can be connected in parallel. The two BAT sockets are also in parallel; 2 or 3 batteries can be connected in parallel, in which case the charging time becomes longer.
• The board has no separate load output; the circuit to be powered is connected to the battery (BAT). If you use a cell without a protection circuit, power the circuit through a battery protection board.
• The CH LED lights during charging; when the battery reaches 4.2V and the charge current drops, the OK LED lights.

Application areas:

•  Solar powered security cameras and wildlife cameras
•  Wireless sensor and telemetry nodes (LoRa, GSM)
•  Weather stations and measuring devices
•  Garden, path and outdoor lighting
•  Camping lamps and portable lights
•  Greenhouse and field monitoring systems
•  Solar charged 18650 power packs
•  Remote tracking and alarm devices
•  Bird house, beehive and animal monitoring setups
   

Points to consider:

•  It is only for single cell (1S) 3.7V lithium batteries. 2S/3S lithium packs, 3.2V LiFePO4 cells and 12V lead acid batteries cannot be charged with this board.
•  This board is the 12V panel version; with a 6V or 9V panel the panel voltage does not reach the MPPT set point of the board, so charging may not start or runs at very low current. The open circuit voltage of the panel must not exceed the 28V upper limit of the CN3791.
•  The voltages of batteries to be connected in parallel must be close to each other before connection; do not connect an empty and a full battery directly in parallel.
•  The board does not prevent over-discharge of the battery; because the load is connected to the battery, use a battery protection board with an unprotected cell.
•  Do not reverse the battery and panel polarity; at about 2A charging the inductor, diode and MOSFET get warm, place the board in a ventilated place.
•  The charge current is about 2A and there is no current adjustment on the board. Do not charge small capacity Li-Po batteries (below about 2000mAh) with this current; use high capacity cells such as 18650 or cells connected in parallel.

Package contents:

•  1 pcs CN3791 MPPT 12V Solar Panel 1S Lithium Battery Charging Board
•  2 pcs PH2.0 2 pin connection cable
•  Note: Solar panel and battery are not included in the package.