Universal USB / DC / Solar Lithium Ion/Polymer charger (bq24074) Adafruit

DESCRIPTION

This charger is the only one you need to keep all your Lithium Polymer (LiPoly) or Lithium Ion (LiIon) rechargeable batteries topped up. No matter the power source at your disposal! The Adafruit Universal USB / DC / Solar Lithium Ion/Polymer Charger can use USB, DC or Solar power, with a wide 5-10V input voltage range! The charger chip is super smart, and will reduce the current draw if the input voltage starts to dip under 4.5V, making it a perfect near-MPPT solar charger that you can use with a wide range of panels.

Even though it was designed with solar in mind, it’s also great as a plain USB or DC charger – we like that you can use 5V or 9V chargers without worry, and the high charge rate is great for quickly charging up those large battery packs!

FEATURES

• 3.7V/4.2V Lithium Ion or Lithium Polymer battery charger
• Charge with 5-10V DC, USB or 6-10V solar panel – can have both USB and DC plugged in at the same time, higher voltage source will be used.
• Automatic charging current tracking for high efficiency use of any wattage solar panel
• Use any 6-10V solar panel
• Two colour indicator LEDs – Power good and Charging
• Set for 1000mA max charge rate – can be adjusted to 500mA or 1.5A by soldering closed a jumper
• Will always draw the most current possible from a solar cell – up to the max charge rate!
• Smart load sharing – automatically uses the input power when available, to keep battery from constantly charging/discharging, up to 1.5A draw. Load output is regulated to no-more-than 4.4V
• Optional Temperature monitoring of battery (requires soldering in a 10K NTC thermistor not included) – suggested for outdoor projects where the battery may get hot (50°C) or cold (0°C).

Improvements over the previous MCP73871 charger:

• USB Type C port for modern computers and chargers
• Up to 1.5A charge rate
• Up to 10V input voltage, 28V protected
• Load output is regulated to never be over 4.4V so it’s safe for 3.3V regulators or 5V boost converters
• No stabilization capacitor is needed (although you can add one if you like!)
• Same load sharing so that DC/USB/Solar is prioritized over battery power when available, to keep the battery from cycling
• Power Good LED lets you know that the charger is working
• Less expensive

However:

• The max load current is 1.5A instead of 1.8A
• There is no ‘Done’ LED – when the CHG LED turns off, that’s how you know charging is complete

RESOURCES

• Primary Guide