# Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer Charger ## Overview Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop. You can pulse the CE pin high briefly to reset the timer. ![](https://cdn-learn.adafruit.com/assets/assets/000/133/748/medium800/components_6091-05.jpg?1732203778) We're always on the look out for better ways to make projects portable: being able to charge your battery in the most convenient manner will let projects run no matter what power is available. The **Adafruit bq25185 USB / DC / Solar Charger Board** , which uses the new [bq25185](https://www.ti.com/product/BQ25185), is a nifty charger chip with a lot of flexibility for different kinds of batteries (LiPoly, LiIon or LiFePO4), charging rates (250mA, 500mA, or 1A) and power sources (USB, DC or solar). It's also a great value, so it's a good upgrade from [MCP73833](https://www.adafruit.com/product/259) or [MCP73831-based](https://www.adafruit.com/product/4410) charger boards. ![](https://cdn-learn.adafruit.com/assets/assets/000/142/618/medium800/components_6091-06.jpg?1772462366) To let folks really explore what this chip can do, we made a basic breakout board with all the things we find most useful: two ways to power/charge including a solar-friendly DC input, adjustable current and voltage, power path management, and status and control I/O. - **USB Type C** connector with 5.1k CC resistors so it will work with any computer or power supply to get 5V and up to 1A - **Separate DC or Solar Input** - Two pads on the side can be used to connect a 5 ~ 18V power supply, which can be used instead of USB. If the input is a solar panel, the charging chip will adjust the current draw so that the voltage does not dip below the battery, thus optimizing the solar power input. No large capacitor needed to stabilize it, and you get near-MPPT capability without the cost and complexity of MPPT. - **Default charge rate of 500 mA** , but you can cut the **IS** jumper on the front and solder either jumper on the back to set the rate to 1A or 250mA - **Default 3.7V nominal / 4.2V max** battery chemistry/voltage for all modern 1-cell LiPoly or LiIon batteries. You can set this to 3.2V / 3.65V for **LiFePO4** batteries by cutting the **VS** jumper on the front and soldering a jumper on the back - **Power Path to Load** - If the load connector is drawing current while the USB / DC/Solar power is attached, it will default to drawing current from the charger and any left over current will go to the battery. That keeps your battery from constantly charging/discharging which will reduce the battery life. The max draw from USB / DC / Solar is still 1A, if you need more current it will come from the battery and the chip can provide up to 3A current spikes from the battery to the load output! - **Regulated 4.5V-max Load Output** - no matter what voltage you have on the USB or DC / solar inputs, the Load output port will never go above 4.5V due to an internal voltage regulator. Keep this in mind, though, when dealing with high currents and high DC voltages as the LDO will make the board start to overheat and throttle the current. - **Three Status LEDs** - Orange Charging LED, red Fault LED, and Green Power Good LED. The charge/fault pins are also available on the left side breakout pads. - **Thermistor -** cut the TH trace and you can connect a 10K thermistor to the TH pad which will adjust the charge rate to keep the battery from overheating. - **Chip Enable** to disable the charger. - Mounting holes! ![](https://cdn-learn.adafruit.com/assets/assets/000/133/750/medium800/components_6091-04.jpg?1732203934) This board is pretty much plug-and-play. Change any jumpers you like and then connect your battery to the BATT port, and the LOAD goes to your circuit. Don't forget the LOAD will never go above 4.5V, but it can go as low as 3.0V if the battery is nearly empty. You can monitor the voltage on the battery and load via the secondary pads on the right side, if necessary. ![](https://cdn-learn.adafruit.com/assets/assets/000/133/751/medium800/components_6091-03.jpg?1732203959) To use with solar, [pick up a 5~7V solar panel](https://www.adafruit.com/category/580), and either cut the connector off to wire it directly, or [use a 2.1mm adapter cable](https://www.adafruit.com/product/2788) plus a [2.1mm terminal block](https://www.adafruit.com/product/368) to get two wires for the DC Input port. If you need a board with higher charge current or a DC plug already on-board, [check out the bq24074 which has up to 1.5A charge rate and a on-board 2.1mm DC jack](https://www.adafruit.com/product/4755). # Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer Charger ## Pinouts Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop. You can pulse the CE pin high briefly to reset the timer. **Revision History:** - **As of February 5, 2025**  - The back silkscreen now has the correct jumper details. ![](https://cdn-learn.adafruit.com/assets/assets/000/142/617/medium800/components_dbl.png?1772462184) Info: The JST connectors on this breakout are [JST-PH (2 mm pitch)](https://www.jst.com/products/crimp-style-connectors-wire-to-board-type/ph-connector/). These are the same connectors on the LiPoly batteries in the Adafruit shop. ## USB Connector At the top edge of the board is the **USB Type C** connector. It has 5.1k CC resistors so it will work with any computer or power supply to get 5V and up to 1A. ![components_usb.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/756/medium640/components_usb.jpg?1732206702) ## DC/Solar Input - **DCIN** - On the right side of are the board are the DC or solar input pads. They can be used to connect a 5 ~ 18V power supply, which can be used instead of USB. If the input is a solar panel, the charging chip will adjust the current draw so that the voltage does not dip below the battery. ![components_solarIn.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/757/medium640/components_solarIn.jpg?1732206898) ## Battery Output - **BATT** - At the bottom of the board is the JST-PH battery connector, labeled BATT on the board silk. By default, the output is 3.7V nominal / 4.2V max battery chemistry/voltage for all modern 1-cell LiPoly or LiIon batteries with a default charge rate of 500 mA. This output is available on the right side of the board as well. You can use this secondary output to monitor the voltage on the battery with a multimeter. ![components_battOut.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/758/medium640/components_battOut.jpg?1732207244) ## Load Output - **LOAD** - At the bottom of the board is the JST-PH load output connector, labeled LOAD on the board silk. It provides a regulated 4.5V-max load output. No matter what voltage you have on the USB or DC / solar inputs, the load output port will never go above 4.5V due to an internal voltage regulator. Keep this in mind, though, when dealing with high currents and high DC voltages as the LDO will make the board start to overheat and throttle the current.  You can monitor the voltage on the load via the secondary pads on the right side, if necessary, with a multimeter. If the load connector is drawing current while the USB / DC/Solar power is attached, it will default to drawing current from the charger and any left over current will go to the battery. That keeps your battery from constantly charging/discharging which will reduce the battery life. The max draw from USB / DC / Solar is still 1A, if you need more current it will come from the battery and the chip can provide up to 3A current spikes from the battery to the load output! ![components_loadOut.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/759/medium640/components_loadOut.jpg?1732207821) ## Status and Control I/O - **TH** and **jumper** - This is the thermistor pad. You cut the TH jumper and you connect a 10K thermistor to the TH pad which will adjust the charge rate to keep the battery from overheating. - **VS** and **jumper** - This is the voltage setting pad. If you are using **LiFePO4** batteries instead of 1-cell LiPoly or LiIon batteries, you can cut the VS jumper and solder the 3.65V jumper on the back closed. - **IS** and **jumper** - This is the current setting pad. You can cut the jumper to change the charge rate with the current jumpers on the back of the board. - **S1** - This is the Status 1 pad. It is connected to the red FAULT LED. - **S2** - This is the Status 2 pad. It is connected to the orange charge (CHRG) LED. - **/CE** - This is the chip enable pad. You can pull this pad high to disable the chip. ![components_controlPinsJumpers.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/761/medium640/components_controlPinsJumpers.jpg?1732208448) ## Current and Voltage Back Jumpers - **Change current jumpers** - on the back of the board are two jumpers to change the charge current rate. If you cut the IS jumper, you can solder one of these jumpers closed to set the charge current to 1A or 250mA instead of the default 500mA. - **Change voltage jumper** - on the back of the board is a single jumper to change the voltage range to 3.2V nominal / 3.65V max instead of the default 3.7V nominal / 4.2V max. This voltage range is used for LiFePO4 batteries. You will need to cut the VS jumper first before soldering this jumper closed. ![components_backJumpers.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/763/medium640/components_backJumpers.jpg?1732210055) ## Status LEDs - **CHRG** - This is the charge status LED. It is an orange LED. It is connected to the **S2** (Status 2) pin on the left side of the board. It will be lit while a battery is charging.  - **FAULT** - This is the fault status LED. It is a red LED. It is connected to the S1 (Status 1) pin on the left side of the board. It will be lit if the board experiences a fault condition. The bq25185 has integrated fault protection for a few conditions: - Input overvoltage protection - Battery undervoltage protection - Battery short protection - Battery overcurrent protection - Input current limit protection - Thermal regulation and thermal shutdown - Battery thermal fault protection - Safety timer fault - ISET and ILIM/VSET pin short/open protection. - **PWR** - This is the power good LED. It is a green LED. If the the board is powered properly, this LED will be lit. ![components_leds.jpg](https://cdn-learn.adafruit.com/assets/assets/000/133/762/medium640/components_leds.jpg?1732209230) # Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer Charger ## Downloads Danger: There is an unmodifiable 6 hour safety timeout on this chip. If the board is charging for 6 hours without any interruptions, charging will stop. You can pulse the CE pin high briefly to reset the timer. ## Files - [bq25185 Datasheet](https://cdn-learn.adafruit.com/assets/assets/000/133/752/original/bq25185.pdf?1732204133) - [EagleCAD PCB Files on GitHub](https://github.com/adafruit/Adafruit-bq25185-Charger-Breakout-PCB) - [3D models on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts/tree/main/6091%20bq25185%20USB%20Charger) - [Fritzing object in the Adafruit Fritzing Library](https://github.com/adafruit/Fritzing-Library/blob/master/parts/Adafruit%20bq25185%20USB%20-%20DC%20-%20Solar%20Lithium%20Ion%20Polymer%20Charger.fzpz) ## Schematic and Fab Print ### Rev B1 **Revision History:** - **As of February 5, 2025**  - The back silkscreen now has the correct jumper details. ![](https://cdn-learn.adafruit.com/assets/assets/000/142/615/medium800/components_schem.png?1772461842) ![](https://cdn-learn.adafruit.com/assets/assets/000/142/616/medium800/components_fab.png?1772461849) ### Rev B ![](https://cdn-learn.adafruit.com/assets/assets/000/133/753/medium800/components_schem.png?1732205019) ![](https://cdn-learn.adafruit.com/assets/assets/000/133/754/medium800/components_fab.png?1732205029 dimensions are in inches) ![](https://cdn-learn.adafruit.com/assets/assets/000/138/303/medium800/components_6091_bq25185_USB_Charger.jpg?1752095701 ) ## Primary Products ### Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer charger [Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer charger](https://www.adafruit.com/product/6091) We're always on the look out for better ways to make projects portable: being able to charge your battery in the most convenient manner will let projects run no matter what power is available. The **Adafruit bq25185 USB / DC / Solar Charger Board** uses the new  Out of Stock [Buy Now](https://www.adafruit.com/product/6091) [Related Guides to the Product](https://learn.adafruit.com/products/6091/guides) ## Featured Products ### 6V 2W Solar Panel - ETFE [6V 2W Solar Panel - ETFE](https://www.adafruit.com/product/5366) These panels come to us from [Voltaic Systems](http://www.voltaicsystems.com), makers of fine solar-powered bags and packs. These are waterproof, scratch-resistant, and UV resistant, and they use 12 high efficiency monocrystalline SunPower cells with 22+% efficiency _(praise the..._ In Stock [Buy Now](https://www.adafruit.com/product/5366) [Related Guides to the Product](https://learn.adafruit.com/products/5366/guides) ### 3.8 / 1.3mm or 3.5 / 1.1mm to 5.5 / 2.1mm DC Jack Adapter Cable [3.8 / 1.3mm or 3.5 / 1.1mm to 5.5 / 2.1mm DC Jack Adapter Cable](https://www.adafruit.com/product/2788) This convenient **3.8mm/1.3mm or 3.5mm/1.1mm or 1.3mm DC to 2.1mm DC adapter cable ** lets you plug one of our [solar panels](https://www.adafruit.com/categories/67) into [our optimized Solar Lithium Ion/Polymer...](http://www.adafruit.com/products/390) Out of Stock [Buy Now](https://www.adafruit.com/product/2788) [Related Guides to the Product](https://learn.adafruit.com/products/2788/guides) ### Female DC Power adapter - 2.1mm jack to screw terminal block [Female DC Power adapter - 2.1mm jack to screw terminal block](https://www.adafruit.com/product/368) If you need to connect a DC power wall wart to a board that doesn't have a DC jack - this adapter will come in very handy! There is a 2.1mm DC jack on one end, and a screw terminal block on the other. The terminals are labeled with positive/negative assuming a positive-tip configuration... In Stock [Buy Now](https://www.adafruit.com/product/368) [Related Guides to the Product](https://learn.adafruit.com/products/368/guides) ## Related Guides - [Introducing the Adafruit Grand Central M4 Express](https://learn.adafruit.com/adafruit-grand-central.md) - [Adafruit Chainable DS18B20 Extender Breakout](https://learn.adafruit.com/adafruit-chainable-ds18b20-extender-breakout.md) - [ADXL345 Digital Accelerometer](https://learn.adafruit.com/adxl345-digital-accelerometer.md) - [Adafruit FONA 808 Cellular + GPS Shield for Arduino](https://learn.adafruit.com/adafruit-fona-808-cellular-plus-gps-shield-for-arduino.md) - [Geofencing with the FONA 808 & Adafruit IO](https://learn.adafruit.com/geofencing-with-the-fona-808-and-adafruit-io.md) - [Adafruit QT Py CH32V203](https://learn.adafruit.com/adafruit-qt-py-ch32v203.md) - [Adafruit Feather RP2040 with USB Type A Host](https://learn.adafruit.com/adafruit-feather-rp2040-with-usb-type-a-host.md) - [Adafruit bq25185 USB / DC / Solar Charger with 3.3V Buck Board](https://learn.adafruit.com/adafruit-bq25185-usb-dc-solar-charger-with-3-3v-buck-board.md) - [Ladyada's Bento Box](https://learn.adafruit.com/lady-adas-bento-box.md) - [Adafruit PiCowbell DVI Output](https://learn.adafruit.com/adafruit-picowbell-dvi-output.md) - [ Adafruit DRV8833 DC/Stepper Motor Driver Breakout Board](https://learn.adafruit.com/adafruit-drv8833-dc-stepper-motor-driver-breakout-board.md) - [Sending Live Sensor Data to iOS with BLE](https://learn.adafruit.com/bno055-ble-ios-app.md) - [Adafruit bq25185 USB / DC / Solar Charger with 5V Boost Board](https://learn.adafruit.com/adafruit-bq25185-usb-dc-solar-charger-with-5v-boost-board.md) - [Adafruit STHS34PF80 IR Presence / Motion Sensor](https://learn.adafruit.com/adafruit-sths34pf80-ir-presence-motion-sensor.md) - [Introducing Gemma](https://learn.adafruit.com/introducing-gemma.md)