Sunny Buddy is a Maximum Power Point Tracking (MPPT) solar charger for single-cell LiPo batteries. This MPPT solar charger provides you with the ability to get the most possible power out of your solar panel or other photovoltaic device and into a rechargeable LiPo battery. Setup is easy: just plug your solar panel into one side of the Sunny Buddy and your battery into the other, then you are good to start charging.
The Sunny Buddy is a switching supply; the output power is given by the equation Pout = Pin * Efficiency. The Sunny Buddy's efficiency has been measured repeatedly to be about 80% in tests, compared to less than 60% best case from comparable linear solutions.
The output of the Sunny Buddy is intended to charge a single polymer lithium ion cell. The load should be connected in parallel with the battery. By default, the Sunny Buddy comes set to a maximum charge current of 450mA with a maximum recommended input of 20V (minimum 6V). It's recommended that batteries not be charged at greater than their capacity rating; thus, the smallest battery that should be charged with the Sunny Buddy is 450mAh.
Each Sunny Buddy comes equipped with an LT3652 power-tracking 2A battery-charging circuit and pre-installed barrel jack and 2-pin JST connectors. It also has unpopulated areas where you can install your own 3.5mm screw terminals, headers or another power jack for added input/output options. A potentiometer on the input lets you set the holding voltage for MPPT — in full sun, adjust the potentiometer until V_SET = 2.8V.
The barrel jack power input supports the PRT-07840 and PRT-09241 solar cells, and the JST connector supports the batteries listed in the Optional Recommended Products list below.
Also below, you can add 3.5mm screw terminals to your order. These can be installed in places on the board for an additional solar panel input (a second power jack can be installed instead) and for a load output (header pins can be installed instead).
You will have to clear jumper JP1 and connect jumper JP2 if you want to use both solar panel inputs. Note also that the load output option is in parallel with the battery, so it will steal some charge current from the battery when in use. Therefore, you should make sure whatever device you connect to the Load is put into Sleep mode or otherwise deactivated whenever possible.
MPPT Solar Charger Resources
Optional Recommended Products for this Item
|Solar Panel, 3.5W, 6V/615mA, 3.5x1.1mm Barrel, 5.5x2.1mm Adapter||+|| US$39.00|
|Polymer Lithium Ion Battery, 850mAh, JST Connector||+|| US$9.95|
|Polymer Lithium Ion Battery, 2000mAh, JST Connector||+|| US$16.95|
|Polymer Lithium Ion Battery Pack, 6Ah, JST Connector||+|| US$29.95|
|Screw Terminal Block, 3.5mm, PCB Mount, 2 Pin||+|| US$0.50|
|Screw Terminal to Male DC Barrel Jack Adapter, 2.1x5.5mm||+|| US$2.95|
|Female DC Barrel Jack (2.1x5.5mm) to Screw Terminal Adapter||+|| US$2.95|
|DC Power Connector, Barrel-Coaxial 2.5/5.5 mm||+|| US$0.50|