Project update 2 of 8
The project is funded. A big thank you to everyone who has pledged!
Components for the first 250 boards have arrived and will be shipped to the Contract Manufacturer shortly. The plan is to build an initial batch of 50 boards for me to run through the manufacturing test fixture, working out any issues, before sending it to the CM for use with the remaining boards.
Feel free to ask questions. One question received so far is about providing more than 2A @ 5V for high-current applications. While the maximum output of the makerPower Solar was designed to match the rest of the charging and battery system, this is possible using an external DC-DC converter as shown below. The makerPower Solar 5V output is used as an enable to the external power supply, allowing its shutdown for low-battery conditions. It is connected to the fused 12V output, allowing measurement of load current and short-circuit protection.
Remember to consider how much charging energy you’ll get in a day and how deeply you want to discharge your battery at night. It’s best to limit nightly discharge levels to around 30% of battery capacity for maximum life. For example a maximum of 5.4 AH/day from an 18 AH battery. makerPower Solar was designed to keep devices consuming typically less than 0.5A running 24 hours a day, even when inclement weather limits charging on some days. This covers most IOT applications, for example a Raspberry Pi 3 webcam with WiFi typically consumes less than 300 mA. Higher current loads, such as satellite radios, should be switched on only when needed.