This Maker decided to build his own MPPT (maximum point of power tracking) charge controller.
Lukas was asked by a friend for help on a solar project. Inspired by an Instructables article, this friend wanted to make (or inspire someone else to make) a system to charge a battery to provide power in his garden. Charging a battery might seem like a simple task, but the a panel’s varying voltage output levels present a challenge. If this voltage spikes at too high of a level, there is a risk of damaging the battery.
If this over-voltage condition were constant, a DC-DC converter, commonly known as a “buck converter” would be well-suited to make the needed voltage conversion. However, since it’s not constant, a “switching converter” would have to be used. Normally a switching converter cycles much faster than an Arduino would be able to handle, but since voltage levels change relatively slowly in this instance, an Arduino’s speed would be quite sufficient. Since this slower speed minimizes switching losses, it would actually be an advantage.
The project is well-documented here, including available design files. Once this neat converter was built, the second step was to test it out. Lukas reports that it does its job with an efficiency of over 95% in the voltage range of interest. He plans to talk about the software involved next, so hopefully we will get to see the entire charging station come together soon!
Atmel | Bits & Pieces 