When I logged the second solar charge last week I had the computer plugged into mains power and the homebrewbattery inverter was switched off. There was basically no load on the battery, and that was visible in how flat the battery voltage curve was when the charging was finished. Today I raised the stakes and left the battery powering the laptop that was performing the logging. On top of this it was a rainy day with substantial cloud cover. Would the charging keep up at all, or would the laptop drain the homebrewbattery too far?

The spikiness of the charge power curve shows the patches of sunlight reaching through the cloud cover. Interestingly, the weather must have deteriorated because no data at all was logged between 3:00 and 4:30 – it got so dark that the PCM 60x charge controller switched off! In the face of this poor weather, 142 Wh of captured energy is exciting.

The underlying downward trend of the battery voltage this time shows the steady load draining the battery. The patches of sun in the middle of the day were enough to top it up and when I got home from work the inverter was still happily providing power for the laptop. My concerns about finding the battery way under-voltage after a day of zero charging were unfounded.

Only one thing failed in this test: my second attempt at real-time remote monitoring “broke” after about 1.5 hours. My next goal is to sort this out and get a live charging monitor on this website.