FYI, I'm an IT guy and an electronics noob, so please be kind. ;)
I've had my Smart Solar 75/10 since 2nd March this year, and it has been great! However, a few days ago, the battery ran completely flat as the battery had not been charged. At the time I chalked this up to bad weather, but since then, the sun has come out and the charge current remains at 0 watts, 1 watt or 2 watts.
Here are the facts of my set-up:
- Two 12v panels wired in parallel, one 10W, one 80W.
- Always-on load of a Raspberry Pi, plus weather sensing instruments and WiFi antenna. Usually draws 0.2-0.3A from the controller's load output.
- Two lead-acid batteries in parallel, 12v 12Ah, and 12v 2.3Ah.
- The controller has not been disconnected or powered down since first installation . The RPi had an uptime of over a month when the battery stopped charging.
- When the battery died and the load was shut-off automatically, I kept the load disconnected to allow the battery to recharge over several days. However, the controller only reported a yield of 3-10 watts all day. Compared to my average yield of 80-100 watts all day.
Here is what I've checked so far:
- Both solar panels are working fine and gave a 20v output under moderate sunlight for the UK.
- I connected the batteries directly to the solar panels with my multimeter in-line. It showed a draw of 3-4 Amps. Immediately I heard a hissing sound like gas escaping from the batteries, and I stopped. Am I an idiot for directly connecting the panels and batteries, or does this show the batteries are toasted and the controller is not at fault?
- I both visually inspected and continuity tested the 20A fuse and it is fine.
- I have reset the charge controller to default settings.
Observations of the charge controller when operating:
- Despite only charging the battery with 1-2 watts, the status of the controller shifted from bulk, to absorbtion and then float within a few minutes.
- When set to 'battery equalisation' mode, the charge current rose to what I would normally expect at that time of day, 20-30 watts.
Apologises if this doesn't really make sense. Please feel free to ask any questions.