Ok I've had this 300 watt 12 volt DIY setup for 8 years. Suddenly it started going off on low voltage disconnect after a few hours. I've got 3- 100 watt panels going 40 feet with #10 stranded wire. I've got 3 deep cycle batteries 100 amp hour each. I only run the batteries down to maybe 70% so plenty of reserve there. Batteries have been tested and no problem with them. I use my setup only for low voltage lighting. I had 9 old landscape lights which were 12 volt. Also 13 small lights that are running at 4.5 volts. They're the little LED lights that run on 3 AA batteries from Harbor Freight, probably cost $1.50 each. Hey they work ok for solar though, nice and bright. System shows its drawing .09 amps to 1.1 amps. Lately the system started going off on low voltage disconnect at 12.3 volts, with recover voltage of 12.6 volts. I got rid of the 12 volt LED landscape lights this week as they were old. There's about 9 watts used right there and I thought that might be my power drain, and causing my low voltage disconnect. Everything now is stepped down from 12 volt to 4.5 volts with the 13 lights I have now. Still have the low voltage disconnect issue. I've got a no frills charge controller rated at 30 amp. I switched it out with another controller. Didn't fix the issue either. One of the panels got hit by something over the summer and cracked the top glass. It appears to be still working ok unless something is shorted internally. I recently unhooked that damaged panel thinking that's my problem. That didn't fix it and this elusive issue is driving me crazy lol. The whole setup is running only 5 hours after sunset and worked ok for years. Batteries charging fully before noon. I can't seem to figure what is draining the batteries down within a few hours. Only other option is to let the system run 5 hours over night without any of the LED lights on. Then check battery voltage at charge controller in the morning. Sorry for the long post but I'm open for ideas on what to check for next. Thanks