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
Help with revamp of small 300 watt setup...Keep getting low voltage disconnect
- Thread starter blindowl
- Start date
MisterSandals
Participation Medalist
8 years for lead acid batteries is a good run, i'd suspect they are gone.
How are you measuring this? Voltage? If so, what voltage.
What disconnect mechanism? 12.3V isn't dead but elderly batteries may struggle to stay above here as they lose their ability to hold a charge.
If you want to milk out any remaining usefulness, you can lower your low voltage disconnect to 12V until that no longer works and then the last gasp down to 11V.
Two batteries are 3 years old, and one is 8 years old. Surprisingly the 8 year old battery was tested with a load tester and a bulb tester, and its doing great. Other batteries checked good too. No bad cells on any of them. Usually the batteries never run below 12.6 volts at night, when I check each battery in the AM. Disconnect and recover voltages can be user set in the charge controller. I'm not a math wiz by no means but I figure 300 AH total for batteries. 50% would be about 150. So I might have as much as 75-80% of full charge left. All the calculators I've used say I should be able to run this with one battery and 1-100 watt panel. I'm big on overkill probably. If I were to suspect one or more batteries dying, which according to testing they're not...Here in the fall-winter I'm able to recharge them by 10AM with an 8AM sunrise. Panels might be getting daylight then, but not direct sun until about 2PM til 4PM. That's with the current problem of the batteries going to the 12.3 volt low voltage cutoff. I'm still stumped with everything I've tried. I suspected one or more batteries, then possibly a panel was shorted or something. That doesn't appear to be it
MisterSandals
Participation Medalist
How are the batteries wired? In a balanced manner or all from one end?
What charge controller?
3x 100W panels in series or parallel?
What charge controller?
3x 100W panels in series or parallel?
Batteries are in parallel and panels are in parallel. Batteries are all connected using 6 premade cables from auto parts store. We're trying an experiment here tonight though. Pulling out all the stops lol. There's two 18 watt LED floodlights 15-18 feet to the left of my 1st closest panel. They're not directly aimed at any panels, but to the left of my closet panel. So those lights put out equivalent of 100 watts each. I'm wondering if that far left panel is picking up enough light, to trick the setup into thinking its the sun coming up? I told the wife not to turn on the floodlights when she goes outside anytime tonight. Then I'll know if the panels are picking up the floodlights. This hasn't been an issue in the past that I know of even with the two existing panels. Adding that 3rd panel might be enough though to mess things up? Batteries.... started at 12.9 volts at 5:45 PM. At 7:15 PM I'm at 12.6 volts. Controller shows I'm drawing 0.9 amps. That 12 volts goes into a buck booster down to 3.7 volts for the LED lights. What the batteries will read at 5AM, well I guess I'll see tomorrow. Maybe batteries are ok and it was something weird that happened one night with them draining lower than usual. Maybe the large LED floodlights on the house are a separate issue. Thanks for any ideas and your help
MisterSandals
Participation Medalist
Does not matter at all.
With 2 panels in parallel adding a 3rd panel will not mess anything up but will add to array amps.
What charge controller?
Sounds like you are not fully charging your batteries.
Is there a reason you have all panels in parallel?
Are your batteries wired in a balanced manner? have a pic of wiring?
The LED spot/flood lights on the house are being picked up by the new panel on the left. System thinks its sunlight, whenever my wife turns on the 200 watts of LED in the fixture on the house. LED is too close to the spectrum of light produced by the sun, according to some articles I read last night. We turned on that 200 Watts of LED light last night, and the solar setup shut off within minutes. Turned the floodlights off, and minutes later the solar setup was working. Re aimed the floodlights this morning so far so good. Battery issue seems to have resolved itself and they were at 80% of full charge at 5 AM this morning
