Help: 300Ah AGM battery, substantially decreased performanc
Hi, I am a full-time RVer with a 400W solar setup that charges my 300Ah AGM battery bank (2 x 6V 300Ah AGM batteries). I also have a 2000W inverter.
One month ago I left my RV for 4 days at an RV park while I traveled elsewhere. My batteries were near 100% charged, and I turned off all systems in my RV so the draw was less than 2A per hour with solar panels still charging about 800-1,000 Wh per day at about 22-24V (around 40 Ah).
When I returned, the batteries had fallen under 12V and were so weak that I couldn't even turn on the TV powered by my inverter. I immediately plugged them into 30A shore power to charge them up to 100%, but ever since then they have been seemingly unable to hold a full charge.
Where I probably made my biggest mistake: It got down to 25-30 degrees F each night while I was away without the batteries plugged into any shore power or trickle charger.
For example, this weekend I had them plugged into 30A shore power for 48 hours and the batteries read 12.75V after detaching according to my BMV-712 battery monitor. Two hours later they had fallen to 12.5V with very minor usage (about 7Ah draw, 14A total or 5% capacity) and they seem to fall to 12.2-12.3V with just one day of normal use (about 75 Ah). With a 300Ah battery bank that's only 25% draw, so the batteries should be about 12.4-12.5V even if I didn't have solar providing charge throughout the day.
I used to be able to go weeks with the batteries staying above 12.2V thanks to my 400W solar setup and minimal usage, only occasionally plugging into shore power or running our 3500W generator. Now I need to run the generator for 1-2 hours each day to keep the batteries from falling below 12.2V. The decline in performance after my 4 days away is stark.
My question: Based on the above, is there anything I can do to restore these batteries to proper working order? Or am I resigned to frequent generator usage or purchasing new batteries?
Thanks in advance for your advice!
One month ago I left my RV for 4 days at an RV park while I traveled elsewhere. My batteries were near 100% charged, and I turned off all systems in my RV so the draw was less than 2A per hour with solar panels still charging about 800-1,000 Wh per day at about 22-24V (around 40 Ah).
When I returned, the batteries had fallen under 12V and were so weak that I couldn't even turn on the TV powered by my inverter. I immediately plugged them into 30A shore power to charge them up to 100%, but ever since then they have been seemingly unable to hold a full charge.
Where I probably made my biggest mistake: It got down to 25-30 degrees F each night while I was away without the batteries plugged into any shore power or trickle charger.
For example, this weekend I had them plugged into 30A shore power for 48 hours and the batteries read 12.75V after detaching according to my BMV-712 battery monitor. Two hours later they had fallen to 12.5V with very minor usage (about 7Ah draw, 14A total or 5% capacity) and they seem to fall to 12.2-12.3V with just one day of normal use (about 75 Ah). With a 300Ah battery bank that's only 25% draw, so the batteries should be about 12.4-12.5V even if I didn't have solar providing charge throughout the day.
I used to be able to go weeks with the batteries staying above 12.2V thanks to my 400W solar setup and minimal usage, only occasionally plugging into shore power or running our 3500W generator. Now I need to run the generator for 1-2 hours each day to keep the batteries from falling below 12.2V. The decline in performance after my 4 days away is stark.
My question: Based on the above, is there anything I can do to restore these batteries to proper working order? Or am I resigned to frequent generator usage or purchasing new batteries?
Thanks in advance for your advice!
