In another thread I explore why my electric
winches are slowing down and the unanimous advice is that I have a battery
problem. Here: Electric winches slowing down - problem lurking?
. Basically my winches slow down quite noticeably while under constant load (about 60 seconds of hoisting my butt up the mast)
I have six 8GGC2 6 volt Gel batteries arranged in three pairs for 12 volts and approx 540 aH. They were new in May of last year and worked fine until I laid up the boat in November with the batteries fully charged. The winter was extra frigid so I'm suspicious the batteries froze. In April the volts checked at approx 3.5 for the bank. Not good. I had to use an automotive charger
to bring them up enough to let my Trace charger/inverter kick in and take over. They've been on shore power
ever since, except while sailing of course, and I've confirmed the charger
setting are correct per the manual.
They seem to lose their charge faster than they used to, and don't hold as high a charge. I did some testing a few days ago hoping this data would help me get help from the experts here.
With the charger turned on my volt meter tells me I have 13.4 volts.
Turn off charger and wait a few minutes (no load on) and the volt meter settles at 13.0 volts.
Next I disconnected all the batteries and took a voltage reading of each one individually. They I reconnected them, turned on enough equipment
to see a 10 amp drain on the bank, and left it that way for 1 hour. Then I removed the load, disconnected all the batts again and took another reading. Below are the before/after readings of my six batts (in Port, Center, Stbd pairs):
Full bank: 13.00/12.6
I also have a new Balmore SmartGauge battery monitor
that has seen several use cycles now and should be calibrated. It tells me my State of Charge is 84% before and 81% after my test. I don't know yet to believe this. It has never gone above 85%, which is disturbing.
Are my one-year-old batteries damaged?
All advice appreciated.