Hi All,
My 3 batteries were manufactured in 2/15 (4 years and a couple of months ago). I have been wondering how long they will last. They are deep cycle marine Group 24 batteries, the regular lead acid kind (not AGM).
I read the recent thread on desulfating with interest. http://www.tnttt.com/viewtopic.php?f=2&t=71499. I have an MPPT solar charge controller attached to a 150 watt high voltage solar panel, which keeps them topped off at 13.7+ volts during the day. A lot of the time while the trailer is parked there is no real draw (except to run the charge controller). My charger doesn't have a desulfating mode.
As a test, today I disconnected the solar and ran the lights and the Fantastic Fan on high for 10-15 minutes (probably a current of 4-5 amps). Voltage came down to 12.3 while the fan was running and seemed to stabilize there. With the surface charge burned off, I then turned off the lights and fan to let the batteries recover. Within 5 minutes the voltage went up to 12.6 volts. The temperature outside was 77 degrees F (25 degrees C).
From what I read, 12.6-12.7 volts is "full" on a resting battery at around 70 F. I have a sneaking suspicion that my batteries can't power my trailer for as long as they used to 4 years ago, but 12.6 volts at rest doesn't seem to be bad. Is my logic sound? (I know I should be measuring specific gravity of each cell but don't really want to go there, and I don't have the equipment.)
For those battery gurus out there, please give me your 2 cents. Are my 4+ year old batteries still ok, and how long should they last? (I don't let them go below 12.2 volts at rest, which I think is 50% charge on a hot day.). Thanks!!