profdant139 wrote:
OK! Some very interesting feelings about batteries are being shared here, and sharing is good. ;)
I think if I had 23 grand at stake, I would be very passionate. I have two ordinary Napa marine group 31s that cost a total of less than $300, and my last set of two lasted for five years with heavy camping use. They lived in my garage on the BatteryMinder when not on the trailer. So I have a lot less at stake, and I probably won't be buying a lot of extra equipment (ammeter, commercial-grade hydrometer, and manual charger). I have one of those squeeze-bulb hydrometers -- it accurately predicted that one of the cells in one of my former batteries was about to go bad, which it soon did. Good enough for an amateur setup.
However, I am very interested in re-wiring my panels with ten gauge wire, not only from the controller to the batteries but from the panel to the controller. I could then install a quick-disconnect between the panels and the controller, so that I could run my cable directly to my batteries and "boil" them. That project does not seem too daunting, even for someone with limited technical skills.
The hard part will be to figure out how much "boiling" is enough, and when to do it. There has to be a "cookbook" out there for non-experts -- if your battery has a rated capacity of X amp/hours, then you should boil it at Y volts for Z hours. I know that is not the expert way of doing things -- but there is a time and a place for lowest-common-denominator checklists and procedures.
There is Mexicowanderer's formula. Barring that, you babysit them while trying to apply a CONSTANT c/20 charge rate in amps, at fixed amps, until V rises at battery terminals up to 16.0V or until your Specific gravity ceases to continue climbing for the weak sister cell, the one cell per battery pack that is always a laggard and running low first in specific gravity. Whichever occurs first while babysitting, SG stops rising, or battery reachs 16.0V, then stop, shut down, and wait 48 hours, then measure open circuit voltage across the terminals. I seem to recall in my batteries, that 12.73V was a good number at 75F temp. Higher the battery temp, higher the voltage. Also measure SG across all battery cells, see if they are all at the same level in terms of battery acid density, did you get all the sulfur off the cells and back in battery acid solution?
