How far should I drain the batteries?

[TX-Foilhead]

For all the stereo guru's; Next weekend I'm pulling a show at a dragboat race, lasts about 20min. Between times we sit in a creek off to the side of the course away from the crowd and there are no other spectators or PA speakers close by. My plan is to run the stereo at no more than half volume and switch between tunes and the PA FM feed. Did a 4 hour test run today on music at about the same volume i expect to use and dropped the batteries to 12.3 volts. I'll get a little bit of a charge from the show with nothing running so I don't expect it to go lower. My question is, is that too low? I usually don't go much below 12.5 volts. The boat will get plugged in nightly so I should start out full all 3 days. The system has about 2000 watts all class D and a 100 amp alternator will be charging 2 group 29's during the show.

[EarmarkMarine]

Some commercial grade deep cycle batteries are okay with 80 percent depletion. But, true commercial grade batteries are REALLY expensive. For your consumer grade deep cycle batteries you do not want to go below 50 percent depletion which is considered 12 volts. This will extend the longevity of your batteries and allow them to maintain an amp/hour capacity closer to the original specs for much longer. A deep cycle battery will give you an inordinate number of shallower cycles but has far less tolerance for deeper cycles.


David
Earmark Marine

[TX-Foilhead]

Thanks David, I tried to overkill everything while I was building it to cover these odd situations that happen every once and a while. I don't generally have the REV 10's at this level when we sit, but in this case we may be 20 or 30 yards from the boat so it's nice to let them do their job. Glad to know I don't have to figure out how to get a generator or keep the listening to a minimum.

[gride]

speaking of alternators, can my 100amp alternator keep up with a pair of deep cycle batteries with 300amp hours @20 amps or 260 amps hours @ 25 amps? i typically start off my cranking battery and run with that, except when the boats off or filling/emptying all the ballast. then i switch back over to the cranking battery if i had turned the boat off and do not run on the deep cycles(pole 2 of perko switch)