Peter I know this goes againt what people say but I opperate our batts the same way as you. I don't have any fancy bells that go off when I hit 12.2 but use them until I notice things running slower. I then check the volts and it is usually in the 10.5 to 11.5 range. I just put new batteries in last week. The last time was April of 1999. We use 4 8D's