The final stage on most chargers is just a bit over 13V, so that's what the battery will read at the end or while the charger is in float mode.
Johnson Controls lead acid conventional flooded cell batteries are fully charged at 12.64V.
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The idea that smart chargers don't fully charge a battery is a myth. The best way to determine the state of charge of a battery is to apply a voltage to the battery and measure how much current it draws. Since that is what chargers do, a smart charger always knows exactly how much charge the battery has. Most chargers shut off when the battery draws less than 1A. A trickle charger just overcharges the battery beyond its designed state because they don't monitor the battery state of charge.
Smart chargers are 1000% better than any other charger for fully charging a battery without shortening its life by overcharging.
I was told by a fellow that workd for O'Rilleys that when you have a deep cycle battery you need to charge it slowly. He said it is designed to give up its charge slowly and if you try to charge it at a fast rate it will damage the battery. Also that regular cranking batteries could be charged faster since they were designed to give up their power faster such as when you are cranking that big outboard.
Was just passing on what I had been told by the folks that deal with batteries everyday. I'm not a battery specialist and don't claim to be. I do batteries like this. If it is down I charge it and if that doesn't work I get another one. I do keep the cable ends clean though. A little care goes a long way.