Originally Posted by o1marc
That's the whole purpose of a deep cycle battery, to discharge slower and longer than typical batteries.
They don't discharge more slowly though. A 150 amphour battery will discharge at exactly the same rate for a given load, whatever it is made of and however constructed.
The difference is that a start battery is designed to deliver very high bursts of current for a very short time, whereas the deep-cycle battery is designed to deliver lower currents, but has the ability to be more deeply discharged and still recover.
However, they still should not be discharged to less than 50% state of charge. If you do that, you will damage them.