Originally Posted by 05mobiuslsv
You answered your own question, a maintainer maintains and doesn't charge worth a crap on a depleted battery. Premature battery failure is in your future if you go that route.
Thats the short answer, the long answer goes into the technology involved with the promariner. Download the owners manual or go to their website and there is enough info there to keep you up all night.
There are a lot of maintainers that are desulfators as well and are a fraction of the price of the promariner charger. These $20-$50 maintainers also have microprocessors and do the float/trickle/sleep things of these expensive chargers. I guess I haven't been sold one way or another and google hasn't provided any definitive answers as expensive chargers also maintain and maintainers also charge. It's just a function of time. I was hoping there would be some solid answers in regards to the need of one vs. the other here.
I guess if you're planning on charging banks with multiple batteries in each bank the expense makes sense. But either way fully discharging a battery will shorten their lifespan as well so you're probably screwed if that's happening unless the battery is a deep cycle.