I've used the 12248 battery minder often. I also have a amp hour counter/ battery monitor. The charger is silent. It has no fan. It makes diagonal wavy lines on Analog TV channel 6, but electrical noise does not really count. The amps taper as the battery reaches higher states of charge.
If a Flooded lead acid battery combines the terms RV/Trolling/Marine/Deep cycle, it is a dual purpose battery, which is just a starting battery which is slightly more tolerant of deeper discharges that a true starting battery. A true deep Cycle battery is constructed differently with thicker less porous plates of slightly different chemistry.
I have a pair of Crown 115 a/h deep cycle batteries.
Crown says to charge them at 20 amps each upto 14.5 volts.
Good luck finding the recommended charging rates for the Everstart.
I have a schumacher 25 amp "smart" charger. When my 2 batteries are low, I use every charging source I have in an attempt to give them the 40 Amps Crown recommends.
I can tell that when I give them close to the 40 amp mark by combining chargers, they are much happier the next time I discharge them compared to when I just let the Batteryminder on 8 amps take 5 times as long to top them off.
Lots of guys over on RV forums are eyeballing older school chargers. When they measure the specific gravity of the cells after using a 3 stage smart charger, they find that it is turning off too quickly, well before the battery is fully charged. If they use the older manual chargers, which might take the battery as high as 16 volts, given enough time, that the temperature compensated specific gravity readings when taken by an accurate hydrometer show that the 16 volts in needed to overcome the internal resistance of the battery , and squeeze all the amps possible into it.
There is a school of thought that you cannot really fully charge a Lead Acid battery unless you can take the voltage above 14.4. The batteryminder does this, but some other low amperage ones will never be able to achieve 14.4 volts, and thus never fully charge a battery, especially a bigger one, and it dies an early death due to chronic undercharging and the sulfation that that causes.