I had a PD9245 for a project for a friend, in summertime, and the fan almost always ran, at varying speeds/ noise levels, depending on the load.( the amps the battery needed to achieve 14.4v)
Generally batteries need to be under 75% charged to accept high amperage for a brief period and amps generally begin tapering at 80%, but this depends on the maximum current of the charging source. It is when they are 50% charged that they will max out a charging source for a good half hour or more which heats up the charging source greatly.
The PD's have good heatsinking and ventilation, and a reputation for keeping batteries pretty healthy.
You can leave it plugged in. From storage mode every 18 hours it will bump voltage to 14.4 to stir up the electrolyte and destratify the acid.
If I were forced into a 3 or 4 stage automatic converter, it would be the PD9245, pd9260 or pd9270, and it would be the 14.8v version unless I had Lifeline AGM batteries, then the 14.4v version would be preferable.
BUt I do the adjustable voltage powersupply thing, and find spinning a dial is faster than holding a button down and being limited to 3 outputs. I personally do not need or want 'automatic'.
I plugged into the grid last night as i went a few days only getting to 99%, and I wanted to heat my showerbag to 100F via my 12v heating pad, which eats up a good 30AH of battery capacity. I kept it at 14.7v until eyes started crossing then I lowered it to 13.7v for the rest of the night. Now I got a very full battery, 5 gallons of 100F water, and a new large groundswell is massaging the coastline and building, and the time to go extract some energy from the ocean.
