I learnt the hard way , I took my van battery out and replaced it with a Numax multifunction 85 amp , I then wired in my pump and diesel heater and sat back .
The battery would have to run the van and supply 6 amps per hour for at least 5 hours a day.
I thought that the alternator and the input from my 120w mppt solar setup would negate the bench charging .
It ran successfully for just over 12 months before letting me down 3 times in a row by not starting the van at the end of the day !
The truth being that every time the battery was used it was then not sufficiently recharged , over time it had lost its memory/capacity.
I now run a stand-alone Numax 105 MF that comes out every day regardless of use , depending on the days weather it can be on charge from between 10 minutes and 5 hours .
Charging every night is absolute key into maintaining the battery capacity, if you are topping it up every day it will greatly improve the cycle life that the manufacturer states .