I have 2 banks with the switch normally set to to only 1 bank, I can switch to both but I don't. I run only one bank at a time and switch every 2 weeks or so.
They are 6V Golf Cart batteries.
Had Trojans and dumped them. Dollar for dollar, Walmart golf cart batteries are the best bang for the buck.
I once ran one of my banks flat..... 1.2 volts.... OUCH...
Carefully coaxed them back using an older car charger
. ( took 2 days ) Got them up to 11 volts and put them on the 100 amp charger/inverter, No problems.
I have two 90 watt solar panels
that keep the house batteries "Mostly" charged",,, if I don't go crazy.... but having that second bank available is a great comfort if I do.
I also have a switch to charge them from the alternator
, but normally I keep it charging
my separate starting and windless batteries.
If my starting and windless batteries wind
up both dead, I use jumper cables
from bank 2 to handle it. Not a great solution but it's for emergencies only.
So all told I have 11 batteries
4 - 6 volt house - bank 1
4 - 6 volt house - bank 2
1 - 12 volt starter battery
1 - 12 volt windless battery
1 - 12 volt AGM
dingy/misc battery ( pretty small so works great for misc stuff)