How long batteries last ?

Just sharing my own experiences with you guys, i been driving for many years on many trucks, and the batteries nowadays are not so good as they just to be, plus that we have a lot of electrical things we just din't have before.
Myself run a 7.6 cubic feet home refrigerator, a 1200 watt microwave, a cooking pot (1000 watt) coffie maker (1000 watt), electric grill (1400 watts) 40 inch Samsung tv with sound bar (340 watt), bunk heater and other electrical things constantly. The Inverter i have its a WZRELB 3000 watt pure sine wave from Amazon, it do use less amps that my old Xantrex that went south and its more reliable that the ones sold at truck stops, coupled with one Lcd digital display energy meter ($11,00) in bunk that let me know all the time the health of the batteries and the system.
The solution i have found after many many electrical problems was: upgrading engine alternator from 135 amps to a Leece Neville 230 amps alternator, upgrading apu alternator from 65 amp to 120 amp DB Electric alternator and replacing the 4 batteries of the truck every 18 months. Volvo dealerships do have very good battery prices, most of the time i find them for $65 to $69 bucks. Changing them myself for less than $300 bucks every 18 months give me peace of mind and less problems. I do also clean the batteries, terminals and posts and grease them (regular grease) every six months. Thats the only way i have found to keep the electricity side up and running with no problems. Hope it helps.
PD: Keep always a good jumper cable with you, you'll never know when its gonna be needed for your truck, or for a beatiful long legs blond gal on the side of the road.