I bought a pair of T 125's for our TT back in 2004. Installed the Charge Wizard which properly modulates the PW house charger. Plugged in at home all the time. When I sold the TT in 2014 they were still going strong so it was a no brainer to do the same thing on our new to us TT. The key to wet battery usage longevity is to not discharge them more than 50%. Though they are designed to go to 0, this adds to there life significantly. Now I have 428 watts solar on a Morning star controller. We spent a week at the beach, dry camping with tw0 college kids charging there stuff and we never ran the generator. So get a battery meter or plug a VOM into the cigarette lighter socket and measure the batteries charge state. I also feed a 2000 watt Xantrax Inverter so we have 110volts for tv's whatever. Still run the frig on gas but when we get lazy, we do plug in the coffee pot!