I have a Lexus that is 6 years-old and we installed fifth battery last month after thorough check of electrical system as arranged by Lexus. Batteries last 12-15 months and after 3rd Lexus battery, I checked four other suppliers and they all recommended 15-20 higher cranking power. The dealer wanted to put in another Lexus battery, but I objected so he paid for Sears Die Hard. The dealer told me we didn’t drive enough and suggested using battery tender. I bought one and used it 2-3 times a month. Last month regular servicing mechanic said it had to be replaced immediately, so Sears put in the fifth battery. This is a second car and drives 500-600 miles a month. Finally, the question–is it reasonably accurate that source of problem is car needs to be driven more and what annual mileage should do the job?
With all the keep alive memory and accessories on this vehicle, I could see a battery issue from lack of use, which would require more frequent replacement. By ‘keep alive memory’, I mean that the car ‘learns’ what is programmed into the computer and adjusts to real world situations; altitude or air density for example as well as fuel quality, and failure in parts and sensors, within acceptable parameters. When the battery is disconnected, keep alive memory is disrupted, the car reverts back to factory programmed parameters, which no longer apply, and has to relearn the feedback and info being sent to the computer module. I would recommend a gel type battery, and the use of the battery tender at all times the vehicle is idle. The battery tender will shut down when battery has reached a certain % of charge, and can be left attached until ready to operate vehicle. As far as mileage the car needs to be driven per year, hard to say. Predicting battery drain is hard to do as there are too many variables involved. Different vehicles have different modules that run and drain the battery at different rates. Starting a vehicle draws 130 or so AMPS, idling the vehicle for 10-15 minutes will only replace 3-5 amps. It’s not really a mileage per year issue, rather a frequency issue. If you drove the car more often, say once per week for 30-35 miles, that should help.