Q: Recently you wrote how infrequent driving will not do your battery any good. Are car batteries being made to last more than three years today? We have a 2005 Lexus with 69,500 miles on the original battery that came with the car. I replaced the battery because it was getting a little weak. The new battery we bought has a three-year guarantee. Are car parts going the way of most items like stoves, refrigerators, water heaters etc? They have a very short life.

A: For over 30 years I've tried to identify an explanation for some automotive batteries lasting many years and others needing replacement after only a couple of years. I have not found a common theme. I've had batteries fail seemingly instantly — wife comes home from the store, shuts off the car and two minutes later I hop in for an errand and it's absolutely dead. On the other hand the battery in my '47 Jeep was used when I installed it over a decade ago. I only drive the vehicle a couple of times each summer yet the battery still fires it right up. And just a month ago my oldest son gave me a battery that had been sitting on the floor of his shop for several years. I charged it up, installed it in our 20-year-old Tahoe and it's been starting the truck all summer.

My opinion is that any quality automotive battery has the potential to last many years. Factors that can shorten its life include an extended period of partial or full discharge, vibration from not being properly secured, under- or overcharging, extreme temperatures, water loss, electrolyte contamination and corrosion on terminals. Thus, my battery maintenance program includes keeping the battery charged — connecting a battery maintainer during significant periods of non-use — plus keeping the terminals clean and tight and the electrolyte topped up with distilled water.

As you can see, there are no "maintenance-free" batteries. Unless the battery case is actually sealed, most batteries claiming to be maintenance-free are actually "low water loss" batteries — the electrolyte level needs to be checked and maintained periodically. Remember to use eye and skin protection when servicing a battery.

I remember a conversation about automotive batteries on my radio show many years ago. After spelling out all my efforts to prolong battery life, a listener called in with the perfect answer — replace the battery just before its warranty expires, approximately every three years. Considering the hassle, cost and time consumed in dealing with a dead battery, it's hard to argue with that logic.

Q: I am a single retired "lady" with my joy and pleasure — a Nissan 350Z. My automotive technician said I have to replace a tire pressure sensor. Labor will be $85.50 and the tire pressure sensor will be $93.16 for a total of $178.66. Does this price look reasonable to you? He also quoted one set of rear brake pads at $54.98 and two rear rotors at $156.98. I can do the left rear brake as soon as I can save a little. He said I could hold off for about a year the way I drive. Is that OK?

A: His prices seem fair. My ALLDATA automotive database confirms the cost of the Nissan tire pressure sensor and 6/10ths of an hour labor for installation and system "relearning." Regarding the brakes, his quote covers rear pads and rotors on both sides — one "set" of pads services two brake calipers. His cost for rear pads and rotors is significantly below the cost of Nissan parts — $78 for pads and $113 per rotor.

Here's my suggestion. Ask your tech if there's a less expensive aftermarket sensor that might save you $20-$40 and start saving for the rear brake job now and continue to drive — and enjoy — the car until your technician tells you it's time for brake replacement According to him, and he seems to be a straight shooter, that should be in about a year.

Paul Brand is the author of "How to Repair Your Car" and "How to Repair Your Truck and SUV," published by Motorbooks.