Q&A: Battery-tenders

Q: I spend half the year in the northeast and half in Florida. I have a car in each location. One of my Florida friends mentioned he uses something called a battery-tender to keep his car from going dead when he’s away for two or three months. He claims it also lengthens the life of his battery. Is this a waste of money or worthwhile?

A: It’s definitely a worthwhile investment if you’re leaving your car in a garage for months on end.

A battery-tender is a battery-charging gizmo that maintains a charge via a microprocessor. The advantages are that when you arrive at your destination you don’t have to arrange for a jumpstart to crank a stored car into action. The device also will probably prolong the life of the battery, which loses its charge gradually when it’s not being used.

Q: When I purchased my SUV gas was cheaper and I bought one that recommended using premium fuel. My husband nagged me to use the next lower grade after a year because of the price of gas. Now he’s insisting that I alternate fill-ups with the mid-range and regular gas and filling up the vehicle when the tank is half empty. I’m doing so but I’m wondering about the potential damage to engine and whether I’m getting lower mileage. Should I be concerned?

A: If you don’t have a high-performance car you can generally get by with using mid-range instead of premium and not worry about wrecking your engine. You may, however, experience sluggish pickup and you’re likely to experience a dulled-down ability to climb hills.

I would never, however, downgrade to regular gas in one that specifically recommends premium. I’ve known people who have done it and apart from the obviously diminished performance, they haven’t had a problem after three or four years of doing that. But I also hear stories of just the opposite, and I think it’s too much of a potential risk to go down two grades.

I am almost certain you’re getting reduced mileage from the lower grade. The only way you can tell that for certain, however, is to quit mixing and matching. Do a fill-up of one grade, drive in your usual fashion until the tank’s empty, make note of the mileage, and then do the same thing again with a fill-up of the next grade.

Feedback: A reader wrote in after a recent column in which I offered several ideas about how to make sure a car you’re buying fits your needs, your lifestyle, your body and your driving habits. He wrote that mine were all valid ideas, but commented that he regularly rents on vacations or business trips the makes and models he might contemplate buying sometime in the future to get a head start on the shopping process. He adds that if a business trip doesn’t present itself he’ll just pony up the $30 to rent a car for the day and see how it feels to drive it in a variety of conditions without having a salesperson sitting next to him. He suggested that I share this idea with others. And I’m happy to do so, since I agree it can be an easy way to get a more prolonged, more intimate feel for a car.

There’s a cautionary note, however. The rental-car version of the make and model you’re interested in may be quite different from what you’ll find on the lot. The rentals are often bare-bones versions that don’t usually include the quickest engines, sportiest suspensions or the most-advanced features. They also might not get the best of care and maintenance. Therefore, you may not get a completely accurate sense of what you’d wind up with if you were to buy one.