How can I change my car's battery while maintaining the memory settings? | Car Doctor
- The Car Doctor recommends using a jump-pack as a memory saver when changing a car battery instead of a battery charger.
- A weak key fob battery can cause issues with restarting a car but should not cause it to shut down while driving.
- The Car Doctor recommends the 2.5-liter engine over the 2.0-liter engine for the Subaru Crosstrek due to its greater horsepower with similar fuel economy.
Q: I plan to change my car’s battery myself. Can I safely keep my battery charger connected to the charging post to maintain all established memory settings?
A: At AAA, when we change a battery, we use our jump-packs as a memory saver. Using a battery charger as a memory saver usually does not work well, because the charger wants to see some voltage to keep delivering 12 volts or that 12 volts becomes unregulated. I prefer to use a jump-pack or even another 12-volt battery.
Also, to be safe, it's a good idea to insulate the positive cable (wrap a heavy cloth around it) just to keep it from arcing while you are swapping batteries.
Shouldn't my Elantra Hybrid be getting better mileage?
Q: I have a 2023 Hyundai Elantra Hybrid purchased last November. The car has been driven 11,000 miles. I am questioning the read on my gas mileage. As an example, yesterday I traveled 17 miles on the highway using my speed control at 55 and part local driving with the EV light always on. The dashboard at the end of my trips showed an average of 37 miles per gallon. The large screen showed only 33 miles per gallon.
My first issue is the difference in mileage on the different screens. My other concern is the low miles per gallon reading. My last vehicle was a Toyota Prius; going on the same trip usually gave me 40 to 48 mpg. Many new gas cars get the mileage I am getting.
Your thoughts?
A: Looking at the owner’s manual for this car, it appears that the two screens and the miles per gallon indicator use different methodology. One uses a cumulative method; the other resets after the car is shut off for four hours.
To see if you can get the systems to sync up, go into their respective menus and reset both. Then drive for, say, 30 miles or so and check the reading.
Regarding the fuel economy, I would expect to see numbers closer to the EPA mileage of 50 miles per gallon, although driving style, winter temperatures and winter formulation of fuel can affect fuel economy.
Where's the best place to list my used car for sale?
Q: I have a 2012 Honda Civic I want to sell. What is the best way to sell it these days? Is it Facebook, Craigslist or is there something better? I appreciate the advice.
A: I have found personally that Facebook Marketplace is the most popular and seems to get the best responses. Craigslist is also quite popular.
You can advertise in local classified listings on your local newspaper website. Then there are national car marketplaces like Autotrader, Cars.com and Edmunds.com.
Keep in mind the wider the audience the better your chances of selling your car but also the greater possibility of fraudulent buyers. Iseecars did a very good article about selling your car that is worth checking out.
Smart car shut down while driving. Was it the key fob?
Q. We had issues with my daughter’s 2014 Smart car. It would shut down while driving, then it was hard to start.
I asked a friend who is familiar with Mercedes-Benz, and he told me to check the battery in the remote. I did and had instant success and never a problem since.
I asked a lot of mechanics I know, and they never heard of anything like it before.
Have you ever heard of this issue?
A: I am glad such a simple fix cured the problem, but I am not sure how. In theory, you could start the car with the fob and then leave it home and drive the car until it runs out of fuel. Certainly, a weak fob battery would cause issues with restarting but would not cause the car to shut down while driving.
Which is the better engine for Subaru Crosstrek?
Q: Which engine would you recommend for the 2023 or 2024 Subaru Crosstrek? I have seen both the 2.5-liter and 2.0-liter four cylinder. Also, what are your thoughts on the longevity of their CVT transmission?
A: Both engines are decent performers and deliver about 30 miles per gallon on average. To me, with similar fuel economy, a bit more power/performance is always good. The 2.5-liter engine makes about 30 more horsepower than the 2.0-liter engine.
As for the CVT-style transmissions, no one has been making continuous variable transmissions longer than Subaru. In my mind, that means they are being made correctly and should have the longevity of conventional transmissions when properly serviced.
John Paul is the AAA Northeast Car Doctor. He has more than 40 years of experience in the automobile industry and is an ASE-Certified Master Technician. Write to John Paul, The Car Doctor, at 110 Royal Little Drive, Providence, RI 02904. Or email jpaul@aaanortheast.com and put “Car Doctor” in the subject field. Follow him on X @johnfpaul or on Facebook.