There are better ways to charge a phone than accessory mode

March 02, 2018
  • By Ray Magliozzi

Dear Car Talk:

I propose to leave my iPhone 4 permanently plugged into my car’s cigarette-lighter socket, engine running or not. When the car is not running, the ignition key would be turned to the “accessory” position. My questions: Would this keep my phone always charged? Could this cause my car’s battery to discharge completely and be unable to start the car, or cause any other problem? – Mark

RAY: Yeah. The “other problem” is that your car could get stolen. If the key is in the ignition, and it’s set to accessory, you’ll light up a few dashboard lights, which will be a neon sign that says “Steal me!” to any passing car thief or delinquent teen.

And they’ll take your iPhone, too. Although an iPhone 4 is borderline – you might get lucky, and they might unplug it and toss it out the window as they pull away.

In terms of the battery, I’m not so worried about your iPhone, on its own, draining your car’s battery, Mark; the car battery is huge compared to your iPhone’s battery. But without knowing what kind of car you have, I don’t know what else gets powered when you put the key in the accessory position.

In the old days, accessory mode basically powered up the radio and the cigarette lighter – which is what counted as sufficient entertainment back in the day. But now, when you put the ignition in the accessory position, depending on the car, the blower motor may kick in, the instrument panel may light up and the infotainment screen may come on. So I think you’d be better off circumventing the accessory position.

Ask your mechanic to safely wire up one of your power ports so that it stays hot even when the car is shut off. And make sure it’s still fused. You don’t want a car fire, either.

Some cars have power ports wired that way, but lots – including, we assume, yours – don’t. But you can change that. Then all you’ll be drawing is the about .08 amps your phone will use, plus whatever the car usually draws when it’s turned off (alarm, emissions computer, keyless entry sensors, etc.). And, crucially, you’ll be able to take your key with you.

And if the phone is all you’ve got plugged in, and your battery and charging system are in good working order, you shouldn’t have any problem starting the car the next day. And your Sleepy LaBeef playlist will always be charged up and ready to go, Mark. Rock on.

Car’s odd behavior on left turns probably signals bad motor mount

Dear Car Talk:

I just bought my wife a new Honda and inherited her old 2005 Volvo S80 T6. My “new” ride has 182,000 miles on it, a killer stereo and an odd problem I’ve never seen before: When making a left turn while moving, the engine will rev, as if in neutral, when I step on the accelerator. Once I take my foot off the gas, the car finds a gear and I can accelerate normally. This doesn’t occur when making a right turn, and it doesn’t happen if I come to a stop before turning left. Have you seen this issue before, and is it anything to be concerned about? Thanks! – K.C.

RAY: It’s not a problem, as long as you’re willing to make three right turns every time you want to go left, K.C.

Actually, this sounds like a classic case of a bad motor mount.

There are four mounts that attach the engine and transmission to the frame of the car. These mounts serve two purposes: They hold the engine and transmission in place, and they provide cushioning to isolate the engine’s vibrations from the rest of the car – so your teeth don’t chatter while you drive.

If one of your motor mounts is broken, the engine will be able to move out of place, and depending on which mount is bad, it could be at its worst when you’re making a left turn. My guess is it’s the mount closest to the firewall.

And when the engine moves, it’s probably pulling on the transmission’s shifter cable, and momentarily putting the transmission into neutral – just as if you had shifted into neutral yourself. When you lift your foot off the gas and the engine returns to its proper position, the problem corrects itself.

So ask your favorite mechanic to check for a bad motor mount. At our shop, we open the hood, put the car in gear, plant a foot firmly on the brake pedal, and then step on the gas – bringing the engine speed up to roughly where it is when you experience the problem.

By the way, don’t do this with the car facing anything, or anybody, you care about. If a motor mount is bad, you’ll actually see the engine lift up out of its cradle. And I’m guessing yours will lift up a lot. So stand back.

That test will tell your mechanic if a motor mount is bad, and, if so, which one. And if you get the mount fixed, this thing ought to run like a dream again, K.C. At least for another week. Good luck.