Will my FM Transmitter drain my car's battery if I leave it plugged in?

Recently bought a very decent FM Transmitter to enjoy Spotify instead of radio. My car is a 2004 Toyota Echo. Will leaving it plugged into the 12V Jack drain the car battery? I've researched a lot and still no definitive answer. The FM transmitter is a bit stiff to pull out from my 12V Jack, plus a bit of a hassle to constantly stick it back in/take it out at the end of every ride I make. When I turn my car off, the FM transmitter seems to turn off as well, since the light goes off along with every other function in my vehicle. But apparently it can still draw a current and slowly drain the battery anyway? If anything I'd like to leave it in during the day, when I run errands, go to work, go to the gym, but take it out at the end of the night when I know I'm done using my car. Thanks for any info.

8 Answers

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  • 3 years ago

    If the outlet stays on when the ignition is off, yes, a little. If the outlet is on only when the ignition switch is on, then obviously not.

  • 3 years ago

    Those draw so little current that they're not likely to have much effect on the battery, but if you don't drive the car for weeks, there might be enough drain to leave the battery low.

  • Anonymous
    3 years ago

    Possibly. Most new cars have an accessory port switched off by the ignition; and, one with a battery logo. which is always hot. If plugged into that one, yes. Even if you see led go out, could be a standby current to keep memory . This or a mere cell charger will kill a marginal battery.. Use a Garbage Freight DVM on 200 mA scale and see.

    if a battery is marginal, a dome light can kill it in one night.

    rented 2010 Toyota Yaris, it had both constantly on and ignition-switched outlets,. so did 2017 Fiesta I rented. both, only a measly 3 amps and Toyota fuse impossible to find. had 3 fuse boxes-!?

    cars back to 1980 had only one; a Real Cigarette lighter, 10 amps; , always hot.

    Source(s): have a 2M transceiver that draws a bit to keep the LiO backup charged that I added.
  • JetDoc
    Lv 7
    3 years ago

    For MOST modern cars, the 12 volt accessory socket (cigarette lighter socket) shuts off when the ignition is turned off, so power is cut to your accessory when you turn the engine off. You shouldn't need to be concerned about running your battery down if you leave your radio tuner plugged in. Even if it DID still draw power while the car was off, it's not a whole lot of power, and if your car battery is in good condition, it would take several days to run down.

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  • Anonymous
    3 years ago

    Not in new modern cars. I'm sure that 04 Toyota car kills the acc power socket when you turn the key switch off.

    If not, the accessory power (windows) usually time out at 10 minutes or when you open any of the vehicle doors.

  • Anonymous
    3 years ago

    You've answered your own question - "the FM transmitter seems to turn off as well, since the light goes off........"

    There is obviously no power going to the 12v jack when the car is turned off, so the FM transmitter cannot draw anything from the battery.

  • Anonymous
    3 years ago

    Test. Get a clamp multimeter and measure the no-load current with the engine and everything off on the vehicle. Measure the current with and without the transmitter. Consider a current over 50 milliamps as a drain. Measure the current about an hour after shutting off the engine.

  • MELONS
    Lv 7
    3 years ago

    yes

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