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BTS3 draining my battery

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  • BTS3 draining my battery

    Installed my BTS3 per instructions on my 2007 BMW Z4. Works great.
    When I don't use the Z4 for 5-7 days the battery goes dead.
    Without putting the key in the ignition can connect my iPhone 11 to the BTS3 cable and it starts charging.
    Is this correct or could I have wired the power wire incorrectly.

    Harold L

  • #2
    In BMW the car "wakes up" when it senses the key, and the BT3 wakes up with the car. This is the reason you are able to connect the iPhone, and it will start charging. In general the BT3 does not drain the battery, however if the battery itself is already weak, as it happens often in older vehicles, adding BT3 can affect it.


    • #3
      I own a 2006 Volvo S80 (Mk.1) with an HU-650 head unit, and a Grom BT-3 connected to it following the instructions.
      Since I connected this module to the car, the battery is low every morning, especially in cold weather like it's now. And when I left my car for a week while on vacation abroad - it barely started after that. And I have noticed a few things. Even with the car off and key in my pocket - my phone is still connected to the BT device. And secondly, with the car completely off, If disassembling the unit's case the red led on it is lit. Does that mean that it drains the battery slowly?


      • #4
        The BT3 in the Volvo turns on and off with the Data Bus in the vehicle. Sometimes these stay active and keep accessories on for a brief period after the vehicle is turned off. I would recommend turning the vehicle off, closing all doors (trunk and hood included), locking the vehicle, and seeing if your phone stays connected to the BT3's Bluetooth after 1 minute.