BMW uses a sealed AGM battery that doesn’t give off hydrogen gas so long as it’s not overcharged. That’s what allows it to be mounted inside the car rather than under the hood. Like others have said, there is absolutely no issues keeping it disconnected infinitely.
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How do I reset my BMW by disconnecting the battery?

Do I need to reprogram my BMW after changing the battery?
Apart from the registration procedure, you also have to code your BMW computer. It’ll be necessary each time you replace your battery, no matter its specifications – whether your battery is similar or extremely different from your old one.
How do you disconnect the negative battery terminal on a BMW?

Does disconnecting battery reset codes?
Disconnecting the battery will clear the error codes and reset the check engine light.
Will disconnecting car battery harm computer?
Disconnecting your car battery will not cause any permanent damage to your computer or ECU (electronic control unit), but it can have some adverse effects. Those include canceling your preset radio stations, forgetting learned shift points, and your car’s ideal fuel/air mixture.
How long does it take for a BMW computer to reset?
Answer provided by Impressive sleuthing skills! You can reset a BMW ECU by unplugging the negative battery cable for 10 to 15 minutes. This should be enough to reset the ECU in most BMW models.
How do I reset my BMW electrical system?
- Step 1: Restart the controller.
- Step 2: Tap the “Trip” button to wake it up and glow.
- Step 3: Continue to press and hold that “trip” button and hold until the “Reset” button appears on the screen.
- Step 4: Reset.
Can I just disconnect the negative terminal?
Q: Can you just disconnect the negative terminal? You can disconnect the battery’s negative cable. All you are required to do is to locate the negative polarity of the battery and disconnect the terminal. Avoid the negative terminal to make contact with the positive one.
How do I reset my car after replacing the battery?
To reset your car, just follow these easy steps: Detach the battery cable for two to three minutes. Reconnect the battery and start the car. Drive the car for at least 10 miles to let the engine control units find any potential problems.
Do I need to reset car after changing battery?
Yes. You will need to reset your settings. Usually the dealer can do it free of charge but no promises. If you take a battery off and put a new one on, if there was anything hooked up the the battery, i.e. the hose you are speaking of, reinstall it.
Do I need to program my car after changing the battery?
Typically, you do not need to reprogram the key fob after changing the battery. However, if you’ve replaced not just the batteries but also some of the internal wiring and electronics, you may need to reprogram it by pairing it with your vehicle once again.
Why do you disconnect negative terminal first?
It’s important to disconnect the negative side of the battery first, otherwise you can cause an electrical short if the positive is removed first.
Which battery terminal Do I disconnect to test the alternator?
So, to be safe, always disconnect the negative battery cable before testing an alternator. Besides this, Before testing an alternator, it is important to disconnect the negative battery cable. This will ensure that you don’t damage the alternator or the battery while testing.
What does disconnecting the negative battery cable do?
The reason why you disconnect the negative terminal first on a car battery is because it helps to prevent sparks. If you were to disconnect the positive terminal first, and then accidentally touch the negative terminal, you could create a spark that could potentially damage the battery or start a fire.
How long does it take for a car computer to reset itself?
So why is the light still on? Here’s something you probably don’t know: after clearing the car’s computer you will need to drive for about 50 to 100 miles. As you drive your car the computer will monitor all the sensors and register the results.
Will disconnecting battery reset transmission?
Disconnecting the battery alone will not reset the transmission on most model vehicles.
Will BMW check engine light reset itself?
Since most BMW models use a Condition-Based Servicing system, your check engine light should reset itself automatically if and when the offending issue has been resolved.
Does disconnecting battery cause problems?
Disconnecting or replacing a battery on a computer-equipped vehicle may cause starting, driveability and a number of other problems, including loss of air conditioning, power accessory functions (door windows, seats, sunroof), false warning lights, even damage to certain electronic modules!
Will engine run with battery disconnected?
Yes, a car will stay running if you disconnect the battery. This is because the alternator should provide sufficient energy to power the vehicle even when the battery is removed. However, if the vehicle dies, you have a faulty alternator that should be replaced.
Why is my car acting weird after a new battery?
Even if you have only disconnected the battery for a short amount of time, they can potentially lose the memory that was stored in their VRAM. This also could include the settings for the engine’s idle, which would cause your car to stall.
What will resetting ECU do?
“Resetting the ECU” is the process of clearing all the long term memory from the ECU’s memory. These variables trim idle speed, fuel, spark, and more. The ECU will also store trouble codes for diagnostic capability.
What does resetting car computer do?
According to carroar.com, resetting your car computer can help out the vehicle by: Allowing you to start your car engine. Getting rid of the check engine light. Fixing any unpredictable engine behavior.
How many miles do you have to drive after disconnecting battery?
WAIT A BIT AFTER DISCONNECTING THE BATTERY When a car’s battery dies or is disconnected, the computer resets, erasing the internal emission monitors required to pass a smog test. You’ll be good to go once you drive 100 to 200 miles with the new battery.
How long do you need to disconnect car battery to reset computer?
You should leave your car’s battery disconnected for a minimum of fifteen minutes and no longer than thirty minutes to reset an ECU. To disconnect a car battery, remove the negative power cable from the negative terminal of your car battery with the use of a socket or monkey wrench.