If your BMW battery has been disconnected for six months, reconnecting it might cause some issues with the vehicle's electronics and systems. Here is what you should do after reconnecting the battery:
1. Reconnect the Battery Properly
Ensure the terminals are clean before reconnecting.
Connect the positive (+) terminal first, then the negative (-) terminal.
Tighten the connections securely.
2. Perform a System Check
Once the battery is connected, check the following:
Dashboard Warnings: Look for any warning lights. Some may clear after driving for a while.
Clock & Date: These may reset and need to be reconfigured.
Radio & iDrive Settings: If your BMW has an anti-theft radio, you might need a security code.
Power Windows & Sunroof: They may need to be reset (open and close fully to relearn positions).
3. Start the Engine & Let It Idle
Allow the car to idle for 5-10 minutes to let the electronic modules reset.
The car’s ECU (Engine Control Unit) may take time to relearn driving patterns.
4. Drive the Car
Drive at varying speeds and conditions to let the battery charge and the ECU adjust.
If the Check Engine Light or other warning lights persist, scan for fault codes using an OBD-II scanner.
5. Reinitialize BMW Features
Steering Angle Sensor Reset: Turn the steering wheel fully left and right a few times.
Adaptive Transmission Reset: Some BMW models require a reset to relearn shift points (this may happen automatically).
6. Check the Battery & Charging System
If the car struggles to start, test the battery voltage.
Ensure the alternator is charging correctly (~13.8-14.5V when running).
7. Reset Battery Registration (If Replaced)
If you are installed a new battery, you must register it with the car’s system using BMW-specific software or a diagnostic tool like ISTA, BimmerLink, or INPA.
If everything works fine after these steps, you should be good to go. If you experience electrical issues, consider having the car scanned at a BMW specialist.
Ideally, store a sealed lead acid (SLA) battery in a location where there’s no danger of getting impacted or having its terminals crossed accidentally, so a shelf out of the way is a good solution. The most important aspect for long-term storage is temperature, though. Storing a battery in extremely hot or cold temperatures can have a ngeative impact on the battery’s performance and lifespan. So choose a spot where the temperature remains relatively constant between 50 and 60 degrees Fahrenheit, or 10 to 15 degrees Celsius.
请教，我们今后可能要两地生活（美国）。六个月南方，六个月北方。住在Condo楼里，没有电源，无法给汽油车的电池充电。大家是否知道，有什么办法能让停在车库里5-6个月的车，保持电池活力？先谢谢各位！
有的人会断开电池负极想省电，其实车不动用不了多少电，电池本身的电压都会自己逐渐降低，而且有的车的ECU没了电池会失去memory checksum，导致要ECU relearn.电池在南方也许能熬上半年。
2V Automatic Battery Maintainer
https://www.harborfreight.com/12v-automatic-battery-maintainer-59000.html?event_id=183667&utm_source=google&utm_medium=cpc&utm_campaign=21905183659&campaignid=21905183659&utm_content=171677805982&adsetid=171677805982&product=59000&store=235&gad_source=1&gclid=CjwKCAiA2cu9BhBhEiwAft6IxMtoU000xWKetekpQ61ivcCOxLqWzTEyfW7332tZA25bzlxJS0gMuxoC1o0QAvD_BwE
有的车的ECU没了电池会失去memory checksum，导致要ECU relearn。
如果可以 把電池的負極綫拆了就可以了
四周有墙吗？如果没有墙挡光，可以考虑买一块太阳能板，如果没有阳光直射，就要买大一点的，停车的地方尽量接收更多的光线，也许能行。
不懂的咋都不会懂！
didn't have door opener.
Got to fix my chinese input.
如果不管，新电池能挺1-2个月。
车里放个1000瓦电源，用计时器控制每天通过电池维护器只充一个小时。
也许可以。如果这个方法不灵，干脆断电得了，还防盗。
Any machine Sitting there not turning for a long time wouldn't be good, not to mention your battery.
我就见过断掉没事儿的，也经历过自己的断开才几天就只能转动engine,但不能idle.原因是ECU断电太久记忆没了。
https://www.amazon.com/dp/B0CHJ4XR2X?ref=ppx_yo2ov_dt_b_fed_asin_title
https://www.amazon.com/OHOVIV-Portable-Charger-50000mAh-Power/dp/B0CZ9C682Z/ref=sr_1_3?dib=eyJ2IjoiMSJ9.xZsn5XnowhGclsP-ag69bNNOYfq_NbghjSG970vESOWwdQFwq4wP5Sum81SJgsZ-tjvPL9w3lMwP-bOQRMHTGjWes1ReIhqi-QHgDEEBr8I7AnGOrS-N-ywUGp0Z7dWMXUlGt7bhEtHGRI91bo3fdUGnkYyjZNTBX3CPqPiym8o26-gTFRqxslR8ANngx160QDGzVt_8kvP7f87GolEO8_PnqHcdCyp7U0IwunuTc5g.G8Bs0xVpMo5KUyqYuNKLzd4_Puo1n5wLPH0gckEJYtU&dib_tag=se&keywords=usb%2Bbattery%2Bbank&qid=1739903074&sr=8-3&th=1
这是个保持电池状态的最佳方法。
是个BMW，不可能自己拆下电池。很感谢各位的建议。看来两栖的生活，还有很多不好解决的问题。再次感谢！
上知天文下知地理的ChatGPT告诉你了：
If your BMW battery has been disconnected for six months, reconnecting it might cause some issues with the vehicle's electronics and systems. Here is what you should do after reconnecting the battery:
1. Reconnect the Battery Properly
Ensure the terminals are clean before reconnecting.
Connect the positive (+) terminal first, then the negative (-) terminal.
Tighten the connections securely.
2. Perform a System Check
Once the battery is connected, check the following:
Dashboard Warnings: Look for any warning lights. Some may clear after driving for a while.
Clock & Date: These may reset and need to be reconfigured.
Radio & iDrive Settings: If your BMW has an anti-theft radio, you might need a security code.
Power Windows & Sunroof: They may need to be reset (open and close fully to relearn positions).
3. Start the Engine & Let It Idle
Allow the car to idle for 5-10 minutes to let the electronic modules reset.
The car’s ECU (Engine Control Unit) may take time to relearn driving patterns.
4. Drive the Car
Drive at varying speeds and conditions to let the battery charge and the ECU adjust.
If the Check Engine Light or other warning lights persist, scan for fault codes using an OBD-II scanner.
5. Reinitialize BMW Features
Steering Angle Sensor Reset: Turn the steering wheel fully left and right a few times.
Adaptive Transmission Reset: Some BMW models require a reset to relearn shift points (this may happen automatically).
6. Check the Battery & Charging System
If the car struggles to start, test the battery voltage.
Ensure the alternator is charging correctly (~13.8-14.5V when running).
7. Reset Battery Registration (If Replaced)
If you are installed a new battery, you must register it with the car’s system using BMW-specific software or a diagnostic tool like ISTA, BimmerLink, or INPA.
If everything works fine after these steps, you should be good to go. If you experience electrical issues, consider having the car scanned at a BMW specialist.
去买个大点儿的jump pack，充满电夹电池上包你半年之后一拧钥匙就着
Ideally, store a sealed lead acid (SLA) battery in a location where there’s no danger of getting impacted or having its terminals crossed accidentally, so a shelf out of the way is a good solution. The most important aspect for long-term storage is temperature, though. Storing a battery in extremely hot or cold temperatures can have a ngeative impact on the battery’s performance and lifespan. So choose a spot where the temperature remains relatively constant between 50 and 60 degrees Fahrenheit, or 10 to 15 degrees Celsius.