Message:warning check battery . I have just replace the battery

1. If you have a sound battery (and you may not) most likely the alternator is providing insufficient charge to the electrical system in the vehicle when driving and the demands of the system are drawing power from the battery.

2. The battery itself may also be weak and need to be replaced. A weak battery will frequently generate system warnings of various kinds. If it is the original battery still in the 2012 car then as a first step replace the battery with a new one as they can easily begin to fail at 3 years.

The electrical systems on these cars are extremely complex and if you still get the warning message after the battery is replaced then take it to BMW service and have them check the car over. Yes I know that is expensive but that goes with buying that particular brand of car. When you have problems in future with these cars, and you will, they will inevitably be quite expensive to fix in many cases and require specialist knowledge.

Check your charging system. Most of the battery life gurantee is months. so you may need to replace the battery

May be time to replace the battery.. or charging problem i advise you to take it to the service center.

Clean connections at battery source. Check adapter and plug of adapter for power and clean terminal of adapter and where it plugs into unit also.

could be but you should get a warning say the alt not charging. check for a draw on the batt like vanity lites staying on ect. you can take it to autozone or any parts place they will check your charging system for free

OK, sounds like the alternator should be replaced.

yes your voltage regulator is bad

This may indicate a problem with the battery or in the charging system. Take the car to an autoparts store and have them check the battery and alternator output. Most parts stores offer this service at no charge. Hope this helped and best wishes.

it could still be the alternator it may have warn brushes or bad reg

This may seem like a dumb question, but have you tested the lighter socket to see if it's working? If the TomTom is plugged in, you shouldn't get a low battery warning.