I have a 2005 bmwci battery light recently started coming on when i turn on car

Hello, Definitely ensure the proper size, strength, power and venting are available in the battery that your vehicle has at this time. This may or may not be influencing the warning light, but either way it is very important. The battery light is typically indicative of a charging system malfunction, such as with an alternator or voltage regulator. Testing in this system will be required -- especially while the light is on -- to determine the source of your failure.