Battery Warning Light

[gringo700]

2006 320I E-90. My red battery warning light appears on start up. If I switch off the engine and re-start there is no light. My alternator is charging perfectly according to AA and an Auto Electrical business. On advice I replaced the battery (original since 2006) The replacement was done at SMG and they re-set the electronics. Any idea why this is happening as battery new and alternator charging correctly?

 

[frs1]

Check your damper pulley

 

[ChefDJ]

Check the pulley or fanbelt.