battery light and transmission failsafe program on 2000 BMW 740i

I have taken my car to a shop that did a diagnostic check said it was my battery so they replaced it with a bmw battery, because the trans failsafe program had come on. now few days later which was yesterday the transmission failsafe program came back on again after driving check engine light came on. Today the trans failsafe program light didnt come on but the battery light did so now dont know what to do can someone please give me some good advice in what to do? Thank You

Asked by for the 2000 BMW 740i
Check alternator charge

Best to monitor charge while driving, alternator might be dropping charge and not providing the EGS with voltage.