Good afternoon All,

After allowing my mini to sit for about 2 months due to work traveling i got home and tried to start it, battery seemed weak, tossed a charger on it. still not happy, replaced said battery with a new one. still attempted to turn over but only sounds like it makes one revolution and it can go no more. hooked up my truck to see if both batteries had been weak. nothing. it almost seems like the engine is hard to turnover or something on the engine IE idler pulley or alternator does not want to spin. Just ordered the serpentine belt tool to remove it but it doesn't come in until i leave for another work trip.

Just looking for any advice and if I am headed the right way or if I am way off basis. Thank you!

 

Just replaced a seized alternator in a R53. Maybe worth while to release the belt and check all the rollers. Sounds like you’re on the right track.

 

What Black Forest said.

I'd add in the meantime check the cables from the battery to ensure they are good the connections are good. While it could be frozen/stuck alternator it reads like a "battery" power problem. That is while the battery maybe good the cabling that carries the juice from/to the battery may not be good.