Okay cool. Will look into 100A batteries.Sounds like weak battery.
You can always first try to recharge your battery with CTEK charger.
Or just replace battery. You can fit 100A battery there. Lot of juice for start. I have 100A Duracell in my sedan E46.
Current battery came from the previous owner and has run flat a few times when I needed a new alternator. Have done overnight charges with my CTEK but maybe it's had enough.