If it’s dropping below 10v during cranking you likely have a weak battery.
Voltage with engine running should be 13.6v+. If not alternator is weak.
If you’re able to stay above 10V during cranking but the charge is dropping overnight something is consuming it. Such as a charger or other customer installed consumers such as a remote start system. Audio system. If none of that is present then I’d see what OEM stuff is staying on.
What’s the voltage during cranking ?
If it’s dropping below 10v during cranking you likely have a weak battery.
Voltage with engine running should be 13.6v+. If not alternator is weak.
If you’re able to stay above 10V during cranking but the charge is dropping overnight something is consuming it. Such as a charger or other customer installed consumers such as a remote start system. Audio system. If none of that is present then I’d see what OEM stuff is staying on.