Classic/Antique Car Repair: 1978 Rolls Silver Shadow Limosine, cold cranking amps, silver shadow

Question
Hey Vern,
We just got our Rolls back from the shop and everything was going fine for a little while. After washing the car my father decided to keep the doors open to let out and humidity that had built up in the car. In the morning the car would not turn over or start. Checked the battery and it seems to be fully charged, the lights on the panels come on and everything turns on, except nothing from the engine. On the Ignition, where the key goes in there is a GEN light that stays on, I don't know if that is relevant but I'm hoping you can help. How do I get my car started?

Answer
Hi Tarek:
Leaving the doors open all night with interior lights on will drain power from battery. Although the battery seems fine, there is NOT enough power to turn-over the starter in a Rolls Royce. You need at least 600 to 800 cold cranking amps for that. I'm sure there are plenty of amps to run the lights. Only need about 50 to 100 amps for that. Get your battery charged and make sure the battery is correct size for that car. I recommend 850 cold cranking amps.