Years ago a mechanic friend of mine intentionally wanted to seize a Datsun engine by running it without oil (a long story). Took over 15 minutes, a lot longer than he expected. As a 16 yr old kid I inadverdently backed my Mom's '70 Mercury wagon off the ramps without oil while doing a lube job, probably about 20 seconds or so. No obvious harm at all. And through cumulative dry starts over an engine's life, it essentially runs many minutes without oil.
A deep cycle battery can provide a surge when needed, but nothing like the surge a car battery can. A deep cycle battery is also designed to be deeply discharged over and over again (something that would ruin a car battery very quickly). To accomplish this, a deep cycle battery uses thicker plates.
Amp Hours, or Ah, is the capacity of the battery. How much current a battery can delivery starting a car is called cold cranking amps. A deep cycle marine battery will typically be more than 40Ah. A 40Ah car battery at 50% charge will more than likely start your car in fair weather.Cold weather is another story. So, to get a completely dead car battery to 50% - 20Ah-would be maybe two days of full sunlight-with only a 50% charge, or about 12.2 Volts.t will take forever and a day to charge a deeply discharged deep cycle battery.......... consider that a small 110v battery charger is putting out 3-5 amps (or 3 x 110 =330 Watts) and the alternator on a car is putting out 20 to 50 amps at 14 volts (280 to 730 Watts). Source(s):