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.
Gel car battery models are also referred to as VRLA batteries. This is because they are designated as low maintenance batteries. The user does not have to add water to the battery to make sure that electrolyte levels return back to normal.A car battery cell that is designated as a gel battery has far less acid than conventional deep cycle car batteries, and this is a tremendous advantage for users.The interior of the battery is filled with a gel electrolyte rather than a battery acid.el car battery models are also referred to as VRLA batteries. This is because they are designated as low maintenance batteries. The user does not have to add water to the battery to make sure that electrolyte levels return back to normal.