[Piotrsko]

Depends on running load and battery capacity. 50 amp load on a 50 ah battery gives you about 40 minutes until the voltage sensitive stuff shuts off. Same load on a 200ah battery gives you about 3 1/2 hours. On my twin 200's in the F250 diesel, I got 6 starts with glowplugs and fuel heaters, headlights and running about 45 minutes before I realized it wasnt charging. No idea about load other than the glowplugs are 90 amps for 2 minutes and the starter uses about 300 amps

16 ga wire is good for 15 amps in household service. If current is higher than that, expect meltification. Dash wiring may not be that big gauge