I'd advise adding another diode between the 317 output and the battery, then adjust the voltage to suit.
Connecting power to the output of many three terminal regulators, with a discharged smoothing cap at the input, can damage them.
Yes, I'd say so, if you want absolute reliability. It will also prevent slow self-discharge via the regulator ref divider.Do I really need a second diode?
Nicely explained. I'll definitely add a second diode. Thanks.Yes, I'd say so, if you want absolute reliability. It will also prevent slow self-discharge via the regulator ref divider.
In a normal PSU, a reverse diode across the reg is OK as the only storage after the reg is from filter / smoothing caps; at worst a a very short pulse in case of a fault or input short.
You have a battery that can likely source 100A or more; connecting that with power off, or anything that shorts the input side, could blast the regulator.
Having thought about the setup a bit more, I'd also add an inline fuse to the battery negative cable, for fault and fire protection, eg. 5A or 10A.