13.6v when running

[Syncrotek]

If the voltmeter used is reading correctly, 13.6v is too low to keep a 12V battery fully charged,
you might have to check it with a known accurate voltmeter, 14.2V to 14.4V is the usual voltage
on the non smart alternator. If the battery has been discharged lately it might take quite some
charging to bring it to ~14.3V.

[ozgti]

Drive from musswelbrook to Sydney and still 13.6. Peaked 13.7

Sent from my Pixel 2 using Tapatalk

[TonyMax]

Your battery stores the cranking power to start your vehicle. Your alternator provides charge to keep the battery charged. The regulator (usually built into the alternator these days) prevents the alternator from over charging the battery and I believe it also determines what voltage shows when the engine is running.