I like having multiple volt meters, I have had them go bad before, read way lower than actual. The battery went dead in my 70S and I wanted to move it. My old 2/10 amp ancient battery charger of Dad's isn't working anymore, my ran over and my free big Schumacher with boost died. My other smaller one with boost died last Summer and I couldn't find my 6 amp mini charger's clamp connection. I use it on the boat batteries which are tied together with the bolt on connection. I decided I needed a proper battery charger with boost. I bought the Dewalt battery charger with a blue light up display. It is very compact and sits under the hood. It has a 24 hour battery conditioner cycle, alternator check function, tells battery percentage, has a 80 amp boost, USB charge port and 6 amp 120V plug in outlet. My point is, you need multiple chargers, meters and tools when you own old cars. Or at least one good one you can trust. The voltage regulator is cheap and easy to change, you just need a paper clip to hold the brushes putting it back together. Your alternator should be 70 amp, which is enough unless you have a big stereo. Buy a charger like the Dewalt and run it through the recondition cycle on your current battery. You also probably need to top up the battery electrolyte levels. Either distilled water or I have been using Vinegar, it is acid, with success. You must be pushing serious voltage to be cooking batteries. It takes weeks or months when a vehicle is around mid 15 volts to boil a battery dry. You need some sort of tester or you are flying blind. Good luck.