Hi I drove my 60 the other day I shut it off and it wouldn’t start. I jumped it and when I got home I put it on a charger. Ever since it’s started right up. Today I was taking out in the mountains to my buddies ranch and after it started I checked the voltage because the battery gauge on the dash was reading about 10 volts. Just out of the red. It’s usually at 12 or higher depending on rpm’s. So o checked voltage today while running I was at 12.26 at the battery. I turned headlights on (still while running) and it went down to 12. I drove it for a few hrs today and the battery gauge stayed the same around 10. After getting home I was reading 12.37 volts. What is my issue. BTW it fires up flawlessly.