Hi Alan, measuring voltage is a good indicator of where your battery is at in between rounds. Fully-charged, YellowTops will measure about 13.0-13.2 volts and RedTops will measure about 12.6-12.8 volts. If you find the battery is getting discharged deep into the 12s or even 11s in late rounds, then a YellowTop is a better option, especially if you don't charge in between rounds.
1uke, I'm sorry to hear you weren't able to get satisfactory warranty service on your battery. Regardless of where it was purchased, we print our 800 number and email address on every battery we sell and are happy to assist customers in getting proper warranty service from their retailer, if needed.
Jim McIlvaine
eCare Manager, OPTIMA Batteries
www.pinterest.com/optimabatteries