In the 1970's and 1980's, lots of Model A people were discovering that their 40 and 50 year-old starters were finally weakening and turning their engines over slower than they used to do. Rebuilding a Model A starter was (and still is) more of a challenge than the average owner wants to take on. So, the big trend back then was to install 8-volt batteries to give those tired starters a "goose".
That helped, but it also created another problem. Actually, two problems. 8-volt batteries were hard on the 6-volt headlight bulbs. It was not unusual for Model A people to carry around a few spare headlight bulbs - just in case. But more seriously, the likewise tired generators of that era weren't able to keep the 8-volt batteries charged. The batteries would eventually run down unless one raised the generator's charging rate to the max - which, of course, eventually burned up the generators. Owners found themselves regularly using battery chargers or the local gas station to "top off" their batteries.
This was before alternators were adapted to Model A's, at least not for the Model A's six-volt system. Some mechanically and electrically-minded mechanics were able to convert alternators for their cars, but alternators set up for Model A use just weren't readily available to the rank and file Model A owner back then. Now that they can be procured from multiple sources, perhaps the charging problem is ancient history for 8-volt batteries? I haven't used one since 1986, not wishing to put up with its disadvantages any longer. Does anyone out there run an 8-volt battery in his Model A, and if so, do you use an alternator? Do headlight bulbs blow out?
Marshall