Thanks for your reply. I hope I didn't make you angry. As a retired government electronics engineer I know a little bit about how these things work, but these day I try to do research online a lot. The following is from aa1car.com's library:
"A smart charger typically has three charging stages. The first is the "bulk" stage that applies maximum voltage (14.4 to 14.7 volts for a 12V car battery) and maximum amperage to quickly bring the battery up to 80 percent of its capacity. This is followed by the "absorption" stage where the charging amperage is cut back while the output voltage remains constant. This stage takes longer because of increased resistance inside the battery as it comes up to full charge. Once the battery reaches about 90 to 95 percent of full charge, the charger goes into a "float" stage and maintains a steady charging voltage at minimal current. Some chargers will also automatically turn themselves off once full charge is achieved."

My charger is a "smart charger" if it makes a difference. My new battery reads about 12.8-13V. Battery charge percentage info is available on many professional sites. To learn more just Google "car battery charge percentage". There are charts listed, and more of them under the Images tab. The following chart is from batteryglobe.com: