Somewhere between 12 and 13
Get a grip man the difference between a fully charged and a completly flat battery is in those figures we are looking for .1 of a volt here. And WTF is a basic battery tester you need a good calibrated digital meter. It totall amazes me when you ask for help and your given info that folk dont read what was written, but still faff around. Go back and read all the posts on this thread, then do some basic tests to confirm the health of you battery.
Sometimes at my age I despair of folks on these forums.
And yes I'm outspoken and a crotchety old git. But hey I'll not be around much longer so I don't GAF.