[Richard and Rhonda]

I don't know the direct answer, but here is a round about way of checking. Take them off charge, and wait for at least two hours before you measure the voltage. If it's 12 or better, at least you are getting signs of life. Now put them back on charge for 4 hours or so, take them off for two, and measure the voltage again. If it is better than before, great!, even better signs of life. If it is flat, then, you have all the charge in them that they will take.

You could read the individual cells with a hydrometer, but the voltage way is an overall check of the battery.

Good luck !!!!!! Batteries do not like to be left in a discharged state, and many never forgive you for it. Also, in your climate, a discharged battery will FREEZE, something you do not want to happen