I've learned a lot about 12 volt since building my TD, but, I still am not real confident about battery basics. This post isn't so much relating to teardrops, but, battery voltages in general.
I've had batteries on my TV and my wife's car both go dead at random times in the last week. I purchased a Noco G7200 just before the first battery quit. First, after giving it a full charge I let it sit overnight and took a volt reading after resting and it came up 12.43. Not especially strong but it is an original from 2015. After a repair cycle which took about five hours I gave it another full charge, let it rest for several hours and it read 12.7. After a night's rest it had settled at 12.57. An improvement but I'm not sure if that's significant for a five year old battery. Anyway, I am cautiously happy that it improved the full voltage reading. Would it have improved the same amount with a couple full charges with a regular old school battery charger? I'll never know.
One question I have about the rest period advised before reading the voltage... I've read wait a half hour and others say wait overnight. What do you think is the optimal rest period? And, while it is resting is it necessary to disconnect the battery from the vehicle? If not, are connected electronics which draw constant power, and, opening the door to pop the hood latch creating a significant difference when all the interior lights and parking lights go on and off?
After my wife's vehicle battery chose not to start the car I repeated the repair process after a full charge. I did not have my multi-meter to get a before repair cycle reading. I hope that I can get those two batteries through this winter and plan on replacing whichever one shows the weakest readings during any cold snaps. Probably will be my wife's for obvious reasons. My wife drives for about ten minutes after each start. I understand this doesn't give the alternator enough time to make up for the starting boost. I am going to try to keep both vehicles on a charger every other weekend to make sure they are always topped off.
I have always wondered how long it will be before the car companies start installing solar trickle chargers on the roof of vehicles. Of course, that might tick off the battery manufacturers as I think it could extend the life of batteries significantly. What do you think?
Tim