House battery voltage under draw?

tommymsw wrote:
To answer some questions...

1. When I say the batteries when NOT under load go back to low 12 again, that is BEFORE they charge back up. They do charge back up to full again.
2. They are also 6v batteries (2 of them obviously). I will check with a meter on the terminals and confirm the reading.
3. I am NOT connected to shore. I do have a solar panel and it does in fact charge the batteries (reading over 14v when charging). I have also driven and charged the batteries. They do charge and seem to hold their charge when not in use.
4. The "load" is minimal. Just a few lights. The volts drop almost immediately when a light is on, but does not seem to continue to drop. As if 12v minus the 1v in use should equal 11v. I was wondering if that is the case?
5. The meter (or at least the display) is far from the batteries. I have a 2000 35ft Winnebago, if that helps?

However, if the volts do appear lower when under load, how then do you know when to stop using them? I assumed you could check them in use and know when you need to stop.

Info not clear IMO. The batteries were one day old. what was the draw down so that later when they were "unloaded" the voltage was low to mid 12s? Furnace etc overnight? What is the scenario/situation?

With a pair of 6s in good shape, being drawn down from full steadily at their "20 hour rate" (of about 11 1/4 amps for 225AH), in 10 hours you will see about 11.6v when they get to 50% SOC. Remove all loads and the voltage should bounce back to about 12.1 (Trojan spec) after a couple of hours

You can cross check for 50% by using your hydrometer and see about 1.180 or so

Unless you have a PD9100 with CW and are using the CW, then in a 2000 year rig, you likely have a single voltage 13.6v converter and you will not have charged them up as you think you did---just not enough time in that one day since new and allowing for the time it took to get them that low. The story is confusing--please clarify.