House Battery Question
I am new to the SMB world. I have a 2000 EB350 I just purchased. The house battery was replaced about 18 months ago (Deka 4D). We went on our first day outing yesterday and I noticed the battery started at about 12.8 V (no load), but would drop to about 12.3 V or so with the fridge compressor running (4.7 Norcold). We were parked, not running anything else aside from sporadic water pump use, for about 4 hrs, and the under load voltage dropped below 12 V. The no load voltage was about 12.2 V.
Before the outing, I plugged the van into AC for 24hrs and put blue ice into the freezer to help the fridge cool down. The fridge was full of cold liquid refreshments for the outing.
Not having any past experience with house batteries, I would like to ask you guys if you feel this is a battery on it's way out. We are planning a trip into the mountains over christmas, part of which will be off the grid, so I would like to make sure we will be able to run at least the furnace and fridge for a day or two.
How low can you safely draw these things down? I am using the cheap cigarette lighter plug in voltmeter.
2000 EB50 4x4, V10