I do this all the time with my battery bank especially when camping off the power grid where my batteries are very important for a succesful camping run. I have a three meter battery monitor panel which looks at BANK1 and BANK2 and reads their DC VOLTAGE level. My third meter reads the DC CURRENT either being pulled from the battery from the various loads in the trailer or the reverse of that when being charged by the on-board converter/charger.
Looking at these meters I can tell if the charging circuit is connected or working and when not hooked to shore power or generator I can get a pretty good idea what my battery banks state of charge is. Of course i am looking for the 12.0VDC point which is very close to the 50% charge state where I don't want my battery banks to get below.
The batteries at fully charged if your 12.6-7VDC. They are at 50% charge state if you read 12.0VDC...
This handy chart shows the approximate charge state of the batteries based on the DC VOLTAGE reading. Of course the absolute way to determine this is to do a HYDROMETER check. Approximate charge state levels works fine for me.
You can use a multimeter as suggested above to accomplish the same thing.
Batteries are just too expensive for me to not keep a close watch on them. They are the heart of my OFF-ROAD camping...
As stated above if you are reading 13.6VDC or higher depending on the charge mode the converter/charger is then you know your on-board converter charger is charging the battery bank when you are on shore power or running from a generator.
Pretty easy daily routine if you have a digital readout battery monitor panel installed. Watching the trailer OEM Percent of CHARGE meter is useless as this meter will read any level you want to see seemly by how you hold your head haha... I have found everyone I have looked at to be almost worthless... This is great idea but you need to have digital meters installed to really know what the charge status is of your batteries.
my battery monitor panel looks like this...
You can see the OEM Percent of Charge status meter in this photo and for most of the time it reads FULL or NOTHING... That doesn't work for me haha..
You can purchase a battery monitor meter system from various vendors with the BOGART ENGINEERING TM2025-RV model probably the most popular.
Roy Ken
