I have one of those SEARS CLAMP-ON AMMETERs model 82369 that costs around $60 from AMAZON. This unit will measure AC and DC amps up to 400A I think it is.
You can simply just clamp around the positive battery cable and it will show your parasitic amps being drawn. It has a nice digital readout showing the small amps being drawn. Then you can go pull some DC FUSES from the 12VDC Power Distribution panel and see which circuit is showing parasitic drains...
This is also a simplified 30AMP Electrical Wiring Configuration for RV trailers showing both 120VAC and 12VDC circuits.
You will need to either plug into a shore power connection when sitting for an extended to keep your battery bank charged or just simply remove the NEGATIVE BATTERY TERMINALs that goes to the trailer frame ground.
I have a FOUR POSITION BLUES SEA Battery Switch for my two battery banks where I can select one, all, or none batteries to use.
If you continuously run your batteries down below their 50% charge state you will run the risk of having to replace them for POOR performance. If you are charging your batteries just using a single mode converter/charger which your older RV Unit probably has you run the risk of boiling out the battery fluids which will also ruin your batteries. If this is what you are currently using you have to check your battery fluids on a regular basis and keep them topped off fluid wise... I would look into replacing your older converter/charger unit for a modern multiple DC VOLTAGE smart mode charging unit. I use the PD9260C 60AMP model for my multiple battery bank setup... This alone will almost take care of your battery bank automatically.
Batteries are not cheap...
Roy Ken
