New batteries loosing charge after sitting a week.

Use really fat wire for the giant switch.
Do internet search on proper AWG size of wire. If you err on the fat side, it is better.

You will probably need also a GIANT crimper to do that job. They are like the size of a large bolt cutter.

And as the other guys mentioned, those giant battery switches are also awesome.
Turns the whole trailer off.

Also remember that these lead-acid type batteries love it when they are getting little bits of charging often. They hate it when they have to sit long periods of time either idle or being discharged deeply. This will shorten their life.
If they are idle a lot, they will grow little stalagmites and stalagtites from plate to plate, eventually shorting themselves out.

I plan to put a solar panel on mine with a charge controller module at some point that will keep the batteries very happy. Trickle charger does the same thing if you have a plug.

Thanks guys,
I already decided to put a disconnect switch in the battery compartment. I will check out the Blue Seas unit.

Jake

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

There will always be phantom drains on the batteries unless power is disconnected at the batteries themselves.
Next thing is, were the batteries fully float charged before being put into service? Its difficult to say how long they may have set on the shelf discharging.

My routine before putting any battery into service is to bring it to a full charge. Use a hydrometer and check each cells spg. and equalize if needed.

Starts at the 12:45
https://youtu.be/Lcx8qNwth_Q

I believe you mean "converter" not inverter.

Install a Blue Seas battery disconnect switch at the batteries & solve the problem forever.

There's always some sort of parasitic draw it seems. Do you have the refer off and the doors open to prevent odors? If so is the refer light staying on? You carbon monoxide alarm may be drawing power? It would be nice to know what's drawing the power, but it's far easier to install a battery cut off for now.

Bill