Missing coach battery

Plug in your shore power cable. Make sure your battery disconnect switch is on and measure the voltage at the battery cables noting which one is positive.

Buy the largest deep cycle battery that will fit the compartment.

The meter reading between the red(+) and black(-) cables should be between 13.8 to 14.4 volts DC. If not, your converter charger could be bad and the reason for taped cables and no battery.

It is hard to imagine you only have two red cables going to the battery box area. RED usually means +12VDC. IT could be if you look around you may find a BLACK cable that comes directly from FRAME GROUND.

I would most definitely hand trace those two RED cables and find the one that goes to FRAME GROUND.

My trailer battery has two 'HOT' cables coming from the POS +12VDC terminal of the battery with one going to the CONVERTER +BAT connection and the other one going to a RELAY that is controlled by my SLIDE switch. I also have a third cable going directly to the trailer FRAME GROUND coming from the NEG -12VDC battery connection.

I would be very CAUTIOUS hooking one of those RED CABLES to the NEG -12VDC terminal of the BATTERY. You must 'HAND TRACE' both cables to see where they go first... Grounding a POSITIVE +12VDC RED active cable will short out something else in your RV. Have fun tracing all of that out looking for a blown fuse (or worse) if that happens.

If you do indeed find one of the two RED cables going directly to FRAME GROUND connection then get some BLACK SPRAY PAINT and paint over the red color cable or better yet replace it with a BLACK color cable you can buy at the local Auto parts store with ring terminals on it.

Always fun purchasing a pre-owned RV - You have no idea what the previous owner has done to it.

just my thoughts
Roy Ken

Go to Walmart and pick up a Marine battery. I found them to have the best price, know which battery to sell you AND they put it in for you.

Agree on the biggest deep cycle battery it will hold.

Agree on physically tracing the wires. The negative wire will go directly to the frame. It may have fallen out and be dangling where you haven't seen it. Look under the RV close to the battery box.

What the others have said. Physically trace the wires to find the ground wire and look for a heavy ground wire, hopefully black.

Not to cause a stir, but I have read multiple times on these forums not to go with Marine batteries because they are not true deep cycle batteries. Since you likely need a new battery, why not just install two 6 volt T-105 Trojan batteries in the compartment nearest the generator, instead of a single house battery. That's what I did on my class C.

Many Class C's come with type 24 batteries - and some (including mine) don't have the space for larger battery. Before you buy make sure you measure the space available (including height).

Hi,

Use a meter to identify the ground cable.

You mention that the house battery compartment is smaller than the one for the starting battery. This may mean that your rig was designed for a single 12 volt house battery and the previous owner mistakenly installed a red cable to go to ground instead of a proper black cable. On our rig with two 6 volt golf cart type house batteries connected in series for 12 volts. There is a short red cable connecting the negative of one 6 volt battery to the positive terminal of the second 6 volt battery and a black cable connected to the negative terminal of the second battery and going to the frame for the ground connection. Make sure that you understand which cable is connected to the frame. If you connect new battery(s) with wrong polarity, serious damage to your RV or fire may occur.
Checking for proper operation of the converter/charger before installing battery is a good idea as a bad converter could damage a new battery. If you are unsure of test procedures, etc., call a mobile RV service or take rig into an RV service.