2019 Montana 3931fb battery ghosting

[Mark_TX]

We purchased a used 2019 Montana and it has two Interstate dual purpose 12v batteries in it. I was puzzled at why a dual purpose battery was used in a situation where cold cranking amps are not needed.

I replaced the batteries with two Us2200 6v volts hoping the deep cycle batteries would preform better.

However we seem to be getting electrical draw when the RV is closed up and everything is off.

What is the best way to figure out what is drawing the batteries down while nothing is in use?

Or should I just get in the habit of flipping the battery disconnect when not in use?

[chuckster57]

There are things in an RV that draw all the time. Radio and LP alarm come to mind. Some battery disconnects don’t truly disconnect the batteries. You could install another one on the battery lead to the trailer or remove one of the leads from that battery.

We use a DC amp clamp to measure draw from the batteries.

[dutchmensport]

If you have the "Montana" and the Legacy package, you have dual batteries because you also have a residential refrigerator. You also have an inverter that draws it's power from the batteries, to power the refrigerator when not plugged into shore power.

There is a red cut off switch inside your front bay area, probably on the wall behind the battery area that kills power to the inverter. You also have the main battery cut off switch for the rest of the 12 volt DC items in the coach.... except the CO2 detector, which is never disabled, unless the batteries themselves are disconnected.

Many folks install a cut off switch on the negative battery cable, as there is only one cable connected to the negative side.

Congrats on your new Montana.

Why not jump over to the Montana Owners Culb forums (sponsored by the same organization that sponsors this site... RV Life. Click Here. You can sign up with the same user ID and password you use here and enjoy using both forum sites. The Montana site is everything specific for Montana owners, this site is for anyone with a Keystone product. Between the 2 sites, you will ALWAYS find your answers.

Enjoy that Montana, you've got a nice one! Happy Camping.

Edit: As far as the dual purpose batteries, unfortunately not everyone understands the difference between a dual purpose and deep cycle battery. More than likely, the original batteries were replaced by the previous owner, or might have even been swapped out by your RV dealership (If you purchased from a dealer) because they either did not know the difference, couldn't find a deep cycle battery, simply did not want to pay the price for a deep cycle batteries, or maybe couldn't find deep cycle batteries the same size as the originals to fit the space where they sit.

[Mark_TX]

Originally Posted by dutchmensport

If you have the "Montana" and the Legacy package, you have dual batteries because you also have a residential refrigerator. You also have an inverter that draws it's power from the batteries, to power the refrigerator when not plugged into shore power.

There is a red cut off switch inside your front bay area, probably on the wall behind the battery area that kills power to the inverter. You also have the main battery cut off switch for the rest of the 12 volt DC items in the coach.... except the CO2 detector, which is never disabled, unless the batteries themselves are disconnected.

Many folks install a cut off switch on the negative battery cable, as there is only one cable connected to the negative side.

Congrats on your new Montana.

Why not jump over to the Montana Owners Culb forums (sponsored by the same organization that sponsors this site... RV Life. Click Here. You can sign up with the same user ID and password you use here and enjoy using both forum sites. The Montana site is everything specific for Montana owners, this site is for anyone with a Keystone product. Between the 2 sites, you will ALWAYS find your answers.

Enjoy that Montana, you've got a nice one! Happy Camping.

Thank you. Yes it is a Legacy with the residential fridge.

I figured these two 6v golf cart batteries had more capacity than the two dual purpose 12v.

Hopefully we have power at our new shop in the next couple of weeks so once that happens I can leave it on shore power, but I may still do a disconnect on the negative.

[Mark_TX]

Oh and unfortunately the Montana owners group doesn't work with the Tapatalk app and that's what I use for all my forums.

[flybouy]

The dual purpose batteries are installed because they are the least expensive battery labeled as "deep cycle". IMO that's false advertising but it is what it is and the "new to RVing buyer typically doesn’t know the difference.

As for discharging the GC 6v batteries it's the parasitic drains. They will drain down any battery given enough time. The CO monitor that was mentioned, the radio memory, the In Command system, even the 12v dc boards in fridge, water heater, furnace, thermostate, etc. will "leak" a little voltage. Lets say you have 200 ah total available with your dual batteries. If they are lead acid you don’t want to drain them below a 50% SOC (state of charge) so that's 100 ahr. If the drain was "only" 1 ahr that 100 hours or about 4 days. Typically, a battery in a trailer will last anout 7 to 10 days max.

[Mark_TX]

Originally Posted by flybouy

The dual purpose batteries are installed because they are the least expensive battery labeled as "deep cycle". IMO that's false advertising but it is what it is and the "new to RVing buyer typically doesn’t know the difference.

As for discharging the GC 6v batteries it's the parasitic drains. They will drain down any battery given enough time. The CO monitor that was mentioned, the radio memory, the In Command system, even the 12v dc boards in fridge, water heater, furnace, thermostate, etc. will "leak" a little voltage. Lets say you have 200 ah total available with your dual batteries. If they are lead acid you don’t want to drain them below a 50% SOC (state of charge) so that's 100 ahr. If the drain was "only" 1 ahr that 100 hours or about 4 days. Typically, a battery in a trailer will last anout 7 to 10 days max.

Correct but we typically tell customers 25% SOC on golf batteries.

I own a golf cart business in North Texas.

I wish I could get some US 145s in it but the "tray/container" is barely big enough for the 2200s.

[flybouy]

Originally Posted by Mark_TX

Correct but we typically tell customers 25% SOC on golf batteries.

I own a golf cart business in North Texas.

I wish I could get some US 145s in it but the "tray/container" is barely big enough for the 2200s.

The 50% SOC is a common recommendation. I've heard, read recommendations of running them doen to 20% but I wouldn't advise it. Too many people read that like they interpret weight ratings and speed limits. If you say you can use 75% of the batteries capacities a segment of readers will think "then it's probably ok to use 90%".

They typically don't put much excess room for batteries. With a great deal of trailers in order to greatly increase capacity requires changing battery type or modifying the setup.