House Batteries voltage drops while in storage.

[RWDJR.]

My house batteries are new, and the voltage drops to 11.6 after 3 weeks in storage. And it’s not plugged in. The switch was off in the upper right hand corner also. What can I be missing......

[keymastr]

You have a draw of some kind. See what is connected on the unswitched side of the battery switches. If absolutely everything is going through the switch then you probably have a shorted cell in one or more batteries

[Old Crows]

Well look, Crow is not a battery expert but several things you should be aware about batteries: their state of charge is temperature dependent; they will self discharge over time; they SoC depends on the type of battery (lead acid is different than LiPo; glass mat lead acid is different than old school lead acids; SoC right now depends on where you started from; and..... it take a hell of a lot of time (sometimes up to two days) to absolutely fully charge a battery bank if it was somewhere around 50% SoC.



Also, you need to find the technical specs on your charging system. Almost all chargers today use a staged regime to quickly replace energy; taper off the charge to avoid damage as it reaches full SoC; and, go into a maintain mode to not burn up the battery. It also may have a periodic desupherization mode to condition the batteries ONCE THEY ARE FULLY CHARGED.



If the battery bank was at max SoC and it dropped to 11.6V in three weeks that MAY indicate that there is some type of electrical vampire at work. If you didn't have that trouble before you replaced the batteries, I'd discount that theory. It's something else.



Crow's advice (well worth what you paid for it by the way!) is when dealing batteries...... NEW does not mean GOOD! IME, batteries are more likely to fail in the first weeks or first months of use. If they get over that 'hump' they will probably go just a wee bit farther than the warranty. (YES.... ever wonder why a battery has, say, a 36 month warranty??? It is because the mfgr knows that 'most of the time' (like 99.5%) those batteries will make at least 36 months and a wee bit more before failure. It's not a number picked out of your hat.)



A last point... I think I've killed more batteries by continual charging.... even with modern high tech computerized chargers. Today's batteries are made lighter, with less materials and higher energy content than your Grand Pap's 6 volter in his Desoto Firedrome Deluxe that could take a stone age charger and leave it plugged in for months if not years. So, it is IMHO better to charge it up... let it cycle a maintenance cycle or three and let it rest.



Here's useful site: https://batteryuniversity.com/learn/

[RVPioneer]

Typically detectors such as CO2, LP and smoke will be powered by the batteries even with the disconnect switch in the open position. Would that discharge the batteries to 11.6v in 3 weeks? Maybe.

Were the batteries fully charged when the coach was put in storage?
Are you able to run the generator where it is stored to fully charge the batteries? This could take a few hours. Also, when you can, check to be sure the batteries are being charged while on shore power.
The fact that it was necessary to replace the batteries on a 3 year old coach indicates that there could be a history of frequent deep discharges and/or insufficient charging. Possibly due to some unknown loads or other issues.

A solar battery maintainer may be beneficial as well as determining what devices are draining the batteries.

[twinboat]

Agree with keymastr.

See what's still running with the battery switch off.
They seem to leave some stuff on the battery side of the disconnect. Things like safety stuff, in case someone is staying in it with the switch off.

I have stored my RV and boat for months and the batteries were above 12 volts.

What is that device connected to the + and - posts ?

[Milford 47]

Check the individual batter voltage when at the 11.6 for the bank and see if one stands out with a lower number, no you don't have to disconnect anything

that way you can eliminate or find a battery issue

I did add a battery rotary disconnect but after changing batteries I don't need it

[Quincy]

The RV has a solar charger on the roof which is supposed to keep the batteries topped off. Where are you storing the RV? If it is garaged or under a canopy of some kind then this system wont work. If the solar panel or its voltage regulator is not working it wont work. 11.6V is a dead battery. Even your radio has a circuit to remember what presets you have in addition to what is mentioned above.

[153stars]

You can use a multi meter to check amp draw... But first I would use an old simple car bulb like an 921 first put it in between a post an cable burns bright a decent size draw . Multi meters will have a 1 amp or 10 amp fuse that you will blow if over the rating try to use a 10 amp. WITH CAUTION you can also use a hygometer to test cells in each battery. They will need to be fully charged first.

[Lt Dan]

On your Phaeton, the inverter/charger is connected directly to the batteries and does not disconnect with the big red switch. You have to make sure the inverter is turned off and as others have said there are still a few parasitic draws. The only sure way is to add another disconnect switch on the inverter line similar to below or disconnect a battery cable.

[RVPioneer]

Originally Posted by Quincy

The RV has a solar charger on the roof which is supposed to keep the batteries topped off. Where are you storing the RV? If it is garaged or under a canopy of some kind then this system wont work. If the solar panel or its voltage regulator is not working it wont work. 11.6V is a dead battery. Even your radio has a circuit to remember what presets you have in addition to what is mentioned above.

Do we know that the OP has a solar charger?

[RVPioneer]

Originally Posted by Lt Dan

On your Phaeton, the inverter/charger is connected directly to the batteries and does not disconnect with the big red switch. You have to make sure the inverter is turned off and as others have said there are still a few parasitic draws. The only sure way is to add another disconnect switch on the inverter line or disconnect a battery cable.

That would explain it.

[twinboat]

Originally Posted by Milford 47

Check the individual batter voltage when at the 11.6 for the bank and see if one stands out with a lower number, no you don't have to disconnect anything

that way you can eliminate or find a battery issue

I did add a battery rotary disconnect but after changing batteries I don't need it

That can't work with parallel batteries. With the cable connected, all will read the same voltage.

[RWDJR.]

Batteries were put in 8 weeks ago, my old batteries were not took care of, and noticed it in Dec. on our first trip with the coach. Stored inside and no solar charger. The screen to the inverter is off when turned off. The box is called a pulse power maintenance system. Was there when we bought the coach. Will look for a draw of some sort or if the inverter is directly connected.

[RWDJR.]

Originally Posted by Lt Dan

On your Phaeton, the inverter/charger is connected directly to the batteries and does not disconnect with the big red switch. You have to make sure the inverter is turned off and as others have said there are still a few parasitic draws. The only sure way is to add another disconnect switch on the inverter line similar to below or disconnect a battery cable.

That looks like a different disconnect box than mine.