Guidance needed for no power in coach batteries

[amarie1]

Need some guidance. My 29FE is parked in a friendly neighbor's lot while I'm visiting family in Oakland CA. I went to show my grandson it and while I was there noticed that the coach batteries weren't working. If the engine is running and/or the generator is running, all is good. I turn on inside lights. The control panel reads that the battery level is full (four red lights). When I turn off the engine or the generator, so that it's totally quiet, all the lights blink off. Even the control panel.

The coach batteries are new (installed in Chicago in April, two deep-cycle batteries) and worked fine during the trip cross-country. It's only been parked about a month. I made sure to turn it on to "Use" (not "Storage") when testing it. I have a multimeter but don't know how to use it. 😉 I could learn on YouTube of course.

I guess I want to find out if the batteries are dead ... I have to drive it or find a RV park with electric to charge it up? Or if there's a circuit thrown somewhere. I did turn a few of the circuit breakers on and off, none of them looked like they were flipped ... any help? Trying to avoid driving to an RV repair place; they're all booked up for weeks. No mobile techs available, from the phone calls I've made. Thanks for any advice.

[Chad Heiser]

The light indicator in the RV that shows battery level is a poor indicator of the batteries' state of charge.  It will show full charge when a charge is being applied to the batteries (like when your generator is running or the engine is running) because it sees the charge going in the same as a charge coming from the batteries.  From your description of leaving the RV sit for a month and nothing working until you start the generator or run the engine, I would say the batteries are dead.  Even with nothing turned on in the RV, there are always things drawing from the battery (typically referred to as phantom draws).  Batteries will also self discharge over time if no charge is applied to them.  It sounds like the combination of phantom draws and self discharge has run your house batteries down in your RV.  If you are placing your RV in storage and want to avoid phantom draws, you need to have a battery disconnect switch near the batteries that completely isolates the batteries from the RV.  This will stop phantom draws, but they will still self discharge over time.  Depending on how deeply discharged the batteries have become, you may or may not be able to bring them back by recharging them.  Lead acid and AGM batteries need to be brought to fully charged on a regular basis or they will develop a memory and will not be able to be fully charged again.

Edited June 3, 2021 by Chad Heiser

[Kirk W]

Let me add a little more to what Chad has already posted. 

10 hours ago, amarie1 said:

Or if there's a circuit thrown somewhere. I did turn a few of the circuit breakers on and off, none of them looked like they were flipped ... any help?

The circuit breakers are for your 120V-ac electric distribution, which is shore power or generator power and they have nothing to do with battery power. In this situation they are not part of the problem. 

10 hours ago, amarie1 said:

When I turn off the engine or the generator, so that it's totally quiet, all the lights blink off.

The fact that your engine starts is an indication that the chassis battery is fine. When you started the generator, did it crank and start without use of the emergency start switch? The generator in ever motorhome that I have ever worked on was connected to the coach batteries and not the chassis battery, so if it starts normally that means that your coach battery is still charged. While the chassis engine running will supply 12V-dc power to your lights and RV electrical system, starting the generator only supplies 120V-ac power so the lights and other 12V items working means that the converter is getting 120V power from the generator and then converting that to supply 12V power to lights and such. It sounds like something is still turned off and the battery out of the system. The only way to know for sure what is happening is by using that meter that you bought, so it is time to learn to use it. 

[amarie1]

okay thanks! No, the generator will not start unless the chassis (the engine) is running. Hrm. 

My mechanic did put a kill switch on the battery but I've not used it. I tried turning it yesterday, thinking maybe somehow I've left the kill switch turned on this whole trip and never noticed (since I was always on shore power when stopping), but I can't budge the switch. It's a green dial but it's half under the left side of the stair step (that holds the batteries) and the half that's poking out, I can't budge either way. Hrm.  

I'll go out there again with a pliers or similar to get a good grip and try turning it, or bend the metal up from the stair step, it could be jamming it.

AM

[Kirk W]

32 minutes ago, amarie1 said:

I tried turning it yesterday, thinking maybe somehow I've left the kill switch turned on this whole trip and never noticed (since I was always on shore power when stopping), but I can't budge the switch.

If you have ever started the generator without using the emergency start switch, then that kill switch is closed. It would be very easy to verify that with a meter, if you use it. The same is true for the battery, but you really need to watch the video and get that meter out. I would not get heavy handed with the pliers just yet, especially since you own the meter already. 

Another indication that the switch is closed would be that if you have ever had interior lights with neither the chassis engine or the generator running and no shore power, the battery has to have been the source of power. 

Edited June 3, 2021 by Kirk W

[amarie1]

when you say "the kill switch is closed" do you mean that it's on (killing the connection to the battery) or that it's off?

The kill switch is a dial type that should be easily turned and it's not budging. So I'm going to investigate that first.

I honestly can't remember if during my last trip I ever turned on the lights without the engine or generator running or being connected to shore power. I must have, but it is possible I never did.

[mptjelgin]

I had a buddy that get very confused with this. He thought that "ON" meant the kill switch was on, killing the connection between his batteries and his RV.  When in fact, the "ON" position meant that the power was "on" between his batteries and RV. 

On my rigs that have had kill switches, the "ON" position was the position you wanted it in for using the RV, while the "OFF" position was for storage. 

[amarie1]

yes it's the double negative thing happening. 😉

[Lou Schneider]

Take your new meter, set it to DC Volts and measure across the cutoff switch - right on the terminals.

If the switch is ON you'll read 0 volts.  If you read 12 volts from one side of the switch to the other it's OFF.

You can also use the same technique to measure the battery voltage.   Set the meter to DC Volts and put the red lead on the battery's (+) terminal and the black lead on the (-) terminal.   12 volts or better is good, less than that the battery is dead or needs to be charged (it won't charge if the cutoff switch is off).

Edited June 3, 2021 by Lou Schneider

[Kirk W]

19 hours ago, amarie1 said:

when you say "the kill switch is closed" do you mean that it's on (killing the connection to the battery) or that it's off?

Most of us from the electrical career fields use open and closed, meaning this:        

The open switch does not pass electricity because the two contacts are not connected. The closed switch does pass electricity because the switch has closed the contacts.

Edited June 4, 2021 by Kirk W

[amarie1]

thank you, great visual! That helps.  In my field (software) we'd say "the kill switch is enabled/disabled" 😉

AM

[amarie1]

update: I took the RV to a local state park campground for one night, and the batteries charged up (learned that part of the multimeter!). I got back, parked it in the empty lot I'm using, put it in Store and enabled the kill switch to cut off the power. A couple days later I went back and put it in Use and disabled the kill switch, and the batteries were still at 12.9, interior lights came on. So that's good.

Tell me this: If the Use/Store switch is set to Use, and the Kill switch is disabled, how long should the batteries last (stay a full or almost-full charge) assuming nothing is turned on except for the "phantom draws" from the carbon monoxide detector and such?

[Kirk W]

1 hour ago, amarie1 said:

If the Use/Store switch is set to Use, and the Kill switch is disabled, how long should the batteries last (stay a full or almost-full charge) assuming nothing is turned on except for the "phantom draws" from the carbon monoxide detector and such?

If there are no other phantom loads that the switch doesn't disable it should stay up several months. Even if it isn't 100% the battery should be fine for a month or two. 

[bruce t]

Kirk if the batteries are on their last legs they may struggle to hold any power! Just a thought. I've had this happen to me. Full charge one day and dead the next. No phantom loads. So maybe a battery or even one cell is the issue.

[Ray,IN]

19 hours ago, bruce t said:

Kirk if the batteries are on their last legs they may struggle to hold any power! Just a thought. I've had this happen to me. Full charge one day and dead the next. No phantom loads. So maybe a battery or even one cell is the issue.

Her initial description states new batteries in April at Chicago.

[amarie1]

They are new batteries ... two of them, AGM 31DT, installed serially in April by my RV tech. Apparently they drained almost totally (voltmeter read 2.9) because, I'm guessing, when I parked it in the storage lot here, I left the water pump on. (I saw the light turn on when I started up the generator a while later when visiting it.) If that was the case then the pump was turned on for anywhere from 5 days to 15 days. 

 

[Kirk W]

Discharging that far could have shortened the life expectancy, but since they seem to be doing OK now, I would not get too concerned.

[Ray,IN]

amarie1, if the water pump and plumbing has no leaks the pump never ran, which means it did not consume electricity. If it had leaked you would have found traces of water or dried stains in your RV and the storage tank would be low or empty.

At this point I think you are taking the proper actions, as Kirk said continue with your present batteries.

[bruce t]

OK I misread and didn't grasp the 'new batteries' bit.