Battery Question on the Interstate

[ATE123]

We'll leave a campsite with the battery fully charged, drive home and have the RV idle for a few days with the battery disconnect off (not connected to shore power in our driveway), and when we hop back in the RV ready to take it on the road, the battery level is nil. Is that supposed to happen? Thanks again for the feedback.

[Protagonist]

It's not normal for either the house batteries or the chassis battery to be dead after just a few days. On a 2014, I believe that the main house battery disconnect also depowers the propane solenoid.

Check these items:
1 - Antenna booster. It may work independently of the main disconnect. If so, and you left it on, it will draw the batteries down very quickly.
2 - Circuit breakers. Those are 120vAC, not 12vDC, but the Magnum inverter/charger might be wired in parallel to the main disconnect, not downstream of it to allow batteries to charge from shore power while the disconnect is off. If so, that also means that it will invert even with the disconnect switched off, unless you kill the power to the AC circuits. I don't really know about the Magnums, but the Tripplite on my 2012 is definitely not shut off when the main disconnect is shut off.
3 - Refrigerator. If the circuit breakers are left on, and you didn't switch the refrigerator off at the dial inside the box, this will be a big parasitic drain just like the antenna booster.
4 - Propane solenoid. 2014 models are supposed to have the propane solenoid downstream of the main disconnect, not parallel to it, but it doesn't hurt to check and make sure.

[jkinglet]

Originally Posted by ATE123

We'll leave a campsite with the battery fully charged, drive home and have the RV idle for a few days with the battery disconnect off (not connected to shore power in our driveway), and when we hop back in the RV ready to take it on the road, the battery level is nil. Is that supposed to happen? Thanks again for the feedback.

Just had the same issue in my new 2013. The issue was caused by not turning the frig knob all the way off (counter clockwise)..past the point where I thought it was off. Resistance, than a click of sorts. problem resolved. Same with the antenna boost. Made sure the green light is off. Jeff

[73shark]

Is the solar panel putting out max current?

[Bikerbill]

Our 2014 model with 2013 chassis has the Magnum. Even when turned off at the control panel, the Magnum itself draws small current I was told by Jim Parrett. When you turn off true master battery disconnect your propane valve is off (no current draw) and the 12volts to the refrigerator is also off. Yes, check the amplifier for the tv (I leave it off except when using it). Make sure you have the radio turned off. It too draws a small amount of power to hold its memory. Several days should not cause what you are experiencing. Are you getting any solar power? Is the sun hitting the panel or are you parked in shade? If still wondering, I'd call Airstream and ask to talk to customer service, after you have read all the manuals first. Also, do yo have any idea of how long your unit sat at the dealer, possibly not plugged into shore power? If the batteries are discharged too low, they may not fully regain total storage capacity without doing an "equalization." But I'd suggest talking with Airtream before doing it and also call Magnum too about equalization charge.

[ATE123]

Thanks for all the smart feedback- definitely need to deal with the antenna booster and the fridge switch. Also, will look at draw from inverter- but a little worried that the battery may be compromised from the rv sitting at the dealership for a long time. Will try the above and see what happens. I'll be excited when I get to the point where I can intelligently respond to other people's queries!

[toskeysam]

One thing you might want to do, just to have a little more information at your disposal...on your solar readout panel....if it is the same as my 2013... scroll down to the amp-hr readout and zero the reading. Then watch each day to see if you have had much input from the solar panel. As others have said in earlier posts, the battery isolation manager will draw 8-10 amp-hr a day, and it cannot be shutoff. If you are not getting that or much over that, you might want to look further. The solar will not bring you back from a discharged state, but it should keep up with th parasitic drains.
I am new at this too....so if any of you vets out there see anything wrong with that let me know.
BTW....routinely idling for exended periods, to charge, is not a good idea...it is hard on the diesel exhaust system. You could get premature clogging of the diesel particulate filter...over time.... It is best to drive around to get the temperature and flow up.

[ATE123]

Looks like solar not drawing anything- and sad but true, I cannot find where I am supposed to turn off the antenna booster. Help?

[Protagonist]

Originally Posted by toskeysam

BTW....routinely idling for exended periods, to charge, is not a good idea...it is hard on the diesel exhaust system. You could get premature clogging of the diesel particulate filter...over time.... It is best to drive around to get the temperature and flow up.

The technical term is "wet stacking," a holdover from semi's where the exhaust is a vertical stack. From Clifford Power Systems:

When the diesel engine runs below its designed operating temperature for extended periods, unburned fuel is exhausted and noticed as wetness in the exhaust system, hence the phrase "wet stacking."

The generally accepted practice to prevent wet stacking, which can permanently damage your engine and turbo in time, is to load the engine to about 75% of its rated capacity. For your Interstate, getting the engine up to at least 2000rpm for about half an hour is enough to prevent wet stacking.

[toskeysam]

ON my 2013....the antenna booster is located in the compartment above the driver, behind the slide-panel, on the left outer wall. There is a small push button there that will turn it off. The pilot LED will go out when it is off.

[toskeysam]

Also...sometimes your solar panel will not be putting anything out, even in full sun. The controller kicks in when the voltage drops below a setpoint, then and only then, will you see a charge coming from the panel.

[ATE123]

Originally Posted by toskeysam

ON my 2013....the antenna booster is located in the compartment above the driver, behind the slide-panel, on the left outer wall. There is a small push button there that will turn it off. The pilot LED will go out when it is off.

That is where I was looking, but I will look again! Thanks!

[toskeysam]

The push button (on mine) is a SMALL black plastic thing. I did not realize it was a button until I pushed it in desperation one day.

[ATE123]

Got it. Thanks. I need to be a tad bit smarter and less impatient!

[Bikerbill]

I just looked over the 12volt Main Schematic for my 2014/13 Ext body, Rear Lounge Airstream WITH solar. These are the various connections that COULD draw/use electrical power from the RV batteries. All other 12 volt electrical items are on the other side of the Main Battery Disconnect (the switch on the door frame). If the Master Battery Switch is off, those other items have no ability to access 12 volts from the RV batteries. I do not know the possible wattage draw on these items. I keep it plugged in when I'm not using it.

1. Inverter receives 12v constantly from RV batteries.
2. BIM (also called Battery Separator)
3. Dash radio is always powered to keep its memory.
4. Solar controller-it probably has some draw as it has an electrical circuit.
5. Tank heaters--only if turned on of course.
6. Rear lounge motor--only if in use to lower/raise the lounge.
7. By-pass engine start push button for Mercedes--only if pushed of course.
8. Master battery disconnect switch--if off then no draw on what is hooked to the main power distribution box.

Per Magnum specs....inverter usually draws 5 watts and NO LOAD 19 watts typical

The BIM-battery separator will charge the Mercedes start battery IF the voltages of the RV batteries are sufficient (don't know the settings) AND the MB engine battery voltages are BELOW a set-point voltage (don't know the settings).

The Carbon Monoxide (C) and Propane (LP) detectors along with the LP tank shut-off valve and the 12v side of the refrigerator do not receive ANY 12volts with the Master Switch OFF. NOTE: the CO detector does have a 9volt battery internally and it reminds you to turn off the 12v Master before opening and changing the 9v battery.

The motorized side step, the step alarm, the power awning (if equipped) and the backup camera all are supplied 12volts from the Mercedes engine starting battery.

[Bikerbill]

Proper charging for Lifeline AGM Batteries and probably most other AGM batteries is BEST achieved with shore/generator power and a 3-stage charging profile type charger/inverter. I will not quote everything but here is the link and you want to go to section 5.4 which is page 19.

http://www.lifelinebatteries.com/manual.pdf

But in a nutshell, you CAN charge your AGM batteries by driving and running the engine of your Mercedes Sprinter, but it must be at a faster RPM than an idle. What I have been told by Jim Parrett at Airstream and also a tech at Magnum, yes, many people think that they can just run the engine for a short period of time to "charge their batteries." BUT this is not the proper or best way to charge your batteries. No one has a good definition of "short" nor do they tell you at what RPM to operate. But we all know that driving your Airstream for several hours a day while traveling will bring your batteries up to proper voltage. BUT what you don't realize is that it is more than bringing up the voltage. It has to do with first BULK charging and then with ABSORPTION charging and then FLOAT charging which all take place with different voltages and amperages. This basically is not done the best when you are using an engine alternator type charging system. The voltages vary when you are driving as the alternator is feeding into the Mercedes engine battery AND the RV batteries. And there is no temperature calculations being taken into the voltage and time variables. That is one reason I added the Magnum temp sensor to our Lifeline battery system. Airstream still does not believe in adding the temp sensor to the batteries.

So the best way to maintain your batteries, keep them plugged into shore power. I've owned 3 Class A motorhomes in the past 20+ years, always garaged when not in use, always plugged in and I never had any flooded cell/AGM batteries fail or run short on life-useage, and the last Class A was 15 years old with 6-8D AGM Lifelines (replaced 2 times in 15 years). And if you do not have access to a 30amp circuit, you can do it with a 15/20amp outdoor outlet. All you have to do is remember to NOT use any appliances that draw high currents: air conditioner, water heater, coffee maker, microwave to name a few. Also reset your Power Control System from 30 down to 20 and this will help just in case you do plug in or turn on high wattage appliances. The amount of amperage/wattage needed to operate the charger portion of your inverter is not that high and the batteries will be able to be properly maintained. Even if you can only "borrow" an outlet from your neighbor in your condo or parking are, its only going to need power for your inverter for maybe 7-8 hours to properly charge your AGM batteries.

[toskeysam]

Great discussion BikerBill....like you, I also added the temperature sensor. It did improve the charging profile somewhat. Especially in those cold winter nights. I am having the guys replace the ME-MR controller with the ME-RC controller and add the battery monitor as well. Also, after log discussions with our tech, they are going to pull the batteries for bench testing. I was able to get a longer lasting (in storage) charge, but it would never stay above 85% for more than 10 minutes (with everything off). The postings from you and many others out there have helped me locate and control a lot of the drains. Mucho thanks.....