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amirm · 07-01-2016, 04:35 PM

Some days you can't help but be grumpy....

Took the Interstate in for its first courtesy check up (4 weeks after purchase). They fixed the couple of things and ordered parts for a couple of others.

As I am always in the habit of doing, before I drive it off I test the battery voltage using the Solar monitor. To my horror, I see that it is flashing 9.7 volts while pumping 3+ amps into the batteries.

Turn on the engine to get the charging going and see that they had left the DC circuits on with the freezer, fridge and full cabin lights on.

I push the button on the tank level to see how the engine battery is doing. That was fine but on the "Aux" setting it was blank!!! It would not even turn on. Drove it home which took 1 to 2 hours. The main bank is now in float mode so has taken decent amount of charge. But the Aux setting shows a blank display if I disconnect DC.

Checked both the engine and (engine) Aux batteries and in all conditions, they show 12.7 to 12.8 volts. And measured the house batteries with the DC feed off and it took has about 12.8 volts.

I am stomped. What on earth is the "Aux" battery setting on the tank level is showing that is not getting powered???

amirm · 07-01-2016, 04:36 PM

Oh, I should add that the Kenwood radio would not stay on if I don't plug in the AC cable or run the engine. It was likely left on and killed another battery. Question is, which one? We so many automatic disconnect in this unit between the engine and house systems that is maddening to try to figure out what the heck is going on!

I said I was grumpy, did I not?

UKDUDE · 07-01-2016, 07:21 PM

Your model likely came with the SB-164 service bulletin as standard. If you check the threads on SB-164, then you will see it has some major drawbacks and many of us have chosen not to have it installed, or have removed it. Amongst other things, this SB will turn off the Precision Circuits display to the tank levels and the house batteries. If I remember correctly, when plugged into shore power, with the SB you need to ensure the batteries are not in disconnect mode.
The dealer likely allowed the batteries to be discharged, but after just a single instance you may be OK.

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HiJoeSilver · 07-01-2016, 07:27 PM

At 9.7 volts the battery is likely permanently damaged and not likely to recover.
Discharging a lead acid battery below 10.5 volts will severely damage it !
Whoever you took it to screwed you. Call and complain.

lewster · 07-01-2016, 07:40 PM

Quote:

Originally Posted by HiJoeSilver

At 9.7 volts the battery is likely permanently damaged and not likely to recover.
Discharging a lead acid battery below 10.5 volts will severely damage it !
Whoever you took it to screwed you. Call and complain.

Not really. Lifelines can tolerate a zero capacity discharge a few times with little to no damage, providing that they are fully recharged very soon after that discharge.

Their capacity will not be diminished, but the total bomber of charge cycles ( useful life) will most likely be shortened.

Good thing they were recharged soon !

Boxster1971 · 07-01-2016, 08:26 PM

I can't believe you drove off the dealers lot after discovering the initial problems. I would have gone in and complained.

- - Mike
2013 Interstate Lounge EXT on 2012 Sprinter

amirm · 07-01-2016, 08:36 PM

I wrote them a nastygram after I got home. But you are right, should have made a fuss right then.

amirm · 07-01-2016, 08:38 PM

Quote:

Originally Posted by UKDUDE

Your model likely came with the SB-164 service bulletin as standard. If you check the threads on SB-164, then you will see it has some major drawbacks and many of us have chosen not to have it installed, or have removed it. Amongst other things, this SB will turn off the Precision Circuits display to the tank levels and the house batteries. If I remember correctly, when plugged into shore power, with the SB you need to ensure the batteries are not in disconnect mode.

I have removed that relay and replaced it with a solid state relay. It only controls the inverter power though, nothing else.

That said, the solid state relay is stuck on! Can't figure out why yet. The manufacturer has such bad instructions. Hopefully it has not shorted on.

amirm · 07-02-2016, 05:49 PM

So after a day of charging whatever feeds the Aux setting in the battery monitor got charged too. I spent 2-3 hours studying the wiring diagrams for the Interstate and there must be mistakes in there as I still can't figure out which additional battery went down in addition to the house set. Or which battery exactly powers the radio.

I wonder why we are supplied with a second Aux battery on the Mercedes front given the fact that we have a house battery. That space could have been used to give us more capacity for the house battery as opposed to three independent system.

amirm · 07-02-2016, 05:50 PM

Also, I have a bunch of apologies in my inbox from the dealer and the service manager is supposed to call me on Tuesday to fall on his sword.

UKDUDE · 07-02-2016, 06:46 PM

Some Interstates appear to have been supplied with the auxiliary battery under the hood. Regardless of that, it does nothing, powers nothing; there are a couple of threads about it.
Regarding the Kenwood, it will run from the chassis battery when the key is in the accessory position; or it will run from the coach batteries when they are not disconnected.
Good luck with the dealer, they need to be held accountable for their mistakes!

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busb2 · 07-02-2016, 07:29 PM

FYI, there is a 12v plug on the bottom right side of the drivers seat that is wired to the Auxiliary battery.

Boxster1971 · 07-02-2016, 08:56 PM

Quote:

Originally Posted by amirm

I have removed that relay and replaced it with a solid state relay. It only controls the inverter power though, nothing else.

That said, the solid state relay is stuck on! Can't figure out why yet. The manufacturer has such bad instructions. Hopefully it has not shorted on.

If you removed the Airstream installed solenoid and replaced it with a solid state relay you might have a problem with dealer. They will claim you modified the system and caused all the problems.

- - Mike
2013 Lounge EXT on 2012 Sprinter

Protagonist · 07-03-2016, 04:07 AM

Quote:

Originally Posted by amirm

So after a day of charging whatever feeds the Aux setting in the battery monitor got charged too. I spent 2-3 hours studying the wiring diagrams for the Interstate and there must be mistakes in there as I still can't figure out which additional battery went down in addition to the house set. Or which battery exactly powers the radio.

Not all Interstates have a battery under the hood. But on those that do, the batteries are like this:
Starting battery is under the driver's footwell. It is a Group 49 AGM.
Auxiliary battery is under the hood. It is also a Group 49 AGM, and is on a GNDN circuit (GNDN = goes nowhere, does nothing). It is intended as a house battery for ambulances, news trucks, and other commercial vans, but Airstream does not actually hook anything up to it. But if you carry jumper cables, if the starter battery gets low, you can use the auxiliary battery to jump-start the engine instead of using the "boost" button to treat your house batteries as starting batteries.
House batteries are wherever Airstream put them on your van, and are two Group 24 AGM batteries.

On your monitor panel, the "Main" is the Group 49 starting battery. "Aux" is the Group 24 house batteries. The auxiliary battery under the hood is not monitored.

The radio is supposed to be powered by both the starting battery and the house batteries so that you can play it with the engine turned off.

amirm · 07-03-2016, 11:14 AM

Thanks guys. I am still stomped that the Magnum monitor would say it was in float mode but upon removal of the AC power, the radio would not turn on. Surely after two hours of driving the Magnum display was telling the truth and that there would have been sufficient power to drive the radio. I measured the house battery voltage and I think it was 12.7 or some voltage like that.

The schematic for the Airstream does show the power connection to main chassis. And mercedes documentation talks about a combiner for the Aux and Chassis battery. Wonder if the the Aux battery saved my bacon by being the only battery still alive after this debacle???

amirm · 07-03-2016, 11:17 AM

Quote:

Originally Posted by Boxster1971

If you removed the Airstream installed solenoid and replaced it with a solid state relay you might have a problem with dealer. They will claim you modified the system and caused all the problems.

They can try

I already have a deep apology from the General Manager of the place and my salesman (who forwarded my email to him). So I don't think this is a problematic case given what happened.

UKDUDE · 07-03-2016, 11:40 AM

Quote:

Originally Posted by amirm

Thanks guys. I am still stomped that the Magnum monitor would say it was in float mode but upon removal of the AC power, the radio would not turn on. Surely after two hours of driving the Magnum display was telling the truth and that there would have been sufficient power to drive the radio. I measured the house battery voltage and I think it was 12.7 or some voltage like that.

The schematic for the Airstream does show the power connection to main chassis. And mercedes documentation talks about a combiner for the Aux and Chassis battery. Wonder if the the Aux battery saved my bacon by being the only battery still alive after this debacle???

The battery capacity may have been depleted but the Magnum will still do its best and go through its phases ending in float.
Regarding the radio, what is the position of the battery disconnect switch when the Kenwood isn't working and you think it should be?

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lewster · 07-03-2016, 08:38 PM

Quote:

Originally Posted by amirm

Thanks guys. I am still stomped that the Magnum monitor would say it was in float mode but upon removal of the AC power, the radio would not turn on. Surely after two hours of driving the Magnum display was telling the truth and that there would have been sufficient power to drive the radio. I measured the house battery voltage and I think it was 12.7 or some voltage like that.

The schematic for the Airstream does show the power connection to main chassis. And mercedes documentation talks about a combiner for the Aux and Chassis battery. Wonder if the the Aux battery saved my bacon by being the only battery still alive after this debacle???

amirm,

Did you have any other charging source for your house batteries at the time the monitor read float charge? If you had the engine on and the batteries were depleted, the charge from your engine alternator thru the BIM would have caused the magnum to go to float charge, as it would have seen this alternator charge as full batteries. An operational, decent solar charging system would have shown the same results on the Magnum.

amirm · 07-03-2016, 10:06 PM

Quote:

Originally Posted by UKDUDE

The battery capacity may have been depleted but the Magnum will still do its best and go through its phases ending in float.
Regarding the radio, what is the position of the battery disconnect switch when the Kenwood isn't working and you think it should be?

Thanks for pushing me on this

. My thought that the radio was only powered by the chassis batteries had led me down the wrong path.

I think the radio was going off when I had the DC switch disconnected. That also blanks the battery monitor AUX reading. I somehow associated these with the Mercedes batteries and not house.

Translating into English

, the only thing that seems to have gone wrong here is the house batteries drained completely. The rest was my brain also drained completely, thinking another battery was killed.

The last thing that remains now is why the solid state switch is latched on. Will troubleshoot that now. Would be sad if it does that if the battery voltage goes too low.

Thank you all. As I get ready to re-do all of this for Lithium system, this has given me more insight into how everything is wired.

amirm · 07-03-2016, 10:08 PM

Quote:

Originally Posted by lewster

amirm,

Did you have any other charging source for your house batteries at the time the monitor read float charge? If you had the engine on and the batteries were depleted, the charge from your engine alternator thru the BIM would have caused the magnum to go to float charge, as it would have seen this alternator charge as full batteries. An operational, decent solar charging system would have shown the same results on the Magnum.

Yes, the stock airstream solar was on and it was sunny. Usually I see it back off when Magnum is running. I think in this case float was right in that I have measured the alternator pump more than 100 amps into the house batteries. Over the 2 hour drive, that should have finished bulk charging and the voltage was high enough for the Magnum to just go into float.