Dead engine battery....quiz (2017 AI)

[Boxster1971]

Wildwilly - thanks for the post - some interesting stuff happening. Sounds like your Interstate was one that sat for a while on a dealer's lot and caused all the batteries to be damaged.

I’ve been over the Interstate wiring diagrams for a few years now and there are only two places where the coach and chassis batteries can possibly interact. One is the Battery Isolator (BIM) the other is the radio, Kenwood or Fusion. Of course, this assumes the Interstates are built per the wiring diagrams. I have found minor discrepancies between the diagrams Airstream sent me for my 2013 model and what is in my coach.

I really don’t understand how the inverter disconnect relay can cause the chassis battery to lose energy. It is powered solely by the coach batteries via Fuse #13 (5A) on the 12VDC Power Center. This relay can certainly cause your coach batteries to go flat faster than earlier models that did not have that relay. The main parasitic drain on the coach batteries was the Magnum Inverter/Charger in standby that used a constant 0.5A. Now with the added load from the Inverter disconnect relay the parasitic drain is nearly double at 0.9A from the coach batteries. A bewildering step backwards fix by Airstream.

The BIM control logic is designed to not drain the chassis battery into the coach battery. But if the coach battery is drained the BIM will connect the batteries for 5 seconds, but only every 10 minutes. I suppose over time this could drain the chassis battery down a lot.

The radio circuit has two power paths. One for main power which always comes from the coach batteries via 15A thermal breaker CB#5, that is NOT turned off by the Battery Disconnect switch. So if radio is left on it is another large power drain. The second path for power to the Kenwood radio is the low power Radio Enable (aka Ignition Power); this can come from the coach 12DC Power Center or from the Sprinter “Ignition On” circuit. There are a pair of diodes in this circuit to prevent cross current.

EDIT: But I just noticed something different in the Fusion diagram. Have to look deeper, more to come on this.

Concluding – it is possible that once the coach batteries have gone flat the BIM could cause the chassis battery to also go flat over a long period. The new Inverter disconnect relay does cause the coach batteries to go flat faster if not disconnected. There are two other items to always check OFF. The LP Valve, controlled but an external switch on the LP fill panel and the TV antenna booster, controlled by a push button switch in cabinet above driver seat.

None of this explains how the chassis battery can go flat when plugged into 120VAC power that keeps the coach batteries full as experienced by the OP, ScottP. I have tinkered with the BIM on my Interstate a lot and discovered two possible failure modes. One is the ground to the control module, a small black wire. If this is disconnected or not properly grounded the relay goes into a “chatter” mode of ON & Off as it can’t determine the voltage of the batteries. The other is the module output power to the BIM relay, a small violet wire. If this is disconnected or not properly connected the BIM relay will never connect the two batteries. This is the wire where I added a switch to turn OFF the Battery Isolator.

BTW – checked my Interstate today about 12:30 PM. Coach batteries at 100% from solar; floating at 13.1V and BIM connected batteries to charge the chassis battery – life is good. So, the BIM on my Interstate only requires 13.0V on the coach batteries to connect batteries – just as the technical document I have indicate.

[Boxster1971]

Originally Posted by VanGo

This is not the case for me. For me:
- It only happens when connected to shore power with house power on.
- The only time I have the house power on is when I'm using the unit.
- In Storage I am outside, with house power off. After sitting for a week or 2 in storage, I check on the unit and both batteries are pretty much fully charged.
-In the cases where my coach battery is drained, I was able to start by using the boost from the house battery.

My unit was ordered and picked up within a week of delivery so I don't think it has anything to do with dealer handling.

VanGo - please clarify. When stored outside you have house power OFF and are not plugged into 120VAC power. If so then solar panel is keeping your batteries full – this is normal and very good.

When you are plugged into 120VAC power your Sprinter starter battery goes flat. Not good.

Put the fact that you can use the battery boost switch to start the engine is good.

This is all very interesting and hopefully Airstream will identify and solve the problem soon

[VanGo]

Originally Posted by Boxster1971

VanGo - please clarify. When stored outside you have house power OFF and are not plugged into 120VAC power. If so then solar panel is keeping your batteries full – this is normal and very good.

When you are plugged into 120VAC power your Sprinter starter battery goes flat. Not good.

Put the fact that you can use the battery boost switch to start the engine is good.

This is all very interesting and hopefully Airstream will identify and solve the problem soon

Your statements are all correct Boxster. The only time I'm plugged in is when in use and the only time house power is on is when in use (so far). And this is the only time I have had battery issues.

Seems pretty crazy that the best way to drain my battery is to plug in to shore power.

[FlyFishinRVr]

Originally Posted by Boxster1971

The radio circuit has two power paths. One for main power which always comes from the coach batteries via 15A thermal breaker CB#5, that is NOT turned off by the Battery Disconnect switch. So if radio is left on it is another large power drain.

This may be true for the '13s, but on my '17 if the Main Disconnect switch is OFF (i.e. red LED OFF, no power to the lights, etc), the Fusion will not turn on. To me this says there's no power to it, but I suppose the power switch on the Fusion could be a "soft" switch and there may very well be power to it, but its internal logic says that if the Main Disconnect switch is OFF, don't turn on when the power switch is pressed. I doubt very much this is the way it works, but I guess it's possible......

[Boxster1971]

Originally Posted by FlyFishinRVr

This may be true for the '13s, but on my '17 if the Main Disconnect switch is OFF (i.e. red LED OFF, no power to the lights, etc), the Fusion will not turn on. To me this says there's no power to it, but I suppose the power switch on the Fusion could be a "soft" switch and there may very well be power to it, but its internal logic says that if the Main Disconnect switch is OFF, don't turn on when the power switch is pressed. I doubt very much this is the way it works, but I guess it's possible......

Yes, right after I posted those comments noticed something different with Fusion installation. That is why I added the note:
"EDIT: But I just noticed something different in the Fusion diagram. Have to look deeper, more to come on this."

Looking at the wiring diagrams for 2015 and 2017 Interstates and the installation instructions for the Kenwood used in 2015 and the Fusion used in the 2017. What I notice - the wire colors of the two Radio power connections are reversed between the Kenwood and the Fusion.

For Kenwood:
Red wire is the switched 12V ignition power
Yellow wire is the Constant 12V power

For Fusion
Yellow wire is the switched 12V ignition power
Red wire is the Constant 12V power

But I’m only looking at diagrams and not the real installations so I could be totally wrong but all these reports of problems with the 2017 with Fusion radios means some of them might be wired wrong.

Airstream may have wired the Fusion installations backwards. Then the Fusion radio will be disabled when the Power Disconnect is OFF, as you describe. Because they connected the Fusion constant power to the 12VDC Power Center that gets turned off with the disconnect. This is the reverse of what Airstream does for the Kenwood radio, which allows the radio to be used when the disconnect is OFF.

With reversed wiring in Fusion installations the Sprinter chassis battery could always supply more power to the radio than in a proper installation. Then with Disconnect ON the Sprinter battery might be providing all the radio power. This would be a significant parasitic drain on the Sprinter battery when the engine is not running.

But I still don’t understand why the Sprinter chassis battery would be drained flat when plugged in and charging the coach batteries from the Magnum unit.

[ScottP]

I do believe that's it!!!

While it doesn't answer all of the questions, I believe it explains the cause of the chassis battery drain.

Thank you for all your effort at identifying the source of the problem.

Scott


2017 4x4 Interstate
Bend, Oregon

[FlyFishinRVr]

Originally Posted by Boxster1971

With reversed wiring in Fusion installations the Sprinter chassis battery could always supply more power to the radio than in a proper installation. Then with Disconnect ON the Sprinter battery might be providing all the radio power. This would be a significant parasitic drain on the Sprinter battery when the engine is not running.

When I switch my Main Disconnect ON (red LED ON, power is going to the lights, etc), my Fusion system automatically turns on without me doing anything. Unless these wires that you are talking about are "soft" sense wires vs. actual power delivery (unlikely), it seems to me that the coach batteries are providing the power in this scenario, which is the way it should be.

My guess is the Fusion system provides 2 power inputs as a convenience for the installer, but internally these inputs are basically tied together (hopefully after going through diodes or similar circuitry to prevent tying the battery banks together through the radio!). If either is on, the Fusion turns on. As a result, I don't think it matters which input is on, as it will draw equal power from either one.

[Boxster1971]

Originally Posted by FlyFishinRVr

When I switch my Main Disconnect ON (red LED ON, power is going to the lights, etc), my Fusion system automatically turns on without me doing anything. Unless these wires that you are talking about are "soft" sense wires vs. actual power delivery (unlikely), it seems to me that the coach batteries are providing the power in this scenario, which is the way it should be.

My guess is the Fusion system provides 2 power inputs as a convenience for the installer, but internally these inputs are basically tied together (hopefully after going through diodes or similar circuitry to prevent tying the battery banks together through the radio!). If either is on, the Fusion turns on. As a result, I don't think it matters which input is on, as it will draw equal power from either one.

On most modern radio systems, the two wires I mentioned are “soft” and sources of 12VDC power. When the switched power is ON it probably enables an internal relay to fully power the radios, up to 12A. When the switched power is OFF the radio draws just a small amount of power (~1 watt or 0.08A) to keep basic setting in memory.

About a year ago, I posted information from the Kenwood installation manual that if you connected the switched wire to a constant source it could drain the vehicle battery quickly. Attaching that manual page to this post. Also, attaching a copy of a file that illustrates how the Kenwood is installed by Airstream to allow you to use it when; 1) the Coach power is connected and Sprinter key is OFF or; 2) when coach is disconnected the Sprinter Key controls power to radio so you can use it while driving with coach power disconnected. This has been the standard radio hookup until they switched to the Fusion Radio system in 2017 models.

The fact that the Fusion radio is turned OFF and then ON buy switching the coach power disconnect tells me Airstream has wired these model differently. The AV wiring diagram in back of 2017 Interstate manual implies that the Fusion should be powered no matter what the status of the coach battery disconnect. But it apparently doesn’t work that way. I’ve attached a clip from that diagram showing the part of circuit that shows it would work much like the earlier Kenwood installations. But notice there is no Sprinter CAN Bus interface shown which would only power radio when key is on. The 2017 diagram indicates the radio should always be available, but it’s not. That implies Airstream has not wired the coach per this diagram.

Based on reported problems I conclude that it is wired to be off when the coach batteries are disconnected and when the disconnect is ON all the power for radio is coming from the Sprinter chassis battery, thus draining it at a rate of 10-12A. This will drain the chassis battery in about 1 hour. According to the PCI manual on the BIM, once a battery is at 11.8V or less the BIM will only connect for 5 seconds - not enough to keep the Sprinter chassis battery charged.

Hope this helps.

[FlyFishinRVr]

Originally Posted by Boxster1971

The fact that the Fusion radio is turned OFF and then ON buy switching the coach power disconnect tells me Airstream has wired these model differently. The AV wiring diagram in back of 2017 Interstate manual implies that the Fusion should be powered no matter what the status of the coach battery disconnect. But it apparently doesn’t work that way.

Based on reported problems I conclude that it is wired to be off when the coach batteries are disconnected and when the disconnect is ON all the power for radio is coming from the Sprinter chassis battery, thus draining it at a rate of 10-12A. This will drain the chassis battery in about 1 hour. According to the PCI manual on the BIM, once a battery is at 11.8V or less the BIM will only connect for 5 seconds - not enough to keep the Sprinter chassis battery charged.

Correct, it doesn't work that way. Main Disconnect will turn it on and off. I assume the ignition does the same thing (i.e. ignition on, radio turns on, ignition off, radio turns off), assuming the Main Disconnect is OFF. With the Main Disconnect ON, I don't think the position of the ignition matters.

As for your assumption that when ON it pulls all power from the chassis battery, I suppose I could test that the next time I'm at my coach by simply pulling the manual disconnect for the chassis batt and seeing if the radio dies.

As far as draining the chassis battery in 1hr, I thought the chassis battery was 80Ahr, just like the coach batteries. If so, even at full draw from the radio it would take over 3hrs to kill it.....

[Boxster1971]

Originally Posted by FlyFishinRVr

Correct, it doesn't work that way. Main Disconnect will turn it on and off. I assume the ignition does the same thing (i.e. ignition on, radio turns on, ignition off, radio turns off), assuming the Main Disconnect is OFF. With the Main Disconnect ON, I don't think the position of the ignition matters.

As for your assumption that when ON it pulls all power from the chassis battery, I suppose I could test that the next time I'm at my coach by simply pulling the manual disconnect for the chassis batt and seeing if the radio dies.

As far as draining the chassis battery in 1hr, I thought the chassis battery was 80Ahr, just like the coach batteries. If so, even at full draw from the radio it would take over 3hrs to kill it.....

All my assumptions are questionable, as I've said before, since I don't have a 2017 Interstate to check. But those of you that do and know how to use a multi-meter and clamp-on current meter could isolate the issues.

OK - 1 hour estimate wouldn't drain the battery, but it could lower the voltage on the chassis battery to the point that the BIM won't charge it, then it would continue to drain and certainly be discharged in 3-4 hours. Again - a guess since I've never checked the BIM in this state.

[dapolrbear]

Originally Posted by FlyFishinRVr

When I switch my Main Disconnect ON (red LED ON, power is going to the lights, etc), my Fusion system automatically turns on without me doing anything. Unless these wires that you are talking about are "soft" sense wires vs. actual power delivery (unlikely), it seems to me that the coach batteries are providing the power in this scenario, which is the way it should be.

My guess is the Fusion system provides 2 power inputs as a convenience for the installer, but internally these inputs are basically tied together (hopefully after going through diodes or similar circuitry to prevent tying the battery banks together through the radio!). If either is on, the Fusion turns on. As a result, I don't think it matters which input is on, as it will draw equal power from either one.

The Fusion system is never really "off" if you just push and hold the power button. It seems to be in a standby mode, there's no sound and the screen is dark but not off, if you shine a light at the screen at an angle you'll see the screen is still on(you can read whats on the screen). It's only true off is when it goes into the bootup sequence when you turn it on.

My 2017 seems to be charging both chassis and house batteries while plugged in. I think the Fusion is running my chassis battery down when parked for longer periods of time unplugged.

[Boxster1971]

Originally Posted by dapolrbear

The Fusion system is never really "off" if you just push and hold the power button. It seems to be in a standby ....

My 2017 seems to be charging both chassis and house batteries while plugged in. I think the Fusion is running my chassis battery down when parked for longer periods of time unplugged.

If the Fusion is powered by chassis battery as I suspect; then yes it would drain your battery. Like leaving the radio on in any vehicle - that's why the power is normally controlled by key. On some vehicles you can get 30 minutes of radio use after key is off.


- - Mike
2013 Interstate Lounge EXT on 2012 Sprinter

[VanGo]

Originally Posted by FlyFishinRVr

Correct, it doesn't work that way. Main Disconnect will turn it on and off. I assume the ignition does the same thing (i.e. ignition on, radio turns on, ignition off, radio turns off), assuming the Main Disconnect is OFF. With the Main Disconnect ON, I don't think the position of the ignition matters.



As for your assumption that when ON it pulls all power from the chassis battery, I suppose I could test that the next time I'm at my coach by simply pulling the manual disconnect for the chassis batt and seeing if the radio dies.



As far as draining the chassis battery in 1hr, I thought the chassis battery was 80Ahr, just like the coach batteries. If so, even at full draw from the radio it would take over 3hrs to kill it.....

I believe this confirms that the Fusion is switched on by the house battery disconnect, but the unit is always powered by the chassis battery?

Steps:
- House power off, ignition On and Fusion ON
- Turn ignition OFF, Fusion shuts OFF
- Turn house Power on (ignition remains off), Fusion comes ON
- Disconnect chassis battery isolator (by the accelerator), Fusion shuts OFF

[FlyFishinRVr]

Originally Posted by VanGo

- Disconnect chassis battery isolator (by the accelerator), Fusion shuts OFF

It's this last bit that I haven't tested. If others have and the Fusion shuts off with house power on but chassis battery disconnected, then it would confirm Mike's suspicion.

I still don't think this would be the "smoking gun" as to why chassis batteries are dying when the coach is plugged into shore power, but it could certainly be a contributing factor based on Mike's great analysis of how the BIM behaves over various coach/chassis battery levels given differences in charge source voltages.....

[amirm]

My head hurts trying to read through the logic for the BIM. This is one device in dire need of a display saying what the heck it is doing. It is the first thing I ditched when I converted to Lithium cells.

[Boxster1971]

Originally Posted by VanGo

I believe this confirms that the Fusion is switched on by the house battery disconnect, but the unit is always powered by the chassis battery?

Steps:
- House power off, ignition On and Fusion ON
- Turn ignition OFF, Fusion shuts OFF
- Turn house Power on (ignition remains off), Fusion comes ON
- Disconnect chassis battery isolator (by the accelerator), Fusion shuts OFF

OK - that confirms the 2017s are wired like the diagrams I've looked at and work like my 2013 Kenwood installation.

No smoking gun as to why the chassis batteries are going flat when plugged into shore power.


- - Mike
2013 Lounge EXT on 2012 Sprinter

[Boxster1971]

Originally Posted by amirm

My head hurts trying to read through the logic for the BIM. This is one device in dire need of a display saying what the heck it is doing. It is the first thing I ditched when I converted to Lithium cells.

You are absolutely right that the BIM needs to provide the user more info. That's why I added an indicator LED so I can easily tell the BIM relay status, ON or OFF. Also added a switch to turn it OFF and a new on/off switch at driver seat to force it on when needed.


- - Mike
2013 Lounge EXT on 2012 Sprinter

[InterBlog]

Originally Posted by amirm

My head hurts trying to read through the logic for the BIM. This is one device in dire need of a display saying what the heck it is doing. It is the first thing I ditched when I converted to Lithium cells.

I can go one further. I've been reading this thread even though it does not affect us with our older rig - it's good to learn new stuff anyway, just in case we discover an analogous issue at some point in the future. But I would lose patience with this one. Yesterday I told my husband, "If this were our rig, I would de-install that Fusion unit and run it over in our driveway, because no one problem-child component of any Interstate is worth devoting that much mental energy to."

[FlyFishinRVr]

Originally Posted by InterBlog

Yesterday I told my husband, "If this were our rig, I would de-install that Fusion unit and run it over in our driveway, because no one problem-child component of any Interstate is worth devoting that much mental energy to."

The Fusion is actually a nice addition IMO.

Based on what we've learned so far, until someone puts a clamp on the Fusion to see how much it's drawing when "off", the real culprit seems to be a dodgy legacy from the flooded battery days. I agree with Mike, and I think the Magnum's charger is doing an excellent job of keeping the house batts at 13.1v, which is what the Magnum provides to AGM batteries in Float mode. Trouble is, the BIM needs to see 13.3v before it will connect the house and chassis batteries together. This is likely because prior to the introduction of the AGMs, the flooded batteries were floated at 13.4v by the Magnum. See the problem?

Sure, the Fusion may be part of the issue by drawing down the chassis battery faster than without it, but there have always been parasitics drawing the chassis battery down. Does it pull it down significantly faster? At this point, we don't know, but IMO that's not the real issue here. The real issue seems to be a "disconnect" between voltage levels needed to keep everything happy when connected to shore power for an extended period of time. Frankly, this must have been an issue ever since AGMs were introduced into the Interstate, but only now has it been raised as a concern.

One solution is to do as one owner has done and any time the coach is plugged into shore power, they attach a small maintenance charger to the chassis battery through a dedicated pigtail that they leave connected and tucked under the floor mat and plug it into the outlet behind the driver's seat (great idea by the way). Another way, and the one that I'm going to use if/when I ever maintain my rig via shore power, is to simply change the setting on the Magnum remote panel and tell it I have Flooded batteries vs. AGMs so it floats them at 13.4v vs. 13.1v. This will ensure the BIM connects the batteries together, and per the Lifeline battery specs, they can be floated anywhere between 13.1v and 13.4v, so no worries there. Problem solved with the push a button. Of course there is a third solution, and is the one Airstream recommends, which is to pull the chassis battery disconnect. It takes about 2 minutes and pretty much guarantees nothing is going to draw that battery down while in storage.

Keep in mind that none of this is an issue when charging via solar, genny, or the engine because those charge voltages are all above the BIM's 13.3v requirement, so all batteries get charged from those sources.

[73shark]

I like solution #2. Hopefully someone will try it to see if it works.