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AndyShane

Chassis Battery Rundown Problem

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Newmar and even Magnum seem unable to resolve this problem, so I turn to the real experts who populate this forum.
 

  • Normal operation continues for days, weeks, at a time
  • Arbitrarily, the Chassis batteries run down in the course of less than 8 hours to 3 VDC, according to the Water & Battery display panel
  • When rundown occurs, Float Charging is indicated with no charging symbol on the Chassis Battery icon, 0 Amps output
  • Holding down the Charger ON/OFF control forces the charger into Equalizing mode
  • After a few seconds of Equalizing mode (not appropriate for our AGM batteries) a second prolonged push puts the charger back into Float Charging mode, 20 or so Amps output
  • Both house and chassis batteries show normally charged mere seconds after this action

If Magnum tech reps are mystified, taking the rig to a local dealer or even Nappanee seems foolish. Any ideas?

 

 

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Andy,

Please tell us what "device" is used to take amps from the inverter/charger to the chassis battery. 

In most installations, the inverter/charger charges the house batteries.  Then some "device" is used to connect the house batteries to the chassis batteries.

One diagnostic test I would run is to engage to boost/combine switch which connects the two battery banks.  Do not use if dry camping or without shore power.  If it occurs, you know the problem is not with your "device" as the boost circuit is a second pathway to chassis battery charging.

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Arbitrarily, the Chassis batteries run down in the course of less than 8 hours to 3 VDC, according to the Water & Battery display panel

Andy, Is there a Generator auto start setup? There are few items that could pull down the chassis batteries that fast. Now ! having said that does the coach have something like this?

https://shop.findmyrvparts.com/monaco-rv-battery-maintainer-LE-415-p/le-415.htm

Rich.

 Andy, Forgot to ask the Model number of your inverter,  where it is located and if it happens only when stored?

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Indeed, could be several different root causes.  As Rich points out if a very high amp draw on the chassis battery (more than the "device" is capable of supplying it-- hence the need to know that the "device" is that allows the inverter/charger to charge the chassis battery) may be the culprit.

Also, agree with Rich-- fully charged multiple battery bank going to stone dead that quickly would require a sizable draw OR bad batteries.  Wouldn't hurt to fully charge the chassis batteries and have them load tested. Wouldn't take too many "stone dead" discharges to materially shorten their life. I know it is an almost new coach, but if the batteries sat stone dead on a dealer lot for awhile.........

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3 hours ago, AndyShane said:

Both house and chassis batteries show normally charged mere seconds after this action

To me this, if accurate, indicates the batteries are not actually depleted/run down. Have you independently tested them  by disconnecting each one and testing voltage level with a load tester? Have you measured for phantom amp draw? This would eliminate the batteries from the equation and narrow the possibilities to a faulty inverter/charger or the "device" Brett suggested; I would expect that "device" to be a BIRD unit+ solenoid in a high-end MH.

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I'd also recommend cleaning battery terminals before spending a lot of time diagnosing.  And it's just a good thing to do anyway ...

A bad or intermittent connection can cause all sorts of "interesting" behavior.  The fact that the shock of equalizer mode clears the condition might indicate the high voltage temporarily removes a high impedance condition.

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1 hour ago, wajames said:

I'd also recommend cleaning battery terminals before spending a lot of time diagnosing.  And it's just a good thing to do anyway ...

A bad or intermittent connection can cause all sorts of "interesting" behavior.  The fact that the shock of equalizer mode clears the condition might indicate the high voltage temporarily removes a high impedance condition.

I think that is a accurate suggestion and concentrate on the grounds both at the battery and where they connect to the frame.

Bill

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Thanks, all. We have a bunch of guests today, so I don't have much time to do diagnostics. I've already been playing with the "device," which on this Newmar is a Battery Isolation Manager.  I really like the dirty terminal notion, or even that of a dead battery. Will look into those.

Thanks for branching me out to look in different directions. Disappointing, that an RV right off the dealer lot would present a challenge like this. Taking it to a dealer 80 miles away presents a twofold problem: counting a chase car's miles, that is 480 miles of driving for each dropoff; with something like this, I'd expect a dealer to either fail to duplicate the problem or go through several repair cycles.


UPDATE:  Even in failure, our rigs teach us about themselves. The wife and I spent the night in our rig, giving houseguests the run of our house (and avoid the drama of leaving some in the bus overnight). In the morning, the MCD Night shades at the DS window, PS window and entry wouldn't budge. Voila! Those are the ones powered by the chassis batteries, which of course discharged overnight. Ten seconds in forced Equalization charging mode restored the illusory normal condition, the shades obediently rose. Today, I'll start removing and cleaning, retightening, etc. 

Edited by AndyShane
Update

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Resolution:

Let's hope this is it. At your urging, I laid hands on the entire system, from batteries to Isolator and back. Connections tightened (none were really loose, only one moved at all), searched chafe points, reviewed flex, intervened for strain relief on several data cables that were drawn tight at the inverter. Then, I removed the smallest electrons from the coach with disconnects, unplugging from shore power, and finally crawling into the mid-cabin basement to reach between the frame rails and manually kill the inverter. 

At this point, let me add that the only charging modes I've seen for weeks have been a default to Float at around 10A, and the Equalizing that I forced to "jumpstart" the chassis charging process after rundown.

So, I reconnected the house batteries first. Then, turned on the Inverter. Next, I plugged in 50A Shore. Then, I reconnected the Chassis bank.

The panel said Bulk charging, 95A. That was different. Later, when it finally went back to Absorb mode, the amps were 15-19A, higher than before. Plus, that elusive Chassis bank lightning bolt icon was visible, indicating that the chassis bank was charging. 

I'm assuming I've solved the problem, since operations a day later appear 100% normal after several charging cycles.

Lessons learned: Magnum, say their reps, isn't responsible for discerning charging voltage. That's where the isolation relay comes into play. These come in a variety of forms; in our case, it is a discontinued one from Precision Circuits, Inc. That company sent us full diagnostics, which showed the relay to be okay. Newmar is the third entity in the battery-charging provider array. They publish settings for the Magnum control panel specific to the Newmar DSDP fleet. Owners are then responsible for dancing with three partners simultaneously, in dealing with charging woes. 

If I were to guess, the money shot for solving my problem was resetting the inverter. That is only an educated guess, largely based on the evidence that every other component in the charging pipeline seemed to check out okay.

I hope future readers can be aided by this  forums entry.    Thanks again to all who contributed.  12-23-2019

Photos: View from inside and out 😋

IMG_4551.JPG

IMG_4302.JPG

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Andy,

I hope the top photo in your post immediately above is the "BEFORE" picture, not after picture.

Float voltage of 12.6 is a full volt low.

And 11.85 on the chassis battery is DEAD.

If you have a "smart combiner" for chassis battery charging, the 12.55 or 12.6 may not be enough to signal the combiner to charge the chassis batteries.

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On 12/21/2019 at 4:43 PM, AndyShane said:

Those are the ones powered by the chassis batteries, which of course discharged overnight.

They may discharge if you weren't plugged in but you later said you were plugged in. They should not be going dead if you are plugged in. Don't you have "auto generator start" on your coach? When they got low the generator should have started.

I can run a couple nights without the house batteries going dead. 

39 minutes ago, AndyShane said:

unplugging from shore power, and finally crawling into the mid-cabin basement to reach between the frame rails and manually kill the inverter. 

Why?

 

58 minutes ago, AndyShane said:

I hope future readers can be aided by this  forums entry.    Thanks again to all who contributed.  12-23-2019

Why? You are still way below the correct charge levels. Your problem is not fixed. 

Bill

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Andy.   I know it's a PIA, but you need to have your chassis battery/batteries, LOAD TESTED as Brett has suggested.  Same with house batteries...just takes one bad cell.  Any NAPA Store will do that.  

I would not be able to  start my coach on 11.85 VDC., no slides, Jacks or steps would be operational, unless I have 13.6+...As Brett said, your house batteries should be float charging at 13.6!

Interesting plane you got. :)

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I agree with Carl, 13.6VDC float is normal.  Exide states my particular batteries should float charge at 13.8 VDC.

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In the manual

If the remote shows an 'internal' fault or the inverter needs to be reset; press and hold the Power ON/OFF pushbutton (see figure 6-1) for at least fifteen (15) seconds until the Charging/Inverting LED comes on and flashes rapidly to indicate the inverter has reset.

Also the inverter light (indicating the inverter is on) should not be turn on when the coach is in storage.  

The reset power button is on the inverter not the remote

Perform the following steps to power-down the inverter: Remove all AC power (utility or generator power) to the inverter. Disconnect the positive battery cable to the inverter. Ensure the inverter and remote control are disconnected from all AC and DC power (the remote display will be blank). After the inverter has been disconnected from all power for 30 seconds, reconnect the positive battery cable and resume operation. Info: There may be a momentary spark when the positive battery cable is connected to the inverter’s terminal; this is normal and indicates that the inverters internal capacitors are being charged

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Ray, that's what I had to do to one of mine,  2 weeks ago!  Has been floating at 13.4/13.6 since and all 110 AC systems are working.  Inverter is off, since I'm on 50 amp shore power.

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On 12/24/2019 at 2:01 AM, manholt said:

Andy.   I know it's a PIA, but you need to have your chassis battery/batteries, LOAD TESTED as Brett has suggested.  Same with house batteries...just takes one bad cell.  Any NAPA Store will do that.  

I would not be able to  start my coach on 11.85 VDC., no slides, Jacks or steps would be operational, unless I have 13.6+...As Brett said, your house batteries should be float charging at 13.6!

Interesting plane you got. :)

Thanks! Also, thanks for all of the suggestions. Oddly, I'm temporarily outdoors (lav servicing) and plugged into 30A and it suddenly seems happy.

The plane is a 2001 Progressive Aerodyne Searey. 'Bout as basic as you can get, for romping around nearby lakes and rivers. All of the "going places" planes are gone. She burns about 3 gallons per hour, fun flying.

Hey, let's talk about storage.

I've perused Newgle and the DSDP manual to no avail. As Huffypuff helpfully pointed out, Sensata tells us in paragraph 4.2 to turn off the inverter when placing mobile installations into storage. So, what does that mean to us?  I'm putting mine back into the garage bay today. It'll be plugged into 50A with the block and water heaters off, heat pumps set to 62F, fridge running.   A couple who bought another brand DP down the street just encountered this, had similar chassis battery problems, were told to store with shore power running the inverter. But, there is that passage, along with another suggesting physical removal of the batteries. I'll guess that the latter isn't right, since my garage temp never strays below freezing. But, is the best shore storage -- we "store" for several weeks at a time, rarely longer -- protocol physically disconnecting the chassis batteries, and turning off the inverter? If that is what Newmar recommends, I'll be happy to comply. But, I cannot find a procedure published by our Napannee friends. As always, your input is appreciated.
 

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Andy,

To really be of assistance on the chassis battery voltage issue, we need to know what "device" charges or connects the chassis battery.  Many, with the low float voltage readings in your picture are functioning exactly as they should (not combine battery banks until they sense proper (higher than 12.6 VDC).

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2 hours ago, AndyShane said:

Thanks! Also, thanks for all of the suggestions. Oddly, I'm temporarily outdoors (lav servicing) and plugged into 30A and it suddenly seems happy.

What does the Magnum battery monitor say? What are the battery readings?

 

2 hours ago, AndyShane said:

I've perused Newgle and the DSDP manual to no avail. As Huffypuff helpfully pointed out, Sensata tells us in paragraph 4.2 to turn off the inverter when placing mobile installations into storage. So, what does that mean to us?

That means if you don't have shore power available turning off the inverter it will reduce parasitic drain on the house batteries in storage.

 

2 hours ago, AndyShane said:

I'm putting mine back into the garage bay today. It'll be plugged into 50A with the block and water heaters off, heat pumps set to 62F, fridge running.

Please report on what the Magnum battery monitor says? What are the battery readings?

 

2 hours ago, AndyShane said:

But, there is that passage, along with another suggesting physical removal of the batteries. I'll guess that the latter isn't right, since my garage temp never strays below freezing. But, is the best shore storage -- we "store" for several weeks at a time, rarely longer -- protocol physically disconnecting the chassis batteries, and turning off the inverter? If that is what Newmar recommends, I'll be happy to comply.

This goes back to storing with no shore power and below zero conditions. You will never see conditions like this where you are. 

Let me know what your readings are above. Make sure your inverter is on. Make sure the charger function is on.

Bill

 

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1 hour ago, WILDEBILL308 said:

What does the Magnum battery monitor say? What are the battery readings?

 

That means if you don't have shore power available turning off the inverter it will reduce parasitic drain on the house batteries in storage.

 

Please report on what the Magnum battery monitor says? What are the battery readings?

 

This goes back to storing with no shore power and below zero conditions. You will never see conditions like this where you are. 

Let me know what your readings are above. Make sure your inverter is on. Make sure the charger function is on.

Bill

 

I don't like what I have this AM: 11.65 on the Chassis, 12.4 for the House. I'll pull the batteries, load test after an overnight of resting.

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Andy,

Your charger is not working, or indeed you have a battery with a bad cell.

But, you have to fully charge them to do a reliable load test.

You may have to use an external charger.

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6 hours ago, AndyShane said:

I don't like what I have this AM: 11.65 on the Chassis, 12.4 for the House.

Is this with it plugged into 50 amp shore power? Was the inverter on? According to Newmar the inverter, converter must be turned on to charge the batteries.

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On 12/27/2019 at 7:48 PM, WILDEBILL308 said:

Is this with it plugged into 50 amp shore power? Was the inverter on? According to Newmar the inverter, converter must be turned on to charge the batteries.

 I haven't talked to Newmar, but an engineer who owns a new Freightliner Tiffin confirmed that the Inverter and Charger are to be left On for 50A garaging, neighbors with a new Forest River got the same verdict from their dealer.

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