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New coach, battery setup questions


RoadTripper2084
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Hi folks, new member here. My new-to-me 1997 Dynasty 36' came with 3 identical batteries, 2 connected in parallel on the bottom tray which I assume are the chassis batteries, and one on the top tray which I think is the House battery. I believe the previous owner mostly drove between 50A service parks so didn't need much House capacity.

I'm planning to upgrade the house batteries for next season but step 1 is to figure out how things are supposed to work, and are currently working. What's confusing me is that when I plug the coach in, I see the maintainer mounted on the electrical panel in the engine compartment light green, and then the voltage for BOTH sets of batteries bumps up:

Chassis: from 12.74vdc to 14.24v

House: from 12.76v to 13.86v.

My understanding was that the built-in maintainer would only charge the House batteries when the coach was on shore power?

In addition, if I then plugin the 3rd-party maintainer mounted in the engine compartment (added by a previous owner), both sets of batteries once again see a voltage change:

Chassis: from 14.24vdc to 14.27v

House: from 13.86v to 13.97v.

Finally, after charging on shore power for approx. 4.5 hours, I unplugged the coach and left it for 15 mins. Then took a further set of readings:

Chassis: 13.61v

House: also 13.61v

In addition, anytime I've used the switch on the dash to temporarily connect the House batteries to the Chassis, I've see no change at all in the dash volt-meter.

All of this leads me to think that all 3 of my batteries are somehow connected to be both House and Chassis batteries?

Is this somehow normal? Thoughts?
 

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What happens when you turn on headlights and dash heater blower? Chassis voltage should drop without running engine and house remain unchanged. The maintainer will try to help it but it got pretty low current limit. If there is no change in the delta, then yeah, something is connecting them.

Edited by Ivan K
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I think your Trace inverter-charger is recharging your house batteries and the original maintainer is only charging the chassis batteries.   It's been a while but I'm not sure the 1997 model had a bidirectional system to join both batteries.  

Monaco originally used two of the large 8D sized house batteries.  I did not have good longevity from the 8D batteries and replacing them was expensive.  I used four 6-volt golf cart deep cycle batteries with each two wired in series and paralleled to the other two.  It's a bit of a challenge but I managed to fit them in the original battery tray.  This system produced better performance and lasted much longer. 

A modern option would be to build your own 13.2v LiFePO4 battery packs.  

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6 hours ago, Ivan K said:

What happens when you turn on headlights and dash heater blower? Chassis voltage should drop without running engine and house remain unchanged. The maintainer will try to help it but it got pretty low current limit. If there is no change in the delta, then yeah, something is connecting them.

So I ran a few tests as you suggested:

Chassis  /  House

Unplugged (no shore power):  13.61v  /  13.71v

Running lights and dash fan on (only): 13.11v  / 12.55v

House lights on (only): 12.76v  /  12.85v

Nothing on: 13.03v  /  12.81

Inverter on: 12.39v  /  13.2v

Pretty confusing numbers, but it certainly seems like the 2 parallel batteries in the bottom tray are actually the House batteries, and the single battery on top is the Chassis (so opposite of my labelling above)?  

 

5 hours ago, vito.a said:

I think your Trace inverter-charger is recharging your house batteries and the original maintainer is only charging the chassis batteries.   It's been a while but I'm not sure the 1997 model had a bidirectional system to join both batteries.  

Monaco originally used two of the large 8D sized house batteries.  I did not have good longevity from the 8D batteries and replacing them was expensive.  I used four 6-volt golf cart deep cycle batteries with each two wired in series and paralleled to the other two.  It's a bit of a challenge but I managed to fit them in the original battery tray.  This system produced better performance and lasted much longer. 

A modern option would be to build your own 13.2v LiFePO4 battery packs.  

Yeah, this rig currently has 3 identical G4D (4D) batteries.

I ran a pair of 6v deep cycle batteries in my last trailer for 12 years, took good care of them and they still powered us through a 4 night boondock last summer. 🙂

Looking into LiFeP04 batteries but need to get my head around all the implications (re: extra equipment required to make it co-exist with the chassis batteries, alternator, etc.). That's my winter project, to figure out what I'm going to do to supplement/replace the house batteries. We like to boondock and this rig has a residential refrigerator, so going to need a bit of battery capacity to avoid running the generator too much.

 

 

Edited by RoadTripper2084
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Check out some of the Will Prowse YouTube videos on building your own Lithium battery.  You buy individual cells, the bus bars and then add a BMS.  

You can build a battery for 1/10 to 1/2 of the already built ones.  

 

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I had a '97 Dynasty.  Unless major rewiring of the original factory wiring, this is how it supposed to work.  The top shelf (single) battery is for the Chassis.  The two batteries wired in parallel are for the house.

When you plug in the coach, the inverter-charger will begin charging the house batteries.  It will go through the 3-stages, Bulk, Absorption, and then Float, as necessary.  The LE-415 maintainer in the Rear Run Bay will take power from the House batteries, once they reach a certain level, and begin to charge the chassis battery.  I found the LE-415 Maintainer to be very problematic - many fail and mine failed with the light on as should be, just no output to the chassis battery.  A replacement, when one can be found is over $400.  There are many other better and cheaper devices now on the market to do the same job.

When the engine is running, the alternator output goes to the Solid State Isolator (the center terminal).  Then on one of the other terminals connects to the chassis battery, and the remaining terminal to the house battery.  When the engine is running, the alternator output is sent to both battery banks, as needed.  Both should read the same, once the batteries are charged (assuming good batteries).  That voltage should be around 14.2 Volts.  Therefore, the engine alternator always charges both set of batteries.

The auxiliary "maintainer" was likely added because the LE-415 maintainer failed.  It's likely plugged into the block heater outlet, and it's purpose is to charge/maintain the chassis battery when on shore or generator power.  This works fine unless you do a lot of dry camping and use solar to charge your house batteries.  In that case, you are not using the generator as much, if at all, and that auxiliary maintainer never gets powered up to charge the chassis battery.  In theory, if you aren't using any of the chassis devices, you shouldn't need to charge/maintain the chassis battery.  Real life experience says otherwise. 

If you plan on using a significant amount of solar while dry camping, I'd recommend either the "Echo-Charger" or "Amp-L-Charge" type device.  These are basically modern replacements of & for the LE-415 Maintainer.  They will allow for charging the chassis battery from the house batteries once the solar charges the house batteries to a certain level (around 13.5 volts) and disconnect them when the voltage drops below a certain voltage (around 12.5 volts) so as to not allow the chassis battery and circuits to discharge you house battery.

I'm attaching the 2-page wiring diagram for the chassis and house batteries.  Please let me know if you have questions.

  -Rick N.

wiring015.pdf wiring016.pdf

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1 hour ago, waterskier_1 said:

I had a '97 Dynasty.  Unless major rewiring of the original factory wiring, this is how it supposed to work.  The top shelf (single) battery is for the Chassis.  The two batteries wired in parallel are for the house.

When you plug in the coach, the inverter-charger will begin charging the house batteries.  It will go through the 3-stages, Bulk, Absorption, and then Float, as necessary.  The LE-415 maintainer in the Rear Run Bay will take power from the House batteries, once they reach a certain level, and begin to charge the chassis battery.  I found the LE-415 Maintainer to be very problematic - many fail and mine failed with the light on as should be, just no output to the chassis battery.  A replacement, when one can be found is over $400.  There are many other better and cheaper devices now on the market to do the same job.

When the engine is running, the alternator output goes to the Solid State Isolator (the center terminal).  Then on one of the other terminals connects to the chassis battery, and the remaining terminal to the house battery.  When the engine is running, the alternator output is sent to both battery banks, as needed.  Both should read the same, once the batteries are charged (assuming good batteries).  That voltage should be around 14.2 Volts.  Therefore, the engine alternator always charges both set of batteries.

The auxiliary "maintainer" was likely added because the LE-415 maintainer failed.  It's likely plugged into the block heater outlet, and it's purpose is to charge/maintain the chassis battery when on shore or generator power.  This works fine unless you do a lot of dry camping and use solar to charge your house batteries.  In that case, you are not using the generator as much, if at all, and that auxiliary maintainer never gets powered up to charge the chassis battery.  In theory, if you aren't using any of the chassis devices, you shouldn't need to charge/maintain the chassis battery.  Real life experience says otherwise. 

If you plan on using a significant amount of solar while dry camping, I'd recommend either the "Echo-Charger" or "Amp-L-Charge" type device.  These are basically modern replacements of & for the LE-415 Maintainer.  They will allow for charging the chassis battery from the house batteries once the solar charges the house batteries to a certain level (around 13.5 volts) and disconnect them when the voltage drops below a certain voltage (around 12.5 volts) so as to not allow the chassis battery and circuits to discharge you house battery.

I'm attaching the 2-page wiring diagram for the chassis and house batteries.  Please let me know if you have questions.

  -Rick N.

wiring015.pdf 116.1 kB · 0 downloads wiring016.pdf 135.1 kB · 0 downloads

Wow - thanks for responding!  I am amazed at the complexity they built into these systems.

Based on my earlier readings it does *seem* like the stock LE-415 maintainer is working, maybe it's not 100% reliable though (labels corrected):

On 10/13/2021 at 12:12 PM, RoadTripper2084 said:

when I plug the coach in, I see the maintainer mounted on the electrical panel in the engine compartment light green, and then the voltage for BOTH sets of batteries bumps up:

Chassis House: from 12.74vdc to 14.24v

House Chassis: from 12.76v to 13.86v.

Q: Do you know if the 120v outlet in the engine bay is only powered via shore/generator and NOT by the inverter? or always powered by any of the 3?

Q: My factory solar panel doesn't seem to provide any charge. The most I've seen on the panel outside the bedroom is 0.1A, but the red "charging" led never lights. Maybe my batteries have been too charged for it start charging them (been mostly on shore power so far)?

Does the solar panel charge/maintain the House batteries, or the Chassis (or both)?

Q: When storing for longer periods (weeks/months), should the rear battery disconnect switches be a reliable way to prevent ghost drains on the batteries, or do I need to disconnect the grounds from the batteries / install a secondary battery disconnect?

Q: Do you have any experience with using LiFeP04 batteries for House batteries in this setup?  Trying to understand the simplest/cheapest setup that will tolerate being charged by the alternator, shore, generator, and solar.

Thanks again!

 

Edited by RoadTripper2084
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My block heater WAS powered by the inverter.  I was amazed, but it was and the wiring diagrams show that.

I didn't have factory solar, but it wasn't much more than a trickle charge. 

I think (I'll check tomorrow) that there was outputs for both.  

The ghost (phantom) draw will continue because some of these loads may connected directly to the battery (smoke, CO, propane detectors, radio memory, etc.)  I added solar to my Dynasty, and I didn't have to worry about my batteries discharging.  I had left the coach unplugged for months after I bought my current Exec waiting for a buyer.  

I just finished building my first LiaFePO4 battery.  I live in Colorado and have been discouraged about the low temp limits so was a bit late getting on the bandwagon.  It took my Lifeline AGM batteries to fail to motivate me.   My first thoughts are the prices are coming down, and there are a lot of poor designs out there. The huge benefits are weight savings and fast recharge.  If you are not planning on dry camping, and plan on using solar to recharge, I'm not convinced, unless you build you build your own, that Lithium is worth the added expense, right now.  That may change as soon as next year. 

Even before I went to LiFePO4 batteries, I separated my Chassis system & my House system as far as charging.  As I said, I have solar (1400 watts).  The original Monaco supplied panel is now dedicated to just the Chassis battery.  The remaining are all dedicated to the house batteries.  When the engine is running, the alternator charge only the Chassis batteries.  When on Shore or generator power my inverter charger charges only the house batteries.  I did leave the option to manually, temporarily, connect the two sets of batteries together with the dash boost switch.  This alloys me to custom tailor each charging source to the type of battery they are charging.  

I have helped many design systems where owners don't have enough solar to keep the residential refrigerator and other things running without the alternator while driving down the highway.  If charging from the alternator while underway is required, I recommend only a DC-DC Charger converter.  

Let me know if you have questions. 

  - Rick N.

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2 hours ago, waterskier_1 said:

I checked and the solar, as originally installed by Monaco was supposed to charge both sets of batteries (Chassis and House).  Here is a wiring diagram of the Solar wiring.

  -Rick N.

 

Thanks. I have now found this diagram in my Owner's Manual. 

Looks like the solar is cut off when the battery disconnect switches are opened. I was worried the controller might be  drain on the battery even in storage. 

In a perfect world, I'd like a drop-in replacement for my wet-cell LA House batteries that was LiFEP04 and that could be charged from the existing gear in the coach.

Am I correct that the House batteries can be charged by the alternator, inverter (when on shore power or generator is running), or solar controller?

Would a DC-DC converter placed in-line between the battery and rest of the coach provide the charge protection/profiles from any existing charging source?  Or I am looking at replacing a bunch of other components as well?

Sorry if this is too broad a question, I'm just starting to figure this stuff out. 🙂

Edited by RoadTripper2084
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When everything is working,  you are correct on the charging.  

LiFePO4  batteries have a different charge profile than flooded or AGM batteries, so the are not "drop in" replacements.  I'm not sure that you inverter/charger is capable of charging LiFePO4 batteries.  Same with the existing solar controller - which really should be replaced if you are going to add more panels because it is inefficient.  The alternator can't be used to charge LiFePO4 batteries.  If your inverter is capable, or you replace it with one that is, you will be able to charge the LiFePO4 batteries from shore or generator.  Most all new MPPT solar controllers can be set to charge LiFePO4 batteries.  The charge is a bigger issues.  

LiFePO4 batteries charge profile is something like (let's talk a 100AHr battery for example, if you by two, double the Amps) 14.4 Volts for 30 minutes @ 50-100 Amps, (what they call 0.5C to 1.0C, where C is the battery capacity - 100 in this example), then to drop back to 13.4 Volts.   The time at 14.4 Volts depends on the State of Charge (SOC) when the charging starts.   Hope I haven't lost you.  Now the problem - engine alternators are not multi-stage chargers, they are regulated at about 14.2 Volts, and try to keep that as long as the engine is running.  This will overcharge a LiFePO4 battery if your trip is more than 30 -60 minutes long.  A second, more important issue is that the alternator is not designed to output 100+ Amps, just to charge a house battery.  That is in addition to the normal charging of the Chassis battery, and running the chassis systems and the house systems.  And that is with just one 100 AHr LiFePO4 battery.  Mods are going to have 200 - 400 or more AHr batteries.  This will overheat & destroy the alternator & possibly associated isolation devices.  Enter the DC-DC Charge converter.  This basically operates like a solar controller (which is a 3 or 4 stage smart changer).  The big difference is a solar controller requires 2 -4 Volts higher voltage input then what it puts out.  That means a minimum of 16.4 Volts.   That's more that the alternator puts out and even if you adjusted it higher, it would start damaging other electrical equipment with that high a voltage.  But a cottercorrectly designed DC-DC Charge Controller can take as low as 12 Volts and output the required LiFePO4 battery profile. 

The DC-DC converter is put between the alternator and the LiFePO4 batteries, not between the batteries and the load. 

Hope this helps, 

  - Rick N.

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Thanks for the reply.

So basically, I'm looking at a new inverter if I want to charge from shore power or the alternator, a DC-DC converter if I want to charge from the alternator, and a new solar controller if I want to charge from solar?

And there isn't one magical box that does all that already? 🙂

 

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