2017 DX3 37BH house battery wiring help

GunTotnHippie · 03-14-2020, 05:25 PM

Hello, I just recently purchased a 2017 DX3 37BH. Decided to upgrade the inverter charger and solar controller to a victron setup running in 24v. It looks like the house batteries are ran directly to the inverter charger. Is the DC supply to the coach for lights after the inverter or does the power come from the DC side of the truck batteries? Wondering if I will have to get a DC to DC inverter to handle the 24v batteries to 12v. Also does the generator feed directly into the inverter charger or is there another component involed? Any other potential problems that could make this difficult like the command center? Any help would be much appreciated.

On a side note is there an external coax connection in the vehicle so I can run a weboost RV antenna without running wires through baggage doors?

**bclemens** · 03-15-2020, 11:54 AM

that sounds like a complicated mess...not sure why the desire to go 24V?

1. We use an inverter/charger, so no converter.
2. Generator/Shore power go through a transfer switch
3. the only external coax is for the park cable. if you don't use that, then the other end is plugged into the winegard plate.

GunTotnHippie · 03-16-2020, 01:27 PM

Quote:

Originally Posted by bclemens

that sounds like a complicated mess...not sure why the desire to go 24V?

1. We use an inverter/charger, so no converter.
2. Generator/Shore power go through a transfer switch
3. the only external coax is for the park cable. if you don't use that, then the other end is plugged into the winegard plate.

Still not clear on how the 12v gets supplied to lights inside the coach. The batteries look like they go directly to the inverter/charger. From there I see a couple 120v coming out to appliances, outlets, etc. What feeds the 12v side inside the coach for the lights and bunk bed tvs?

BTW 24v systems are twice as efficient so when building a big solar system you should be working with a minimum of 24v. I have 24v components that are going in it and my custom lithium battery bank is wired for 24v. 12v also costs more ultimately and will never put out as much power as a 24v or 48v system.

**bclemens** · 03-16-2020, 05:31 PM

I understand why to use 24V, my point was more, why convert a system that is already 12V. We have looked at 48V as there are some A/C's that run that way (just non-ducted). So if efficiency is the key, then you might as well dial it up at that point since its just as hard to try and convert a 12V system to either.

As for connection, as I recall that should come off the batteries to a distribution block/hub to the 12V panel. I'd have to check for sure.

sconnors11 · 03-17-2020, 10:19 AM

I haven't posted much about it, but I'm running three Tesla Modules at a nominal 24V. I use Orion 24V -12V converters at 70A at each. Here's a link:
https://www.victronenergy.com/dc-dc-...v-24v-48v-110v

I wasn't sure if the generator pulled from the chassis battery of from the house, so I bought two. The slides and everything else work fine. I wanted to test with just one, but I never got around to it. It's simple to test and I can try with one if you're interested.

One downfall is that the engine won't charge the batteries, but there's so much capacity I can run one of the ACs for several hours without worry.

The batteries do work quite a bit better than lead acid, but it cost me about 7,000 for 15Kwh once everything was said and done. I also dropped about 500 lbs when switching from the 6 6V lead acid batteries.

**bclemens** · 03-17-2020, 10:32 AM

I did confirm....the 12V system is fed off of the batteries behind a big 12V circuit breaker. So coming off of the batteries that should be fairly simple to trace.

**bclemens** · 03-17-2020, 10:48 AM

And yes, therein lies the benefit to higher voltages. Lithium. Those things take power like a fire hose, versus lead acid taking it through a garden hose.

At that point, they actually make alternators designed for this For example, Volta makes (or gets) a 56V alternator that mounts to the Mercedes chassis. Approved by mercedes. that way on a fairly skinny wire, you are pushing serious power to the batteries. Then via an inverter you can run the air without a generator. Just the alternator. It gets a little sticky when you consider they don't want you idling that chassis a ton.

Ideally, we would have a matching 56V A/C that would run directly off the alternator, but then we also need it to run when connected to shore power and inverted. So, the best way to cover all (3) is to just use those sources to charge the battery and leave the A/C 110V inverted.

sconnors11 · 03-17-2020, 11:02 AM

I did look for a bit for a 24V aux alternator that would fit to the ISL while retaining the stock Alternator, but came up empty. I'm okay with the lack of engine charge because I have a Generator Auto start that'll kick on if the batteries draw too low. The generator is set to come on for an hour it'll handle the AC and house loads while it throws 105A (2500 watts) at the batteries.

This is all theory because I have yet to pull the batteries low enough to trigger the AGS.

I have 1kw of solar charging the batteries that seems to be more efficient at 24V, amperage is down in the mid thirties as opposed to limiting my charge controller at 60A in the 12V volt system.

I'm an mechanical engineer and can't help but tinker... DC power makes sense to me.

**bclemens** · 03-17-2020, 11:08 AM

We have been toying with some different charge controllers, including the Victron. I like that it is remote mounted and displays on the phone app. So I can see the battery monitor along with the solar in one app.

My demo rig will have the Victron solar controller (MPPT) along with a 2nd inverter to test out the A/C running off the batteries and alternator only. Also the door speaker panels and any other toy I can throw in

membership has its privileges. Oh, and testing out some rigid panels. It'll be like Christmas....if the world is not shut down by the June Rally (I mean gathering)

sconnors11 · 03-17-2020, 11:59 AM

I've been running Canadian Solar 36V 330W house panels on the roof of the Dynamax and all is well. I had run house panels on the previous rig for 6 years too. The price per watt can't be beat and even if one dies you'll still be ahead. I have yet to have an issue with any panels and I have been driving some unimproved roads to go boondocking with both rigs.

I've had good experience with MorningStar MPPT 60 solar controllers for more that 10 years on different projects , they're not cheap, but no moving parts and great performance makes 'em a good value. You're right about the web interface of the Victron, though. The Morningstar will reply to CAN queries, but it wont be ready to run like the Victron ap.

I was using Victron Battery monitor but wasn't overly impressed with accuracy.

I'm now running a 4KW Magnum 24V Puresine Inverter/Charger, and while the current detection is sub par it too seems to work well.

My previous rig was 100% inverter powered with a 2500W Xantrex inverter charger and I never had an issue with battery life.

When I bought the Dynamax I converted to a Magnum 2800W 12V inverter that ran the whole coach. I ran the A/C off of that while driving, with solar and alternator helping the batteries support the load. All was good for hours of driving without running the generator. A few times in hot weather and longer drives in traffic the TV would act up while playing for the wife and kids. She turned the generator on and everything was fine. Running the generator took the load off the 6 6V lead acid batteries while charging them at around 100A for an hour or two.

I should add that I added a Microair box to the front A/C so it wouldn't trip the 2800W inverter. It didn't work straight away. I haven't tested the rear A/C (no Microair box) to see if it'll run on the 24V inverter.

**bclemens** · 03-17-2020, 01:43 PM

Quote:

Originally Posted by sconnors11

A few times in hot weather and longer drives in traffic the TV would act up while playing for the wife and kids. She turned the generator on and everything was fine. Running the generator took the load off the 6 6V lead acid batteries while charging them at around 100A for an hour or two.

I should add that I added a Microair box to the front A/C so it wouldn't trip the 2800W inverter. It didn't work straight away. I haven't tested the rear A/C (no Microair box) to see if it'll run on the 24V inverter.

That is sort of why we stopped offering it. We had a guy that got this set up and was driving 10 hours in high heat. It could not quite keep up and would have to start the gen....he was either a nightmare to deal with, or maybe even tried to sue us, possibly both. We eventually stopped offering it because if you did not understand its limitations, then the bad apple blamed us for it being defective.

We can put all the disclaimers in the world...but it still cost money to defend ourselves, even when we're right.

sconnors11 · 03-17-2020, 02:16 PM

Gun hippie,

Sorry for going off on a tangent.

I can take some pictures, but what I did was remove the batteries and connect the battery leads to the output of the previously linked DC-DC converters. This way the coach doesn't know any different.

One thing:
When using an inverter/charger turn off the converter in the breaker box that would normally charge your 12V battery bank. I removed the breaker and put a wire nut on the wires, covering with a plate made for purpose.

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