[Chad]

In my vintage (’99) Marathon implements a power-shedding policy. Anything on the “Aux” circuits will be shed before the load exceeds 50 amps on a split phase leg. If your “Aux” circuits show zero amps, you either have none of the devices on the “Aux” side on, or the “Aux” side has been shed, i.e. there was an overload in the past. In my bus, there is a Techlink button to reconnect the Aux loads.

My house battery is configured in two 12V banks in series producing 24V. The 12V lead is a center tap. Usually there is an equalizer to ensure that 12V loads do not just empty the lower bank.

All the generator/inverter information is on the Techlink screen in my bus. If you don’t have Techlink, the inverter displays can show AC/DV voltages and amps.

Gerald

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1984 96" with 8V92TA

(remodeled Liberty Coach)

Greenwood, MO

[Randy]

Post a picture of your panels your asking about in your thread. The signals showing up on meters would come from current transducers: voltage, amerage for AC and DC which the cables pass through and feed the meter.

[Billy]

Thanks very much for the kind responses.

The 1995 rig does not have TechNet or any other computerized multiplexing system, but uses what Marathon calls a “Latch Board”. It is a printed circuit board that communicates with a very big series of relays that take up an enormous panel for the 12/24v systems.

I understand about the Equalizers and the desire to balance the battery banks, but just wasn’t sure at which point the 12v is supplied versus the 24v. Marathon isn’t extremely forthcoming with wiring schematics. The 3 equalizers are new and the 4th connected item is an isolator which is the original, as I understand it.

Here is a photo of the LED screen output.

John

[Billy]

John

If you figure this one out let me know. I have an almost identical digital panel in same location 96 Marathon. Some of the readings appear to be somewhat correct however others are obviously not.

I have the same/similar latchboard and relay panel you do.

I haven’t opened the electrical box behind shore connection in wheelwell yet, but from what I understand Oregon had a law when these were built in the 90’s that required electrical supply to be able to meet everything coach could demand, so there would have been originally two 50amp shore connections – one to each panel. Since then most have had these two input feeds tied together requiring only one 50amp shore connection. Which leaves two panels, main and aux, each with two legs/220v feed. Kinda confusing, and not 100% sure this is correct – but I’ve heard/read same info from more than one source.

Rick May (Parliament/USA Coach) had told me (if I understood him correctly) there was a device that plugs into the headphone jack looking connection (mine is lower right on digital panel) used to calibrate those readouts. I’ve never pursued that so no idea. Most of my transducers are up above the main DC relay panel.

[Dick]

If all gauges show either “0” or “8888” there is likely a general fault in your display/transducer setup. Since the display lights up my guess would be a power issue with the common transducer board/amplifier.

I’d check for tripped panel breakers first. Make sure none of the small breakers below your digital display are tripped. If you have access to the back of the display panel, you can check for blown automotive fuses if there are any.

You should be able to follow wires from one current transducer (looks like a donut with a wire going through it) to the transducer board and ensure wire continuity. Check supply voltage for that transducer board. Check for leaking or blown capacitors – a common failure point in older electronics.

If all else fails, a trip to Coburg may be in order. I had a Techlink issue and they were able to fix it within 30 minutes a few years ago. No parts required.

[Archived]

1. There is a device that connects to the plug that is used to calibrate system only Marathon would have this as this was their MDM data management system pre Techlon.

[Ronald]

Further discussion revealed the following:

Some of my beliefs were correct (!)

1. Phase 1 is what I know as “Leg 1” 50amp service – amps/volts

2. Phase 2 is what I know as “Leg 2” 50amp service – amps/volts

Auxiliary is there because the electrical panel was built/designed when electrical codes required changes to meet RVIA and/or other codes. Apparently, there were fears of too much current being pulled through a given line, so Marathon chose to “split” the electric in to 2 50-amp legs plus a third pair of Auxiliary 50 amp legs in order to distribute the load across multiple lines and therefore meet codes in existence at the time for load shedding and/or management. It is my understanding that the code requirements were new, and Convertors had to decide how to tackle the load issues. This also helps to explain why the Auxiliary 120v panel has different breakers and wiring setups across different rigs.

Please don’t shoot if I don’t have this technically correct from a code or legal perspective; not my area of expertise.

So….in replacing or revamping the panel, what is really needed are 4 pair of 120v ac voltmeters and ammeters, 1 12v set of voltmeter/ammeter, and 1 24v set of voltmeter ammeter. I’m considering replacing all of the gauges myself and mounting a panel in the same place as the non-functional gauges.

So…here is the question…. For the 12v and 24v applications, how many amps should the gauges read as a maximum if one is installing gauges (assuming analog here)…what would the max DC amperage be at any given time so that the gauge covers a wide enough spread to capture the amperage and return something meaningful? Choices for gauge scales run from milliamps to 200amps (!).

Thanks for any assist….
John

[Mike]

John I think any time you would pull more that 50 amps the main on power supply post would trip.A gauge slightly above you should be fine.

[rafael]

I’m still slowly slogging at the display board with no success.
I was able to pull the panel and found 5 bad/leaking capacitors and a disconnected wire from the board to the circuitry (unknown exactly what it does because can’t get any schematics from Marathon).

Apparently, a gentleman made these displays in his garage for Marathon for a few years; at present new ones are not available nor doe anyone repair them. So I attempted a repair by replacing the capacitors and re-soldering the loose wire.

No real joy. The display now reads 0 (only a single zero) and not all zeros illuminated as previous. On the plus side, I didn’t blow anything up; on the down side, the display still needs replacement and I have no information about charging levels.

I’ll most likely replace the panel display with analog gauges and create a new panel when I complete some other more pressing repairs.

Posting as info only, ’cause I always wonder “what ever happened with” for threads with no firm termination.

John

[Bill]

If you decide on replacing your panel, I’d go with digital displays vs analog ones. Lots of them on Amazon.

E.g. https://www.amazon.com/Hailege-Multimeter-PZEM-061-Voltmeter-Transformer/dp/B08C555GKP/ref=sr_1_17?dchild=1&keywords=AC+volt+ammeter&qid=1611287259&s=automotive&sr=1-17

DC amps depends on your setup. Best is to measure amp draw with a DC clamp ammeter before you buy the meters.

If you have 2KW inverters on 24V you’d want at least a 100 amp meter and shunt/transducer per inverter or 200A for both of them at the battery. For the 12V side, I’d measure your amp draw with all the lights and 12V loads on. It might be close to 100 amps unless you changed all the bulbs to LEDs.

[Archived]

Hi and thanks so much for the feedback.

I like digital and would prefer to go that route, but reading the specs on the link that you sent specifically states not to use the gauges on Modified Sine Wave current, which is what we have.

The rig has 2 Heart Freedom Interface 24v 2800 EMS modified sine wave inverters.

I’d be interested in learning about digital gauges that can handle modified sine unless I win the lotto and then replace both inverters with Pure Sine 🙂

I apologize that I didn’t state my rationale for analog; Digital would be awesome but web searching hasn’t found any that state that they are good w/ Modified Sine, and I haven’t had time to call around….chasing leaks, ‘ya know.

Thanks again – perhaps one of the other gurus who hang out in these parts may have suggestions?

John

[rafael]

You’d need True RMS volt/ammeters to accurately measure modified sine waves. They do exist TRMS voltmeter