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Topic: Javelina, TriMetric, ARC 50 readings (Read 672 times) previous topic - next topic

Javelina, TriMetric, ARC 50 readings

Need some assistance:

Javelina volt read out is - 12.9 
TriMetric reading is        - 13.5 
ARC-50 reading is          - 13.4/5

Which is correct?

I would guess the Javelina reading is low, and if the Javelina reading is low, does the auto Gen start use this reading?

Where does the Javilena reading come from?

I did notice that our Gen set started automatically the other night when we were drycamping at Marfa.  With 750 amp hours (3 Deka 8a8d) we should have more than enough power to last 6 hours.  Ran the generator from 8PM to 10PM and shut it down with TriMetric showing 100% @ 13.5 amps.  Aux comp. and HWH off.  The gen started about 5:45 AM.  We do have a residential Samsung refer and obviously other phantom draws have an effect.  However, if the Javelina is showing a lower volt charge could I have an issue with our Dynagen auto gen start?

As noted in other threads the usual low setting/start point for the Dynagen is 12.2.  If the Dynagen is looking at the Javelina reading and is .5 volts low from the get go I can understand why the Dynagen started the genset.

My plan to identify the data and compare the 3 data points is to unplug, turn on Dynagen and watch the gauge readings when the gen starts.  I suspect that the gen is starting prematurely.  Then check readings of the 12 volt wires from batteries to Dynagen, TriMetric and Magnum.  Right?

Your thoughts are appreciated.  :)

(Edited gen start time from 5 PM to 8 PM)

 





Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #1 –
I would start by using a known good DMM to check the voltage right at the battery terminals.

Are all three devices reading the same battery bank right at the terminals?
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer

Re: Javelina, TriMetric, ARC 50 readings

Reply #2 –
Suspect your Javelina is reading voltage "far downstream" of the batteries and is the least accurate.  Look at your wiring diagram, but suspect it is sensing voltage as read at the dash not battery.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Javelina, TriMetric, ARC 50 readings

Reply #3 –
Quote from: wolfe10 –
Suspect your Javelina is reading voltage "far downstream" of the batteries and is the least accurate.  Look at your wiring diagram, but suspect it is sensing voltage as read at the dash not battery.

That is where our Javelina Audit reads the voltage - from the in-dash switch that powers the Audit, wired to the dash fuse panel via wire 24
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #4 –
Thanks for the responses.

I have  Milwaukee 2235-20 DVM.  Not the best but so far it's been pretty good.

I will have to get back into the battery storage compartment to verify the position of the wires that read the voltage and verify battery voltage.  I suspect that the batteries are good as they are only 1 year old.  As for the sensing wires, I can only recall where the TriMetric wire and shunt is attached.  It is attached to the last Neg. terminal in the battery series.  I do not recall where the others are.  I can only guess that they are attached to other terminals.

Thanks again.  :)


Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #5 –
Quote from: Carol & Scott –
Need some assistance:

Javelina volt read out is - 12.9 
TriMetric reading is        - 13.5 
ARC-50 reading is          - 13.4/5

Which is correct?.........................

My plan to identify the data and compare the 3 data points is to unplug, turn on Dynagen and watch the gauge readings when the gen starts.  I suspect that the gen is starting prematurely.  Then check readings of the 12 volt wires from batteries to Dynagen, TriMetric and Magnum.  Right?

Your thoughts are appreciated.  :)

(Edited gen start time from 5 PM to 8 PM)
Scott,
Easy question to ask but there may be a larger number of variables than you imagine. 
Welcome to the challenges that a nuclear power plant faces regarding the accuracy and precision of instrumentation and control (I&C) systems that are spread over long distances.
First, because the batteries in a FT are a pretty fair distance from the readout instruments and controls that you mention, it is a fact that the measurement points will usually not be at the batteries but will be at some other convenient and logically accurate point somewhere nearby the instrument or control. 
Because the various possible FT connection points have evolved over time, the only way to know for sure where they are connected in your coach is to physically trace the wires.  From experience, I know that our (prior) 1998 and (current) 2002 coaches are very different in that regard. 
Now add the complication that wherever the chosen connection points are, they may well not be very accurate with regard to true B(+) at the battery.  Consider that the voltage may be sensed downstream of many physical connection points, all of which are subject to mechanical connections with oxidation/corrosion occurring over time and also subject to variable load conditions such as headlights on vs. headlights off, other large DC loads on or off, etc. 
Finally, consider that the precision of the measurements and displays between the DMM, the Dynagen, the TriMetric and the Magnum will vary widely.  If all four were sitting side by side, directly adjacent to the voltage source, I all but guarantee you that they will all read differently when compared to the high impedance, precision, digital voltmeter standard (and does the DMM itself have traceability to NBS standards?).
Industrial processes get around this by using parameter to current transducers (pressure, level, voltage, flow, temperature, etc. to 4 to 20 Ma or 10 to 50Ma Full scale transducers) (e.g. 10 Vdc to15 Vdc = 4 to 20 Ma DC, so 12 Vdc = 12Ma DC everywhere in the instrument display or control loop, no matter how long that loop is).  That would be far too expensive for motorhome applications where the accuracy and precision of the I&C do not need to be as exacting. 
So what to do? With a high impedance DMM and a precisely variable DC power supply, one can change the voltage at the source (battery) end of your chain of connection points that you want to consider.  Then you record voltages at the source and at the pickup point of your display instrument or at the generator start control of your interest and you record the full table of corresponding values.  To be accurate, you need to record the values in both the increasing and decreasing directions because readout instrument and control component hysteresis will also be present in the overall instrument or control loop.

Using this method, you can improve the readout accuracy (if there is a way to calibrate the display, and you can set the actuation point(s) of your control device precisely).  Of course, if later the readout and control loop connection points (oxidation or corrosion) or load influences  change, then your good work gets thrown off.  I use Corrosion X at the connection points to mitigate those sorts of changes.

Good luck and imagine what the readout or control loop challenges would be if, say, a 0 to 100 psig indication and control loop had to be maintained at (+or-) one tenth of one percent of Full Scale (+or- 0.10 psig) accuracy and precision in a control loop thousands of feet long and only accessible during outages.  Most nuclear plant I&C loops that have anything to do with reactor and engineered safeguards are maintained (+or-) 0.1, or 0.5, percent of full scale.  And there are thousands of them, taken in two out of four (or more) control and protective trip logics.
Hope this helps you think through the larger variables and how to approach accuracy and precision.
Neal
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Neal (& Brenda) Pillsbury
'02 U320 SPEC, 4200, DGFE, Build #5984
'04 Gold Wing
'07 Featherlite 24'
'14 Jeep Grand Cherokee Summit
MC #14494
Exeter, NH & LaBelle FL
Quality makes the Heart Soar long after Price is Forgotten

Re: Javelina, TriMetric, ARC 50 readings

Reply #6 –
WOW Neal.  That is a lot to chew on.  :D
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #7 –
So far.......

Volt readings from the Javelina, ARC50, Trimetric and the Auto Gen Start module do not match but the readings are consistent.  What is interesting is:

I turned on the microwave for 3 mins and with the Auto Gen Start set to 2 mins the generated started.  That is good, however,  now that the microwave of off and I set the Generator switch to Auto On the green light comes on immediately and so does the generator.  Of course the Auto Gen Start volt reading when the switch is set to auto start is: 11.7 while the Javelina showed 12.1, ARC50: 12.5 and Trimetric showed 12.4.

So it appears that the Auto Gen start volt reading is "stuck" at 11.7 when the Auto Start switch is activated.  Hmmmm.

The other interesting is that the ARC50 is showing -23A and Trimetric shows:  -5.6A.

Contacted Magnum Tech support and the -23A reading comes from the battery positive and negative posts on the Magnum MS2812 and the Trimetric/Bogart reading comes from a shunt attached to the last negative battery terminal on the bank.  I would guess that the Trimetric is getting a false "voltage use" reading somehow.  Guess I'll have to call them.

Not sure what all of this means but am sitting unplugged with the TV on monitoring the readings fro the Javelina, ARC50, Auto Gen Start and Trimetric.
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #8 –
After a few hours I was able to reset the Auto Gen Start.

Sitting for 7 1/2 hours with the Direct TV on and a few lights and monitoring all of the readings, the Gen Set started.

Trimetric:  12.2
ARC50:  12.1
Javelina:  11.7
Auto Gen Start:  12.1
Trimetric showed:  94% state of charge.

Don't know what that all means but I would presume with the TV and lights off I should be able to make it through the night.

I did confirm that the settings for the Trimetric are correct, I think.

Some thing doesn't smell right but I'm tired of this game for now.  Will chew on it for a while and re-address.  :D


Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #9 –
Only 1 (one) wire from your negative battery terminal to one side shunt, as many as you want on the other shunt terminal ?
Dave W. (AKA Toyman )
'03, 270, 36', Build 6095, Pulling whatever I hook it to.

"Don't cry because it's over. Smile because it happened."
Dr Seuss

Re: Javelina, TriMetric, ARC 50 readings

Reply #10 –
Quote from: Michelle –
That is where our Javelina Audit reads the voltage - from the in-dash switch that powers the Audit, wired to the dash fuse panel via wire 24

This is likely why the Javalina readout doesn't jive with the others - it's simply reading the voltage at an in-dash switch.  Possibly if you clean dash connections and make sure the dash has a good, low impedance "ground" it might read closer to those on the actual batteries.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Javelina, TriMetric, ARC 50 readings

Reply #11 –
Don't know how many wires from the other side of the shunt can handle.

I have thought about doing some cleaning to get a more accurate Javelina reading but I do not think it is worth the effort today.  Right now I have what I think are two good readings and they are the ARC50 and the Trimetric.  They are always within 0.1 of each other.

 :D
Scott & Carol Seibert
2001 42' double slide U320 - Sold
Previous - 2002 36' U320
 

Re: Javelina, TriMetric, ARC 50 readings

Reply #12 –
This is such a great forum. Here we have a very wonderful discussion of accuracy of gauges and what that all means. Kinda reads like an engineering explanation. Another thread is a discussion of whether to use a spreadsheet on one's computer to track fuel and other expenses or to simply write in a notebook if at all. What a group  ;D  You can get any itch scratched in any number of ways.  ^.^d
Larry
1996 U295 36'
Build # 4805
Actually we sold it but just like to lurk