House Battery Sense Location

[BigNick1]

I have thought of a different scenario and I want to present it to the group. I believe, but haven't proven the genset is starting from the chassis battery. I believe this because I was running the coach off the inverter the other day, (1rst time). Backstory on that is the refer could only run off shore power or generator, I wired it to an inverter receptacle in the basement and it runs great, now I can go down the road without running the genset and be confident the food is good. Anyway, as I ran the coach off the inverter I noticed the battery condition status on the AGS app didn't budge off full charge and my sense wire for house battery is connected to the genset start posts on the cabinet. This makes me believe these are chassis batteries because the Xantrex remote showed an almost complete discharged state for the house batteries after some time, this should have triggered AGS. I manually started the gen normally from the start switch and recharged. The AGS didn't do its job in this scenario since I have it set to start the gen at 11.2.

So, this brings me to the question.

Where can I find a house battery sense location towards the front of the coach?

Right now the closest place I can think of is where the batteries connect to the inverter/charger. Is there a location forward of this point so my wire run isn't so long?

[tngengineer]

I installed a battery monitor on my coach, not your brand. The monitor was a Sensata, that talks to my inverter. The installation manual states the monitor needs to be connected directly to the battery posts (via fuse) in order to get an accurate reading of battery voltage. And that is where I connected it. Now I know the state of charge of the house batteries, and while I do not have the AGS that can autostart the generator when state of charge reaches a specific point, I have had some success correlating AGS indicated voltage with state of charge (currently set to start at AGS indicated 11.6V). Hasn't let me down.
FWIW

[YC1]

Can't help with the location of the wire but am concerned that your coach batteries do not seem to be charging while driving.

Am I clear on this? That is, your house batteries running the inverter should be getting charged IF your battery combining system is working correctly.

Again, I am not familiar with your yr and model setup but to add some information to the mix try this.

While monitoring the house batteries with the inverter running the refer and plenty of interior lights on to put a load on the system. PUSH the emergency start button while the engine is running and see if the house battery voltage comes up. This will tell us if you have some sort of solenoid that combines the batteries.

This information alone won't sort it because you could have two separate paths from the alternator to the house batteries. One being a heavy duty solenoid for emergencies and the other could be some sort of Diode isolator system that has failed its path from the alternator to the batteries.

None of this applies to your AGS system of course, or likely does not but fixing one issue at a time may solve both.

[96 Wideglide]

They mis-wired my AGS sensor at the factory as well. My AGS module is mounted in the front run bay, and it was easy enough to remove the sensor wire from chassis batteries to house batteries right there.

[BigNick1]

Originally Posted by 96 Wideglide

They mis-wired my AGS sensor at the factory as well. My AGS module is mounted in the front run bay, and it was easy enough to remove the sensor wire from chassis batteries to house batteries right there.

These are pictures of the forward electrical bay. The diagram list everything as chassis power, doesn't look to promising for house battery power. Any other thoughts? Appreciate the input so far.

[96 Wideglide]

Where is your AGS module located?

[BigNick1]

I mounted it to structure in the front just behind the head lights outside the generator bay.(for some reason the picture attached 90* out)

[YC1]

With the ignition off, shoreline off, solar off, Or just shut each bank of batteries off one at a time and measure the voltage on the right and then the left of the long tie board that seems to connect to the solenoid at the bottom. If you get voltage on one side and not the other you may be onto finding a source for the battery sense you want.

The pictures could be misleading and that solenoid could be a combining relay for charging but not for aux start.

To be clear, that box in the other picture is the Generator start control? I would be curious to add the information of it to my files if there is a number or model on it.

Is this something you added or was it always in the vicinity?

[jacwjames]

I believe this is the newest version of the Cummins Auto generator start option.
https://www.cummins.com/generators/m...r-start-system
Another member did an install of this last year, I didn't pay attention since I already have the earlier version EC30W version. This has it's own internal sense that is part of the wiring harness but I don't use it. My generator does (based on the wiring diagram) starts off the house batteries. Bought it to monitor inside temp in case loss of power kills the AC's. It will sense high temp and start the generator.

I have the RV20212 invert and RG7 display that has AGS function. I believe the voltage sense is in the inverter itself.



In my front drivers side electrical bay there is a large circuit/fuse board that is the interface for the house and chassis systems. There is both a house and chassis (+) stud that provides power to the systems. I would think something like this would provide a good reading of the house battery voltage.

[wamcneil]

Yeah, according to your wiring diagram it doesn't look like you've got house battery power in that electrical bay. Mine has an unswitched bus in the bay labeled 'Domestic Hot', but I'm not seeing an equivalent in yours.
Why on earth would somebody replace the original relay with a 500A blue sea remote battery switch just to energize the ignition circuits? That type of remote switch would normally be used to combine the house and chassis batteries.
Ideally any battery sense wire would attach to the battery positive post or as close to that point as practical.
If you attach to the inverter's positive post, there may be a significant voltage drop between there and the battery, causing the generator to start prematurely, and then stop early.
Cheers,
Walter

[BigNick1]

Originally Posted by YC1

With the ignition off, shoreline off, solar off, Or just shut each bank of batteries off one at a time and measure the voltage on the right and then the left of the long tie board that seems to connect to the solenoid at the bottom. If you get voltage on one side and not the other you may be onto finding a source for the battery sense you want.

The pictures could be misleading and that solenoid could be a combining relay for charging but not for aux start.

To be clear, that box in the other picture is the Generator start control? I would be curious to add the information of it to my files if there is a number or model on it.

Is this something you added or was it always in the vicinity?

jacwjames is correct, and I did the write up on the install. I hadn't completed it because I couldn't find house battery power up there. Here's the website:
https://www.cummins.com/generators/m...r-start-system.

I believe the relay is the start power relay, previous owner put a Blue Sea Systems relay in there. The box is the Gateway for the Cummins AGS+ system, I mounted that in there to the frame rail.

In regards to your post, how do I shut off the solar panel and Im not sure how to shut down battery banks other then to mechanically disconnect them.

[BigNick1]

Originally Posted by wamcneil

Yeah, according to your wiring diagram it doesn't look like you've got house battery power in that electrical bay. Mine has an unswitched bus in the bay labeled 'Domestic Hot', but I'm not seeing an equivalent in yours.
Why on earth would somebody replace the original relay with a 500A blue sea remote battery switch just to energize the ignition circuits? That type of remote switch would normally be used to combine the house and chassis batteries.
Ideally any battery sense wire would attach to the battery positive post or as close to that point as practical.
If you attach to the inverter's positive post, there may be a significant voltage drop between there and the battery, causing the generator to start prematurely, and then stop early.
Cheers,
Walter

Thanks Walter, yes its quite a relay, as I said in the pervious post the previous owner put it in there. Maybe he was in trouble and that was all he could get his hands on, don't know but, it works good, lasts a long time. He went over kill on the inverter too, its a 3012, I'm sure a 2012 would've sufficed.

Significant wire run your suggesting, front to back. It can be done but oh my, how to snake it through there.

[jacwjames]

Are you sure the AGS does not internally sense the starting voltage.



I have not uses my Onan AGS for low voltage start but I'm pretty sure that it has that capability and there are no other connections to the battery bank other then the ~6awg starting wire.

If I get a chance I'll scroll through the setup on it and check.

[BigNick1]

Originally Posted by jacwjames

Are you sure the AGS does not internally sense the starting voltage.



I have not uses my Onan AGS for low voltage start but I'm pretty sure that it has that capability and there are no other connections to the battery bank other then the ~6awg starting wire.

If I get a chance I'll scroll through the setup on it and check.

Thanks jacw, I really appreciate you digging in. I know a really good Beaver coach mechanic about 60 miles out, I'm going to visit him today and pick his brain.

Here's the manual location:
https://www.cummins.com/sites/defaul..._I2_202106.pdf

I've attached pertinent captures.
AGS1 describes capabilities.
AGS2 is from installation section and is a bit of a misnomer, it describes "engine" and "start" batteries, it should be chassis and house.
AGS3 describes setting up the app and for monitoring house and it is correct
AGS4 is from the wire diagram is somewhat correct it shows red wire to house and gray wire to engine which should say start. (which really on my coach is the CHASSIS battery)

I believe industry standard is house and chassis, start and engine are misnomers, why Cummins put that in there is anyone's guess, probably the manual was written by someone that knows nothing about RVs.

Additionally I've been in contact with the rep, he advised me to find a house battery sense location for the red wire.