Need to find where 2-3 volts loss between full batteries and inside of 2023 T@b 320

2

Comments

  • kimch
    kimch Member Posts: 57
    edited October 2
    https://tab-rv.vanillacommunity.com/discussion/comment/223279#Comment_223279

    This sounds good (I read it after posting my most recent) and I'll try it tomorrow, but I'm totally unclear on "DC Fuse Panel Point B." I see the diagram but am clueless what that is in my WFCO.

    And which is the Meter Connections Figure?

    If you can clarify those, I'll try your steps. Thank you.

  • Grumpy_G
    Grumpy_G Member Posts: 784
    https://tab-rv.vanillacommunity.com/discussion/comment/223274#Comment_223274

    Did the voltage in the camper change when plugged in ? Voltage at the battery is not the issue.

  • kimch
    kimch Member Posts: 57

    A few minor comments on this:

    "Nearly the same, problem is not wiring from battery to cabin.

    1. One of the DC Load circuits has an issue or
    2. Plug-in meter or the socket could have issues. Ideally all measurements should be completed with the same meter. However, the Alde is reporting a lower Voltage as well. so plug-in may be fine.

    Also suggest you completely ignore the Monitor Panel LED reading, beyond does something light, as that style Monitor is trash and reads "fair values" when the battery is near dead."

    Way back I tried the little plug-in meter in two 12 volt ports to confirm the port wasn't the issue. Also I use the LED panel only for ballpark checks which it is pretty good for, I find. For example, yesterday briefly I got the 12 volt plug-in showing 12.85 or so. I checked the LED panel and it showed 4 lights (full). The 12.85 went away and the LED was back to one light. Also when solar kicks my batteries into float and the plug-in shows 11+, if it's high enough, the LED will show 2 lights, not just one. In other words, over the years I have found it reliable as a ballpark check on power in the camper.

  • MuttonChops
    MuttonChops Member Posts: 2,072

    @ kimch Will respond to your 5:43PM post, not the early 5:38PM post (believe you learned answers)

    kimch said: . . . totally unclear on "DC Fuse Panel Point B." . . .

    You have to remove the Power Center Cover Plate:

    panelclar.jpg

    Side Note: Meter picture shows negative lead to dc panel negative connection.
    That wire goes to the Ground BUSS, you can use it as meter ground or use the Buss bar.

    '18 320 S, pitched axle, 3020HE; PNW based

    TV: '17 Colorado V6 Z71 4x4, Tow Package, GM Brake Controller
    TV: '25 Canyon AT4
    Adventures: 50 Nights: 415 Towing Miles 50,650

  • kimch
    kimch Member Posts: 57
    edited October 2
  • kimch
    kimch Member Posts: 57
    https://tab-rv.vanillacommunity.com/discussion/comment/223285#Comment_223285

    Ah, thanks! Hopefully once I take off the cover, it'll be obvious to me.

  • kimch
    kimch Member Posts: 57
    https://tab-rv.vanillacommunity.com/discussion/comment/223282#Comment_223282

    No. Not at the 12 volt port in the camper.

  • kimch
    kimch Member Posts: 57
    edited October 2

    MuttonChops is unavailable today and I cannot figure out what is Point B in his Meter Connections Figure he posted earlier. I have the cover off the converter. Can someone please tell me what Point B is?

    Update—it has to be the round metal piece to the lower right of the green. If so, I get 6+ volts there, so more than the 2-3 volt drop that MuttonChops referred to.

    26D9B04F-7FB6-47F6-A0D8-D6292ED35E35.jpg
  • kimch
    kimch Member Posts: 57

    Here again are his instructions and diagram.

    Screenshot 2026-10-02 at 11.11.21 AM.png
  • kimch
    kimch Member Posts: 57

    I think maybe it's the silver round thing on the black to the lower right of the panel. I'm going to go try that. If it's not that and anyone knows what it is, please still let me know.

  • kimch
    kimch Member Posts: 57

    New focus. Assuming that silver thing or the little indents under the remaining two fuses are Point B, I get readings only of 6+ volts, so per MuttonChops, that would point to the disconnect switch or junction box as the source of the voltage drop.

    I think the disconnect is fine. I tested its connectivity yesterday and that was fine. Today (again), I put the positive on one post in the switch, the other to camper ground and got 13+ volts which is pretty close to the batteries directly. I did the same on the other and got nearly the same. So I'm thinking that's telling me the voltage to and from the switch is fine.

    Is my thinking correct? If so, do I need to open the junction box on the side of the frame, under the camper? And if so, what if any testing (other than looking for visible issues) should I do?

  • kimch
    kimch Member Posts: 57

    Everything in the junction box looks fine—no corrosion, no signs of mice, nuts tight (though I couldn't try them—they're small and close together, but finger checking them found nothing loose). I'm at wits end.

  • Grumpy_G
    Grumpy_G Member Posts: 784

    You're thrashing. Limited experience troubleshooting electrical issues, jumping from one thing to another, random measurements with no clear description of how it was measured. Remember we can not see how you are doing things. Granted, I might assume you perform the steps the way I do them so I'll try to be very precise.

    Back to the task at hand: The left picture from @MuttonChops is misleading because it shows the circuit board from a different larger power center. The test points shown do not exist in the model in our campers. You are correct the connection labeled +VCC is where the wire from battery positive comes in. You state you measured 6V there, where did the other lead of your multimeter connect to ?

    Also, I'd like to come back to testing power from the converter. With the battery switch off and the camper plugged in, do you have any 12V power in the trailer (lights etc., not talking about the outlets) ? From what I gathered you have one of these voltage displays that plug into a 12V socket ? What does it show in this scenario ?

  • kimch
    kimch Member Posts: 57
    https://tab-rv.vanillacommunity.com/discussion/comment/223300#Comment_223300

    I would not agree I'm thrashing. Today, for example, I focused only on MuttonChop's steps.

    Re your first question—the ground I used was what MuttonChop said, the bus bar on the floor behind the converter where a ton of white wires are screwed down.

    I won't have the camper plugged in for a few days but I'm fairly sure with the battery switch off, nothing inside the camper works. Can you explain what you're thinking or trying to get at? I don't see how anything inside the camper could work even when plugged in with the battery switch off. I did confirm continuity of the switch—none when it's off, good when it's on.

  • Grumpy_G
    Grumpy_G Member Posts: 784

    Ok. There should be an exposed solid copper wire on the back of the power center which grounds to the frame of the trailer. Measure voltage between the +VCC point and the copper wire please.

    What I'm trying to do with the 120V AC/battery off exercise is to get an idea of where to look next. The trailer has two (three if you count solar but that is not available all the time) sources of 12V power: The battery and the converter/battery charger. With the trailer plugged in the battery can be disconnected, or even not be installed. The converter supplies power for everything 12V in the trailer. So everything 12V inside the trailer should work even with the battery disconnected. If not, there might be another issue.

  • kimch
    kimch Member Posts: 57
    edited October 3

    I'll consider hitching it up if I can find time this weekend and let you know.

    First, though, I'll try your +VCC point and copper wire test and let you know the results.

  • Grumpy_G
    Grumpy_G Member Posts: 784

    Ok, I wasn't precise…. With the trailer plugged into 120V the battery can be disconnected, or even not be installed. I wasn't talking about plugging into a tow vehicle, although that also provides 12V to the whole trailer via the battery charge line. However it probably will also suffer from the same voltage drop because it uses the same wiring as the battery.

  • kimch
    kimch Member Posts: 57

    Grumpy_G: "Ok. There should be an exposed solid copper wire on the back of the power center which grounds to the frame of the trailer. Measure voltage between the +VCC point and the copper wire please."

    Can you please tell me in advance what this will tell us?

  • kimch
    kimch Member Posts: 57
    https://tab-rv.vanillacommunity.com/discussion/comment/223304#Comment_223304

    I did that the other day and plugged a house lamp into a 120 outlet in the camper and it turned on just fine. With the battery switch off, I'm pretty sure, but either way the light wouldn't depend on the batteries. I don't remember if I tested the 12 volt camper lights so it sounds like I should do that again, as that's what you're asking for, correct?

  • Grumpy_G
    Grumpy_G Member Posts: 784

    Can you please tell me in advance what this will tell us?

    The trailer frame is connected to 12V negative just like in most cars. It will tell if the voltage drop is on the negative side between the busbar and the battery.

     I don't remember if I tested the 12 volt camper lights so it sounds like I should do that again, as that's what you're asking for, correct?

    Yes. As I wrote, the converter should power everything 12V in the trailer with the battery disconnected.

  • kimch
    kimch Member Posts: 57
    edited October 3

    Grumpy_G: plugged in to house power, both with battery switch on and switch off, camper shows over 13 volts and four lights on monitor. So all looks good.

    Some history—I first noticed problem when voltage would show low. I’d switch the disconnect off and on, sometimes 2 or 3 times, and the voltage would show higher. Until it stopped connecting. I replaced that switch a few months ago. Just some history. New one seems fine except ongoing 2-3 volts ( more like 3 lately) voltage drop.

    Wire test later…not for a few hours probably.

    Any insights from the plug-in test?

  • Grumpy_G
    Grumpy_G Member Posts: 784

    Any insights from the plug-in test?

    Yes, no issues in the power center and it confirms the voltage drop happens in the wiring from the battery to the power center. Once you measure voltage between +VCC and the copper ground wire we'll know more.

  • kimch
    kimch Member Posts: 57
    edited October 3

    Grumpy_G: to the copper wire from the +vcc on the green part I get 12.44 or so. The camper is showing 12.5 on my plug-in. The sun is out. The batteries are at 13.97, 14.04 battery per Victron app.

    I just turned off “battery enabled” in the Victron app and camper down to 12.2, now back to 12.6 at the plug in with solar on. That sounds right to me.

    your thoughts?

  • kimch
    kimch Member Posts: 57

    I put the positive ( red) probe on the metal button above the”+VCC, the black on the only plain copper wire from the back.

    image.png
  • kimch
    kimch Member Posts: 57

    I just tested the +VCC and copper again. 11.75 on the multimeter matches the 11.8 on the 12V plug-in, but the batteries are at 13.5 (showing 98% full, 100% SOH). So as before, roughly a 2 volt difference between the batteries and the camper interior.

  • Grumpy_G
    Grumpy_G Member Posts: 784

    Sounds like it was working earlier but now you're back to the same problem. The copper wire and the bus bar are two different paths to ground, they ultimately connect in the junction box. Similarly 12V positive connects in the junction box so I'd do some testing there. There are two junction points next to each other at the end of the row, one with (mostly) white wires, one with (mostly) red wires. White is the negative side, red the positive. Measure voltage between the two, then do a wiggle/tug test on the wires. Finally disconnect the battery using the switch and loosen the nuts of the two junctions and check for corrosion between the eyelets. Spray some contact cleaner in there for good measure and retighten.

    Question about your disconnect switch: You wrote you have two wires exiting from it ? Typically there is one wire from the battery and one going towards the trailer, unless it was modified at one time. Can you post a pic of the switch and of the battery showing the battery posts ?

  • kimch
    kimch Member Posts: 57

    No. One red wire to one post, one red wire to the other on disconnect. I don’t know which is in, which out. It was not altered. I bought this new from a very reputable dealer.

  • kimch
    kimch Member Posts: 57

    Some of the ends of these wires st the bus look pretty yech to me. Should I pull and cut them a bit, or have they been ruled out as the problem?

    image.jpeg
  • kimch
    kimch Member Posts: 57
    edited October 4

    Grumpy_G no it wasn’t working earlier today. It’s staying 1.5 to 2 or so volts lower in the camper.

  • olivia890
    olivia890 Member Posts: 2

    I’d start by tracing each white wire from the battery area and checking where it connects. A multimeter can also help identify which wire is carrying power or is acting as the main connection. I’d label each wire as you trace it so you know what they control.

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