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Battery Disconnect

N7SHG_HamN7SHG_Ham Member Posts: 1,261
in Battery/Electrical & Solar
I have a 2019 400 with factory solar installed. I just turned the battery disconnect off for the 1st time and it seems to have zero affect, lights, water pump and my factory installed Victron BM 712 all seem to carry on as normal. Unsure why at this point? I need to look into this for winter storage, but with solar I am not too worried about a dead battery during usage. And yes there are wires apparently hooked to the battery disconnect switch :)
2019 T@B 400 Boondock Lite
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Comments

  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 9,747
    The shunt for the Victron and display are powered by a small, red cable directly from the + terminal, so the disconnect switch does not turn it off.  It has very little draw.  Are you able to run a load off your panels via your charge controller independent of the battery?  If you have an effective voltage, you may be able to run those.  Cover the panels and see what happens.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • N7SHG_HamN7SHG_Ham Member Posts: 1,261
    @Sharon_is_SAM yeah, I may see what happens after dark, but right now it acts like the switch isn't hooked up. I am wondering if it got bypassed when the factory wired in the BM 712?
    2019 T@B 400 Boondock Lite
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  • jkjennjkjenn Member Posts: 6,394
    It sounds possible. 

    2021 T@b 320 Boondock "Mattie Ross" | 2021 T@b Nights: 239 | Total nights in a T@b 455 | 2022 Jeep Grand Cherokee L Overland | T@b owner since 2014

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  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 9,747
    • Well, the battery switch runs off the + terminal, the shunt is off the negative, so go figure.  Maybe the switch is defective?
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • BrianZBrianZ Member Posts: 1,765
    The battery switch is on the + line?  I thought it was on the negative, or is this a change, or only for some models or configurations?  
    -Brian in Chester, Virginia
    TV: 2005 Toyota Sienna LE (3.3L V6)
    RV: 2018 T@B 320S, >100 mods 
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  • Sharon_is_SAMSharon_is_SAM Administrator Posts: 9,747
    No, it us on the + line and it always has been - no change.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • DenisPDenisP Member Posts: 542
    I we have a 2018 400 with factory solar and the battery disconnect allows for solar charging but all other 12 volt functions are off. ( fan, lights, phantom draws ( tv, Jensen, detectors...). You may have a faulty battery disconnect. 
    2018 T@b 400, 200ah Lithium with Solar
    2013 Tundra TRD 5.7L
    Massachusetts
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  • N7SHG_HamN7SHG_Ham Member Posts: 1,261
    Update, after dark tonight I turned big red switch off and all is dead, apparently with sun on the solar panel, everything keeps on working.
    2019 T@B 400 Boondock Lite
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  • ScottGScottG Administrator Posts: 5,553
    I'm curious to know how all that is wired up. I've been under the impression that the solar controller is wired directly to the battery, but it sounds like in your case there may also be an additional unswitched link to the converter. Maybe via the "load" output on the controller?
    2015 T@B S

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  • N7SHG_HamN7SHG_Ham Member Posts: 1,261
    @ScottG yeah, unsure, maybe one of these days I will trace some of that out, mostly wanted to know if the switch was bad and it does seem to work when no sun. So I am thinking if off in winter storage parasitic drains are gone unless there is enough light to power them and that works.
    2019 T@B 400 Boondock Lite
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  • AmyJoAmyJo Member Posts: 24
    I smelled what I thought was battery gas and the battery was warm when I had it on shore power.  I am not sure which way is disconnect on the battery switch for the 2018 TAB 320S,  Is the picture of the battery on the big red switch vertical when off and horizontal when on?  Please be patient with my elementary questions.  I am a newbie at this stuff.  The meter is reading 13.6 so I guess the battery is OK.  
    Sliver and white 2018 T@B 320S bought 10-21 in Sarasota, FL.  
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  • BaylissBayliss Member Posts: 1,357
    edited October 2021
    @AmyJo, it could be different depending on how the switch was originally installed.  Below is a photo of what the disconnect switch looks like when battery power is "On" and sending 12V power to the trailer.  Look for the green label and "ON."  The switch needs to be "on" for the converter to charge the battery and to provide power to the electric brakes while towing.

    When set to "OFF" - - red label - - the 12V power is no longer going to the trailer OR the trailer's brakes, so you always want the battery disconnect switch set to "ON" while towing. 


    2019 T@B 320 S Boondock Lite; 2007 Toyota Tundra 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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  • pthomas745pthomas745 Moderator Posts: 3,961
    edited October 2021
    "Battery gas"?  If you are smelling a sulfur "rotten egg" smell from the battery, that is the sign of a real problem. Unplug the trailer from shore power immediately if that is what you are smelling.

    And: any battery plugged in and being charged will read.....13.6 or so.  This is a "false reading".  But, that isn't important right now!  What are you smelling around your trailer?

    There are no dumb questions!
    2017 Outback
    Towed by 2014 Touareg TDi
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  • MarcelineMarceline Member Posts: 1,605
    AmyJo said:
    I smelled what I thought was battery gas and the battery was warm when I had it on shore power.  I am not sure which way is disconnect on the battery switch for the 2018 TAB 320S,  Is the picture of the battery on the big red switch vertical when off and horizontal when on?  Please be patient with my elementary questions.  I am a newbie at this stuff.  The meter is reading 13.6 so I guess the battery is OK.  
    I agree with @pthomas745
    If you are smelling anything from the battery I would immediately unplug the trailer from shore power and then turn the battery switch to the off (red) position. Be extremely careful around this battery as the smell could be a sign of a serious problem and batteries can explode.

     Is your battery a sealed battery? If not, have you been checking the water level? 
    San Francisco Bay Area
    2013 CS-S us@gi
    2015 Toyota Tacoma PreRunner Double Cab
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  • AmyJoAmyJo Member Posts: 24
    I took the battery to Interstate and they said it was ready to explode!  OMG the dealer told me it was good.  Thanks for the information on the battery disconnect switch.  
    Sliver and white 2018 T@B 320S bought 10-21 in Sarasota, FL.  
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  • pthomas745pthomas745 Moderator Posts: 3,961
    @AmyJo Batteries can break.  The plates can come loose and short themselves out, etc, etc.  There is a lot going on inside that little box.  Here is a site with a picture of a "lead acid battery". 


    2017 Outback
    Towed by 2014 Touareg TDi
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  • [Deleted User][Deleted User] Posts: 0
    Bayliss said:

    When set to "OFF" - - red label - - the 12V power is no longer going to the trailer OR the trailer's brakes, so you always want the battery disconnect switch set to "ON" while towing. 


    We always tow with the battery set to off.  Doesn't seem to be a braking issue for us.  We have an electronic brake controller. I'm guessing your comment is only for towing without any add-on brake controller?  Please correct me if we've been doing this wrong...
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  • dragonsdoflydragonsdofly Member Posts: 1,927
    @Ping, yes, you are wrong. You must tow with the battery "on". Your electronic brake controller cannot send a signal to engage the trailer brakes if you (tow vehicle) and the trailer part ways. It is then that the emergency signal to engage the brakes is sent to the trailer. If you have the battery "off", there is nothing to stop your 2,000 lb projectile. If disconnected, with the battery "on" the trailer brakes engage and stop it. Your battery must be on as it is the power source for emergency braking in separation accidents.
    2017 t@b sofitel(Dr@gonsFly)TV 2015 Silverado 2500hd(Behemoth). Wyandotte, Michigan.
    Draco dormiens numquam titilandus.
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  • MuttonChopsMuttonChops Member Posts: 1,710
    Ping said:
    We always tow with the battery set to off.
    Doesn't seem to be a braking issue for us.  . . .
    Please correct me if we've been doing this wrong...

    The battery cut-off switch should be in the On Position while towing.

    You are correct that while the tow vehicle 7-pin is connected your trailer brakes work fine independent of the cut-off switch position.

    The issue/problem occurs if the trailer hitch or coupler fails and the TV and trailer separate.  When that happens the 7-pin will be ripped out.  Having the battery cut-off switch in the On position will allow the rolling free trailer to brake to a stop when the emergency break away switch activates.

    Reference Diagram:

    '18 320 S,  pitched axle, 3020HE; PNW based
    TV: '17 Colorado V6 Z71 4x4, Tow Package, GM Brake Controller
    Adventures:  54   Nights:  341  Towing Miles 43,780
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  • Denny16Denny16 Member Posts: 5,431
    edited October 2021
    There is nothing magical about the break-a-way braking system.  The little cable that goes from the TV to the TaB is connected to a switch, when the cable is pulled on hard (as in case of a trailer separation) the cable pulls out part of the switch that keeps the brake circuit open, once the cable pulls put the switch bit, the switch closes and the brakes are applied with power from the trailer’s battery.  

    This is all very mechanical, no sensors, or interaction from the tow vehicle or it’s brake controller.  The battery cut off switch needs to be On or the brakes will not work after a separation.
     Cheers 
    2018 TaB400 Custom Boondock,  Jeep Gladiator truck, Northern California Coast.
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  • [Deleted User][Deleted User] Posts: 0
    thanks to all three!  today I learned something helpful when I wasn't even looking for it.  we'll add it to our checklist and hope it never is called on to do its part.  we'd certainly like the trailer to stay attached, or stop if disconnected from the TV
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