External Battery Charger

Basil48192
Basil48192 Member Posts: 437
in Battery/Electrical & Solar
I'm sure this has been covered, but I haven't been able to find the specific information.
I am installing two, new lithium 12v batteries, in parallel, into my 2021 T@B 320S.  

Due to all of the issues I've seen on this forum, I am not changing out my converter.  My plan is to let the old converter charge the batteries to around 85% (or whatever it ends up being), then letting my solar panels charge them up to 100%.  I realize I need to change my solar controller settings.

Lastly, in the event we have little sun, I purchased a Victron external battery charger.  Because I shouldn't need it very often, my plan was to simply connect to my installed batteries with alligator clips and then remove them when complete.

My main question:  Will turning off my factory battery disconnect switch be sufficient to isolate the T@B while charging with the Victron?  I know there are a few items that are powered outside of the switch.

Thank you in advance!
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Comments

  • elbolillo
    elbolillo Member Posts: 558
    Turning the battery disconnect off will isolate it from the Tab. I had a Victron external charger that I connected to the battery using the supplied M8 eyelet cable. That way the cable was always connected and I just had to connect the charger to it. I never turned off the disconnect.

    _____________________________________________________
    Ken / 2023 Tab 400 “La Bolita” (39,000+ miles) / 2024 Toyota Sequoia

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  • Basil48192
    Basil48192 Member Posts: 437
    @elbolillo.  Thank you!  I am planning on doing exactly the same thing.  So, you didn't turn the disconnect off, even when you were charging?

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  • elbolillo
    elbolillo Member Posts: 558
    Basil48192 said:
    @elbolillo.  Thank you!  I am planning on doing exactly the same thing.  So, you didn't turn the disconnect off, even when you were charging?

    No. I didn’t see any reason to do so. I didn’t turn off the disconnect when charging via solar. And I didn’t use the WFCO converter to charge either.

    _____________________________________________________
    Ken / 2023 Tab 400 “La Bolita” (39,000+ miles) / 2024 Toyota Sequoia

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  • Horigan
    Horigan Member Posts: 870
    You can permanently install the Li charger in parallel to the non-Li WFCO and Li solar chargers.  That's what I did and have had no issues. 
    Rich
    2019 T@b 400
    2025 Toyota Highlander 2.4L Turbo
    Bellingham WA
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  • Basil48192
    Basil48192 Member Posts: 437
    One more question (maybe!):
    My T@B sits in my driveway while not in use.  Due to small parasitic draws, the batteries drop down a few percent at night, then the rooftop solar brings them back up to 100% during the day.  Is this a good practice?  I've been over-whelmed with the information on the internet...so I'm not really sure.
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  • Horigan
    Horigan Member Posts: 870
    No issue with that.  Is the draw with the battery switch off?  A measurable drop over night with the battery switch off would be surprising.
    Rich
    2019 T@b 400
    2025 Toyota Highlander 2.4L Turbo
    Bellingham WA
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  • Basil48192
    Basil48192 Member Posts: 437
    @Horigan.  No, that is with the switch on.  But it still seems a little high.  It's basically the draw from all of the device screens and lights (CO/Propane detector, smoke detector, radio screen, etc.).  According to my solar panel, it seems to be about a 0.5 amp draw.  So, for the roughly 10 hours that my panel doesn't get light (it faces north), that would equate to about a 5 amp/hour loss.  Since I have 200 AH capacity, that would drop the SOC down to about 97.5%.
      
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  • Horigan
    Horigan Member Posts: 870
    Okay.  Makes sense.
    Rich
    2019 T@b 400
    2025 Toyota Highlander 2.4L Turbo
    Bellingham WA
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  • mjwaldner
    mjwaldner Member Posts: 59
    When I did our lithium upgrade I decided to go with a Victron Blue Smart charger instead of upgrading the built in charger. This has worked out great. I installed it just behind the WFCO power center. It technically would fit in the same place the WFCO charger is but I was concerned about over heating. I keep the old one in place but disconnected it. This way we have a backup if it was ever needed.
    2021 T@B 400 BD
    2025 Toyota Tundra / Nashville, TN
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