Wiring for Portable battery charger and Shunt

Sharon_is_SAM
Sharon_is_SAM Member Posts: 10,061
in Battery/Electrical & Solar
Quick question.  We have a solar negative pigtail to the load side of our Victron shunt.  We also have a portable battery charger that we have been hooking directly to the battery.  In light of the shunt, should we be charging with the portable battery charger with the negative on the load side of the shunt?  Does it make a difference with shunt function?
Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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Comments

  • elbolillo
    elbolillo Member Posts: 549
    Ideally, you would connect all loads to the shunt. I did that with my Victron portable charger that had a quick connect.
    _____________________________________________________
    Ken / 2023 Tab 400 “La Bolita” (31,000+ miles) / 2024 Toyota Sequoia
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  • webers3
    webers3 Member Posts: 435
    For the shunt to function correctly, ie: provide correct battery status, ALL loads have to be on the negative side, including charging

    2017 T@B 320S   2019 Jeep Cherokee - Southern Connecticut
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  • Sharon_is_SAM
    Sharon_is_SAM Member Posts: 10,061
    Ok.  So, if I charge the battery fully with the portable charger on the battery, then sync the Victron BMV, will the BMV SOC be accurate on discharge?
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • AnOldUR
    AnOldUR Member Posts: 1,728
    edited April 2025
    Ideally you want a busbar attached to both the positive and negative battery terminals. Your shunt should be between the negative busbar and the battery terminal. All your wires, including the chargers should be connected to the busbars. 

    At least that’s what I did. Someone corrected me if I’m wrong. 😑 
    Stockton, New Jersey
    2020 nuCamp T@B 320S * Jeep Wrangler
    60,865 camping miles through the end of 2025

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  • rfuss928
    rfuss928 Member Posts: 1,181
    edited April 2025
    Sharon_is_SAM said:
    Ok.  So, if I charge the battery fully with the portable charger on the battery, then sync the Victron BMV, will the BMV SOC be accurate on discharge?
    Yes, that is a good process to establish 100% SOC and it makes no difference which side of the shunt you connect ground.  But, if you want the shunt to keep track of the portable charger contribution to the battery's state of charge in the future, the charger ground should be on the "load" side of the shunt. This will also allow you to monitor the portable charger performance.

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  • Sharon_is_SAM
    Sharon_is_SAM Member Posts: 10,061
    @AnOldUR - another way is to either attach a load side lead directly to the shunt or at the junction box.  We have done both.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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  • Gomers2
    Gomers2 Member Posts: 122
    @webers3 and @AnOldUR and others are correct and provide good info above. For those who may still be confused here's another way to say it: the only wire coming from the "battery" side of the smartshunt should connect directly to the battery negative terminal. All other negatives go through the load side. This ensures that the smartshunt can count all the current flowing through it and give you an accurate state of charge. (I learned about this the hard way as my camper was wired wrong from the factory. The solar panel controller negative was on the battery side of the smartshunt, so state of charge increases were never counted.) 
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