Victron Smart Shunt Midpoint Monitoring

manyman297
manyman297 Member Posts: 1,433
in Battery/Electrical & Solar
I’m getting ready to install two LiTime 100ah batteries and just found out about midpoint monitoring. Apparently it’s a better way to monitor the health of two or more batteries in series or parallel. Does anybody have any insight into this at all? I currently don’t have my smart shunt wired like this but I’m unsure of if it’s worth the extra work.
2021 400 BD
2020 Tacoma TRD Off-Road 
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Comments

  • elbolillo
    elbolillo Member Posts: 558
    I’ve only read a bit on the usage of mid point monitoring. Doesn’t seem like something that is very useful for small battery banks.

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

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  • manyman297
    manyman297 Member Posts: 1,433
    I read similar but anything that would help give better insight into the health of each battery would be great.
    2021 400 BD
    2020 Tacoma TRD Off-Road 
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  • YanniLazarus
    YanniLazarus Member Posts: 366
    It made me feel good to see the midpoint difference for my 2 6V AGMs is .2% - with my new Victron smart shunt. 

    The more I know about my battery health the less likely I am to panic buy something new!
    Yanni Lazarus 2020 T@B320S, 2018 RAV4 Adventure, Central CT
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  • Grumpy_G
    Grumpy_G Member Posts: 740
    Midpoint monitoring is only practical for batteries that are connected in *series*. In case of an RV that means 2 x 6V golf cart batteries in series, not parallel 12V batteries.
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  • manyman297
    manyman297 Member Posts: 1,433
    Yeah, I was confused about this but after looking at the wiring diagrams it may only work (or is just more common) in series wiring.
    2021 400 BD
    2020 Tacoma TRD Off-Road 
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  • Grumpy_G
    Grumpy_G Member Posts: 740
    It only works for series configuration. Take the simple case of two 6V batteries in series. Midpoint monitoring compares how much charge the individual batteries take and alerts if there is a significant difference. If a cell in either battery fails in this configuration it takes down the whole battery bank. With parallel 12V batteries a failing cell reduces the capacity but does not leave the battery bank completely non-functional. I suppose one could run a smart shunt per battery to detect problems with an individual battery.

    As a side note, many LiFePo batteries have battery management systems that can be monitored via bluetooth. That would be the easiest way of monitoring individual battery and even cell health.
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  • manyman297
    manyman297 Member Posts: 1,433
    @Grumpy_G Thanks for the info! It sounds like I should’ve done midpoint wiring when I installed my smart shunt initially…I just didn’t know about it.

    The new LiTime batteries showed up. Impressed with how they were packaged. Build quality feels good. I hope they last.

    I’m planning on installing them using bus bars. Does anybody know how to size a bus bar to these batteries? The common bus bar sizes I’m seeing are 300A.
    2021 400 BD
    2020 Tacoma TRD Off-Road 
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  • Grumpy_G
    Grumpy_G Member Posts: 740
    The batteries put out 100A continuous/280A for 5 seconds. A 300A bus bar is fine.
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  • manyman297
    manyman297 Member Posts: 1,433
    Thanks @Grumpy_G
    2021 400 BD
    2020 Tacoma TRD Off-Road 
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