Where does the shunt go

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donkoop asked Mar 23, '23

Where does the shunt go

good day,

I'm installing new house bank on boat with 3AGM 110AH Victron's with a Sterling battery to battery charger. I'm a bit confused as to where the shunt should be placed so I can monitor the house bank but not the starter battery.

see attached photo of proposed wiring. Should I be adding a negative cable from house to neg buss for the shunt and remove the neg jumper from starter battery to house bank? Sterling recommends neg's as I have them in diagram but that doesn't account for a BMV.

Cheers

Don

BMV Battery Monitor SmartShunt

new-battery-wiring.png (79.1 KiB)

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Answer 1 · 2023-03-24T09:42:43Z

pwfarnell answered · Mar 24, 2023 at 09:42 AM

Put it in the cable between the two batteries on your drawing or your idea of moving that cable to the negative bus with the shunt in. If you have a 12V negative ground connection then that should connect to the negative bus or the starter battery. The shunt must be the only thing connected to the house battery negative.

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kevgermany ♦♦ commented · Mar 25, 2023 at 04:58 AM

@donkoop

For clarity, it is the only connection to the negative terminal of battery 3 in your diagram, except for the link to battery 2.

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Answer 2 · 2023-03-25T12:47:07Z

donkoop answered · Mar 25, 2023 at 12:47 PM

Thanks for the responses. I wired it in yesterday, seems good to go.

Attached are before and after diagrams.

current-battery-setup.png (64.8 KiB)

new-battery-wiring.png (81.8 KiB)

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Answer 3 · 2023-03-25T16:13:24Z

Kevin Windrem answered · Mar 25, 2023 at 04:13 PM

A couple of things:

Fuses are intended to protect WIRING from fault currents. The largest fault current will come from the batteries so the fuses should go as close as possible to the battery.

You should connect all positives to battery 1. Better yet, connect all batteries 1, 2 and 3 positives to a bus bar with equal length cables and make all connections to the bus bar. Same for negatives. This balances the load between batteries better.

A good resource:

https://www.victronenergy.com/upload/documents/Wiring-Unlimited-EN-(P).pdf

Setting the switch to the BOTH position will upset the state of charge reported by the shunt. It also shorts the input and output of the Sterling!!! I would recommend finding a switch that does not have a BOTH position.

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donkoop commented · Mar 26, 2023 at 02:04 PM

Thanks Kevin,

I leave the switch in 2 (house) position all the time.

I didn't see the potential 'short' with the Sterling unit if switch is moved to or through the BOTH position, doing so with the Sterling ON or OFF would be bad either way I'm thinking. What would the consequence be of that operator error? I'll have to somehow 'lock' the switch from movement till I can find an OFF/1/2 switch

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