question

andrew-gerngross avatar image
andrew-gerngross asked

SmartShunt SOC Calculation and Configuration

My boat has three 65ah AGM batteries (new) connected in parallel and charged by 30 amp shore power.

When connected to shore power and running a constant load of approximately 1 amp my Smart Shunt's SOC (state of charge) degrades over time toward 0% suggesting that the load is depleting the batteries.

Is this possible? Is the tiny load really depleting my batteries while they are being charged?

NOTE: I haven't changed the app configuration except to set the capacity to 195ah. Also, I have read the manual and seen the video but I'm still not sure what changes I need to make for this configuration.

SmartShunt
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4 Answers
snoobler avatar image
snoobler answered ·

Shunt installed backwards?


Charge or load not passing through shunt? The only thing that should be connected to the battery bank main (-) is the shunt. If you connect anything directly to the battery, the shunt can't see it.


Shunt needs zero current calibration?



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andrew-gerngross avatar image andrew-gerngross commented ·
Seems the installer didn't connect the charger to the shunt as you suggested.


When I said the shunt was installed correctly I was referring to whether the system and battery wires were backwards or not.

Had been assured by installer (not a Victron reseller) that the charger minus didn't have to be connected to the shunt. Which didn't quite make sense at the time but I believed him. There's a clear consensus on this forum and FB that the installer was wrong.

So thank you for you quick and correct reply!

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snoobler avatar image snoobler andrew-gerngross commented ·


Glad to hear your instincts were challenged!
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andrew-gerngross avatar image
andrew-gerngross answered ·

Thank you.

Shunt is installed properly. Reads amp/watt loads appropriately.

When there is zero load app shows zero current so the zero current calibration is probably unnecessary.

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pwfarnell avatar image
pwfarnell answered ·

What is the battery charger negative wire connected to.

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andrew-gerngross avatar image
andrew-gerngross answered ·

Not certain. Not on the boat at moment. But what is the charger - supposed to be connected to if not the battery?

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Alexandra avatar image Alexandra ♦ commented ·
@Andrew Gerngross

The shunt, which is why the question was asked by @snoobler ... Are you sure it is wired correctly?

It is a common install error.

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andrew-gerngross avatar image andrew-gerngross Alexandra ♦ commented ·
@Alexandra I was responding to the first part of snoobler's question about whether the shunt was installed backwards. It only subsequently became clear that the rest of his comment was relevant and precisely on point!
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snoobler avatar image snoobler andrew-gerngross commented ·
If you connected your charger to the battery and bypassed the shunt, the shunt can't see the current from the charger. Charger must be attached to opposite side of the shunt from the battery.
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