question

kwillz avatar image
kwillz asked

SOC never goes up, only down?

I inherited a Smart Shunt installed by the former owner - 2019 Airstream International. It has two 100Ah lithium batteries (Battleborn), a Zamp Cinder 40 Solar Controller, 4 Zamp 90W and 1 Zamp 70W panels on the roof, two Zamp 90W panels connected to solar ports for ground deployment. Progressive Dynamics 9145ALV Converter/Charger. The SOC on the shunt never seems to go up - only down. No matter if it gets a solar charge, a charge from home from a 15A circuit, or plugged into a 50A circuit at a campground. Shouldn't it increase when it gets charged? I can get voltage from the shunt or the solar controller (and they correlate perfectly) but the SOC does nothing but go down to zero - despite the fact I have plenty of battery to operate what I need to. Thoughts??


battery charging
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1 Answer
pwfarnell avatar image
pwfarnell answered ·

The shunt is not wired up correctly. The only connection to the battery bank negative should be the battery side of the shunt, in other words only 1 wire from battery bank negative to the shunt battery connection. All other negative wires, loads, chargers, starter battery negative AND the chassis ground must be connected to the system/ load side of the shunt. The most common mistake in RVs and campers is leaving the chassis ground or starter battery connected to the battery, it must be moved to the shunt system side. The other common problem is people connect the solar charger negative to the battery, it must be connected to the load side of the shunt. Think about it, for the shunt to count power in and out it has to flow through the shunt, anything connected direct to the battery bypasses the shunt and will not be counted.

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