Off Grid Update

7.27.2016 – Wednesday

Things at the cabin have become routine. Everything just works and I’m not aware of any lingering bugs with the system. The battery monitor used to go on the fritz under just the right circumstances but that was remedied by removing the solar charger input from the shunt. The meter automatically resets to full when the batteries are fully charged. The batteries are also watered roughly every three months.

IMG_9840

June 10, 2016 – lightning near Lena, WI

Here is a quick glimpse of the current settings on the system (I’ve been tweaking them for years and have settled on these inputs for the past two years now):

 Xantrex C60 (PV Charger)

  • 13.8V FLOAT (CHG)
  • 14.7V BULK (CHG)

Xantrex RS3000 (Inverter/Generator Charger)

  • 20A Power Share
  • 100% Max Charge Rate
  • 10.5V Lo DC Volt
  • FLA Batt Type
  • 1540Ah Batt Size
  • 55W Sense Below
  • 8s Sense Interval
  • 3 # Chg Stages
  • 15.5V Egz Volts
  • On Force Charge
  • 85V Lo AC Volt
  • 45Hz Lo AC Freq
  • 135V Hi AC Volt
  • 65Hz Hi AC Freq

Victron BMV-600s (Battery Monitor) 

  • 85% CEF (charge efficiency factor)
  • 1.20A Ith (current threshold)
  • 1.25 PC (Peukert exponent)
  • 14.4V Vc (charged voltage)
  • 1500Ah Cb (battery capacity)
  • 50% DF (discharge floor)
  • 2.5% It (tail current)
  • 1 min Tcd (charged detection time)
  • 1 Tdt (ime to go)

 

The only area left to perfect is the battery monitor. Since it no longer keeps track of the solar charging it needs to reset when the batteries reach 95-100% SOC. Getting these settings just right takes a little persistence and some trial and error. Currently, the Battery Monitor will reset to 100% SOC (full charge) when the following conditions are met: 14.4V Vc or greater with 2.5% It or less (38.5 amps) for 1 minute Tcd. It resets most of the time when the Solar Charge Controller’s green light comes on indicating full charge. Because the battery monitor doesn’t track amps from the solar charger the only two variables that come in to play are Vc and Tcd. I may try lowering the Vc at some point. Currently, the system has been resetting to full-charge when left alone for a day or two between visits.

The system is now going on 7 years old! So far everything is working great and there are no signs of wear and tear. With the cabin only occupied 120 days per year I continue to hope for longevity of components and batteries.

 

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