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« Last post by Vic on Today at 12:01:18 PM »
Hi Al, and Larry,
As Larry noted, the SOC that is calculated from the WbJr data is approximate. Obviously, the Gold Standard for SOC of Flooded batteries is from measurements taken from an accurate Hydrometer (or Refractometer). The longer period between full charges, the less-accurate is this SOC calculation. Assume that your Classic Resets SOC to 100% upon its transition from Absorb, to Float.
There are many factors that reduce the accuracy of Wb calculated SOC, like rate of discharge (and probably even rate of charge), battery efficiency variations, etc.
Agree with Larry about battery efficiency for FLA batteries. Would start at 80% for a new, but broken-in FLA, and be ready to reduce this setting, as needed. MN Engineering recommends 94-ish percent for FLAs, but this setting seems more appropriate for Sealed batteries (AGM, Gel), than FLAs, IMO.
Hydros need to be RINSED, RINSED, AND RINSED YET AGAIN with Distilled Water after each measuring session (would not let the Hydro sit, unrinsed for more than a couple of hours). Rinsing preserves the Hydro accuracy.
IMO, Flooded batteries should be fully-charged at least twice per week, perhaps once per week may be OK. The deeper the Depth Of Discharge, the more frequent should be the full-charge -- do not let a deeply discharged FLA sit, without beginning a full charge.
Fully charging FLAs from a genset is usually not desirable, BUT for off-gridders in Northern climes, there little choice. It must be done when the battery bank needs it.
One or two Pilot Cells should be chosen early in the lives of FLA batteries. Usually, these cells would be chosen from the cells that have the lowest SG, when the bank is fully charged. This will allow a quick way to measure the SOC of a FLA bank.
Al, what are the SGs of each cell in your bank, when fully charged?
How are you generally fully-charging this battery bank -- Solar, or Genset?
Agree that 6 - 7 hours of Absorb is very long. But in Winter, perhaps this is OK, as you are unlikely to have this long a Solar day for the Classic to charge. Perhaps this is in reference to the Absorb time setting in the Inverter/Charger ...
A bit of a minor nit, is that the advertised Ah Capacity of 1104 should really be reduced to 1050-ish Ah, as Surrette specs Capacity for 1.280 SG electrolyte, instead of the most-common fill electrolyte of 1.265. Will make little difference, as actual C varies a bit from cell-to-cell.
FWIW, the Surrette 4KS25 banks here have the Efficiency set to 77% IIRC. It really should be set a bit lower, at that ... they are in their 14th year of service (and we do Skip one day on one bank, and three days on the other).
More later, FWIW. Good Luck, Vic
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