Mick:
Here’s a thought: If the system has an FNDC, the charging may be programmed to terminate at a specific SOC. I have been told by OB tech support, and I believe this, that using SOC and battery voltage over time and/or charge taper to control charging is like the old adage, “too many cooks.” My understanding is the best parameter for terminating an absorption charge is charge taper, if your system has this option. Taper is the best indication of complete charging. This is typically set at 3% of the 20 hour AH rating. All other charge termination options should be disabled. Too many charge termination “cooks” may be the cause of your problem, Mick and the problem Drake posted I believe just today. I have been meaning to write some thoughts on the very concept of SOC. As I understand it, SOC is a calculated value, using AH in versus AH out and adjusted for charging efficiency. I believe this process has a high probability for inaccuracy because the actual efficiency value is a moving target. It changes with temperature, battery charge state, battery age and probably other factors. This belief is reinforced by the fact all of these SOC measuring systems must have a built in recalibration that typically occurs when some voltage over time condition is met. The default values for this reset to 100% SOC are deliberately too low to ensure calibration actually occurs, but it gives clients an inaccurate impression of when battery charging is fully accomplished. Way too often I have seen clients manually terminate generator charging of a battery bank prematurely because they see the SOC is 100% and yet their generator is still consuming fuel and making noise, something they do not want to occur unless they know it is required. This means batteries do not get the absorption time they need for a long life span. I have contemplated discontinuing installation of FNDC units for this reason. In fact, the only benefit I see to an FNDC unit is to allow battery parameter logging. I tell my client to ignore any number followed by a % sign. I am BCC-ing several clients on this post because I want them to have more background on why I say this. I am interested in what others think about the benefit, or lack thereof, of using derived SOC values. William PS: I would not assume a recently purchased system has the latest firmware. Wm Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 *From:* RE-wrenches [mailto:[email protected]] *On Behalf Of *Mick Abraham *Sent:* Friday, January 8, 2021 12:46 PM *To:* RE-wrenches *Subject:* [RE-wrenches] Radian Charges 1 hour per calendar day Happy Friday, Mechanix~ Drake Chamberlin wrote about the Radian inverter that began running a "too short" absorption interval after several years of normal operations. Drake said the possible culprit is inverter firmware per Outback; I wish to add a data point & follow up questions: I sold an Outback SE-830BLU-300AFCI Systemedge Package--which includes Outback batteries & all for quick deployment--to a longtime retail client in the Autumn of 2020. Firmware seems likely to be the latest version on all components since it shipped from OB so recently. The client's internet service to the site was lost along with everything else in a CA wildfire--so I can't look in remotely & I can't physically travel to the site. He has much prior experience with inverter/chargers, off grid living etc. but he's new to the Radian, Mate3s, etc. My off grid client reports his new Radian is shifting to float before the Absorption target voltage is even reached & the shift occurs around 56.1 volts battery voltage on the way up. The battery is cool, not warm. He's been through the menus & couldn't find a likely suspect for this behavior. The FM100 PV controller on the same system is able to push the battery to the absorption target then hang there as would be expected before it shifts to float. That's if the daylight lasts long enough, of course. As with Drake's client, my friend needs to be able to pump the battery to a higher state of charge with his generator than what he's getting. His upscale (but lead acid) Outback BLU batteries we bought in the package seem at risk of harm due to this problem--& I'm sure Drake has similar concerns. I asked the client to reboot the generator AC (breaker off, then back on) to see if he could push the battery closer to the absorb voltage that way but I am still waiting for that answer. Thanks to the clues & cues from Drake, I'll cut & paste this into a trouble ticket with OB. While waiting for that to percolate through the system, here's one more question for the hive mind: * When a Systemedge Package is purchased complete with batteries & all, are the chargers & the FNDC battery monitor already pre-programmed for the battery type & size? Here's hoping, and as always, the Wrench List is the Bomb! Mick Abraham, Proprietor www.abrahamsolar.com Landline: 970-731-4675 Cell phone or for text messaging: 970-946-6584 ᐧ
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