This case also sounds like the classic loss of battery capacity as Larry
hinted. The genset is running too often. Time for a load test. --Dave
On
Mon, 22 Apr 2019 08:40:51 -0700, Starlight Solar Power Systems wrote: Hi
Glenn, Simply because he specified the energy removed during the time
period was about 6kWh. The 100Hr rate capacity for this cell is 1150Ah or
about 55kWh of storage in the bank. 55kWh/100 = about 550W which are the
claimed overnight loads. Using the 20Hr rate (960AH) would indicate higher
loads or a greater percentage of capacity loss. I was just trying to give a
more accurate consumption total to compare voltage.
Larry
Crutcher
Starlight Solar Power Systems
On Apr 19, 2019, at 4:14 PM,
Glenn Burt wrote:
Hi Larry, I am curious why you would use the 100Hr
rate for this approximation and not the 20 or 24Hr one, since that is the
period in which Mac is reporting the anomaly. Happy to learn the details!
Thanks, Glenn FROM: RE-wrenches ON BEHALF OF Starlight Solar Power
Systems
SENT: Friday, April 19, 2019 3:10 PM
TO: RE-wrenches
SUBJECT: Re:
[RE-wrenches] Operating Voltages Outback RE High Capacity Battery Mac,
Only removing 6kWh from 46kWh of storage should not be able to produce
the voltage sag to trigger AGS. That's only about 13% at a 100Hr rate.
Voltage should be no where near that point. Have you verified actual
voltage when the AGS is triggered? Loose wiring or terminal corrosion can
cause voltage drop but I would think that an easy find/repair you would
have checked. Saying the battery easily charges to 100% worries me as
sulfated batteries do that. Healthy LA batteries take many hours to reach
full saturation. Has cell voltage been compared for non-uniformity? Has the
equalization charge been performed? I am not a fan of the unusual
low voltages that Outback prescribes for EnergyCells and seriously wonder
how these voltages can properly maintain these cells. CV is below the point
where balanced O2 and H2 evolution takes place. But, thats off point.
Larry Crutcher
Starlight Solar Power Systems
On Apr 19,
2019, at 10:27 AM, Mac Lewis wrote: Hello Wrenches, We recently
inherited an Outback system that I've been keeping an eye on via Optics.
Its a dual stack 3648 VFXR, with about 4kW of PV with a single string of
EnergyCell 1100RE battery bank (reported to be ~6 months old) ~.46 kWh at
C20. I have been observing how the system functions and how the
voltage behaves. We keep getting 2 minute voltage starts on the generator
in the middle of the night that don't seem necessary judging from how much
energy has been used from the battery bank. I am hesitant to tweak anything
because these battery set-points are a bit different than I'm used to.
As per Outback: Absorb Voltage is 55.6V for 2 hours Float Voltage is
54.0V I've slowly been dropping the 2 minute start voltage to see if
there is a bottom, but I'm hesitant to take it much lower (maybe I should).
2 minute start voltage: 44.8 V. The system easily charges the
battery bank to 100% (and easily reached the 2 hr absorb time) every day.
The flexnet DC is correctly set up and calibrated. The load on the
system is pretty consistent. They use between 400 and 600W throughout the
night. An average night, they may use about 6 kWh before the voltage
sags below the 2 minute start voltage and it starts the generator.
Just curious if our 2 minute voltage needs to be dropped or if these
batteries are degraded. What corrective changes can I make to get better
performance? I have and will call Outback about this, but I'd like
other perspectives as well. Thanks as always for your expertise
-- Mac Lewis
--
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