Given that the LBCO would happen probably without solar or limited anyway the fm-80 is going to read battery volt because no current. Sorry I confused the issue previously
Just calibrate the fm-80 with no solar production and you should be fine.
Jay
On Jan 7, 2025, at 4:26 PM, Bill Battagin via RE-wrenches <re-wrenches@lists.re-wrenches.org> wrote:
Looks like a lot of unknowns. Another head-spinning idea.....One
method to my wanting to use the FM80 might be to set a LBCO
voltage too high just to simulate a shutdown, have a fluke on the
battery bus and another on the aux output, load the battery to
drop battery voltage. When to aux activates read the battery
voltage at the bus and the FM80 voltage at the display Fluke using
minimum-volt recording, if there is a difference I would use that
difference to set the aux LBCO.
Bill
Feather River Solar Electric
Bill Battagin, owner
4291 Nelson St. (Shipping)
5575 Genesee Rd. (USPS, UPS)
Taylorsville, CA 95983
530-284-7849, 258-1641(cell)
CA. C10 Lic # 874049
Solar Powered since 1982
Home of the Sunny Side Up
On 1/7/2025 6:28 AM, jay via
RE-wrenches wrote:
Hi Mac,
yeah its confusing.
As far as I know, the fndc only controls the FNDC functions.
its own internal AUX, and AGS % which you can control through
the inverter relay or the FNDC relay.
All the other AUX relay functions are controlled by the
device the AUX is in.
Adding some nuance here, and I could be mistaken
about all of the functions that get taken over by the
FNDC voltage.
When you calibrate the FNDC, it "shows" the voltage
on the Mate as the FNDC voltage if there is an FNDC in
the system. I also believe that it defaults to the
FNDC voltage for some logic operations like AGS
voltage starting etc. I am not certain that LBCO uses
the inverter voltage or the FNDC voltage, probably the
inverter voltage. I assume that all Mate operations
default to FNDC voltage. I would also assume that the
aux relay will rely on the charge controller voltmeter
driving the relay.
One way to detect calibration issues is looking at
the device status pages on Optics. Each device will
show a voltage and that will correspond to the
device. If something looks very different, it may be
worth calibrating. I have found most of the devices
need calibrating at some point, charge controllers,
inverters and the fndc.
There are certainly voltmeters on each device, but
I think some of the logic is affected by uncalibrated
FNDC and I have found it very helpful to calibrate it
carefully if I'm installing Lithium. Certainly, your
SOC calculation needs a calibrated FNDC.
Going to disagree. The FNDC only
provides its voltage it doesn’t populate to the
other devices.
You still have to set the inverter
and CC separately, a poor design.
Depends on which mate you’ve got
where the fndc voltage is located.
One reason I don’t like the CC
voltage for aux control is that it gets off while
higher charging due to VD. And with lithium which
spend almost no time at lower absorb amps, it
could effect the actual end volts.
And for whatever reason I have
definitely had CC accuracy wander over time. IE
the voltage calibration gets off for some reason.
Depending on the exact lithium, might
not be a problem, some have wider upper limit than
others.
I assume that it wouldn't matter if the
FM80 is calibrated but you will want the
flexnet perfectly calibrated if you are
using Lithium. It's a very annoying but
worthwhile process. Don't drop the little
nuts.
The flexnet acts as a master voltage
device so the system will default its
voltage readings to the flexnet voltmeter.
I'm not sure if the aux function of the FM80
uses the FM80's voltage or the flexnet
voltage to drive the relay, but this could
explain the issue.
I've tried to calibrate the
voltage displayed on the Mate with the
Fluke on the battery bus bars but it
doesn't seem to take after the
adjustment in "calibrate". But The
Flexmax 80 does calibrate perfectly to
the actual battery voltage and its in
the FM80 aux landing that I'm using for
this go-around to shut down the inverter
to save the batteries.
'Manually' meaning.....?
Thanks,
Bill
Feather River Solar Electric
Bill Battagin, owner
4291 Nelson St. (Shipping)
5575 Genesee Rd. (USPS, UPS)
Taylorsville, CA 95983
530-284-7849, 258-1641(cell)
CA. C10 Lic # 874049
Solar Powered since 1982
Home of the Sunny Side Up
On 1/2/2025 5:53 PM, Mac Lewis via
RE-wrenches wrote:
Hi Bill,
Are all your voltages
calibrated? Mate, Flexmax, FM80?
Where are you reading the
voltages?
I
am trying to use the "low
battery disconnect" in aux
mode in a newly
installed OB FM80 CC for
Li battery low voltage
protection. I can't use
the 19 year old OB VFX
inverters for obvious
reasons. The plan is to
run
the 12 volt output from
the aux output to a NC
relay to open it at 50
VDC of the bank of
SimpliPhi 3.8M batteries.
50 VDC is SimpliPhi's
recommendation for LVD.
The "output" of the relay
would be connected to
the VFX's ON-OFF landings
of that little green
terminal block in the AC
side of the inverter and
just act as a simple
switch for the inverter to
turn it off to save the
batteries.
I'm using one
of my newer FM80's as a
test run and have
programmed the voltages
in Low Battery Disconnect
mode and then put it
in auto mode. However, as
the CC goes below the
voltage set point, the
AUX output does not turn
on (time set for 5
seconds), as evidence in
the
CC's home screen and by
checking for 12V at the
AUX terminal block.
Any ideas of
what I'm missing here to
make this work? I
know the other solution,
thousands of $$ for new
inverters which would
be great but these folks
have already invested
quite a chuck on array
replacement and charge
controllers.
Thanks for any experience
with this.
Bill
Feather River Solar
Electric
Bill Battagin, owner
4291 Nelson St. (Shipping) 5575
Genesee Rd. (USPS,
UPS)
Taylorsville, CA 95983
530-284-7849,
258-1641(cell)
CA. C10 Lic # 874049
Solar Powered since 1982
Home of the Sunny Side Up
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