Running out of power - Resting

Started by off-grid-geeks, March 08, 2018, 03:25:21 PM

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boB

#15
Quote from: Matrix on March 31, 2018, 09:37:12 PM
QuoteYou can temporarily connect the PV positive to battery positive while watching the battery voltage closely to
make sure it does not go up 28 or 29V for but only a few seconds.

boB ... slightly off topic,  but aren't voltages higher than that during normal  charging?   EQ is 32.4v on some 24v banks.  What happens to batteries if those voltages were held long periods of time.  Hours?

After the battery voltage rises to 32 volts, it's gonna rise really high really fast and ruin the batteries
pretty quick if there aren't any loads.

The bulk of the charging happens below around 29 to 30 volts. With a high voltage array and an MPPV
of around 50 volts on a 24V battery, it can get worse pretty fast. That's kinda why you gotta stop at a
reasonable point when doing an uncontrolled charge like this.  If it's a large array compared to battery
size, then switching off a string or two might make it work better so battery voltage doesn't rise so
fast.

boB
K7IQ 🌛  He/She/Me

off-grid-geeks


off-grid-geeks

#17
Quote from: Resthome on March 30, 2018, 11:48:03 PM
Vic is correct as usual, we need the RFR #. And your firmware versions. If you are getting a RFR 104 and you have old firmware you need to update to the latest firmware. And make sure the MNGP is not in the Daily logs or the Classic will reboot. No other charging source to you battery bank? Is the Classic in Bulk or Absorb when it goes to Resting? Also if the battery voltage is higher than the Absorb set point the Classic will go to resting.

It was in Bulk, Absorb had not started yet.
Batt voltage below absorb point.
MNGP was not in daily logs, I leave it on the #4 display, WebJR.
There was no other charging source to the battery bank.

RFR was reason code 1 (Low Light)

off-grid-geeks

Quote from: dgd on March 31, 2018, 04:34:23 AM
Ogg,
When you noticed the Classic change to resting you left it that way the rest of theday?
You also say its been running 4+ years.
I’d suggest a complete power shutdown for the Classic, keep it off for at least 15 minutes to let everything in the circuit boards discharge. Shut off the battery breaker for the Classic and the pv input breaker too.
Recheck all the cables into the Classic as copper cables have a tendancy to creep loose over time also checking the cabling to the breakers.
If the problem persists then it may be time to get thespare Classic unpacked and installed so you can arrange to get the original one serviced by midnite 😀
Dgd

Yep, left it that way because I was off site that day. Next sunrise all was well again.
On both of the other occasions this happened, I did do a complete shutdown, but shutdown was only about 5 minutes. Upon reboot, the problem was still present, still resting.
I have retightened all connections upon the prior two occurrences.

off-grid-geeks

Quote from: boB on March 31, 2018, 05:02:06 PM

When this kind of thing happens, the most important things to ask are the battery voltage (24V) and two different PV
input voltages...   Open circuit PV voltage (Voc) and I am assuming in your case it is 67 volts.

The Voc input voltage is just that, open circuit or OFF.   The big question is...  Does the PV voltage drop
down at all when the Classic goes to Bulk MPPT ?  It should ALWAYS drop down from Voc when trying to
charge.... In fact, it should drop to around 80% or so of Voc if no shading on the panels.

If it is not dropping input voltage down, the either the Classic is broken and needs to come back, OR
it is possible that the top control PCB circuit board has come partially unplugged from the power
board underneath.  It doesn't hurt to turn off the power to the Classic (input and output) and try pressing down
on all 4 corners and the middle of that PCB and then turn it back on again and see if the PV input voltage
drops down some from Voc.

If the input voltage does drop down from open circuit, then it could be a bad (high resistance) PV connection.

If that doesn't help, then I would call for an RMA. 

You can temporarily connect the PV positive to battery positive while watching the battery voltage closely to
make sure it does not go up 28 or 29V for but only a few seconds.

If the batteries are thirsty for energy, that should put a bit of SOC back into the batteries to help out.
But this won't put out a lot of power since the maximum power point voltage of the PV is in the 50 volt
range most likely.  If you do this, just be careful the battery voltage doesn't rise too high for very long.

But geesh!....  4 years it's been working !  Looks like our planned obsolescence  circuitry is early
by one year.   

Just kidding :)

boB

Thanks, I'll do those voltage checks and post back later.