My neighbor's off-grid solar system stopped working, and she is away for the winter.
She has a 24V system (4 6V Rolls in series). Voltage is now about 10 volts. Yeah, pretty bad. She had left the inverter on. One of the PV circuit breakers in the combiner box had tripped. Her "smart" charger (from generator) won't charge the batteries.
The Classic is non-responsive - nothing on the screen. My assumption is the voltage from the batteries is just too low to fire up the Classic. Can the Classic start on just solar power, with no working batteries?
I tried turning off the panels, hold down both arrow keys, and turning on the PV again. Nada.
I will try to charge each half of the batteries with a small 12 volt dumb charger so maybe I can get system voltage up to 22V or so, which I think would then restart the Classic. There is no portable 24V charger on the island. What is the minimum voltage for the Classic to run?
Or is it likely the Classic is fried or something?
She just got the Rolls, so it is worth the effort to try and resuscitate them. I realize they may be damaged, but I hope not fatally.
Any other ideas or suggestions?
Best thing to try is what you said - see if you can get charge into batteries enough so that they have enough voltage to turn on the Classic - it won't turn on if battery voltage is too low .
If the batteries have sulfated up so much that they will not come up in voltage then there isn't much you can do - the batteries are bad.
If you caught them soon enough and get some charge in them then there should be hope .
I just wonder what made the PV breaker trip - maybe another problem ?
Be interesting to know how much load is on the system that took it down so low . Not sure what kind of inverter but seems like it should have shut off when voltage got too low to save the batteries - most do .
You said just one of the PV tripped - if there are multiple strings of PV in a combiner box the others should have done some charging . Or did the main PV breaker trip ?
Whatever - sounds like some investigation with a digital volt meter and checking the whole system for connections is in order.
Larry
If you have the clearance to do the work !
I would check the system out , Disconnect the inverter & the batterys into a 12Volt setup 2x2 , use the charger & get it up to 12 volts , Fire up the classic with a reboot & pick 12Vdc to help the charger . After a time , Back to 24Vdc battery & then Reboot the Classic to see 24Vdc . Right now it's all about saving the batterys .
VT
Krementz,
Connect the solar panels directly to battery bank. If you have sufficient sun then a few days should get the bank voltage up for you to reconnect the Classic and see if the batteries have come good.
dgd
The Classic only needs about 10.5 to 11 volts to come on. FYI
Once he Classic comes on it only needs about 32 volts coming off the PV in order to start BULK charging since this is a 24 volt system. (24x130%=31.6)
Before you go tearing up the system I would just try and get the Classic to boot up by using an alternative method to get the batteries over 11 volts.
Kyle M
I "bumpstarted" the batteries by dividing into 2x12, with a tiny 6A dumb charger and a 20A smart charger hooked in parallel.
That was enough to get the Classic running again. It was also enough to let the inverter charger charge from the generator.
Rainy today, so essentially no PV today, but it looks like all is well. Won't know the final condition of the batteries for quite a while; l hope we get some sunshine soon.
don't forget to check for a hot battery (6V) on the ones(?) that were not still holding a charge.
So, what caused the breaker to trip?
Assuming here
Back feed into the panels ??
VT
Glad I see 2x2 & getting better ,
I don't know what would cause a breaker from the PV panels to the combiner to trip. No lightning happened. No grid to backfeed. Generator has been off.
There is a MS blue light surge protector. With the tripped breaker off, it lights as normal. If the bad circuit is held in place, it goes out.
My first thought was some chafed insulation on the roof, but further reflection tells me that that would not make sense. Superficial inspection of the roof panels look OK.
Anybody have any ideas? I don't know what I am looking for.
If the Surge Protector blue LED is on when the circuit is open but goes off when the circuit is closed and energized that says something is pretty goofy. I am assuming you are talking about the DC circuit . Is this surge protector on the combiner box outside , or inside at the main DC panel ?
Maybe you can draw out a schematic or take a photo inside of the box where the surge protector is connected -- not sure how deep you digging into this system or your skills .
Someone needs to evaluate the system for troubles.
Larry
Also if your system was a 24Vdc with an inverter & you swapped the battery connections to make a 12Vdc (2x2) the inverter should NOT be part of the system in a mode of 12Vdc !!
So how is the gen charger through the inverter working ?
Quote from: krementz on October 25, 2017, 02:03:57 PM
It was also enough to let the inverter charger charge from the generator.
VT
The combiner box with the blue surge protector is inside on PV DC side, between the panels and the Classic. The Classic then goes to a combiner box with the inverter cables, and cables to the batteries.
I separated the batteries to two 12V pairs, with the inverter disconnected. The little dumb charger was enough to activate the smart charger. so I could charge each pair with 26A until it about 11.5V. Same with the other pair. Removed the portable chargers, reconnected the pair, then ran her crappy 15A 24V charger off the generator. I calculate it will take 20-30 hours to recharge if the inverter really is a continuous 15A, which I doubt. It is not a 3-stage charger.
With about 15 hours run time, the batteries rest about 25.5V, so making progress.
Very Good to hear !
Well done
VT
krementz,
If it is possible to fully-charge the batteries, and measure the SG of each cell, as a reference (record these SGs), and EQ the bank, this would be a good idea.
It is common for Flooded batteries that have been discharged to this low level, to have some cells that were discharged to zero volts, and then, further discharge tries to charge those cells in REVERSE polarity. If this is the case, usually those cells/batteries may appear to be more, or less fully-charged, until they need to supply loads (without a CC or charger supplying power). Since those cells really have little Capacity to supply loads for any real amount of time, the battery bank voltage often crashes.
Another sign of this, is that the apparent self-discharge rate seems high, and these cells/batteries usually have lower terminal when rested over night, even with no external load on the battery bank.
Hope that the above is not the case.
Good Luck, Vic
"further discharge tries to charge those cells in REVERSE polarity."
I can't see that with new set of Cells that went down to .8 VPC
They should come back , but less strong .
Reversed charge I could see !
I have seen car Batteries in a RR that were reversed charged . They were dead on a disconnect , So was the RR shunts & ECU's .
VT