I would deeply appreciate it if someone knowledgeable could take a look at this data for me and provide some insight into my current situation. The first month of data was recorded in summer and the latest 3 months over winter.
Basically:
Moved into a rental place 6 months ago. Had a 1380 hour raylite 12v battery bank with only 600w of panels and a 40a CC to fill them. Installed my system, 1500 watts of panels, midnight classic CC, alongside the landlords. Everything was hunky dory for the first 4 months. Plenty of power coming in each day to suit our needs and so battery health was not even really factored in. The landlord had said the batteries were only a couple of years old.
We home school 3 kids between 4 adults and I was seeing all of this power going to waste on sunny days so we got a couple of desktop pc's for the kids to use as learning centres and games. Discovered pretty soon that the batteries didn't appear to be holding charge very well, dropping below 12v seemingly very quickly if both desktops being used after the sun has stopped hitting the panels when we should have had plenty of power stored up.
Found the battery log book in the battery bank container. Turns out batteries are 7.5 years old and have no records of any maintenance done since 2010. I told the landlord I thought the batteries were unhealthy, she thought she was going to be getting 25 years out of the batteries..... She finally made it out about a month after being told to check the 30 day history on her CC. Completely ignorant about solar systems, shes read the a/h in to a/h out values, saw the low battery voltage being below 12v on numerous occasions and the SOC value saying 0% and lost her @*#&. Couldn't hear a word of my knowledge, trying to tell her that my solar system can bring in 3 times as much power per day as hers and wasn't factored in in her records. That the voltage recording on the CC jumps up .3v after shutting down the 45a odd load the desktops pull, jumping straight back to 12v+. That we bought a generator and 2 40a battery chargers when we realised the batteries were healthy and those values aren't factored in (not even in the data I've recorded, making the -480a value far more realistically like -200 max). The SOC value was something unfamiliar to me, but seemingly gets higher the more drained the batteries are (looking at the data). She proceeded to go out and fill every battery well above the high mark of the level indicators in her craze, mistaking it for the low one... I tried to tell her what she had initially shown me... no dice.
The last month of data is probably among the highest usage that we've had in 6 months as the Missus had gotten into the game ark that really pulls the power. I would have thought given a healthy battery that the huge amount of sun coming in from the previous two months to the latest one would have been more than enough to prevent a drop to 11.6 under load on those several occasions during the 5 days of little sun.
I have included the first month of data, wondering if there is any way to demonstrate that the batteries have remained in similar health from the beginning. Expecting to see a significant shift in k/q h in patterning and increased float times due to less capacity and batteries reaching the 14.7 faster and faster if the batteries had been damaged due to our use. This I don't really see, factoring in the difference in daylight hours from summer to winter. Is this accurate? I have been over my system with a fine toothed comb, initially concerned I may have been bringing in too much charge with both systems combined for a less than healthy battery, but the manual for the raylights says up to 40% ROC is fine and I am surely be within that without knowing how damaged they are.
Any advice or recommendations?
well, all you have done is expose a very [poorly cared for battery...... that unit should have been getting 138A charge and itis getting less than 40 ... that is if there was enough PV to generate that... BIG batteries like that need an EQ to stir up the electolyte and keep the plates from sulfating... Sadly It is doubtful if you can reclaim them, it sounds like a large paper weight now...not saying that you can not try but don't expect a miracle...
hth
Quote from: Westbranch on July 12, 2016, 12:44:33 PM
well, all you have done is expose a very [poorly cared for battery...... that unit should have been getting 138A charge and itis getting less than 40 ... that is if there was enough PV to generate that... BIG batteries like that need an EQ to stir up the electolyte and keep the plates from sulfating... Sadly It is doubtful if you can reclaim them, it sounds like a large paper weight now...not saying that you can not try but don't expect a miracle...
hth
Westbranch said it. The system was doomed to begin with, and is way under paneled.
But when voltages started to crash, you should have shut down loads rather then continue to drain the batteries
Thanks for the replies, appreciate it!
So its basically a given that the batteries were buggered from the beginning given my first month of data comparison? Thats good to hear...
Had the guy who actually installed the solar system 7.5 years ago come out to check today. He was very supportive. Commended me on my system set up and choice on the classic. Basically agreed it was mostly the landlords fault on preliminary inspection. He's coming back monday to do some more thorough testing, see if we can bring them back at all.
Quote from: mike90045 on July 13, 2016, 02:25:03 AM
Westbranch said it. The system was doomed to begin with, and is way under paneled.
But when voltages started to crash, you should have shut down loads rather then continue to drain the batteries
Is that even if the batteries jump back up to 0.3v after shutting down the load, and sit at 12v+ the rest of the night on most of those occasions?
FYI, a fully charged "12 Volt" battery should be at about 13.2 Volts when at rest, ie more than 3 hrs without charge being applied...