When I looked at the system first thing in the morning batteries were 92% SOC
The Classic was in absorb when batteries were at 94%. Voltage was 29.8 volts current 8.2 amps. PV voltage 85.6 volts and 245 watts
Once SOC reached 100%, battery voltage was 27.7 volts.
I would have expected the Classic to be in bulk charge rather than absorb for longer. Should this be the case?
Also, just an off subject question. Before I changed my batteries I had a 12 volt 440 AH bank and now I have a 24 volt 300AH bank.
Will I have increased capacity or as I’m running a 24 volt inverter rather than a 12 volt inverter or will my available capacity have decreased?
Thanks,
Quote from: asdex on August 31, 2016, 03:57:24 PM
When I looked at the system first thing in the morning batteries were 92% SOC
The Classic was in absorb when batteries were at 94%. Voltage was 29.8 volts current 8.2 amps. PV voltage 85.6 volts and 245 watts
Once SOC reached 100%, battery voltage was 27.7 volts.
I would have expected the Classic to be in bulk charge rather than absorb for longer. Should this be the case?
Also, just an off subject question. Before I changed my batteries I had a 12 volt 440 AH bank and now I have a 24 volt 300AH bank.
Will I have increased capacity or as I’m running a 24 volt inverter rather than a 12 volt inverter or will my available capacity have decreased?
Thanks,
Hi asdex,
Not exactly clear (to me) just what was the sequence of events.
When the Classic makes its transition to Float, the Net Ah should reset to zero, and the SOC should be reset to 100%. With AGMs, the Vfloat seems about correct ... depending on how weather the Classic was delivering any current, etc.
You show a WBjr in your Signature, so assume that you are using an EA setting to end Absorb (with a Absorb Time as a backup). As you know, when the EA has been reached for 30 - 60 seconds (forget which), the transition to Float will occur. If the batteries were not very deeply discharged, the Bulk and Absorb times will not be too long.
Some questions;
What is the EA setting that you are using?
Roughly, how long did that Absorb stage take?
SOC readings when using any Battery Monitoring device are only approximate, as there are many, many factors that affect the real SOC, and quite a few of these factors are difficult to measure/calculate.
Also, you are familiar that battery voltage varies considerably with variations in battery temperatures. It might be possible that some of what is troubling you about the charge process this morning, might, possibly be partly due to a change in battery temperature ... dunno ...
Speaking of Capacity, this is a term assigned to batteries. If you had a 12 V battery with 100 Ah Capacity, it could deliver a certain amount of energy to a load.
If you had a 100 Ah 24 V battery it could deliver about twice the amount of power to a load, and yet have the same nominal Capacity.
This is if both batteries were in the same condition, charged to the same real SOC, were discharged to the same ending parameter, and so on, but you get the idea.
It is in Bulk until the Absorb setpoint is reached, then it goes to Absorb until it either reaches the end of Absorb time or ending amps if you have that set - then it goes to Float.
And like Vic said the SOC will go to 100% as soon as it reaches Float.
So it may not be in Bulk very long if the voltage climbs up fast to Absorb setpoint.
Larry
Quote from: asdex on August 31, 2016, 03:57:24 PM
When I looked at the system first thing in the morning batteries were 92% SOC
We encourage phrasing that more like that "WBJr reported that the batteries were at 92%. Unfortunately its something of a rocket science to accurately measure SOC, and we need to be aware that what we are "measuring" with the classic is a rough guess only. You can after extensive tuning get it pretty close.
As a rough guide a battery will be in bulk until around 80% SOC, absorb for the last near 20%, then float for the final finish off.
Unless you have a bad connection or questionable batteries,
what you described is perfectly normal for SOC% to be around
where you saw 92% when going into Absorb. BULK/MPPT only
happens below set point voltage as crazy mentioned.
Your "energy" capacity is roughly battery amp-hours multiplied
by nominal battery voltage.
At 300 AH X 24V you have around 7,200/4,800 watt-hours = 1.5
times your previous energy capacity.
It will take a bit longer than 1.5 times to charge than before if your PV array
is the same... Approximately...
boB
Hi, thanks for your replies. Thinks are a bit clearer now.
Below are the settings in the log.
4246 0 EndingAmps 0
4247 5 EndingSoc 5
4149 294 Absorb Set Point Voltage 29.4
4139 7107 AbsorbTime 7107
4153 0 Minimum Absorb Time 0
4154 7200 Maximum Absorb Time 7200
4236 7107 AbsorbTime 7107
4150 276 Float Voltage Set Point 27.6
I have seen the system in absorb for 4 or 5 hours.
I haven’t set absorb time or ending amps so maybe I should do this. Ending amps seems best I expect.
I’m up there again in a couple of weeks so will set ending amps and observe.
Any idea of an end amp figure? I would probably go for something like 5 amps.
I’m not sure why the ending SOC is 5 but all these settings except absorb and float voltage are default.
Thanks,
Quote from: asdex on September 01, 2016, 07:26:32 PM
....I have seen the system in absorb for 4 or 5 hours.....
How many sun hours on your planet ? Takes me 3 hours to get out of Bulk, there's not 4 hours left !
Well my panels don't actually need direct sun to start charging the batteries. They start at about 8am charging and the batteries are charged at around 11 or 12am. The sun goes off the panels at about 4:30pm at this time of the year. Even on a cloudy day they preform much the same. So 8am to 4:30, that's eight and half hours. I didn't realize this was unusual.
The Classic always looks to be in absorb most of the time. It does go to float but then the water heating starts and it cycles between absorb and float.
Cheers,
Do you use Mymidnite ? Perhaps you can take a screenshot of the graph and share that - showing battery volts, SOC, system amps, etc. That really helps see what is going on over time.
example of mine from yesterday
(//)
Larry
Thanks, nice looking graph. I'll give it a go next weekend when I'm there,
Cheers,
Oh, it looks like I need to be on the internet to run My Midnite which I can't do unless its just for a short time. I have only 3G at the farm.
asdex, what is the size of your batteries in amp-hours ?
Next, around how many kW-Hours or amp-hours of energy
from the classic do you see at the end of a good sunny day ?
This is a nice little sanity check on the system.
To get an idea of ending amps, what is the lowest output current
that you see towards the end of an absorb cycle ?
The EA will be somewhere close to that low value.
Without a Whizbang Junior the value will not be perfect though.
Also, even though you may have a good ending amps value,
your batteries will still want a nice long absorb cycle once in
a while (days) to keep them from sulfating which , unfortunately,
ending amps by itself can keep from happening.
boB
Hi boB, I have 3 strings of 2 x 12volt batteries so 24 volts and 300 AH in total.
I'll take better note of the AH of energy and absorb amps when I'm there next time.
Is the picture attached, the AH per day which resets when the controller goes to rest?
Thanks,
In your photo that is the daily kWh which resets at midnight .
Larry
Yes, that shown is the energy or kilowatt-hours but you can see the amp-hours by
pressing the STATUS key once. The status screens go one by one and wrap back
around to the kW-Hour screen shown in your picture. There is not enough space
on one screen to show all of the pertinent information without switching screens.
But kW-Hours as shown is maybe close enough. 0.7 kW-H isn't all that
much but maybe that doesn't matter depending on the size of your batteries
and how many amp-hours your pull from those batteries before re-charging.
But to go from 100% SOC down to say, 75% SOC, you have to put back
at least 25% and then some more amp-hours because the amp-hour
efficiency is not 100%. That efficiency is fairly good though, say, somewhere
in the 90 percent area.
For instance if you went down to 75% SOC, you would have to put somewhere
around 32% back in to get back up to 100% SOC rather than just 25% amp-hours
taken out.
boB
My wife is at the farm this week grafting trees and she read 0.5kW at 10pm which isn't much. I don't see much info on this.
Would this figure be higher if the batteries were more discharged though the day?
I'm expecting this is the case.
If so when I'm there this weekend I'll drain the batteries down more.
It would be nice to have a figure of what the PV panels could have provided on a given day (sun strength, cloud etc) without it being dependent on battery SOC.
Then you could work out efficiency and do some tweaking easier.
I'll get here to re-read again tonight incl AH's and SOC.
Cheers,
just for comparison, we have been here for 5 days in a row, with clear skies and torrential down pours .... yesterday was sunny and the battery started at 82%SoC we pulled in 4.3 Kwh a new record!
... Normally we taken in 1.5 to 2.2 Kwh on a nice sunny day, with batteries at ~90% SoC...ABSORB by 2 pm with real charging starting at ~11:00due to shading... ABSORB Volts set to 27.8V , temp adjusted and battery temp is ~ 19.0* C
The SOC is just what is taken out - and then recharged into the battery .
The daily kWh will also include both the SOC amount plus any loads that are being used during the day too. So if it took 2 kWh to fill the batteries back up to 100% but you also pumped water during the day that took 3 kWh then the daily kWh would be 5 kWh . So all the energy that the controller puts out is shown in daily kWh .
Larry
I see thanks. In that case we should get a high kwh figure tonight as she has the water heating on.
Cheers,
Just got an update from the farm. kWh now 1.9
Battery output 44 amps 27.8v
PV input 1220 watts 77.5v
Batteries in float.
If a load is on at night then that energy use will be reflected in the SOC .
Larry
Quote from: ClassicCrazy on September 05, 2016, 10:26:50 PM
If a load is on at night then that energy use will be reflected in the SOC .
Larry
Yep and it would depend on the solar production of the following day to see if it is al put back in and reflected in the next days kW.
We are only on the boat occasionally so here is a sample of output.
Hi, I have a photo of the Classic screen and see 148AH which seems alot for a day from a 1920w PV array.
Does it sound correct?
Picture attached.
Thanks,
How many kWh was it for the day ? On my system that is all I pay attention to and means something to me. It would also be a value that is comparable for others if they have 12v, 24v , 48v systems .
Larry
I thought this reset at midnight each day.
Hi asdex,
YES, the Ah should reset at 11:59:59 PM, Local time each day. The reset may need to be enabled -- " arst ", or similar ... forget. FWIW, Vic
Hi Asdex
I'd make that a bit less than 4.5 KWh
My Array is about 5Kw and On a fine day in winter we can get about 18KWh with low batteries
in summer with diversion to the water heater (1800W) we have been up to 25KWh in a day
We are In Taranaki, New Zealand
so Looks ok to me
Cheers
Alister
Thanks SuperTed, that does look correct going by your comparison.
I'll hunt around in my log file for the reset at midnight as well.
Cheers,
There is a reset at midnight setting but it is to reboot the Classic at midnite , which some of us have on from when there were some firmware inconsistencies .
I believe the kWh going back to zero at midnight is by default and I don't know if it can be changed - never tried it.
Just thought I would mention that so there was no confusion. Rebooting also sets the kWh back to zero so that is why it is done at midnight so it doesn't mess with the kWh reading - but I think the SOC is remembered and not erased with a reboot.
Larry
Thanks, yes I searched my log file and didn't see a function to reset kWH or AH at midnight.
Cheers,