Author Topic: Dialling in the SOC reading...  (Read 929 times)

alyaz

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Re: Dialling in the SOC reading...
« Reply #15 on: February 18, 2019, 12:19:49 AM »
Thanks Larry. 
3.3 kW solar. (1.5 kW Helios - MN Classic 150 CC; .8 kW CSun - MN Classic 150 CC; 1 kW Sharp - MN  Classic 250 CC); Magnum PAE-4024 Inverter, AGS, ARC, BMK. Whizbang Jr., Midnite Solar battery monitor, 5 Midnite SPD’s. 24V Rolls 4KS21P - 1105 a/hr FLA.  10 kW Perkins Diesel.

Vic

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Re: Dialling in the SOC reading...
« Reply #16 on: February 18, 2019, 01:28:04 PM »

   ...   Here’s another question (yes, yet another question).

What is the correlation between the absorb voltage and reaching the end amp setting.  For example, is there any difference using an upper parameter absorb voltage setting versus a lower parameter absorb voltage setting when using end amps?  Or as long as I am in the ballpark (in my case between 29.4 - 30v) will the batteries accept and react to the end amps the same?  Hope that makes sense.

Hi Al,

If the Absorb voltage is changed on your FLA batteries,   it WILL affect the current that is charging the battery.   This will have some effect on the desired EA value,  and you would need to watch the WbJr current into the battery to find how the Vabs change affects this current.

Raising Vabs will increase the battery charging current (and should dictate some increase in the EA value) to terminate the Absorb at the appropriate time,   and lowering Vabs  will decrease this current,   and could easily require some reduction  in EA value.

Our choice of an appropriate EA value,   is in the area of the WB battery current where (it)  has STOPPED decreasing   Often there is a reasonable Jitter in the WB current value. This Jitter can make it difficult to really see when the current has stopped decreasing,  especially when viewed on the MNGP (at least on the systems here,   that use EA).

Am sure that you have significant changes in the amount of Solar production from one day,   to the next,   this time of  year. Short Solar days and inclement WX often dictate somewhat higher Vabs under these conditions.  Generally use the lowest Vabs that will allow your batteries to be fully charged (as noted by Larry).

FWIW,   Vic
« Last Edit: February 18, 2019, 02:16:09 PM by Vic »
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

alyaz

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Re: Dialling in the SOC reading...
« Reply #17 on: February 18, 2019, 02:07:39 PM »
Thanks Vic. 

I’ve got my numbers working now.  Guess we will see if and how quickly the % falls off as time passes.

One thing I find amazing though is how on top of things a person really needs (needed) to be before the Whizbang Jr.  Everyone around this area is absorbing the heck out of their batteries everyday, based on absorb time.
« Last Edit: February 18, 2019, 07:03:28 PM by alyaz »
3.3 kW solar. (1.5 kW Helios - MN Classic 150 CC; .8 kW CSun - MN Classic 150 CC; 1 kW Sharp - MN  Classic 250 CC); Magnum PAE-4024 Inverter, AGS, ARC, BMK. Whizbang Jr., Midnite Solar battery monitor, 5 Midnite SPD’s. 24V Rolls 4KS21P - 1105 a/hr FLA.  10 kW Perkins Diesel.

alyaz

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Re: Dialling in the SOC reading...
« Reply #18 on: February 22, 2019, 09:42:53 AM »
I know you guys have explained a lot of this to me already, so sorry for that.  Seems I need the explanations framed in my situation to make sense for me... 

So in a perfect world, do you guys try to set your end amps as low as possible so that your controllers move into float fairly seamlessly?  In other words, I lowered my end amps from 12 to 11 and when I have had time to watch the amps ramp down, they move pretty continuously lower until the end amps are below 11 and the controllers go into float.  Wondering if I should try 10.5 or is this ‘end amp number’ best predicated on SG readings?  Or is the battery bank not really fully charged till the amps level off (which I am having a tough time deciphering from the Wzb Jr graph).  Before I set up the Wzb Jr, I was watching the amps fall as low as about 9 before levelling out.  And am I slicing hairs here, in other words, is the difference between 11 a and 10.5 a or 10 a so minute that it’s not worth worrying about.  Thanks.
« Last Edit: February 22, 2019, 09:47:36 AM by alyaz »
3.3 kW solar. (1.5 kW Helios - MN Classic 150 CC; .8 kW CSun - MN Classic 150 CC; 1 kW Sharp - MN  Classic 250 CC); Magnum PAE-4024 Inverter, AGS, ARC, BMK. Whizbang Jr., Midnite Solar battery monitor, 5 Midnite SPD’s. 24V Rolls 4KS21P - 1105 a/hr FLA.  10 kW Perkins Diesel.

ClassicCrazy

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Re: Dialling in the SOC reading...
« Reply #19 on: February 22, 2019, 12:53:36 PM »
I think it is easier to spot the leveling off using Mymidnite graphs . Use full scale option . When you have the graph ( or past days graphs) on the screen you can select which parameters you want displayed  - so use SOC, whizbang amps, net amps , etc  - you can choose which ones you want to display.  The good thing is that once the graph is up you can drag the mouse along the graph and the data on the left will change to the point of the day where indicated.  So start out and night 0 amps coming in , then as the sun comes up  you see the amps go up, the negative net amps get charged, the SOC percentage climbs, and you can see the spot where it goes from Absorb to Float.
If you look back a week or so you can get an idea of what your system is doing - ideally you want to see SOC get to 100% when it goes from Absorb to Float and that should be the point where the amps on the graph start to level off.

Larry
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Westbranch

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Re: Dialling in the SOC reading...
« Reply #20 on: February 25, 2019, 12:41:44 PM »
I use Grahams Android App on my tablet , as it gives me a better , larger, view than a smart phone.
I set the EA to 5 amps and then watch at the end of the day, in winter we lose the sun behind the mountain ~ 2 PM, so have to wait for it to get up over the ridge before I can get a real EA estimate...  about the  end of March.
As Larry said you look at the 'tail end' of the graph and look for the flattening of the curve, which should be visible to the eye...
Now use the visually determined value and reset the EA setting, next day see wheat your vales are and do your SG readings and if you don't like it work from that point.

Have fun
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alyaz

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Re: Dialling in the SOC reading...
« Reply #21 on: May 12, 2019, 09:52:26 AM »
So got everything set up nicely but what I have noticed as of late (has been sunny every day) is that with ‘end amps’ set up, the batteries are only in ‘absorb’ for about an hour or so before the ‘end amps’ setting is reached (and SG readings show full charge). 

I clued into this as my Midnite Solar Battery Monitor has the lights on it that shows a yellow light if the bank hasn’t theoretically been fully charged within the last week.  The criteria for the monitor yellow light, as I am sure you know, is that the batteries must be at 29.4v for a least two hours, for the monitor to reset to green.

So yesterday I watched the timer before it got to the EA setting (and reset) and figured out that this is what must be happening.  It seems much of my charging is occuring in Bulk and not much absorb time (at least with this much sun) is needed to reach the EA setting.

So... if the bank is reaching EA and not absorbing much, should I be ‘zeroing’ out the EA maybe once a week and just letting the timer take it through a longer absorb cycle?

If I do that, I get the batteries to absorb longer, but my SG readings climb too.  Currently the EA settings, even with the short absorb time, are currently getting the batteries up to the 1.275 / 1.280 SG limit.

Fwiw, I already have my absorb charge voltage at the low end (29.4v) and my EA at 12a.  (Steve at Rolls suggested 12a to 14a).  I have played around with EA’s, setting it lower than 12a, but my SG readings climb a bit too high.

Does sulfation occur under these conditions?  Thoughts?  Thanks.
« Last Edit: May 12, 2019, 09:57:27 AM by alyaz »
3.3 kW solar. (1.5 kW Helios - MN Classic 150 CC; .8 kW CSun - MN Classic 150 CC; 1 kW Sharp - MN  Classic 250 CC); Magnum PAE-4024 Inverter, AGS, ARC, BMK. Whizbang Jr., Midnite Solar battery monitor, 5 Midnite SPD’s. 24V Rolls 4KS21P - 1105 a/hr FLA.  10 kW Perkins Diesel.

Westbranch

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Re: Dialling in the SOC reading...
« Reply #22 on: May 12, 2019, 01:41:55 PM »
What happens when you add 0.1V to the Max /voltage for Absorb? How many minutes longer does the Absorb last?sorb?
How many days will the experiment  take till you get a full Ab?
 :)
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CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
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boB

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Re: Dialling in the SOC reading...
« Reply #23 on: May 12, 2019, 01:53:44 PM »

So... if the bank is reaching EA and not absorbing much, should I be ‘zeroing’ out the EA maybe once a week and just letting the timer take it through a longer absorb cycle?

If I do that, I get the batteries to absorb longer, but my SG readings climb too.  Currently the EA settings, even with the short absorb time, are currently getting the batteries up to the 1.275 / 1.280 SG limit.

Fwiw, I already have my absorb charge voltage at the low end (29.4v) and my EA at 12a.  (Steve at Rolls suggested 12a to 14a).  I have played around with EA’s, setting it lower than 12a, but my SG readings climb a bit too high.

Does sulfation occur under these conditions?  Thoughts?  Thanks.

Sulfation may very well  occur when you don't Absorb once in a while at least.  This is typical.

Other than that, I think you have it right.

Skip Bulk Days was made for your scenario.   A combination of skip days and EA usage would have been even better though.

Sulfation should not happen as long as a good long absorb cycle happens at least once every few days at least or maybe once per week ?

I'm not sure what too high of a specific gravity is though ?  A higher value just means that the electrolyte has more sulfuric acid in its solution which in my mind means there is less of it on the battery plates ?  What I mean is that if you can see a higher SG, then there is more on the plates ? So if too much is left on the plates, wouldn't that mean eventual partial sulfation ?

 I'm not an expert on that theory though so you will want to ask your doctor  :)   (i.e. the battery manufacturer, someone who knows this)

boB
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mike90045

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Re: Dialling in the SOC reading...
« Reply #24 on: May 13, 2019, 12:46:51 AM »
If Specific Gravity is still rising,  the batteries are still charging. 

 Once the SG stops climbing, you are needlessly gassing the batteries and causing + plate corrosion.

You cannot raise the SG too high, you can only raise it to the set-point of the factory fill.

You can slightly extend the battery life by only charging to 95% full daily, but you still need to get to 100% to drive the sulfur off the plates and back into solution.    The longer the sulfur sits on the plates, the tighter it sticks, and once bonded, you have lost that portion of battery capacity.  The plates have started to sulfate and special measures are required to reverse it.
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boB

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Re: Dialling in the SOC reading...
« Reply #25 on: May 13, 2019, 01:18:38 AM »
I think you hit the nail right on the head, Mike !

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