Hey there, so over the last week I've noticed a pretty drastic decrease in my daily charge... By what seems to be about a 2/3rds average loss. The panels are a pair of Canadian solar 250w panels wired in series, into a classic 150, into a 24v bank. Today, with full sun, I came back to a total charge of 600 watts, whereas I would normally expect to see at least 1.5-1.8kwh. I checked all the connections and they are good. The only thing I can see is that one particular cell appears to have "branched" for lack of a better word... It looks like the top of a tree as seen from a bird's eye view, though it is not cracked in the slightest, the glass itself is fine. The pattern is confined strictly to that one cell. Any ideas on how to trouble shoot this?
Not sure this will work, but you could try covering each panel separately and check to see if there is a difference in output, I am thinking that one will give you close to your measured out put and the other very little... if it is damaged.
How is your angle of incidence? close to optimal?
I have the panels set to 30° approximately. They are fixed.
What is your PV's Voc and what is the Max Power Point voltage that the input runs at ?
boB
Hi Bob, the voc is 37.2, the ooc is 30.1v. I'm uncertain on how to answer your second question... Is that a property of the panels or a setting on the classic?
I suspect the cell that has "branched" has overheated and what you are seeing is burned EVA on top of the cell. If that is indeed the case it would likely cut all output from that panel and possibly consume some power from the other panel.
Quote from: BlackwaterPark on December 06, 2015, 07:21:46 AM
Hi Bob, the voc is 37.2, the ooc is 30.1v. I'm uncertain on how to answer your second question... Is that a property of the panels or a setting on the classic?
What is the Vmp spec on the panel you are using?
John, it looks like these are the ones, http://www.civicsolar.com/product/canadian-solar-cs6p-250p-250w-poly-blkwht-solar-panel
vmp = 30.1v
I'm afraid that 37 volts, open circuit (Voc) is on the edge of being too low for a 24V battery bank.
37Voc would put your max power point voltage (Vmpp) around 0.80 X 37 = 29.6V
which is close to your 30 volts you mentioned. It may be that the MPP voltage is
even lower than 80% of Voc which is even worse.
Check to be sure that Low Max is turned ON in the TWEAKS menu to enable the PV input
to be as close as possible to the battery voltage also.
What is the battery voltage and charge mode when you see low power ?
Maybe the stage is Absorb or Float, in which case the power can be very low
due to it not needing much power in those modes.
boB
Quote from: dbcollen on December 06, 2015, 11:04:19 AM
I suspect the cell that has "branched" has overheated and what you are seeing is burned EVA on top of the cell. If that is indeed the case it would likely cut all output from that panel and possibly consume some power from the other panel.
dbcollen may be correct if you can see a problem on the panel.
http://www.europe-solar.de/catalog/index.php?main_page=page&id=44 (http://www.europe-solar.de/catalog/index.php?main_page=page&id=44)
Bob, under tweaks I don't see a "v max†setting. It just says vbatt on left, then " offset", then Vpv on right. Under vbatt, it is 0.00, and under that 24.8. Under Vpv, 0.0, and 8.4 under that.
it says your battery V = 24.8 and the PV is 8.4 (maybe) and neither of those voltages are being adjusted or corrected (0.0)
The PV voltage, if the sun is gone , is a 'remnant' and will slowly drop after sundown but usually will be at about 50% of normal V during the evening, eventually it zeros out...
ps 24.8 under no load is below 80% charge..
hth
Ah, NM...I found the sub menu. Lmax is on. I located some of the problem I believe.... There appears to be some shading from pines among the ridge that didn't seem to be a problem last year. It's been hard to notice this year seeing as I'm spending every daylight hour working now. Today I was able to stay home and watch what was going on. Under full sun when there was no shading, I was seeing about 16 amps coming in, so I guess that's not too bad. But with shading it dropped down to between 1 and 3 amps for most of the day... Which would explain my 600 watt harvests, heh.
Oh man, below 50% charge? That's not good... My Wb says 77%. Wonder if it's been wrong this whole time..
Whoops, my bad, that should have read 80%.... your WBjr is probably pretty close... sorry :-[
have you read this info from NAWS?
http://www.solar-electric.com/deep-cycle-battery-faq.html/#Battery%20Voltages
Oh thank god, lol. Whew... I've had this system up for 13 months now and its been beautiful (modest though it's daily task is). At least according to the wbjr, and I've not let the batteries slip below 65%, and generally they nearly never go below 75%... Except these last 6 or 7 days. Yup, I've read that before... I must have spent over a year combing that forum and asking countless questions, devouring past posts and articles/ guides, etc, before putting this system together. It's a good remedial though... I'm sure I forgot more than I remembered, heh.
BWP, yes, trees growing and shading might also be the problem. Darn infestation of plants and foliage !
You should see 100% SOC once in a while as your Classic SHOULD complete an Absorb cycle
now and then to de-sulfate the batteries. When it completes the Absorb cycle naturally,
(usually after a couple of hours time), then it goes to Float and at that time it should
reset to 100% State Of Charge.
Doesn't need to do this every day but once every week or two at least... Otherwise your
batteries will be no good after so many months or so.
If partial shading, that's good you found that !
boB
Yup, I generally get to float a few times a week. The only thing I've yet to do is equalize the batteries. I checked the waters levels periodically and have only had to add a little water to each cell once, after about 9 months... These are the T-105REs
I'm guessing because my discharge is very light and steady in general, an avg of 3.5 amp (per hour)draw. Should I be doing a regular equalization?
Quoteonly had to add a little water to each cell once, after about 9 months
You are undercharging your batteries !!
either
get more solar PV
run a generator in the morning to Bulk the batteries, and let PV Absorb
reduce your loads
If you are not using much water in 9 months, you are undercharging. Every other month should require watering. And without a vigorous Absorb, the electrolyte will stratify into different layers and eventually ruin the batteries. When my batteries are in Absorb, the room sounds like it's full of hissing snakes ! Lead acid batteries will not gas nearly as much as my NiFe cells do, but they should gas and bubble some to stay healthy.
I'm not sure what I could do different about that... Normally, those panels keep the bank 85% and up, absorb happens at least 4 times a week for a couple hours a day, and they do make that sound. Then they typically go into float. What would more panels do, if the two I already have are keeping the back charged up? Should I change the absorb setting to longer periods? It was my understanding that those RE Trojans used a lot less water than the normal 105s.
This last week and a half, however, has been virtually sunless and there's no end in sight. Never seen such a stretch like this ever. Currently, the batteries are sitting at 66% and I have been using the generator exclusively for the last five days, inverter off. I don't have a charger, and I find myself at an impasse... If I spend the 500 or so to set up a charger, then I won't be able to get the bigger inverter/charger I need anyway anytime soon. I want a vfx3524 to run the pump and have charging ability. If I don't do something relativly soon though, I suspect the batteries will suffer. The inverter upgrade could happen within a month, but if I end up getting having to get a charger out of necessity, then the opportunity to get the inverter will be lost for a good long while.
BTW, it bears mentioning that my typical load is about 3.5 amps. During the weekdays, from 7a-5p, there is no load aside from whatever the classic is using, as the inverter goes off, and then off again from around 11p till 6a. We probably use somewhere in the vicinity of 400 watts daily.
Quote from: BlackwaterPark on December 12, 2015, 09:39:37 AM
absorb happens at least 4 times a week for a couple hours a day, and they do make that sound. Then they typically go into float.
Should I change the absorb setting to longer periods?
If I don't do something relatively soon though, I suspect the batteries will suffer.
Absorb V is the first target, the second one is Absorb V for X amount of time.. that is when you truly finish the main part of a 'full charge'.
You need too Absorb for a
longer period..Period!
Otherwise you will soon have a lot of scrap lead...
Start by adding an hour to the timer, if it's not enough add more time.
Lots of discussion over on NAWS forum on this topic...http://forum.solar-electric.com/discussions
hth
"Absorb V is the first target, the second one is Absorb V for X amount of time.. that is when you truly finish the main part of a 'full charge' "
I don't understand this. What is absorb V? The voltage that absorb triggers at? Second, how do I determine when the batteries have absorbed enough?
I'm guessing at this point that the best thing I can do is add a charger and two more panels which I could do much sooner than adding a big inverter charger. If I'm following this correctly, the idea is to get past bulk and into absorb as quickly as possible to ensure that the absorb phase has adequate time to do it's thing as thoroughly as possible? So.... Charger recommendations for a bank my size?
"Iota DLS-27-40: 24 Volt 40 Amp Regulated Battery Charger", would this be a good choice for a charger on a 225ah bank? There's also a samlex 40a model, which is a fair bit more expensive, but NAWS seems to only recommend the Iota. Thoughts?
I don't understand this. What is absorb V? The voltage that absorb triggers at? Second, how do I determine when the batteries have absorbed enough?
There are 3 stages to daily charging, BULK , ABSORB and FLOAT
See page 91 of the current manual
http://www.midnitesolar.com/pdfs/Classic_manual_REV_2056.pdf
Bulk MPPT-
Maximum current charge stage, the Classic is trying to bring the batteries to the Absorb voltage set point. We are basically putting all available power into the batteries.
Absorbâ€"
Constant voltage charge stage to fill the batteries. The controller is regulating so maximum power will not be seen at this time. The Absorb timer is also counting down to the switch to Float
Floatâ€"
Constant voltage charge stage with a lower voltage than the Absorb charge point. The controller is regulating so maximum power will not be seen at this time
there is one more stage and that is Equalize BUT IT IS NOT DONE DAILY, RATHER AS NEEDED. Before an EQ is done the bank must be fully through the Absorb phase.
Equalize-
Constant voltage charge stage to equalize the batteries. The controller is regulating so maximum power will not be seen at this time. The Equalize timer is also counting down to the switch to Float
as well there is a full description on page 32 of your manual, called Battery Charge Stages and Meanings
hth
Hi B w P,
What IS your Absorption voltage setting in the Classic Charge menu?
What is your Temperature Compensation setting?
Are you using the Battery Temperature Sensor (BTS) with the Classic?
Check the Limits in the Charge menu -- make sure that you have set the Limit of temp compensated charge voltage to something appropriate for Flooded batteries.
Also, use your Hydrometer to MEASURE the Specific Gravity of EACH battery cell, and record those readings in your battery Logbook, and please let us know, at least, the range in SGs.
Thanks, More later, Vic
Absorption V: 28.6, f loat: 26.4 eq:31. The absorb was set for two hours, reset it to 3.5.
T-comp: -5.0 mv
BTS: yes
Limits menu: min 26.4 max 31.0... If that's what you are referring to. When I initially set the system up, I set all the values according to Trojan recommendations for my specific batteries, and nominal voltage.
Hydrometer: don't have one. I suppose I should order one when I place my charger order today. Concerning that, I do have one question: It looks like the charger I should be getting is a 25amp Iota, seeing as no one anywhere has recommended any other brand. Seeing as this unit is for bulk and absorb, is there a reason that I should get the IQ4 add on module?
I'm also curious, looking at the Iota 27-25 specs, that it's voltage is 27.2. If my batteries call for absorption voltage of 28.6, how does that work if this unit can't get to that voltage?
I'm also uncertain of what additional equipment I will need to hook up the charger... Just a 30a breaker? I want to be able to charge while drawing power from the bank ( as I suppose most people would, heh). Thank you guys for your input so far... Really appreciated.
I dont fully understand your use scenario, on the one hand you reach float a couple times a week, but on the other hand your SOCs stay at higher levels generally. Do you have a big bank, small PV setup? The ideal ratio of PV to battery is one where your peak charge rate is about 0.1C for example:
225Ah bank, 0.1C = 22.5A,
which needs PV (at 24V) = 22.5A *24V *1/0.77= 700Wp
So if you have less than that you might want to consider bumping it up a bit. People who run systems on that rule can easily complete a charge cycle on each sunny day.
Also note that the classic is a big charge controller, capable of managing 4kW of panels. For this reason is has a concomittment level of tare. This means in practical terms that the lowest amount of PV you should use a full classic on relates to keeping the tare under say 5% of production which is something like (its complicated because the tare varys by time of day):
Tare 6W = 144Wh/d
Required production= 144Wh/d *1/ 0.05 = 2880Wh/d
Min PV= 2880/3= 960Wp (assuming production of 3Wh/d per Wp)
So again either bump the PV (and battery) up some more, or get a smaller controller like the Kid which has a much lower tare.
Lastly, seems like your missing a few basic concepts on the charge termination. Others have explained pretty well. I understand that you have a WBJr. The purpose of WBJr is to manage absorb termination (think of SOC estimation as a side benefit). To set this up properly:
- turn on 'use WbJr' for absorb termination
- set absorb time high, maybe 4 or 5 hours
- set end amps intially to 2% of your bank AH, = 0.02 * 225Ah= 4.5A.
- what this means is that the bank will go to float when either the absorb time is reached or the EA is reached which ever comes first.
- monitor a couple of cycles and at the point where float is triggered confirm that its EA thats triggering it, and that your SGs are at your 100% full target as specified by the battery maker. Adjust the EA up or down to suit.
If you are doing anything less that this, you are just guessing that your bank is ever fully charged. And murphy will happily step in and guarantee that it is NOT. You cant rely on the SOC from any kind of battery monitor as they are just models and depend heavily on correct parameters, temperature, and lots of real world complexities.
Hi B w P,
Thanks for the detailed reply.
I would guess that your Absorb voltage is a bit low, but we do not know just where you are located. But, would guess that your target SG is about 1.277 - 1.280, which would imply you would want somewhat higher Vabs.
31 V is probably the recommendation from Trojan, but, to me this is a bit too low -- AND, IMO, your EQ voltage should be Temperature Compensated, there is a setting in the T Comp menu (is that it ??).
Also, you should set the high voltage ABOVE the recommended EQ voltage to accommodate cool/cold batteries, and a possible desire in the future to increase the EQ voltage due to a specific need (but possibly forgetting that the Limit is set to 31 V, also IMO).
More later, Thanks, Vic
Yowzers. So, to try and answer some of the questions:
Zone,
My bank isn't big, but my usage of confined to very small draws in general. Led lights and TV, and charging misc electronics. The reason my SOC stays high is because normally it only has to recover about 8-12% to get back to 100%, or so I thought...at least by the wbjr, which I guess is no real indication of the real SOC. So, the panels are probably not enough for the bank, even considering my low usage. Perhaps it would be good to start with the basics again...
The pv array consists of a pair of Canadian solar 250w modules, vmp of 30.1, wired in series through 60' 6awg to the classic. As Bob had mentioned earlier, perhaps they are too low voltage for my 24v bank?
Would another pair of the same in series and paralleled to the other two help here, or should Iook for higher voltage panels? What are ideal panels for my system? I had thought that one of the major benefits to mppt was flexibility with what panels one could use.
The reason for the classic was because at some point I had planned for between 6 and 8 panels total. When I had originally designed the system, my thought was to use a kid and not a classic, but a lady from midnight ( also from Maine apparently) had told me,via a phone call, that the kid wouldn't handle 4 of those 250w modules very well, and more or less talked me into getting the classic.
So far as where I'm located, it is in the western Maine foothills. Normally, I would hit an absorb cycle every day for a few hours... But that hasn't happened in a good 10 days now, as we have been pretty sunless and I'm now encountering shade that wasn't nearly as big a problem last year at this time. Hence my questions about a charger ( which Im still pretty unclear about).
So, I guess the next step is a charger, and hydrometer to assess where my bank is really at, which I am ordering tomorrow.
The pv array consists of a pair of Canadian solar 250w modules, vmp of 30.1, wired in series through 60' 6awg to the classic. As Bob had mentioned earlier, perhaps they are too low voltage for my 24v bank?
If you have them in SERIES they are adequate for charging a 24V bank...
If you add 2 more in SERIES you will have a much better charge capacity.
But that hasn't happened in a good 10 days now, as we have been pretty sunless and I'm now encountering shade that wasn't nearly as big a problem last year at this time.
Yup, that darned low sun and short hours will get you. For my system and loads in the summer if I just wanted to replace my use (fridge, lights, internet)I could get away with just 8 of my panels, ~ 1100W. We get > 12 hrs of sun ;D
But right now due to the winter conditions etc., etc., I can only leave the Net on for monitoring and very light use when out there, AND have 1680W and have also used the genset for 3 hrs + each visit ???
It is a race you don't want to lose... PV is cheap right now!
Quote from: BlackwaterPark on December 13, 2015, 06:26:20 PM
My bank isn't big, but my usage of confined to very small draws in general. Led lights and TV, and charging misc electronics. The reason my SOC stays high is because normally it only has to recover about 8-12% to get back to 100%, or so I thought...at least by the wbjr, which I guess is no real indication of the real SOC.
To reiterate, keeping charge levels high is one thing, but ensuring that 100% is what is really essential.
Quote
So, the panels are probably not enough for the bank, even considering my low usage. Perhaps it would be good to start with the basics again...
The pv array consists of a pair of Canadian solar 250w modules...
Well by the time you add 150Wh for the CC idle, then theres your inverter idle, not sure what your using there, but that can eaily add up to 500Wh or even more. With 500Wp of solar in maine winter even without shading, youd be doing well to get 2 sun hours a day average over a month, so thats = 500W * 2 * 0.77= 770Wh. As you can see after your gears idle there isnt a whole lot left over.
Quote..., vmp of 30.1, wired in series through 60' 6awg to the classic. As Bob had mentioned earlier, perhaps they are too low voltage for my 24v bank?
Would another pair of the same in series and paralleled to the other two help here, or should Iook for higher voltage panels? What are ideal panels for my system? I had thought that one of the major benefits to mppt was flexibility with what panels one could use.
2S 60 cells is fine, i agree with WB. Thats 60-70V total Vmp, which is just dandy. 1S would definately be too low as Bob said.
Quote
The reason for the classic was because at some point I had planned for between 6 and 8 panels total. When I had originally designed the system, my thought was to use a kid and not a classic, but a lady from midnight ( also from Maine apparently) had told me,via a phone call, that the kid wouldn't handle 4 of those 250w modules very well, and more or less talked me into getting the classic.
Well 6 or 8 you will find things get easier. The kid is good for 30A, which is about 720Wp into 24V. It would clip a chunk off of 1000Wp on sunny days thats for sure. But for 2 panels, youre good to go.
QuoteSo far as where I'm located, it is in the western Maine foothills. Normally, I would hit an absorb cycle every day for a few hours... But that hasn't happened in a good 10 days now, as we have been pretty sunless and I'm now encountering shade that wasn't nearly as big a problem last year at this time. Hence my questions about a charger ( which Im still pretty unclear about).
Sounds like you are close, just need to get that hydometer, and get those absorbs a bit longer.
What angle do you have the panels at? In the winter a lot of folk in your neck of the woods tilt the array up real tall to shed snow and get help from snow reflection.
The panels are positioned at about 30° . so my plan is to keep the classic and add 2 more panels very soon, and another two by summer. The inverter is just a samlex 600sa, which has a tare of .43a, and is off for around 15 hours a day typically, so it's a pretty miniscule loss really. If not for wanting to eventually pump water, without using the genset, I could do with this inverter indefinitely. But that's another issue for another time.
My more immediate concern is the charger. What I'm wondering is is the Iota 25-27, which is stated to provide a steady 27.2 vdc, able to bring the bank voltage up to the higher voltage recommended for absorb?
Just spoke to an Iota tech and he set me straight on how the charger works, recommending the DSL 27-25 with an external IQ4. Those guys seem to know their stuff!
Quote from: BlackwaterPark on December 14, 2015, 07:51:57 AM
The panels are positioned at about 30° . so my plan is to keep the classic and add 2 more panels very soon, and another two by summer.
30 degrees from the horozontal? That is pretty shallow for your latitude, and will effect your winter performance.
Presumably thats the roof pitch. Something to think about.
QuoteThe inverter is just a samlex 600sa, which has a tare of .43a, and is off for around 15 hours a day typically, so it's a pretty miniscule loss really.
Ok, so that takes the inverter tare to =0.43*24* (24-15)= 93Wh/d.
So total gear tare in the 250Wh/d range. What did i say your production was... 750Wh/d. Take off 10% for shading and 10% for off angle, and that leaves you with around 450Wh/d on average.
QuoteIf not for wanting to eventually pump water, without using the genset, I could do with this inverter indefinitely. But that's another issue for another time.
Inverters are problematic like that. We keep asking midnite for a stackable small inverter with low tare, and hopefully we will see something one day.
QuoteMy more immediate concern is the charger. What I'm wondering is is the Iota 25-27, which is stated to provide a steady 27.2 vdc, able to bring the bank voltage up to the higher voltage recommended for absorb?
A charger will help with your present production shortfall thats for sure. On the setpoints issue, well, does it really matter. You can use even the crudest of chargers to do the bulk in the early morning, and let the solar do the absorb. and eq.
Good luck with your system upgrade. Feel free to holler if you have more questions.
Heh, I knew that didn't sound right when I have the angle... Was using my clinometer app, being too lazy to forage for the angle finder. This is what smartphones have done to me. They are 68°... Should have remembered that from when I set them up a year ago.
Alrighty, so I've obtained some proper equipment and have been able to take some readings on those batteries. The Iota charger (25a), and a hydrovolt to test the SGs.
At present, after leaving the charger running for many hours ( with the IQ4 module plugged in...I got it externally on the Iota techs recommendation), the charger is showing float status, the classic is showing 100% SOC, and everything is turned off. the voltage under no load is 26.5v...( from 27.1 while the charger was doing its thing).
The readings on the four batteries: (taken under no load and disconnected from rest of system)
Battery 1: Battery 2: Battery3:
6.68v. 6.66v. 6.64v.
Cell 1: 1233. Cell 1: 1210. Cell 1:1216
Cell 2: 1205. Cell 2: 1215. Cell 2: 1216.
Cell 3: 1215. Cell 3: 1218. Cell 3: 1230.
Battery 4:
6.65v
Cell 1: 1222
Cell 2: 1225
Cell 3: 1210
So, from what I've been reading, the cells seem to be in a SoC of between ~60-80%? What can I do here? The charger has dropped the current down to about 4amps or so. Is it alright to run the charger AND the classic at the same time? Not that there's much sun to be had up here during this time of year.
Blackwaterpark,
If I had those readings I would do an equalization charge more often, you should not have more than about .010 difference between the cells...... .050 difference and you are headed for replacing the set
Your max deviation is .027 does not indicate good maintaince. I would cycle these a bit harder than you are doing then eq. To get a better balance
I recovered a set of 4 Rolls-Surette S-530 L-16's headed for the scrap pile for $20.00 and recovered them to 100% capacity using my methods.
Set your absorb to a much longer time , if you have a Whizbang , set it up for end amps at a reasonable value for your batteries and do an equalization several times....you want to see all the cells gassing freely. If you are using water recycling caps such as water savers....open or remove them,
Notes on distilled waters... They are not all the same! I make colloidal silver for health reasons and I have discovered that a lot of distilled water is not as pure as claimed! Some has enough metallic particles that my .999 pure silver electrodes are coated with impurities from the distilled water!
Batteries do not like non-pure water! Unsolicited advertisement for Arrowhead Puritas Water, I don't have to clean my electrodes using Arrowhead Puritas Water like I do when I use off branded water! I only use Arrowhead Puritas Water in my batteries and for my colloidal silver process. Maybe my bias, works for me.
I use approx 1.8 gallons/ month distilled water in 8 ea L-16 batts, 2 sets, 1 rolls-Suretts and 1 Interstate
Hope this helps, Tecno
Thanks Tecno, the info helps. Equalization will be tricky for me, because I'm away from house from sun up till sun down, the sun being very scarce this time of year where I am, and bring somewhat under paneled as I am. I wish there was some way to force the Iota charger to equalize, but it only appears to initiate that function after seven consecutive days of float... Which isn't going to happen here.
I'm guessing that you can't run a charger through the classic and do it that way? Worst case scenario, I'll just have to replace the bank come spring, when I double my array and get more proactive about doing regular EQs (I've only done a manual one hour EQ once in the 14 months I've had the batteries)
Is there some other piece of equipment anyone knows about that can equalize manually?
BwP, I can't remember if it was mentioned above but the way to do an EQ is to start your Bulk in the early AM (pre dawn?) and when the charger gets well into Absorb ( Amps decreasing), switch to Solar power and let the solar do the long slow work of Absorb and Float and then EQ if possible... hth
Yes, I do believe that was brought up.
Can the EQ cycle be programmed to occur that day when it has the opportunity? The problem in general is that I'm never there during the period of time where an EQ would take place.
I did some reading up in various places about doing an EQ, and most say to monitor the progress by periodically checking the SGs every hour or so to determine how long the cycle should take. If one is not around to do this, what might be the best approach?
Also, concerning the end amps setting... I used to have it on a value of 4 (on a 24v 225ah bank). After hearing from everyone that the absorb cycle wasn't likely lasting long enough, I changed the parameters of absorb time from 2 to 4 hours and reset the end amps to 0, figuring that the timer alone would ensure a longer cycle. Should I reset the end amps value?
Another question... Should I never run both the pv input AND the charger at the same time?
In reverse order, yes you can run the charger and Inverter simultaneously. Best that you are there to shut off the charger once your target state is achieved. The two units will self regulate based on their individual settings. ie 2 Classics may 'read' the voltage differently, slightly, and change from Bulk to Absorb ,relatively , in unison but not exactly together. If the settings are the same the change over is not too significant...
I have my WBjr setting for EA to 0.1A, to max out the absorb over the winter due to minimal hours of sun interception right now, in summer I set it to 1%
I would want to be around for the EQ as the process stresses the battery by doing an overcharge... I am cautious.... your call.
I have EQ set to OFF on my system... however I have my Absorb rate set to the max V right now and EQ is only a tad higher and , if done is for 16 to 24 hours... AGMs not FLA type.
Quote from: BlackwaterPark on December 12, 2015, 01:53:47 PM
"Iota DLS-27-40: 24 Volt 40 Amp Regulated Battery Charger", would this be a good choice for a charger on a 225ah bank? There's also a samlex 40a model, which is a fair bit more expensive, but NAWS seems to only recommend the Iota. Thoughts?
SO, we see that B w P has a 24 V inverter which has NO charger built-in, and is looking for an external Charger to supplement the PV.
As has been noted previously, the IOTAs as supplied, will only do an EQ every seven days, which does not work for PV-charged off-grid system.
There have been those on another forum (Wind-Sun), who have opened IOTA chargers and tweaked a Voltage-Setting potentiometer to increase the nominal charge voltage. It is not clear that this ability is available in all Iotas, and there could have been a design change in those that previously had this ability.
And, B w P asked about connecting a Charger, like the Iota, to the input of the Classic. In general, this approach is not a good idea, and specifically, these battery chargers really do not have a sufficiently high voltage to allow almost any Buck-Converting MPPT CC to function well (IMO).
B w P, you really DO need to fully charge, and then EQ your battery, soon.
I do not know of a relatively inexpensive stand-alone charger that has the ability to EQ a 24 V battery on command. AND, a candidate charger should really have the ability to vary the EQ (and Absorb) voltage, and allow these voltage settings to be Temperature-Compensated.
An Inverter-Charger, like the OB you mentioned is, by far your best bet, for programmable capability -- and you would need a Mate to do this custom programming.
FWIW, More Later, Good Luck, Vic
The Xantrex TrueCharge line of chargers may have enough capability, with the Optional Battery Temp Sensor (BTS) and the Optional Control Panel.
They are not inexpensive, ... but:
http://www.bassdistributing.com/Marine/xantrex-truecharge-2-24v-30a-battery-charger-8042430
Just as an example. There may have been some reliability issues with some of these chargers, so look at the reviews.
FWIW, more later, Vic
Quoteafter leaving the charger running for many hours..., the charger is showing float status, the classic is showing 100% SOC, and everything is turned off. the voltage under no load is 26.5v...( from 27.1 while the charger was doing its thing).
The [SG] readings on the four batteries: (taken under no load and disconnected from rest of system)
Battery 1:
6.68v.
Cell 1: 1233.
Cell 2: 1205.
Cell 3: 1215.
Under your present circumstances you need to pretty much ignore the battery monitor SOC. To take a proper rest voltage you need to allow about 4 hours after its come off charge with no loads. Now as for your SGs they are low. Given the banks history no suprises there. What happens with a sulphated battery is that it presents as charged too early to the charger, and the charger throttles back. In order to try to break that cycle you need to EQ. As WB said if you use the IOTA early in the day slash overnight, then the classic will be able to do an EQ in just about any weather. EQ doesnt take much current at all, if its done after an absorb. I would try 2 or three good long EQs, keep the water level up as needed, then try to cycle them a bit and see if the SGs come up. If they dont, then, yes, new cells are in your future.
Quote from: zoneblue on January 07, 2016, 09:38:37 PM
Quote
Battery 1:
6.68v.
Cell 1: 1233.
Cell 2: 1205.
Cell 3: 1215.
.
... As WB said if you use the IOTA early in the day slash overnight, then the classic will be able to do an EQ in just about any weather. EQ doesnt take much current at all, if its done after an absorb ...
For Flooded batteries that really need an EQ, it usually requires a relatively large current to reach the EQ voltage and a relatively long time to accomplish a full EQ. And, it appears that this battery really needs a charge, and more than one EQ cycle.
It is often good to limit the EQ current to about 5% of 20 hour Capacity, which can extend the time to reach Veq, and the time required to accomplish as much of an EQ that will benefit the battery.
Hours of bright sun could allow the Classic to produce enough current to reach Veq on a given day, perhaps, but it does look like this battery has needed an EQ for some time.
FWIW, just my experience with FLAs, Vic
Midnite eq occurs without doing absorb first. However some others do the absorb first so it runs cooler. Vic, is what you are saying that in a situation like this, getting some energy into the cells is exactly what they need?
Quote from: zoneblue on January 08, 2016, 01:39:46 PM
Midnite eq occurs without doing absorb first. However some others do the absorb first so it runs cooler. Vic, is what you are saying that in a situation like this, getting some energy into the cells is exactly what they need?
The first part of what I was trying to say, was that it does look like this battery bank really needs an EQ. This is something that the common Iota Chargers appear to be unable to accomplish for most off-grid systems, as their EQ happens automatically, every seven days of applied AC power to its input (as I read it).
And, in a more indirect way was also trying to say, that, given the recent weather conditions at the site, it seems like the Classic would be unable to "finish" charging the battery and get to the target EQ voltage in any reasonable length of time, because, this usually requires a lot of current delivered into the battery, and usually takes a long time.
YES, getting the battery fully charged, soon, seems very important. AND performing a meaningful EQ, perhaps over a period of days looks to be important as well.
I DO realize that the Classic does not require a full Absorb, prior to an EQ, and that the Classic does not perform an Absorb as a part of its EQ. On the systems, here we only EQ from PV, and the Classics are the only CCs online, so am very familiar with the drill.
The suggestion of limiting EQ current (when the EQ target voltage is approached, or has been reached) IS to try to reduce heating, and also it is said that undesirable compounds can be created in the battery, if large currents are available in the initial part of the EQ, as I read it.
Agree with you that the current usually required to finish an EQ is relatively small, but getting there often requires considerably more current to reach the target voltage, and naturally this current tapers, as the EQ does its job.
The subject battery bank is not too old, and if it has not been deficit-charged for a long time period, Corrective EQ should not be required.
There are many things about this system that cannot be known at this point.
All FWIW, and so on. Vic
Wow. A lot to absorb for sure. Thanks to all the input, I'm making headway in not repeating the same mistakes for my next bank, and possibly can even resuscitate this one. The good news is that my bank, at 600 bucks, is a minimal investment compared to the average offgrid bank. So if nothing else, I'll look at that as the tuition cost to battery maintenance 101.
Thought I might have the chance to EQ this weekend as I'm home all day, but it looks like gray skies and light wintry mix... After a whole week of actual good sun that I couldn't be here to take advantage of. I'll try it anyway, given that the EQ doesn't require much current as I was just informed.
So my next step is obviously another set of panels paralleled to the first. I'm assuming this will help the bank reach these voltages sooner, thus providing for longer and more effective absorb cycles and EQ opportunities?
Also, scrolling though the menu I noticed the "rebulk" setting, which was placed at a valur of 8. Is that right? What is the rebulk feature?
For the moment, the iota is charging and I disabled the IQ module so that I can run its absorb without hitting the float. In light of the lack of light today, that seems the only sensible route. Seeing as the SOC reading isn't doing much good, I guess simply monitoring the voltage and temp are my tools to gauge what the batteries are doing.
Thanks so much for all time taken to help me out with this... I suspect it's exhausting reiterating the same concepts time and again to each new person that comes along with the same problems.
So, started the Iota charging at 830, the bank under light load is 24.3v and by 10:45 the voltage has raised to about 27.2 at which point I used the dual voltage jack to get 28.3v input. All the while, the classic is running, but not a whole lot of helpb (V in at about 56v average... Counting the charger). At 11:00 I enable the EQ. Bank Voltage still at 28.3v, temp gauge reads 22°C. I add some water to each cell... Not a lot, just bringing the levels from about 1/4" to 1/8" from bottom of fill hole. Batteries making occasional glugging noise. Wait an hour, take SG readings at 12:00 (3 times per cell)... All cells redlined at 1150 or worse (which I'm guessing is because all the water I've added hasn't mixed much and is throwing the reading off?) Bank voltage holds steady at 28.3v still. Input voltage reads ~40v, battery sounds remain occasional glugging as before.
1:30 now, bank voltage still at 28.3, input voltage at 39ish, and so far for the day I've garnered a whole 100 watts of pv input. Iota still charging in its absorb mode, and the Wb is reading 5.8a input from the charger. The voltage input does occasionally spike to 69.ishv for brief seconds though. SOC reads 100% ( not that that matters much)... Should I just continue to run the charger? It doesn't seem likely that the bank voltage is going to rise higher than the 28.3 it's been at for hours now. EQ is still enabled, but I'm unsure that its doing much of anything ( the classics EQ value is set to 31.0 and its absorb is 28.2). Although the EQ mode is still enabled, the classic appears to be resting.
Keep charging... recovery is a long process... Think of how long it took to get the batteries in their current state...
Thanks WB. So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.
The battery wont reach EQ sort of voltages until bulk is finished. That will depend on start SOC and charge rate. If the iota is charging at 0.1C and the battery is at say 50%SOC, then it will take 0.5/0.1 * 1.4(ish for charge effciency) hours to charge. In that example thats 7 hours. What i and wb were suggesting was getting the bank to that stage early in the day and letting the classic do the EQ on what little solar you have. That might mean running the iota over night if the SOC is down a bit. Maybe you need to consider shedding your loads off the system until you get the SGs up to target? If that bank is savable , now is the time to do it.
Quote from: BlackwaterPark on January 09, 2016, 02:46:30 PM
Thanks WB. So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.
Yes, as soon as the taper reachs a current that youre confident the classic can produce for several hours, then trigger the manual EQ with the classic. You want it to bubble real good. Your new water will mix up and the SG will hopefully come up.
Bwp,
I keep a turkey baster in my battery kit, I stir the added water into the acid with it for mixing , and before specific gravity readings. I have Iota chargers , 2 DLS-55/IQ4 , in series connected with a center tap to the batteries. I do not like the way the Iota's handle eq. so I only let my Classic do the eq. in manual mode, I keep an eye on it.
Recovery is not easy, it took a month to fully recover my sadly abused Rolls Surette's. (They sat dead for a year. 0.05 volts for the set)
Hope this helps, battery life is all about maintaince.
Td
Quote from: zoneblue on January 09, 2016, 03:06:31 PM
Quote from: BlackwaterPark on January 09, 2016, 02:46:30 PM
Thanks WB. So should I just watch the temp as an indication of when to stop charging? Current temp is 21°C. The charger has dropped down to 4.6a, so I'm guessing it's tapering down it's absorb cycle, as Im only using it as a two stage charger ATM.
Yes, as soon as the taper reachs a current that youre confident the classic can produce for several hours, then trigger the manual EQ with the classic. You want it to bubble real good. Your new water will mix up and the SG will hopefully come up.
Zone, that was particularly helpful and instructive. Thank you.
B w P,
YES, you really do not want to add water to batteries until they are really in Absorb, and there is good likelihood that a full Absorb will be completed that day -- would suggest adding water about half way through a normal Absorb. The only exception being if you discovered that some cells had the plates partially exposed, then add water to just cover the plates with a bit more fro good measure, then place on charge, and add recommended water level during Absorb.
You are trying to recover your battery bank, so you should remove all loads on the battery immediately. It the loads are those on the inverter, you could possibly run them on the genset while running the Iota.
When you see the input V to the Classic rise for a very short time every few minutes, this is probably the Classic doing a Sweep, to fint the Max Power Point -- this is a good thing.
At 28.3 V battery voltage, your Flooded batteries are NOT in Absorb, the Iota may think that IT is in Absorb, but your batteries are not yet there.
Yes, you should completely ignore any SOC readings from the WBjr, it will be most accurate, when the Classic transitions to Float, and the SOC will reset to 100%.
The only real measure of the SOC of your battery, is your Hydrometer, and adding water when there is not fairly aggressive bubbling, good mixing of the water into the electrolyte will probably take some time.
Am not too optimistic that the Classic will be able to do much charging or EQing until there are some bright sunny days in succession.
28.2 V (IIRC, this is what you mentioned as Vabs) as an Absorb setting on the Classic is really far too low, at this point. It makes little difference now, but such a low setting can make the Classic stop doing any meaningful charging while the Iota is also charging, and could easily cause the Classic to Rest, it the Iota causes the battery voltage to rise much above this set value.
Good Luck, Vic