Hi, I see this information on another solar site and wanted to check what Midnite Classic uses think.
Battery Charging Part 1.
Yes you are killing your batteries if you use Solar to Charge them and follow battery manufactures recommended 3-Stage Charging Voltage Set Point. Stop that stupid, you are killing your batteries. You are sheep being led to slaughter. Step out of that line. All it takes is one Step to the RIGHT.
It is not that battery manufactures are wrong or misleading you, It is the application the manufactures assume are wrong. They think you are using a commercial AC Powered Smart Charger with unlimited time and power. Wake up you do not use commercial power or AC chargers expect once a month for maintenance on a generator right? You use Solar which is a very SOFT SOURCE of limited Power and Time. You got just 4 short hours in 24 hours to get the job done. Guess what?
Greater than 90% of all of you are killing your batteries from deficit/severe under charging, and following the manufactures recommendations are only making it worse.
With a commercial charger you start charging in Bulk until you hit about 80% SOC, then switch to Absorb which lowers the voltage a bit, current slows down and tapers to 2% of C. (about 6 clock hours) then you switch to Float and your battery continues to charge overnight and becomes saturated and fully charged by morning.
Well guess what? It is impossible for you to fully charge a lead acid battery on Solar unless properly oversized by design which you likely failed to do to start with. Even a properly designed system is going to come up short in winter months. There is just not enough Sun Hours in a Day to fully Saturate your battery.
Battery manufactures are getting slammed with warranty claims from Renewable Energy users. The claims are a result of chronic under charging and sulfated batteries. Many manufactures have revised their charging procedures for RE users. They have done away with Bulk Absorb, and Float voltage Algorithms. Today they aim at Maximum Smoke. Trojan calls it a Daily Charge of 2.47 vpc which use to be roughly Equalize voltage levels. What they are doing is forcing your Charge Controller to operate in Bulk mode or Max Smoke from Sunrise to Sunset. Still may not get your batteries fully charged. But still significantly more power stored than setting the voltage to a lower value.
So what do you do? Well what you should have been doing from the start. Use your Temperature Compensating Hydrometer to find the right voltage if there is one. For roughly 90% of you there is No Voltage High Enough you can set your controller to get the batteries fully charged up, because you do not have enough panel wattage to begin with. For those of you who find yourself in that situation, all you can do is limit the damage by cranking the voltage to MAX, and then every couple of day run the genny to get your batteries back to 100%. Don’t like that idea? Tough Titty said the Kitty, you made your bed, now sleep in it.
For the rest of you where you do have enough power panel wattage to get fully recharged most of the time, you are not going to use the manufactures recommendations, you are going to find the exact setting using your Hydrometer.
So that leaves you with only 2 voltages to concern yourself with Daily Charge on your Charge Controller, and EQ on your AC charger used on your generator. OK at this point you may be asking yourself how I do that when my Charge Controller is a 3-Stage Controller? The answer depends on what Controller you have:
• Set Bulk = Absorb = Float if your controller allows. Initially set it to 2.47 vpc
• If your Controller will not allow you to set all three modes to the same value start by setting Float to the desired voltage like 29.6 on a 24 volt battery system. Then set Absorb as high as the software will allow that is less than Float like 29.5 and 0 minutes or hours. Set Bulk like Adsorb except try the same as Float first, or lower like 29.4
What this is doing is forcing your controller to behave like a simple Constant Voltage â€" Current Limit algorithm. (Max Smoke) Basically your Controller will stay in Constant Current charging until the battery reaches the Float Set Point. When that is reached the current will taper off, and if you’re lucky enough to have enough Sun Hours and panel wattage you should see that current taper down to about 1 to 2% of C indicating full charge. C is the battery AH specification at the 20 hour discharge rate. So if you have a 100 AH battery would be 1 to 2 amps. The point of doing this is to get as much energy as possible into your batteries with the very limited amount of time you have with Solar. If you have the system designed properly and lucky you will get back to 100% SOC, but do not count on it.
So how do you know if it is right or not? Pull out the Hydrometer, that is what you bought it for. When the Sun starts to set low in the sky, check your Specific Gravity. If it is too low, you need to raise the voltage, if voltage is maxed out and you still are not fully charged up, GUESS WHAT? You do not have enough panel wattage.
If you have enough panel wattage, you will find the right voltage. But do not relax, your job is not over. Conditions change by day, week, month, season. What worked last week may not work this week.
So let’s get started on a proven method that works. First order of business you have to have a Temperature Compensated Battery Hydrometer, and you must learn to use it and use it often. You cannot use a volt meter to tell the State of Charge in a battery. Voltage is only an indicator. It can only tell you if something is way out of acceptable limits like Equalization or equal voltage between cells, or if your batteries are really low. But a volt meter will not tell you the SOC. There is only one way to measure SOC and that is with a Temperature Compensated Hydrometer. Don’t worry they are not expensive, less than $10. Deka makes a really good one and you can order it online. So get to it. To learn how to use a Hydrometer read this.
OK regardless of how new or old the batteries are we need to get them fully charged and Equalized. This is best done with a generator, and if you are off grid, you had better have a generator and a commercial AC charger. A generator is required to perform Preventative Maintenance like equalizing your batteries as needed (about every 4 weeks or as needed). And carry you through cloudy days. If you do not have a generator you have no choice but to use your controller, but it could take several days using your controller. EQ can even take 12 to 24 hours with a generator.
To Equalize is a controlled over charge. Check your battery manufactures specifications for the correct EQ voltage but it should roughly be 2.5 to 2.6 volts per cell. So if your battery voltage is:
• 12 Volts = 15.6 volts
• 24 Volts = 31.2 volts
• 48 volts = 62.4 volts
To learn how to equalize read this. You are going to need the Hydrometer. Did I mention you must have a Hydrometer?
OK now that you have EQ time to set your controller voltages. Take note this is a starting point, not a definitive. Initially set your voltages to 2.46 volts per cell:
• 14.8 Volts @ 12 volt system
• 29.6 Volts @ 24 volt system
• 59.2 Volts @ 48 volt system
When you notice your controller indicates the batteries are fully charge or current has tapered down, take a hydrometer reading and see what the SOC is. If it is low, you need to raise your voltage. If it is high you should notice gassing and need to lower the voltage. Repeat as often as necessary until you find the sweet spot. Do not be surprised if you cannot reach 100% SOC. That would mean you panel wattage is too low and you will need to be using your generator more frequently. Don’t EQ the batteries to frequently. If you are not able to get to 100% bring them up with a generator about every 2 or 3 weeks. Just don’t let the batteries get below 50%.
Once you have found the sweet spot don’t completely relax, because it will not last. Seasonal and even monthly changes will be required because the Sun Hours change from week to week. What worked last week may not work next week. Basically in warmer months you will be running lower voltages than cold months. In cold months you will be running higher voltages than warm months. Don’t fear because you should be performing weekly Preventive Maintenance which checking Specific Gravity with your new Hydrometer. Did I mention you need a Temperature Correct Hydrometer?
Thanks to Sunking.
Is he correct? Simplified answer=== Partially.
I will not get into correcting all the obnoxious statements that he spewed.out the
It is my opinion that 99% of the active members here know all about the Commercial/Industrial chargers Industry uses and the incompatibility (unachievable without Grid or Generator ) to Solar based charging , regardless of the brand
Thanks for your reply.
Being in the 1% do you think I should reset my classic voltages to that metioned in the text given that for the last six months my classic reaches 100% SOC but just checking with a hydrometer yesterday the reading was 1150?
Thanks,
WEll, change to me is misleading... You do not want to make changes to all the variables you can , in one massive adjustment ... doing so will result in you not knowing what worked and whar did not.
first, how do your settings doing the summer period? Float every day? SG in the recommended range? Probably are...
Next is to compare your Bulk/ Absorb Voltage to the recommended higher(est) voltage from your Batt. maker.
Do/did you lengthen the Absorb time limit?, it needs to be much longer (like 2X or more) in the winter than in the summer. depending on just where you are situated.
Is your End Amps value in the lower part of the recommended range 1 - 3% ? A lower EA value also extends the Absorb time..
In essence, a longer Absorb will probably be ended when the sun drop over the horizon...
This should get you started...
ps, I use 2 sets of settings, one for summer and one for winter
hth
The battery normally float every day summer and winter. Occasionally in winter we miss float for a day or two. Not often. I haven't used a hydrometer until now instead going by the Classic and Wizzbang figures.(my mistake it seems). I haven't programmed ending amps. I haven't adjusted absorb time which is two hours. Voltages are at manufacturer values of absorb 29 volts and float 27 volts.
I looked for the charge specs and could not find anything for solar .... then I was looked for the Solar charging specs and this thread came up and is almost identical to your issue... nothing seems to have changed since then...
http://forum.solar-electric.com/discussion/21837/crown-cr430-charging-recommendations
hth
I didn't read the whole rant but it sounds pretty much what we have been doing.
Set all voltages at the highest end the battery manufacturer allows and extend absorb time to 2-3 hours. Not exceeding maximum current acceptance of the batteries of course.
Every situation is unique. Different array sizes, different shading and times of day. If they use too much water something will need to be backed off and if they don't reach proper SpG then they need more of something, balancing generator run times and such.
We tell people to look at it as generator and batteries with a solar bonus when available. Some run summer without generators but few get very far when the angle gets low and the clouds roll in.
Thanks very much for the information. Soon as we get some sun I'll make some changes.
Cheers,
I think the standard recommendation on these forums is for people to study their batteries when they get them and monitor the current and SG while also using and tweaking SOC to get a good setting for the Ending amps.
My understanding of the voltage range for batteries would be to start with the lower part of the range and raise it as needed as the batteries age.
My battery supplier says heat is the worst thing for batteries longevity so keeping them cool - air space between the cells if possible helps.
I also did not try to digest that long blurb but it seems more intended for people who undersize their PV and discharge their batteries too far , especially in the winter when day length is reduced.
Larry
Hi asdex,
Agree with Larry, that this seems to assume that folks usually undersize PVs.
The post that you copied may have been old. This situation was more common, five, or more years ago, when PVs were expensive, and batteries, less-so.
The standard recommendation is to follow what the battery manufacturer suggests. If the battery manufacturer does not provide charger settings for solar-charges systems, then ask them for those.
This battery manual included RE (Renewable Energy) charging settings:
https://www.solar-electric.com/lib/wind-sun/Crown-Deep-Cycle-Product-Support-Broch.pdf
For off-grid systems it is very important to monitor battery condition frequently. For off-grid Flooded battery systems use your Hydrometer to measure the actual SG of the battery bank once per month (or so) when you believe that the batts are fully-charged. Record these readings in the Battery Log Book (number/letter batteries/cells with felt-tip pen).
Among the cells with the lowest SGs from those readings, choose at least one Pilot Cell per string of batteries, and use those for a quick read on the nominal SOC of the battery bank.
RINSE, RINSE ... AND RINSE AGAIN, the Hydrometer after each measuring session, to preserve the accuracy of the Hydrometer.
Any battery Monitoring device will ONLY give approximations of the SOC of the battery, even when battery parameters are entered into such devices. The greater number of days since a REAL full charge on the battery, generally, the less accurate will be the SOC reading on any battery monitoring device, including those from the WBjr/Classic combo.
Recall that you are in NZ, so, your solar days should not be too short, depending upon shading, PV elevation angles/azimuth, etc ...
At SGs of about 1150, the battery is at a fairly low SOC. You should not worry about changing the Absorb voltage, And the Absorb time NOW. Would suggest about 30 - 30.5 Vabs for now, and about 6 - 7 hours Absorb time.
When the battery gets as fully charged as possible, you should EQ at the high range of recommended Veq. Of course monitor the battery temperature (you are using the Classic's BTS, aren't you?) during EQ, and stop the EQ, before reaching a battery temperature of about 40 degrees C.
More Later -- bottom line, get those batteries charged NOW. If you need to run your generator, and have a good charger, use it.
FWIW, Vic
Hi Vic, thank for your advice. I am charging them up with my generator today. I can do this via my Outback inverter but will compare it with my 24 volt battery charger.
One thing I notice is although the batteries are showing 1175 on the hydrometer, the Classic SOC is 100% so seems to be reducing charging to the batteries.
How can I change the SOC so its more accurate?
Thanks,
PS, the voltages in the PDF you mention are what I have been using for the last year and everything looked good until I tested with a hydrometer and found the batteries to be 1150.
You can adjust the SOC with the efficiency and capacity in the Whizbang setup . Also make sure you have the temp set correctly in there according to your battery manufacturer .
Larry
Hi asdex (is your name Al?),
Regarding the Setup of the WBjr, several things;
As Larry noted you should have the battery Reference Temperature set to the reference point used by Crown. This would generally be 25 C. Some battery manufacturers use 27 C.
You will usually want the SOC to reset to 100% when the Classic transitions to Float (on its own). From the WBjr Manual,
" ... The Net Amp-hours tally can be configured to reset every time the Classic goes to float. To set this option, go to the “TWEAKS†menu and press “MORE†four times. Select “WBRST†and press the UP or DOWN arrow keys to select “YES.†Press Enter to save. “NO†(or no reset) is the default ... ".
You probably have that set correctly.
One of the most important WB parameters, is to set the battery CHarge Efficiency to a good starting point for your Flooded batteries. The Ah efficiency of healthy new Flooded batteries (FLAs), is about 85%. This value will tend to diminish, as FLA batteries age. If you have set this number in the 90s, as the manual suggests, this might part of the SOC reading inaccuracy shown by the Classic.
And, again, if your Vabs and Absorb time are not set to generally fully-charge the battery bank, when the Classic goes to Float, and the Classic is set to show 100% SOC at that point, then, this number could be quite erroneous, showing 100% SOC, when the battery is far from that.
Please ignore the stated SOC, until you get the battery bank fully-charged. Then, after confirming the WB Set-up parameters, you can try to adjust the SOC number closer to the reality of the battery SOC.
FWIW, Vic
Thanks, I have reset the efficiency from 95% to 85% and checked the reset which is correct. The battery temp comp is 20 deg C and 0.1%. I have set absorb to 30 volts for now but SG is still low at 1175 as we have had no sun the last two days. I have a 6.5kva generator and 25amp 24 volt battery charger which I have been using but the charger only charges the bank at about 7 amps. This is when set to boost. Not sure why the charge current is being limited by the batteries.
I have set ending amps to 2 and ticked " use WBjr for end amps". Rebulk volts??? Is on 8.
Cheers,
Graham
That sounds high for the Absorb voltage and too low for the ending amps. Might be boiling your batteries a lot with those settings.
You may have an automatic battery charger made for vehicles. They taper off the charge as the battery voltage rises - so people don't cook their batteries .
Larry
Yes it is a vehicle type. I"ll try charging again using the Outback inverter/charger. I'll just keep the absorb voltage high until the batteries are charged up the start tuning with the hydrometer.
Cheers,
Graham
Hi Graham,
Thanks for the additional info.
The Outback's charger should be able to do a better job of charging your batteries, as you can fairly easily set an appropriate Vabs, and Veq (if needed).
Many automotive chargers, these days have relatively low output voltages. This might be what is causing a relatively low charge current when using it.
The Outback inverter can adjust the charge voltage based upon the battery temperature, if it is setup to use the Remote Temp Sensor, as you know. This can be an added benefit when using the OB.
When charging from the auto charger, what was the battery voltage shown on the Charge Controller?
Have you measured the SG of each cell in the battery bank?
If you measure the terminal voltage of each battery during charge, you can get an idea of how well balanced each battery is compared to the others.
What are those voltages?
There should be no issue in using a relatively high Vabs for batteries that are at a low SOC, as these batteries seem to be. Many off-gridders use similarly high Vabs settings, particularly during Winter months, and others use these settings all year. This is well above Gassing voltage, but for deep-cycle Flooded batteries, it should be fine until the bank is more fully charged, and then EQed. If/when the battery bank is in its best condition, asdex can try adjusting the Vabs, and perhaps Absorb time, to fully-charge the batteries on most charge cycles.
Thanks additional info that you can supply, Vic
My response to the Op's opening comment. I have been round and round with the same subject on this forum and on the Sun King forum, I have yet to get my 24 volt 435 amp hour batteries to fully charge unless I set my absorb voltage ro 31.5 volts and my end amp to 4.3. In 4 months I have had to add almost no water at all. And my temperature in the winter in Florida has never gotten above 30 degrees Celsius . I have the absorb time set to the maximum and it's not that I run out of daylight, but if I use 29.6 volts as an absorbed charge voltage (manufacturers spec) , the charger just stops charging because it thinks that the batteries are full. But when I test the gravity they are not.
I called Trojan and told them what I was getting, and they said charging at 31.5 volts is not a problem. It is better than having undercharged batteries all the time. And they went on to tell me that golf cart batteries are charged at 32 volts everyday at the end of the day for the next day. Trojan said it is way better to overcharge than undercharge. But I was concerned about charging at such a high voltage because of corroding the plates. And I wonder if Trojan was merely telling me this, knowing that I was shortening battery life by charging at too high a voltage with my solar charger?
But I have monitored my batteries very closely and at this time of year so far what I have found is it takes 31.5 volts at the absorb setting to get a full charge according to specific gravity. Which is 1.277 for Trojan Batteries. If I use a voltage lower than this, save 30.5, I do not run out of time, the charge controller simply stops charging too soon. It stops charging at the end amp set point, but the gravity is still too low.
Somebody correct me if this is wrong, but it is my impression that overcharging (within reason) will disassociate more water into gas, but does not chemically harm the plates at all. It just becomes a maintenance issue, having to add water all the time.
Charging Flooded batteries to the Gassing Voltage, and above does cause Erosion of the positive plate.
But this erosion is nothing to worry about, as this erosion comes along with fully-charging Flooded batteries.
Not fully-charging these batteries is much worse for them, than is the plate erosion, at least for off-grid systems.
Excessive EQing can be more detrimental on FLAs, of course ...
Chronic under-charging these batteries is generally worse than chronic "overcharging" them,
All IMO, Vic
Thanks Matrix, that has seemed to be my issue too.
I have set my absorb voltage to 30 volts for now to try and get the charge up. Hydrometer is now 1175 on most cells.
Cheers,
: I would try 30 volts and Optimum conditions, test the gravity and if it is not come up to fully charge, on the next day I would increase by two tenths of a volt. And continue to do an increase until you have found a voltage that fully charges the batteries
The good news is with the Midnite solar charger you are only setting the absorbed voltage most of the charge is taking place in bulk which is constant current, but not constant voltage so the voltage at you set for absorb does not get reached until the end of the bulk change. . What I have seen during bulk charge is that it runs about 29 to 30.5 volts when I have my voltage set to 31 +. It only goes over to the highest voltage of 31 when when it's nearing and crossing over to absorb
One fairly important thing is, that even with "most cells at 1.175 SG"s, the battery bank is essentially D E A D.
Screwing about, but not really trying to actually get these batteries CHARGED, is NOT a good thing.
It is quite possible, that this battery bank will never recover, but allowing Flooded LA batteries to remain below about 50% charge for, even a few days often makes recovery a long process, that yields a battery bank with low Capacity, and a very high self-discharge rate.
Personally, I would get out the whip, and really work to see if this bank will recover. It is quite often the case, that an FLA bank that has not been well cared for, with some cells at 25% SOC, or less, will have some cells with 0% SOC, which will NEVER RECOVER.
It is not clear, from what has been stated here, just how long this bank may have been sitting, at these very low SOC levels. The longer that FLA banks sit at low SOCs, the much more difficult will be any possible recovery.
Basic rules of thumb for most Deep Cycle FLAs, is, never discharge below 50% SOC. Any bank that has been discharged to 50-ish % SOC should be IMMEDIATELY recharged, fully -- banks in this state should not sit at fifty-ish percent SOC, for even one day.
asdex, have you measured the terminal voltage of each battery? What were those readings?
Not to be too emphatic, just My Opinions, good luck, Vic
Just checked the voltages:
6.386
6.373
6.350
6.354
Total 25.47.
The batteries will be at their lowers level being 07:30 now.
Hydrometer readings around the 1175-1180 mark.
Hi Graham,
Thanks for those battery voltage readings. The variation is not as large as I'd expected -- better than my guess.
What type of Hydrometer are you using? Is it a glass float inside a glass tube? Is it a Hydrovolt, or is it a plastic case with a plastic pointer, or (less likely) plastic case with floating colored balls?
So, your system is off-grid, right?
Do you know approximately the number of Ah used from the battery bank, each day?
More later, Thanks, Vic
Hi Vic, I'm using a glass hydrometer with weighted glass float. I think it's ok as distilled water although off the scale looks at about 1.000. I'll buy another tomorrow as backup and comparison. Yes we are completely off grid. Nearest grid power 5km away. I guess we use about 1.2 to 1.5kWh a day.
Cheers,
Graham
Hi Graham,
Thanks for the additional info.
Good that your Hydrometer is the glass/glass type. Having several, is often a good idea.
Your power usage seems low for your L-16s. So, if the SG readings are fairly accurate, and you have reasonable solar production, and daytime loads light, your batteries should get a full-charge on most sunny days.
More later, Thanks, Vic
Hi have a new hydrometer now and it reads 60 points higher than the old one. I'm expecting the old one to be wrong as cell voltages are 6.9, 6.9, 6.83, 6.9. hydrometer is 1260 with the new one and 1200 with the old. Both hydrometers look very similar. I have been looking online for a solution I could make up of a particular density to test the hydrometers but haven't had much luck.
I'll start checking with the new hydrometer each day and see if I can adjust the absorb voltage.
Cheers,
I used to use a refractometer, easier than a hydrometer. I always had issues with the float sticking to the side of the tube.
Like this one
https://www.amazon.com/dp/B01CQVHTCW/ref=asc_df_B01CQVHTCW5384724/?tag=hyprod-20&creative=395033&creativeASIN=B01CQVHTCW&linkCode=df0&hvadid=198055320371&hvpos=1o6&hvnetw=g&hvrand=17715052216741866600&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9021375&hvtargid=pla-356241290548
Yes I have a refractometer like that too . I believe if you calibrate it with some distilled water that is same temperature as your battteries then it is temperature compensated too. You only need a couple drops of he electrolyte so I would use the glass hydrometer to get the sample drops. They show a lot more precision . Just take proper precaustion with putting acid up near your eyes .
Larry
Thanks, I'll get one of those. I see them on AliExpress.
RZ Automotive Antifreez Refractometer Freezing point Urea Adblue Battery fluid Glass water tester meter ATC Tool RZ115 NZ$18.70.
Cheers
Hi asdex,
Good that you have a new Hydro, and that the SGs appear to risen.
Had meant to Link to the following Surrette Battery article on Measuring SGs:
http://support.rollsbattery.com/support/solutions/articles/4347-measuring-specific-gravity
There have been discussions regarding using automotive type Refractometers for SG measurements. You will probably want to make a Calibration fluid, to ensure accurate readings, at least, from some Refractometers.
If one is careful when taking readings with a Hydro, they can be accurate and repeatable ... just RINSE, RINSE and RINSE after each measuring session. If you see any bubbles on the Hydro float on inside the glass tube, your readings will be suspect.
Seems that your situation was not as dire as expected -- a good thing!
Let us know how you are doing, and if you are using a Refractometer please let us know how it works for you. Thanks, Vic
I would calibrate mine using distilled water to the bottom line. Seems like I heard that if you really want to ensure preciseness you would want to get a calibration acid fluid and also check it up on the upper lines too. But I never did that .
Larry
Thanks for that information.
I might add my two spare panels to my existing system.
I have 6 JASolar panels and I'll add the two Suntillite panels. I have attached the specifications of both. Will the Midnite Classic be ok to add the two panels in parallel?
Thanks,
Graham,
The JA Solar PVs are 72-cell types. The Suntillite are 60-cell PVs. Their Vmps are not close enough to work well on a single CC.
The standard rule-of-thumb for PV matching, is that the STC Vmp voltage should, ideally, match within 5%, and should not be a 10% or greater mismatch for PVs different PVs wired in parallel, as would be your case.
The Vmp difference is greater than 10% (about 16%), so, this would not be a great match, IMO.
Vic
Ok, thanks for that info. I might buy a couple of 72 cell panels. I think our existing setup is ok to charge the batteries but we also heat our water in summer with the panels and a 24 volt element.
I have the absorb voltage at 30 volts at the moment and are watching water level and hydrometer readings.
OK Graham,
Did run the Classic Sizer for your existing 6 JA Solar PVs. You do have a bit of room for some added PV power, although, it is often best to not run power electronics at, or near their maximum limits.
Attached the Sizer output for six 320 PVs.
FWIW, Vic
Thanks for that. Seems it's going to be a bit tricky then. I'll see how the batteries go at charging up at the higher voltage first and wait for my refractometer to arrive.
Thanks,
I ordered a refractometer from one of the links on this thread. Got it yesterday, calibrated the instrument and checked a few cells.
When I was at or nearly fully charged
Refractometer (https://smile.amazon.com/gp/product/B01CQVHTCW/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) = 1.281
Glass Hydrometer (https://smile.amazon.com/gp/product/B0050SFVHO/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1) = 1.281 (after temp comp)
Hydro Volt = 1.286
Each is repeatable, So I will continue to use the Hydro Volt because it is the easiest to use/read and just subtract .005 as I might at times have been slightly under charging at times because it reads .005 higher than the others.
Graham, I do hope you get it all sorted out. For me I am having to charge at 2.64v per cell to get fully charged. I have no idea why that is, but I do know if I use a lower voltage (2.46v - 2.58v) what happens is the Classic does not time out stops charging because i have reached my end amp setting of 4.3 amps (for a 435ah battery) and I am not fully charged.
Trojan said it was OK to charge at that voltage, but oddly, when I did an EQ last night, the SW charger would not go even that hi. I ran at 31.4v and not the 32v I had it set at. I think that may have been temp comp or something. But I have found the SW for everything but an inverter to be less than acceptable. Maybe i have a dude, but Schneider tells me that its doing what it is supposed to do.
But here is something to wonder, I did not do a fully charge,EQ and then record the SG when I placed these batteries into service (my bad). But after an EQ I can get the cells to rise to 1.287-1.298. Now that I have good repeatable readings on 3 different instruments, Do you consider fully charged to be 1.277 (Trojan spec) or do you go all the way to what you can fully achieve (1.287-1.298) for a full charge?
Quote from: Matrix on March 02, 2018, 07:22:05 AM
... Graham, I do hope you get it all sorted out. For me I am having to charge at 2.64v per cell to get fully charged. I have no idea why that is, but I do know if I use a lower voltage (2.46v - 2.58v) what happens is the Classic does not time out stops charging because i have reached my end amp setting of 4.3 amps (for a 435ah battery) and I am not fully charged.
Trojan said it was OK to charge at that voltage, but oddly, when I did an EQ last night, the SW charger would not go even that hi. I ran at 31.4v and not the 32v I had it set at. I think that may have been temp comp or something. But I have found the SW for everything but an inverter to be less than acceptable. Maybe i have a dude, but Schneider tells me that its doing what it is supposed to do.
But here is something to wonder, I did not do a fully charge,EQ and then record the SG when I placed these batteries into service (my bad). But after an EQ I can get the cells to rise to 1.287-1.298. Now that I have good repeatable readings on 3 different instruments, Do you consider fully charged to be 1.277 (Trojan spec) or do you go all the way to what you can fully achieve (1.287-1.298) for a full charge?
Matrix,
It is possible that Trojan has changed the chemistry of their FLAs, from what was being used in the past
Had wondered that with many/most automotive batteries being Lead Calcium, if that changed the economics of deep-cycle batteries -- perhaps there is less Antinomy in deep cycle batteries. This should reduce the amount of Gassing. This could mean that for taller batteries, higher voltages might be required for a full-charge, and to fully mix the electrolyte.
You are doing the right thing, by increasing the Vabs and Veq, and measuring SGs to determine what these voltages need to be.
But for my 13 year-old Surrette FLAs, your voltages would be amazingly high for my batteries.
Regarding {b}, Have mentioned this previously, in another Thread, that some folks recommend waiting to take final SG readings, after the battery has been in Float for two hours, or so (IN Float, vs Float-MPPT). It is possible that there could be some false SG readings that could be caused by plate debris suspended in the electrolyte, that requires some time to settle out. This debris could change the density of the electrolyte.
Just a quick couple of thoughts. Vic
Quote from: Vic on March 02, 2018, 04:36:25 PM
But for my 13 year-old Surrette FLAs, your voltages would be amazingly high for my batteries.
Regarding {b}, Have mentioned this previously, in another Thread, that some folks recommend waiting to take final SG readings, after the battery has been in Float for two hours, or so (IN Float, vs Float-MPPT). It is possible that there could be some false SG readings that could be caused by plate debris suspended in the electrolyte, that requires some time to settle out. This debris could change the density of the electrolyte.
Just a quick couple of thoughts. Vic
13 years ... I hope I get that much "mileage" out of my Trojan L16s. That would more than pay for the cost of replacing them at that time :D. At this point, it will take me 5 years to have saved enough to be able to replace the batteries alone (not including the Solar/Inverter system)
The hard part about going into float for a few hours, is usually when I hit float (as I did today here at 5:15pm) ... I have made 9.2 kwh's, but now that sun is going down, I start actually using battery power again, so there is "wait time" where the batteries just sit in float, at least not for very long. Perhaps I will turn on the electrons for the grid and let them sit for a while and go re check. Today my weakest cell hit 1.284 as the CC went into float.
Matrix, how many cycles do you have on those cells now?
Quote from: Westbranch on March 02, 2018, 06:22:02 PM
Matrix, how many cycles do you have on those cells now?
Well they went into service Oct 16, 2017, Normal discharge 25-35%. 5-6 times I intentionally discharged down to 55-50% SOC. And I have probably skipped 15 days where the batteries sat in float all day, So I am guessing 80-110 cycles ... maybe a touch more.
Quote from: Vic on March 02, 2018, 04:36:25 PM... some folks recommend waiting to take final SG readings, after the battery has been in Float for two hours, or so (IN Float, vs Float-MPPT). It is possible that there could be some false SG readings that could be caused by plate debris suspended in the electrolyte, that requires some time to settle out. This debris could change the density of the electrolyte.
Well i let them sit for 3 hours with no load. Float ended at 5:45. Retested my known weakest cell and my highest cell. Weakest was at 1.282 down from 1.284 at the end of absorb. Same .002 point margin for the strongest cell. And there is an 11 point gap between the highest cell and the lowest cell. Trojan says EQ when the gap becomes 30 point or more.
Hi there,
I'm a bit of a newbie when it comes to batteries and charging but I have an extensive technical background so I'm pretty comfortable with all other aspects of my solar kit. I know much of this is covered in other posts so I apologize if I am doubling up but there is a lot of information on this forum to dig through! I'm just looking for opinions on a couple of assumptions I am making based on a bunch of different posts I have already read here on the forum.
So based on the other posts I should start with a bit of info on my system. This is a portion of my final system set up to get me through construction.
4 x 230W Sharp ND230 panels
1 x Classic 150
1 x MS4024PAE Inverter
24V Battery Bank (Full River AGM) 830AH (aiming for 20% DOD)
I have managed to learn (from this forum as well as other sources) how to determine the settings I need for my system like bulk, absorb, float voltages, temp compensation, max current etc. My system has been online for about two weeks now and is getting through absorb mode into float a few times a week even though it has not been particularly sunny. I have set my absorb time to 4Hrs based on a forum post where a user with the same battery type as mine was given an absorb time directly from FullRiver. Now based on posts I have read here I am learning that in order for the Classic to adjust absorb time based on end amps I should add a Whizbang Jr. which I will do in the spring when I build the final system.
The Manufacturer recommends end current at 0.7% which is about 5.8A for my bank. What I am seeing using the MyMidnight website is that the Classic is going all the way through the 4Hr absorb time. At that point the classic current has dropped down to about 3A. I hit 5.8A at about 2Hrs. So a couple of questions here. I don't know if the recommended absorb time from a manufacturer is a minimum or a set time. Does staying in absorb too long adversely affect battery life? If so, should I adjust my absorb time to 2Hrs or perhaps add some buffer (say 2.5Hrs) to compensate for times when PV output drops below absorb current? If I set to 2Hrs and get sun shading I may undercharge. Can I trust the MyMidnight timeline for this assumption or should I check open circuit voltage of the batteries (because they are sealed) to confirm SOC? By the way, I can also see SOC through the Magnum remote monitoring system. I know it is not completely accurate but it does give me a good idea of what is coming in and going out.
Hopefully I am at least on the right track here. My batteries are new so I'd like to optimize the charging as soon as I can. Again, apologies if I am doubling up but I have not found a specific response about staying in absorb longer than recommended. Thanks!
A good ABSORB period is essential to a complete charge,.... you did not say if you are getting cold winter weather right now, so if you are ....the only way to get to the ABSORB target with low incoming PV power, without the WBjr is to use an estimate of the additional time it takes, in the summer you should not have any issue...
So leave the settings as is till after the equinox that will be here in about a week... get the WBjr and enjoy...
Mymidnite graphs will give you a good approximation of what it going on with the batteries if you don't have a load on them at the time they are charging.
Sounds from what you said they are filling up in about 2 hours absorb time. You don't want to over charge AGM batteries . AGM will also charge , but more slowly when they are floating . So if it was me I would lower the Absorb Time to 2 hours , and then confirm everything when you get the Whizbang - sooner you get that the better . Of course you also need to get the shunt along with Whizbang installed in the negative of your system with only one connection on one side of shunt going the the battery .
Larry
Here is a document link for my AGMs.. it explains a lot about FLAs and AGMs construction and operation
http://www.cdtechno.com/pdf/ref/41_2128_0212.pdf
and the home page for that document
http://www.cdtechno.com/resource/support_doc.html
lots of good reading
Quote from: Westbranch on March 17, 2018, 09:20:21 PM
Here is a document link for my AGMs.. it explains a lot about FLAs and AGMs construction and operation
http://www.cdtechno.com/pdf/ref/41_2128_0212.pdf
and the home page for that document
http://www.cdtechno.com/resource/support_doc.html
lots of good reading
That is one of the most informative things I have read on the subject of charging ... and trust me ... I have read a lot.
Quote from: Westbranch on March 17, 2018, 04:24:49 PM
So leave the settings as is till after the equinox that will be here in about a week... get the WBjr and enjoy...
Quote from: ClassicCrazy on March 17, 2018, 08:55:35 PM
So if it was me I would lower the Absorb Time to 2 hours , and then confirm everything when you get the Whizbang - sooner you get that the better . Of course you also need to get the shunt along with Whizbang installed in the negative of your system with only one connection on one side of shunt going the the battery .
Larry
Interesting, two different recommendations for the absorb time. It does seem that absorb time is one of those grey areas with different opinions. But there is definitely consensus on getting a WhizBangJr . I was going to wait to order one with the balance of my system and ground racks in a month or so but I think I'll go ahead and get that in right away.
Quote from: ClassicCrazy on March 17, 2018, 08:55:35 PM
Of course you also need to get the shunt along with Whizbang installed in the negative of your system with only one connection on one side of shunt going the the battery .
Larry
Yes, I do already have a shunt installed for the Magnum BMK.
So I decided to play it safe and went out today today and lowered the absorb time to 2.5Hrs which seems to be a safe time to get to the 5.8A range for my bank. I'll keep an eye on it for a few days and will hopefully be able to get the WBJr installed within a week or so if it's in stock at my local supplier.
Thanks for the document links Westbranch, perfect read for a Sunday afternoon. And thanks both of you for the information!
When you install the WBjr, watch and see how long the ABSORB time is to 5.4 or what ever value you settle on and note the battery temp and ambient temps... the choice will then go from an And/Or situation, ie whichever value comes first to a hard 5.4 A or ?? value chosen, time is overridden. ;)
Got it thanks! Makes sense. I think the WBJr will really help, especially in the spring when I add the other 20 panels and 2 Classics. Right now so little is going in and out my batteries that the temps barely move and absorb starts about an hour after sunrise.
I'm having a blast with this stuff! This is way better than my day job : )
When you hear fans run , you'll feel the move .
WBjr is an eye opener to the Classic & you .
WestBranch and I will send a smoke retrieval balloon !!
Be safe and double check , if in doubt , post here as we all have needed help to see the direction .
VT
Thanks guys!
I got the WBJr installed today. I have an e-mail in to Full River to see if they have any specific info for efficiency and temp compensation for battery capacity. Right now I went with 95% for efficiency and 1% /1C. The one parameter I saw on the Classic that I haven't seen mentioned is the value for rebulk. Is this a value setting in Amps that determines when bulk mode kicks in? The default is 8A, so if I am in absorb or float and I start drawing more than 8A it kicks back to bulk? Or is this something else? How do you determine the value for this?
Rebulk is a voltage not current setting . It is if the voltage drops down real low during the day after it has already gone through Absorb and Float. I never changed it and I don't think most people use this feature . Sure I will get corrected if I am wrong.
Watch your SOC and if it is getting to 100% before all the amps you have used are filled back in then you know you have to change the efficiency . You want it to more or less match .
Larry
Hi belevac,
ReBulk (RB), is a voltage setting. When the battery voltage falls to the value of this voltage setting, the Classic will begin a second Bulk charging stage for that day.
The Default is 8 V, which effectively turns OFF ReBulk.
IMO, ReBulk is not often used. But, for systems with limited battery capacity, or special situations, RB can be useful.
If you choose to use it, RB needs to be set below Vflt.
Battery efficiencies for AGM batteries are usually in the mid, to low 90% range.
Fullriver should also tell you the Reference Temperature. It is usually 25 degrees C. This is the turning point for temperature compensation, and also used when calculating battery Capacity vs temperature.
Also, in the Charge>Limits menu you will probably want to set Limits on Temperature Compensation for charging by the Classic -- Fullriver should be able to tell you this, as well.
Some of these battery characteristics are noted on the manufacturer's DataSheet.
My 2c, Vic
Thanks again! So I will leave rebulk off. I heard back from Full River within a few hours. In case someone searches for it efficiency for the DC400-6 is 95% and capacity change per degree Celcius is 0.16%. All other pertinent data is shown on their spec sheet or product webpage.
Quote from: ClassicCrazy on March 23, 2018, 07:46:59 PM
Watch your SOC and if it is getting to 100% before all the amps you have used are filled back in then you know you have to change the efficiency . You want it to more or less match .
Larry
Good tip thanks! I guess I will be able to adjust this as the battery bank ages to keep my Remaining AH display a bit more accurate.