Charge controller settings

[Sunking]

Since I can't get my float up above 27.5 any suggestions for the absorb voltage and time?

Sorry but there is no answer. There is no voltage high enough you can set your controller to fix what you do not have.

As you are learning solar is not capable of fully charging a battery. Especially if you live in a climate that has winter and undersized to start with. To EQ a battery requires up to 24 hours on a generator or commercial AC charger. As I said earlier Absorb is not a timed event. You simple do not have enough panel wattage to to replace what you use. Your Inverter with no load on it doing nothing, uses more power than your panels can generate in a day.

In other words like this. It cost you $50/day just to survive, but you only earn $25/day. You are either going to starve or freeze to death. Whichever comes first. The only thing you have working for you right now is cold weather. Your specific gravity is so low, it is just a matter of a short period of time before your batteries are past the point of no return. The cold weather slows down the process some what.

Sorry but turning up the voltage on your controller cannot fix your problem. It does not turn up the wattage you do not have. You are in deficit charging, and there is only one solution. If I were you, I would take the batteries home, put them on a charger to see if you can save them. After that you need to completely rethink things out and come up with a workable solution.

Good Luck

[Diesel Pro]

Today's update: SG ranged from 1.245 to 1.230 today. I went through the controller again and found out that the float just needs to be lower than the Absorb by .1v If the absorb is reduced then the float automatically reduces on the controller.

I am now set 31v EQ 29v Abs 28v float I set the EQ to run 3hrs. The sun was out decent while I was there, but even at 31v the batteries did not want to take much amperage. I'll check back again next weekend and see about bringing the float up some more if necessary.

[Sunking]

Merry Christmas Diesel Pro and hope you have a great New Year

Today's update: SG ranged from 2.45 to 2.35 today.

No sir, it did not. I assume you must be have cell voltages confused with Specific Gravity. 100% pure Sulfuric Acid SG equal roughly 1.834. SG of 2.35 or higher is impossible except maybe on the planet Mercury where a cold winter day is 900 degrees. A fully charged battery SG ranges from 1.255 to 1.275 at 77 degrees F. Slightly lower if colder. Try reading this as it should help.

I am now set 31v EQ 29v Abs 28v float I set the EQ to run 3hrs. The sun was out decent while I was there, but even at 31v the batteries did not want to take much amperage. I'll check back again next weekend and see about bringing the float up some more if necessary.

OK this is either good news or bad news. If you see cell voltages at 2.35 to 2.45 vpc, very little charge current with good strong Sun suggest a fully charged batteries. That would be the good news. The bad news maybe is if you have been confusing SG and cell voltages could be telling you your batteries are being over charged. Make sure you have a good Temperature Correcting Hydrometer and know how to use it correctly.

Don't freak out if you have been over charging. You want to error on dipping your toes in the over charged side of the razor blade, but not to much. Over Charge = Corrosion, extra capacity, and shorter battery life. Under Charge = Sulfate. lower capacity, and even shorter battery life. No such thing as PERFECT. it is a moving target you cannot hit like a pea shooter trying to hit a fly at 100 yards, Impossible.

Good luck

SK

[Diesel Pro]

Thanks to all who have chimed in so far, and Happy Holidays to all.


I corrected the SG readings in my previous post.. It was just getting into the green band, but probably not as consistent as one would like. Seemed to be higher readings to the left end of the bank (positive I believe) and lower to the right end. Cabin room temp is 40-50f but the Hydrovolt is also temp corrected. I do have a Raytek that I could shoot them with to record temps if necessary.


If I am following correctly it looks like I should shoot for a SG of 1.265 with a tolerance window of say + .02 and a - 0

[Sunking]

Corrected my SG readings in my previous post. Cabin room temp is 40-50

OK bad news. Your batteries are severely over charged if the SG reads 1.3 to 1.45 . ASAP lower all voltages to Float.

As I said from the start a weekend use has no use for 3-stage chargers and will just severely shorten the life of your batteries. Your hydrometer is screaming at you telling you to lower the voltages immediately. Let your Hydrometer tell you to what voltage to use. The range will be roughly 26.5 to 27.2 volts. Whatever it takes to keep the SG around 1.277. At 40 degrees F electrolyte temp should be 1.289

[Sunking]

Specific Gravity (flooded/wet batteries only)

1. Fill and drain the hydrometer 2 - 3 times with distilled water before drawing a sample from the battery. Repeat between cell readings

2. Measure specific gravity readings for all battery cells.

3. Correct specific gravity readings for temperature by adding 0.004 for every 10

[Diesel Pro]

I re-corrected. I am at the bottom of the range of green on the hydrometer. 1.245 was my max. I too have had issues with the software. I found that certain symbols like degree would mess things up.

[John Galt 1]

Diesel, Make life easy on yourself and get a temperature compensated hydrometer. I use a Hydrovolt https://www.solar-electric.com/catal.../?q=hydrovolt+ With the hydrovolt there are two dials that allow for automatic temperature compensation. When testing the 1st cell realize the hydrovolt will need to be filled a time or two to get the meter temperature dial to match the battery temperature. After that testing is fairly fast and easy.

After testing all cells always rinse the hydrovolt out with clean water at least 3 times. This keeps residue from building up in the meter making the dials not spin freely.

[Sunking]

Diesel, Make life easy on yourself and get a temperature compensated hydrometer. I use a Hydrovolt https://www.solar-electric.com/catal.../?q=hydrovolt+ With the hydrovolt there are two dials that allow for automatic temperature compensation. When testing the 1st cell realize the hydrovolt will need to be filled a time or two to get the meter temperature dial to match the battery temperature. After that testing is fairly fast and easy.

After testing all cells always rinse the hydrovolt out with clean water at least 3 times. This keeps residue from building up in the meter making the dials not spin freely.

I would NOT make that recommendation. as any mechanical electrical hydrometer is pretty much worthless. Nor are they reccomended by any quality battery manufactures or supplied/sold with batteries. For $35 you can buy a Lab Quality Master Hydrometer used to test and calibrate hydrometers. Pretty much the exact same as $6 to $10 Deka Temp Compensated they give away with Deka batteries. Try reading what the top battery manufactures recommend like this from Rolls.

Hydrometer Types

Hydrometers come in many sizes and shapes. We recommend a hydrometer with a float, contained in a glass vessel with a rubber bulb to draw the acid into the tube. Stay away from floating colored balls as the extra inaccuracy results in very subjective testing. The hydrometer should give you a numeric reading directly from the instrument. A good hydrometer is accurate to +/- 0.005 points so 1.265 could read from 1.260-1.270. The instrument accuracy should be known.

As to testing the calibration, the only dead nuts test is using a weighed volume of Acid, or a Master Hydrometer. Exactly the the same type Deka sells, and Rolls, Trojan. C&D, etc recommend. However with double distilled water you can get withing +/-.005 points accuracy which just happens to be the accuracy of the Deka model for $6. A Master Hydrometer is +/-.001 points accuracy you can get for $35 to $150 but are fragile. I suggest you go with and listen the manufactures recommendations.

FWIW there are some electronic hydrometers professional battery testing agencies and utilities use out there is you have 3 to 4 digits to spend. But they are not as accurate as a simple Float Type. Most pros use a Master Hydrometer or just a Deka checked at the shop with a Master before deploying out to the field.

[Diesel Pro]

Another setting question: Rebulk

The Classic 150 has a rebulk voltage setting. As I understand this setting is used to tell the controller how much voltage drop it needs before entering bulk mode. I believe by default it is set at 8. To me this sounds quite high (or low by main voltage standards) and I could probably well reduce this setting to 4v drop? Not that I am going there regularly, but...

[Sunking]

You want to set it to as high of a numbers as it allows so it never Rebulk's or disables Rebulk. You want no part of it.

As I have been trying to say is you want absolutely no part of a 3-Stage Charger for your application. You want strictly a FLOAT CHARGER. I will say it again, you want STRICTLY FLOAT CHARGER and no part of a 3-Stage Charger. The so called 3-Stages are Bulk, Absorb, and Float. You only want a FLOAT CHARGER.

3-stage chargers are for daily cycle applications, and used to charge a a battery as fast as possible. Sounds great huh? Wrong it stresses the battery and shortens battery life. FLOAT CHARGERS are the kindest gentlest charging algorithm for lead acid batteries. That is why utilities, military, industry, and communications use them. They make make huge battery investments and want to make their batteries last 10 years. You cannot do that with 3-Stage Chargers. But 95% of Solar Users cannot use a FLOAT CHARGER, there is not enough time in the day as it takes 16 to 24 hours to complete a charge cycle. Ironically 90% of solar users do not have enough time in a day to use 3 Stages either as Absorb can take 12 hours, but that is another story and I do not care.

Rebulk does not have much use and poorly conceived notion. It is for folks, 90% of all solar battery users with grossly undersized panels, assuming you will complete all 3 cycles in a day well before sunset, and then use so much power after it switches to FLOAT the battery is actually being Discharged and the panels cannot maintain Float Voltage, and thus voltage starts to drop.

Well if you know anything about batteries and battery chargers you quickly understand just how STUPID that notion is. Both user and manufactures are clueless that buy into that. Well actually it is the User who is most likely ignorant. For the manufacture it is a Bell and Whistle added so they can charge more for their product. OK you might be wondering what is wrong with the idea. Real simple if your panels cannot keep up and batteries are being discharged, turning the charger voltage back up is not going to do anything except lead you to the wrong conclusion making you feel better.

All it takes to figure out what is wrong and going with the idea is simple math and logical thinking. If you have a 100 watt panel generating 100 watts, and you are using 120 watts ought to be blantly clear what is going on. Your batteries are discharging and turning the voltage up on the charger is not going to change or do anything. Just like the Brightness Knob on a TV, turning it up is not going to make what you see on the (.)(.) Tube any smarter. All it does is allow you to see more (.)(.)'s or Tube's

So by setting the Voltage lower as you indicate is the exact opposite of what you want to do. Essentially what it means if you set it to say 4 volts means if you are Floating at 28 volts and the battery voltage dips to 24 volt (completely discharged) that somehow magically turning the voltage up to 30 volts is going to save the day. Complete nonsense. Turn the voltage up as high as it will allow you to completely defeat the worthless Bell and Whistle. If it is 8 volts is more than enough or if you can DISABLE it completely.

You are a weekend user and have absolutely no use for 3-Stages, and doing so only results in shorter battery life which you can do without please.

Hope that helps and good luck. .

[John Galt 1]

SK, Is there anything related to homeowner solar ownership that you aren't super critical of? By your own admission you don't use solar at your home so your hands on experience for home use solar is non existent.

There are many people who actually use solar on a daily basis who have found that the Hydrovolt is a reliable and easy to use instrument. I've got several hydrometers and actually use one at least weekly. When did you last use a Hydrovolt? or any other hydrometer for that matter?

And keeping a battery constantly on a float charger will not mix the electrolyte shortening the battery life.

[Sunking]

SK, Is there anything related to homeowner solar ownership that you aren't super critical of? By your own admission you don't use solar at your home so your hands on experience for home use solar is non existent.

I nave designed and built over 200 large scale off-grid solar systems. A couple large Grid Tied for Wally World. I do use solar in my Ham shack. How many systems have you built and paid to design?

I can easily do solar off-grid battery if I wish for a lot less money than most can do it. I just prefer not to pay 5 times more for electricity like you when cheap grid power is available in unlimited quantities. I make sure folks know if they go off grid they are asking for a large utility rate increase, very limited power, and a new part time job. Best you wished you knew that before diving in off-grid huh?

Hydrovolt? or any other hydrometer for that matter?

No Sir not me. Read the reviews from IEEE battery committee while in conference, lectures at Batt Con, and others I trust like battery manufactures Use to use bulb units almost every day for 40 years, Not so much any more, maybe once a month now to check the ham shack batteries and once in a while on friends golf carts. Thanks for asking though, I appreciate the feedback.

And keeping a battery constantly on a float charger will not mix the electrolyte shortening the battery life.

You need to tell every phone company, data centers, all utilities, IEEE, DOD, DOE, and all the other alphabet soup pros that John. I am sure they will pay you a fortune for what you know. For weekenders the batteries get cycled weekly, and like all pros do, should be EQ their batteries monthly during routine maintenance John .Perhaps you can enlighten me please if you don;t mind and have the time. I wil pass it on to the battery manufactures for you. Who knows you might get a high paying job in lead smelter.

So you want to keep dancing?

I will say this though and give you some credit. If you want to pay 5 times more than you have to for an Electric Hydrometer no problem here. Just check calibration with distilled water first to see how far it is off, and then make corrections.

Thank you for you support and have a nice day.

[Diesel Pro]

I purchased a Hydrovolt at John Galt's recommendation and I like it. Paid to much? probably, but it works for me. I'll call it "good enough for who it's for"

I have 1280w rating worth of panels. That should be good plenty to handle my 430ah bank. More than adequate to maintain my battery bank IF I get my settings correct. I've worked the voltages up and believe that I am very close with my float charge setup.

Rebulk? It is my understanding that this is sort of a fast catch up mode so that in the event that I run the batteries low, it captures as much energy as it can in the brief window of opportunity that we have. Right now I am set as a float charger, but if I drop 8v it will charge aggressively. I believe that is what I want once in a while as I have read that the electrolyte needs to be "stirred" on occasion to prevent stratification in these tall batteries.


In late March to early April comes maple season. This will make me a 24hr weekender for 2-4 successive weekends (weather dependent) with a full week to catch up in between. I have yet to decide if I will lean on my batteries and run my 1200-1300watt RO load on them for a few hrs straight, or if I'll run the little EU2000 generator. I can't help but think that a nice deep cycle on the batteries would be more good than harm. Then I'm back to a float charge guy for the most part.

[Sunking]

Rebulk? It is my understanding that this is sort of a fast catch up mode so that in the event that I run the batteries low, it captures as much energy as it can in the brief window of opportunity that we have. Right now I am set as a float charger, but if I drop 8v it will charge aggressively.

That is the idea but does not work quite the way you think. Assume for a moment yu get to the cabin, batteries are fully charged, floating, fat, and happy. Life is good. You start turning things on, and the panels are supply all the power because it is still late morning. Batteries are fat dumb and happy floating away completely unaware anything is going on. They are not charging or discharging, they are floating because because the panels are supplying all the power

Now Wifey and kids arrive. TV, xbox, stereo, and every light is turned on. Mom and kids are in and out of fridge so the fridge is running. Despite full noon sun your panels cannot keep up with the demand. They are generating max power and impossible for them to generate anymore power. Your batteries are discharging and making up for what the panels cannot supply.

So you have rebulk and it triggers. What happens? Well assuming nothing has changed and you are still demanding more power then the panels can generate, nothing happens. Your batteries keep right on discharging and voltage keeps right on falling. You can crank the voltage 100 volts and that will not change or do a thing. The only way the voltage will start to go back up is when demand drops below supply. In other words when you when you start turning things off and your load demand drops below what the panels can generate.

How much power can the panels generate? Whatever the conditions on at the time. Let's say 1 in the afternoon and they can generate full power but your batteries discharge say 30 % and the voltage is 24.5 volts . It does not make any difference if your controller voltage is set for 29.2 volts (Bulk) or 27.2 volts (Float) because your panels are generating as much power as they can trying to recharge. Bulk and Float are just names of Voltage Set Points. Your batteries receive the exact same amount of charge current. Voltage of a charging battery is just a by product current and resistance.

So what is the real difference. Well as your batteries charge, the voltage starts to creep up to Set Point. They are bubbling away taking full power from the panels. If your voltage is set to 27.2, when the batteries reach 27.2 volts,current starts to taper off to zero amps, and the voltage will not rise above 27.2 volts Now you are Absorbing despite we call it Float. When current stops, you are 100% charged and we now call that Float.

If the charger is set for what we call Bulk or 29.2 volts works exactly the same way. Panels pump max power either way. Only difference is with the voltage set higher they pump max power an extra 30 to 45 minutes, thus takes less time to FULLY recharge in theory. Works everytime if you have a commercial AC charger on utility or generator. Not so much with solar. The irony here is assuming you have your system sized correctly, and for whatever reason use so much more power in a day (more than designed) that causes your controller to switch back to Bulk mid day after a recharge earlier that same day, there is not enough sun left in a day for either Bulk or Float to recharged because the panels are going to pump as much power as conditions allow, and by sunset never reaches either set point of Bulk or Float.

If you daily cycle your system, then use 3-Stages as it is faster than Float. But that is harder on batteries resulting in shorter cycle life via Corrosion aka over charge or higher voltages. 3- Stage charging takes up to 12 to 16 hours. Float Charging is less stressful on batteries thus extending cycle life but takes up to 24 hours. You are a weekend user and have the option to float charge. Your choice. Use 3-Stage when there, then switch to Float when you leave. I do not care what you do OK? I am just giving you facts so you can make a informed decision.

I believe that is what I want once in a while as I have read that the electrolyte needs to be "stirred" on occasion to prevent stratification in these tall batteries.

Well true, but again you are missing half the info leading you to a False conclusion. Very true if your batteries just Float 24 x 7 x 365 and rarely ever discharged like utilities and telephone companies operate. That is why those guys EQ charge as needed every couple of months to stir things up. The electrolyte gets stirred up as part of the recharge process be it 3-Stage using higher voltages or a lower voltage Float charge. Any Off-Grid users, even weekend users should have a generator with a simple 1 Stage Float Charger set to Equalize Voltage for required EQ charging and covering your but for cloudy spells. So as long as you are exercising proper maintenance, Stratification is not an issue.

Lastly one final comment on the Bell and Whistle called Rebulk. One has to assume for Rebulk to operate the batteries must have already fully recharged and the charger is in Float mode right? Sure I am right, as that is the only logical way it could work. For you that is 27.2 volts, and 27.2 volts is 100% State of Charge on Float charge, not to be confused with SOC open circuit voltage. So now the million dollar question an Bert Simpson DOH moment. What should that Rebulk voltage be set at if used.. 2, 4, 6, 8, 10 volts or what. OK what is your answer?