Charge controller settings

[Diesel Pro]

So after a week with the inverter on and idling and poor sun I found the batteries down to the 1.225 range. I switched off the inverter and after a week of reasonably decent sun with zero demand the batteries were still hanging a bit low. in the 1.24 range. The production number on the Classic 150 said it made a mere .3kwh after what was a day with plenty of sun. I know there was enough sun off and on during the week and it has enough capability to do more.

I would think that 28.4v should be plenty of a float charge. Unsure about creeping the float charge up any further so I increased the absorb from 28.5 to 29.5v for this week's test and the inverter is back on and idling.

[Diesel Pro]

I'm not talking about heating it completely, just thinking that I could determine a manageable resistive load to add a little bit of supplemental heat from a system that already exists. It could be on a timer even and/or a thermal switch. Could be as simple as a light bulb like we used to use in the pump house years back to prevent freezing. My thought is that a little exercise of the system would not be a bad thing. For right now the minimal heat from the inverter idle process will be helping.

[inetdog]

Sorry but forget that idea. You do not have the battery capacity, and if you did would bankrupt you. Propane is a whole lot less expensive.

Where I am (No. Cal) propane costs about the same as electric resistance heating (at $.20+ per kWh).
Electric heat pump is cheaper than propane. Natural gas is the best, but not available everywhere outside urban areas.
PV stored in a battery rather than just surplus from the panels, on the other hand, is the most expensive of all.

[Sunking]

it. At some point I'd like to consider a small resistance based heater to help reduce my propane use.

Sorry but forget that idea. You do not have the battery capacity, and if you did would bankrupt you. Propane is a whole lot less expensive.

[Diesel Pro]

Looks like 28.4 is right where I need to be. I arrived and the charge was in float at .7 amps so it was more or less done.

I now have 2 hydrometers: 1) Hydrovolt and 2) EZ Red

The EZ red is more optimistic by about 10 points, but basically I'm at 1.265 +/- 10 points with 1.275 readings on some cells with the EZ red. I did not have a lot of time to play around. What I did for this coming week's test was I restarted the inverter and left it idle with the same controller settings. This should give the system just a very modest bit of load to exercise it. At some point I'd like to consider a small resistance based heater to help reduce my propane use. I'm at a point that I come up just a bit short of the season with the thermostat set at antifreeze.

[Diesel Pro]

Well if I do as well with these as I did in my boat I should be OK. My boat is used 3-5 times a year, maybe more. I have no meter on the trolling batteries, but I have taken them down to where the power is noticeably reduced. After each outing I just plug in and the trollers charge at 5amps each off a dual bank Guest charger and the starting battery is on a Battery Tender waterproof 800. Run it overnight and park until next outing. I typically repeat before next outing. Boat sits all winter with batteries installed and disconnected. I got 8 yrs of service and the trollers were still going if only a little weak. Never a hydrometer, water, or anything... Starting battery finished this season and will be replaced just for good measure.

[Sunking]

I guess next check should tell the story. I now recognize that I have plenty of horsepower and just need to creep my settings up. I guess 17 points spread on SG is not too bad and realistically should be tighter next test.nge but ran out of loads. I guess I could have run the microwave, but I know that if the batteries demand it will pass 1200w with ease.

17 points is real good and why I made you look it up yourself , do the drill and never have to ask again.

Crown is pretty darn liberal stating 50 point spread. Rolls, Trojan, C&D and other manufactures state state a much tighter 30 points which you are inside of. I sugest 30 points as you default. Crown will not take issue with it. As you have discovered set point voltage suggestions are just that, a starting point. With solar applications the voltage set points will most always be higher. For most there is no voltage high enough and a down hill ride from day 1 to dead batteries.

Good Luck to you and Happy New Year

[Diesel Pro]

I guess next check should tell the story. I now recognize that I have plenty of horsepower and just need to creep my settings up. I guess 17 points spread on SG is not too bad and realistically should be tighter next test.

During Sunday's EQ session I leaned on them hard with my 32v EQ setting and the wattage used from the panels was only in the 500 range most of the time. I turned on loads in the cabin just for grins and managed to get the wattage up to the 8-900 range but ran out of loads. I guess I could have run the microwave, but I know that if the batteries demand it will pass 1200w with ease.

[Sunking]

First things first. You are trying to EQ the batteries to save them. Crank the voltage up to 31 volts until EQ'd then go back to float. Better yet get them on a generator and get it done. Like I said you cannot do EQ and maintenance with Solar. Takes to dang long, and impossible if you use the batteries. Now if you cannot be there, Float will eventually work, at least by spring. Or you can set it for a week with Absorb = 29 and Float = 27 to speed things up a bit. .

As for what the max High to Low spread on SG should be has already been answered a couple of times. It is right in your Owners Manual, last page under Trouble Shooting. Also take note the approx recommended charging voltages on top of page 3 under RE USERS. You are not going to see to see what you expect. Crown has already updated and done away with archaic 3-Stage charging. Like Trojan and some others only specify:

Daily Charge sometimes called Absorption is for Daily Cycle users. 29 volts
Float for batteries using Float Charge method. 27 volts
Equalization for equalization. 31 volts

All you have to remember is 2 and 27 as a starting point

Bare in mind those are Ball Park voltages and only your hydrometer knows the specific voltages you should use. It is going to rane +/- 1 volt assuming your panels and batteries a properly sized and matched. If you are going to error you want more panel wattage than necessary like gas in your car. For daily cycle users, many find there is no voltage high enough except for maybe a month in summer or if they leave for a few days and turn everything off. That is when they learn they should have more panel wattage, generator and hydrometer. What you will likely find, the job never ends. Lowering voltages in summer months and raising them in winter months. It is your new part time job, with no vacations, no time off, and you have to pay for the privilege and not get paid.

[Diesel Pro]

Making progress here with charge status. Back to John Galt's comments the Crown batteries seem to want 1-1.5v higher setting after a while. I think we'll be in really good shape soon

Bat 1
1.255
1.255
1.2475

Bat 2
1.2475
1.240
1.250

Bat 3
1.250
1.2475
1.245

Bat 4
1.2375
1.250
1.250


Changed charge controller settings to 32 EQ, 28.5 abs and 28.4 float. The sun came out nicely so I ran a couple hrs of EQ on it. They took decent amperage, but not excessive. Quickly tapered to 10-15 amps. I was preoccupied with other tasks, but I did check the previously low cell right before running out the door. It was 1.375 and it was now at 1.255 with the controller on float.


So how balanced/equalized do I want to be?

[Sunking]

Remember the Donner Party 1846 !

You mean the Donner Dinner Party for 87 people? I think Hannibal Lector brought the Chianti right?

[Mike90250]

...... When I'm running heat tape on water lines and low sunlight in winter, I want as much juice in the bank as I can get.

Only at 1400 feet, 20 miles from the ocean, but it's cold enough to bust up the windshield washer water tank in the winter, Stupid nanny state only allows window washer antifreeze to be sold in the "alpine counties".

Remember the Donner Party 1846 !

I think Calif must set the record for the longest state, measured north to south, it's longer (800 mi) than half the eastern seaboard (Florida to Maine is 1,342 miles)

[Sunking]

When I'm running heat tape on water lines and low sunlight in winter, I want as much juice in the bank as I can get.

Mike you must be at altitude up Northern in CA. Heat Tape in CA caught my attention. I kind of know where you live, but never gave high altitude any thought. Funny because one of the worse blizzards I have ever been caught in is Truckee enroute to Tahoe from Sacramento.

Well I take that back. Memorial Day weekend, first day of Summer vacation season on I-40 AZ/NM border Gallup NM of 2008 I think. We were in route to Lost Wages IN 2008 I think.. Got to Gallup in a White Out storm and they closed I-40. Quite a site seeing Wifey and I in shorts and tank tops looking for a motel to ride the storm out over night. Got to Lost Wages two days later and they were at record cold and flood waters had just cleared out. Denver had a record snow storm that weekend. If I remember correct that same storm went through to Washington DC, buried the cherry blossoms, and they had to cancel the Global Warming Conference due to record snow and cold.

[Mike90250]

For my oddball voltage bank, I have re-bulk set so that if heavy loads cause the batteries to sag below the setting, the charger will re-start a bulk cycle if the loads abate and there is sufficient sun. Otherwise, could start the evening with 15% out of my bank. When I'm running heat tape on water lines and low sunlight in winter, I want as much juice in the bank as I can get.

[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?