Two "free" solar panels

[Mike90250]

You want your charger to be able to supply 10% of the battery capacity,
so if your battery is 200ah rated, you need a 20A charger. if you add another bank of cells, you now have a 400ah battery and need 40A of charger

Add up your solar amps and your AC charger amps, there are times you need to run both to keep things going, if one is insufficient.

[Cajun Bill]

Thank you for responding Mike. Yes, I will be adding another bank of batts that I will parallel with my original set to keep the voltage at 24V so that should give me about 400AH. Presently, I can get about 7 hours overnight before my batts get down to 60-70% SOC. With the additional batts, I should get enough AH to run the load overnight, but I don't believe the two panels will provide enough power to recharge batts during the day AND run the load. I have two 280W panels (the free ones that started this process &#128512 that produce 9 amps max as I have them in series. I suspect I will have to add another set of panels, but don't want to spend the $$ just yet so that is why I am adding the charger to the "equation". (That and from what I read in Sun King's stickey "Are you killing your batteries?" indicates I will probably need some additional charging capacity to obtain Equalization voltage, occasionally/often.) Now, if I add the two additional panels to end up with a series/series/parallel array (if I wire them all in series I will end up exceeding the CC voltage capability), that should give me 18A max. Is that correct?

So, following your statement that I should have a charger capable of producing 10% of my batt AH, I will need 40A of charging capacity total. If I can get 18A from my panels (on good days), that leaves me short according to you since the charger I am soon to receive is only a 15A charger. Using that line of reasoning, I need to substitute it with at least a 25A charger? Yes, maybe I should probably have a 40A charger for long periods of time of no sun conditions, but I'm not sure I'm willing to invest that much at this time. Or am I being "penny wise and pound foolish" again?

What say you? And thanks for giving me that rule of thumb regarding the needed charging capacity.

[Sunking]

Cajun C/10 is a good rule. However any Lead Acid can handle up to C/8, and good quality batteries like Rolls and Trojan can easily handle C/6 to C/5. This becomes important when using a generator because you want to minimize fuel burn and engine run time. That can also be applied to a standard AC charger if you want to charge as fast as possible. Not required, but good to know there is some room for improvement.

But as a General Rule it is safe to say all lead batteries should be charged no slower than C/12, and no faster then C/8. C/10 is the sweat spot in the middle. Its all about the application.

So let's say you are using a 24 volt 400 AH battery. Your charge range is C/12 (33.3 amps) and up to C/8 (50 amps). Real easy to find the panel wattage range.

Watts aka Power = Battery Voltage x Amps.

24 volts x 33.3 amps = 800 watts
24 volts x 50 amps = 1200 watts.

Want C/10 charge rate? Then 24 volts x 40 amps = 1000 watts.

Your kids in 5th grade can do the math it for you. Oops forgot you are in the USA. Make that college grads might be able to do the math if they have a computer and a Twitter account to get help from friends.

How in the heck did you guys come up with Billary and Chump for POTUS? You guys in the USA are so screwed and brainwashed you are being led to slaughter like sheep and cows.

[Cajun Bill]

Good info SK. So, in summary, if I add two more panels, I'll get 280 X4=1120 watts which should be adequate for my needs as long as there are not too many non-sunny days in a row. Now, until I add the extra two panels, if I use an AC charger, I can make up the difference when necessary. Now my decision is which charger? I have the 15A coming in soon, but is that adequate, especially without the two extra panels that I will be adding at some point or should I go with the 25A or even the 40A? What is your recommendation?

Regarding Chump and Hillary, I totally agree with you. Either one will be atrocious, but I think Hillary will be worse for our constitution. As far as how we got here, it is because, IMHO, we have so many "low information voters", i.e. voters who are too busy trying to catch a Pokemon and watching American Idol to be properly informed on important issues. The second reason, IHMO, is because our media does not do it's job and takes sides, especially on the liberal, left wing side. This is
especially true of the major networks and sometimes, even Fox News. Where are you located? When you spoke about Florida, I assumed you were in our country.

[Mike90250]

i warned you about Free Solar Panels.

When you get to large battery banks to feed large inverters, you can get Inverter - Chargers, that connect to the generator and can provide high power battery charging
(my inverter could charge 80A at 48V, if my generator was large enough) There are smaller ones too, that double as high amp chargers.

[Cajun Bill]

i warned you about Free Solar Panels.

When you get to large battery banks to feed large inverters, you can get Inverter - Chargers, that connect to the generator and can provide high power battery charging
(my inverter could charge 80A at 48V, if my generator was large enough) There are smaller ones too, that double as high amp chargers.

Yes you did Mike, but I have learned a lot. I'm not one to be able to learn from the written word, I have to experience it myself. I know you and SK have given me the basics regarding the size of the AC charger I need, but I'm still on the fence as to which one I should purchase. I feel the 15A is too small, the 40A is probably overkill so maybe the 25A is the way to go? (Why do I feel like Goldilocks and the porridge?)

[Sunking]

Where are you located? When you spoke about Florida, I assumed you were in our country.

I am an Ex Pat living in paradise, Panama. I was your neighbor just to your west border in the country of Texas. I grew up in Las Vegas, Tulsa OK, and Shawnee OK. Military brat so we moved a few times while growing up. My Father was a Col in the USAF. I was ROTC in high school graduated from OSU, and served in the USN on board USS La Jolla SSN 701. When I got out of the Navy I started as an Engineer for a electric utility in Oklahoma, then moved onto Telecom, then started my own biz in 2003 after I was laid off during the dot.com bust

I retired early and got the hell out of the USA. Today I live where it is Spring year round, and NO STINKING INCOME TAXES or RED TAPE to deal with. During my career I worked with a lot of electric and telephone utilities with lots of Storm Recovery experience. Turned 60 2 days ago and I still do Hired Gun Work aka Contract Consulting through my company I own in TX. Utilities fired Lineman and Construction decades ago and replaced them with Contractors. Saves them a lot of money, and as a Contractor you make 3 times as much money. I still work with the same people, just get paid a lot more and do not have to put up with their BS.

[SunEagle]

Go ahead and rub it in for us still stuck on the Main land and having to go thru a presidential election year.

[Sunking]

Sorry SE. But the USA looks like it is going through the largest political conspiracy in US history that could bring the down the Eagle. The way many see it is Chump has no intention to win, he is a democrat insurgent backing Bilary and making sure she gets elected. Chump is one smart SOB and looks like he and Billary figured out how to destroy the GOP and get rid of them forever. You guys have been played and check mated. You just do not know it.You guys are fat and happy sheep being led to slaughter. Getting to the point race riots and/or civil uprising or revolution could happen.

[Cajun Bill]

Sorry SE. But the USA looks like it is going through the largest political conspiracy in US history that could bring the down the Eagle. The way many see it is Chump has no intention to win, he is a democrat insurgent backing Bilary and making sure she gets elected. Chump is one smart SOB and looks like he and Billary figured out how to destroy the GOP and get rid of them forever. You guys have been played and check mated. You just do not know it.You guys are fat and happy sheep being led to slaughter. Getting to the point race riots and/or civil uprising or revolution could happen.

I though the same thing SK at the beginning of the primaries, but I now think Trump does want to win (don't know if he was ever an insurgent). If the GOP is on the way to destruction, it is by their own hand because they refused to hold Obama's "feet to the fire" because they were so timid. The American people, at least on the GOP side, have had enough from them and that is one of the main reasons Trump won the GOP nomination IMHO. The race riots might, in fact, happen one of these days, that is why one of the best businesses to be in since BHO was elected Prez has been selling guns and ammo.

BTW SK, we have something in common: I retired 11 years ago (about the time Trump was making the leaked "hot mic" tape) from AT&T with 37 years service. While I started as an installer, 90% of my career was spent as a "phone cop".

[Cajun Bill]

Okay, it's been a few months since I last posted so I have another question. The circumstances are that I ended up with a 45A MPPT CC and a 25A AC charger (to equalize batts once a month) using two strings of 4 Costco Interstate 6V batteries paralleled (best guess is they are 220 AH batts). My adjusted daily watt hour usage, (according to SK's sticky) is 29,700 (I use 3 days as reserve capacity) if I run both the freezer and fridge on solar/batts. At this point, I can only consistently run the fridge (1,430 W/day) on solar (unless I get too many cloudy days in a row). When I try to add the freezer (1,870 W/day), I can only get 24-36 hours before batts get down to 50% SOC. My question is: if I add another string of same sized batts, paralleled, am I overloading my CC and/or PV panels (two 280W wired in series) and would that probably provide enough WH to, somewhat consistently, run both my fridge and freezer? Keep in mind, I monitor daily and I am the "switch" to change back and forth from AC to RE as needed.

[Sunking]

Okay, it's been a few months since I last posted so I have another question. The circumstances are that I ended up with a 45A MPPT CC and a 25A AC charger (to equalize batts once a month) using two strings of 4 Costco Interstate 6V batteries paralleled (best guess is they are 220 AH batts). My adjusted daily watt hour usage, (according to SK's sticky) is 29,700 (I use 3 days as reserve capacity)

Huh? 29,700 what. Certainly not watt hours.

if I run both the freezer and fridge on solar/batts. At this point, I can only consistently run the fridge (1,430 W/day) on solar (unless I get too many cloudy days in a row). When I try to add the freezer (1,870 W/day), I can only get 24-36 hours before batts get down to 50% SOC. My question is: if I add another string of same sized batts, paralleled, am I overloading my CC and/or PV panels (two 280W wired in series) and would that probably provide enough WH to, somewhat consistently, run both my fridge and freezer? Keep in mind, I monitor daily and I am the "switch" to change back and forth from AC to RE as needed.

OK lets assume you have 4 6-volt golf cart battery and each battery is 220 AH. That is a total of 4 x 6 volts x 220 AH = 5.28 Kwh capacity. In a properly designed system enough to use roughly 1 Kwh per day and that is it. That means 3 days until you must shut down. Not enough to even run the fridge.

As for the controller question is real easy.

Amps = Panel Wattage / Battery Voltage

You have a 45 amp MPPT Controller. That means maximum Panel Wattage = 45 amps x Battery Voltage.

Do the math.

45 amps x 12 volts = 540 watts
45 amps x 24 volts = 1080 watts
45 amps x 48 volts = 2160 watts.

Or you could just read the Controller manual. But all this means nothing. You have 560 watts of panels. Assuming a 24 volt battery means you need at least a minimum 28 Amp MPPT Controller. and a 24 volt battery capacity of 220 to 320 AH. Bottom line there is nothing you can really do. What you have is only going to give you 1 Kwh of usable electricity during Winter, and up to 1.5 Kwh/day. Not enough to run your fridge..Forget the freezer. If you add batteries, means you must add panel wattage. You are stuck.

To run both you are going to need.

24 volt battery capacity = 680 AH. You do not even have 1/3 of that now.
Panel Wattage = 1800 watts. Again you are no where close to that.
MPPT Controller = 75 amps. Again you are no where close to that.

[Cajun Bill]

Ah Sun King, good to hear your melodious "voice" again. I have grown appreciative of your direct nature, i.e. "cut thru the crap and tell it like it is". Maybe I didn't say it clearly enough, but I have TWO parallel strings of four 6v batts so shouldn't the AH be added to show that I have about 440AH, not 220? Yes, even that is not enough, but if I add another "string", would that not be enough to give me 660AH which is awful close to your stated "680AH"? Now, I can't argue with your "suggestion" that I need to add two more panels (and probably another CC), but as I said "I am the switch" so if I run down the batts as far as 50% DOD cuz of too many cloudy days, I simply switch over to AC till the CC (or my AC charger) brings the batts back. This is not a "set it and forget it" setup so I monitor it closely enough to keep my batts from over discharging. The question is "if I add a THIRD string of 6V batts, will I be overloading my CC/PV panels and shouldn't I be able to run both appliances for a longer period of time if I add the third string (at least for some period of time---especially if I have a series of sunny days)?"

As far as the 29,700 (of what), I simply followed your example in your sticky "How Many batteries and Why tutorial" using 3,300 WH (you used 3,000 WH) with a 1.5 fudge factor to get 4,950 WH, then I used 3 days of reserve capacity multiplied by 2 (for 50% depth of discharge) which give me 6 days (you used 5 days) and then followed your third step and multiplied 4,950 WH and six days which equaled my "adjusted daily watt hour usage" which would give me 29,700 WH (you came out with 22,500 WH. Why is that not correct oh wise one?

By the way, how you like how Trump aka Chump is doing so far? I have to say that I'm pleasantly surprised by his cabinet picks and executive orders so far. And his pick for SCOTUS is outstanding. Hell, he might even turn to be a Champ rather than a Chump.

[Sunking]

I have TWO parallel strings of four 6v batts so shouldn't the AH be added to show that I have about 440AH, not 220? Yes, even that is not enough, but if I add another "string", would that not be enough to give me 660AH which is awful close to your stated "680AH"?

OK my bad.

Lets cut to the chase and I will do a better job explaining.

Batteries require a minimum charge rate of C/12. Where "C" is the battery Amp Hours capacity. FWIW they also maximum charge rate C/8 to C/6. Perfect is C/10. The numbers 6, 8, 10, and 12 are hours. So a 440 AH battery requires 440 Amp Hours / 12 Hours = 37 amps. 660 AH requires 55 amps. Understand?

It takes a 1000 watt panel to deliver 37 to 40 amps in a 24 battery. What I am trying to convey to you is you do not have enough panel wattage to support the batteries you have now. So NO to adding more batteries at this time. First thing you need is to increase panel wattage to support the batteries you have now. If you did that then you can get away with running your fridge and freezer.

Last thing is your panel wattage is not enough to replace what you use in a day. Adding more batteries will just make things worse. Put another way you are going to take a 3000 mile road trip in the Cowboy Cadillac with 10 gallons of gas and no money for more gas. Adding a bigger gas tank does not fix your problem.

[Cajun Bill]

OK my bad.

Lets cut to the chase and I will do a better job explaining.

Batteries require a minimum charge rate of C/12. Where "C" is the battery Amp Hours capacity. FWIW they also maximum charge rate C/8 to C/6. Perfect is C/10. The numbers 6, 8, 10, and 12 are hours. So a 440 AH battery requires 440 Amp Hours / 12 Hours = 37 amps. 660 AH requires 55 amps. Understand?

It takes a 1000 watt panel to deliver 37 to 40 amps in a 24 battery. What I am trying to convey to you is you do not have enough panel wattage to support the batteries you have now. So NO to adding more batteries at this time. First thing you need is to increase panel wattage to support the batteries you have now. If you did that then you can get away with running your fridge and freezer.

Last thing is your panel wattage is not enough to replace what you use in a day. Adding more batteries will just make things worse. Put another way you are going to take a 3000 mile road trip in the Cowboy Cadillac with 10 gallons of gas and no money for more gas. Adding a bigger gas tank does not fix your problem.

Ah so Oh Wise One. Sorry I'm so thick, but in all your stickys, I never saw such a simple explanation for the exact question I was asking. You have now clarified this for me and my quest for the answer is over. The "Cowboy Cadillac" analogy was brilliant and nailed it perfectly.

Sooooo, now to my last question: How do you like Trump so far?