Cannot understand this Chinese solar charge controller

upnorthandpersonal said:

@corporal_Canada

- It would be a good idea to start from the beginning: do a power audit (what are the exact power requirements, how long do each of those run per day, etc). This will give you an idea of how much solar and battery you're going to need.
- Batteries are currently dropping in price, solar panels are pretty cheap already, and there is no need to limit to 100W panels or anything. A decent charge controller (i.e., not PWM) is going to make a big difference.
- Don't buy anything yet: do the calculations (or learn how these work, understand them), make sure you know why you're going to make the decisions you're going to make.
- Baby steps

Comme on dit en français: petit à petit, l’oiseau fait son nid.

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Oh the bird makes his NEST, sorry I didn't bother to translate 1 word, finally got it

12VoltInstalls said:

That’s assuming automotive battery parameters. The grp27 DC walmartha batteries I used for several years would ‘rest’ at 13.1-13.2; summer surface charge would be 13.8+
We don’t expect cheap dc batteries to do that because we don’t think it’s normal. The chart is still useful, but I’d want to charge much higher - well over 14V - and ‘float’ at 13.8 for best performance.

The chemistry knows nothing of human contrived charts. ‘Technically’ a 6-cell FLA isn’t ‘fully charged’ until its “absorbing” theoretically 16V+, but we don’t do that, don’t use that because it won’t hold there by nature anyways, and repetitive high states of charge shorten the lifespan of the battery.

I’d be wondering if there’s any way to hammer the battery up to 14.2-ish or more for days on end see if it will rest a bit higher for you.

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Unless you have just rewritten the laws of physics- nope...

You missed one line...

"12.7 is 'fully charged' while not being charged and no loads connected/turned on..."

which is what that table applies to...
NOT the charging voltages- they tell you nothing about a batteries state of charge

(I would be 'extremely surprised' if any L/A chemistry battery 'rested' at over 13v- thats higher than many float chargers run at!!!)

corporal_Canada said:

I honestly don't want to tamper with any of the charge controller settings if I even can, I'll just have faith that the manufacturers knew or know what they are doing

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Did you select the battery TYPE in the settings?? (most have 'preset' charge configurations in them- but you do have to tell it which of the several types available you actually have...)

They can't know what you have- so you have to tell them- they can't do a 'one size fits all'

Think of it like buying a tyre for your vehicle- you can't just walk in and ask for a 'tyre'...
you want this???

or this?

Get the wrong one- and it won't work real good (if at all)
Same with your charge controller- it needs to be set up- the manufacturers can't make a different model for every single possible combination of panels and batteries out there...

corporal_Canada said:

6months of just keeping the solar panel clamps (alligator clip sorry) connected... And then I used the battery (discharging) for 12 hours and that's it....

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12 hours of discharging (at what load)- it would have to be a very small one to not overdischarge the battery- and again- if the charge controller isn't set right, or the panels is mismatched to the charge controller- your recharge rate could be tiny...
(assuming the panels (2x300w and 2x100w- Voc, Imp ratings??? wiring configuration???)- on a unknown generic elcheapo charge controller (ratings??? (we know its a 20A and 'probably' a PWM)- PVmax input voltage???,- type ie PWM/MPPT???)that has possibly been damaged..., with dodgy connections on top (again a possible source of damage to the controller)
urgh
We REALLY need the details- they matter...
Depending on them you could get a barely functional (if at all) system to an adequate system (those cheap PWM charge controllers with the wrong panel ratings/ configuration could be giving you barely any charge current at all...)

Properly set up, a decent MPPT charge controller with appropriately rated panels can work in practically any conditions...
eg
here's my own at the old campsite- charging a 12v battery bank, at 8AM, 100% overcast and showers all day), with the sun still down behind the trees (arrow pointing at it- just to the left of the tree on the right by itself, down in the treetops) and its already putting 4.4A into the battery bank (38-40A in good conditions)


Dawn- only half the sun visible above the horizon, panels still fully shaded by the trees, and already half an amp flowing in...


Thats off 3x 250w panels- set up properly and not that different in total power to your own (750w for mine against 800w for yours)

Bop said:

I would be 'extremely surprised' if any L/A chemistry battery 'rested' at over 13v- thats higher than many float chargers run at!!!)

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Try it. They can and do. Many, many days I came home 8-9pm to see 13.1V on my fla bank.

A ‘float charger’ doesn’t really charge, it holds a given voltage trickle. But 12.7 is too little imho

Charging fla takes a couple volts higher than static voltage to absorb.

Bop said:

Unless you have just rewritten the laws of physics- nope...

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Physics has little to do with it. Chemistry does, however.
And I haven’t rewritten anything, just related facts. I’m no chemical engineer but that is how it works. You can probably find the same white papers and theses I read years ago out there somewhere on the interestingnet to this day.

Although I’m not interested in debating a subject I’m not a well-versed expert in, I am not persuaded to defend the facts, either. Pretty sure I’ve read similar things in either this site or another offgrid power site so if you’d like to explore further you can but I’m not digging it up.

12VoltInstalls said:

Try it. They can and do. Many, many days I came home 8-9pm to see 13.1V on my fla bank.

A ‘float charger’ doesn’t really charge, it holds a given voltage trickle. But 12.7 is too little imho

Charging fla takes a couple volts higher than static voltage to absorb.

Physics has little to do with it. Chemistry does, however.
And I haven’t rewritten anything, just related facts. I’m no chemical engineer but that is how it works. You can probably find the same white papers and theses I read years ago out there somewhere on the interestingnet to this day.

Although I’m not interested in debating a subject I’m not a well-versed expert in, I am not persuaded to defend the facts, either. Pretty sure I’ve read similar things in either this site or another offgrid power site so if you’d like to explore further you can but I’m not digging it up.

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Chemistry does follow the laws of physics- and a lead acid cell (6 of in a '12v' nominal battery in series) gives a known voltage

A lead–acid battery's nominal voltage is 2.2 V for each cell. For a single cell, the voltage can range from 1.8 V loaded at full discharge, to 2.12 V in an open circuit at full charge.

In fact there are tables we use (and they haven't changed since I did my apprenticeship 40 years ago) that specifically correlate battery voltages and specific gravity levels with the state of charge... (not that you can measure the specific gravity in many batteries- not without a drill lol)


I REPEAT- I am talking about the rest voltage of a nominal 12v battery when it is fully charged- NOT on charge, not with a load connected, and 'rested' (ie neither charged nor discharged for at least quarter of an hour...)

Charging voltages are a completely different kettle of fish (and can vary with the particular type of battery in use due to the electrolytic carrier in use ie gel/AGM are quite ineffecient as electrolyte carriers and need higher charge voltages than flooded cells), but the chemical reactions involved always produce the same results in voltage output...

OffGridForGood said:

Say you have a hose running water into a bucket (incoming PV), and a tap in the side of the bucket letting water out (inverter running loads) the bucket is the battery:

if the hose runs faster than the tap, the bucket (battery) is filling.
if the hose runs slower than the tap, the bucket (battery) is emptying.

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And if the bucket is full and loads are covered, the hose is magically turned down at the prefect and real time amount for the situation.

Bop said:

Chemistry does follow the laws of physics- and a lead acid cell (6 of in a '12v' nominal battery in series) gives a known voltage
View attachment 193552
A lead–acid battery's nominal voltage is 2.2 V for each cell. For a single cell, the voltage can range from 1.8 V loaded at full discharge, to 2.12 V in an open circuit at full charge.

In fact there are tables we use (and they haven't changed since I did my apprenticeship 40 years ago) that specifically correlate battery voltages and specific gravity levels with the state of charge... (not that you can measure the specific gravity in many batteries- not without a drill lol)


I REPEAT- I am talking about the rest voltage of a nominal 12v battery when it is fully charged- NOT on charge, not with a load connected, and 'rested' (ie neither charged nor discharged for at least quarter of an hour...)

Charging voltages are a completely different kettle of fish (and can vary with the particular type of battery in use due to the electrolytic carrier in use ie gel/AGM are quite ineffecient as electrolyte carriers and need higher charge voltages than flooded cells), but the chemical reactions involved always produce the same results in voltage output...

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Something you probably forgot since your apprenticeship (after all, it was 40 years ago - meaning you're no spring chicken)... But it's important.

Resting voltages indicating SoC are a function of time since charge was terminated. Most specifications indicate a substantial resting period - some as long as 24 hours. My Rolls FLA specify 20 hours.

It is VERY common to see FLA resting above 13.0V for at least a few hours after charge charge termination.

sunshine_eggo said:

Something you probably forgot since your apprenticeship (after all, it was 40 years ago - meaning you're no spring chicken)... But it's important.

Resting voltages indicating SoC are a function of time since charge was terminated. Most specifications indicate a substantial resting period - some as long as 24 hours. My Rolls FLA specify 20 hours.

It is VERY common to see FLA resting above 13.0V for at least a few hours after charge charge termination.

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I prefer to leave them at least an hour- but I have never seen any hold a raised voltage for anywhere near 20 hours (even on the Rolls lol)- almost all the initial voltage drop occurs within the first 15 mins or so (maybe half an hour on cold days)

ScrotusGobbleBottom said:

And if the bucket is full and loads are covered, the hose is magically turned down at the prefect and real time amount for the situation.

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Say like the float valve in a toilet cistern or cattle trough...
Basically the charge controller is the solar version of this...

And like a float valve, if the SCC settings are wrong, you can 'over-flow' the battery/bucket and have a mess on your hands!

OffGridForGood said:

And like a float valve, if the SCC settings are wrong, you can 'over-flow' the battery/bucket and have a mess on your hands!

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Actually it makes for a good analogy for something said at the beginning of the thread

You have the hose coming in filling the tub (the solar panels putting charge into the battery)- the charge controller is the float valve and stops the tub overflowing by shutting off the water flow as needed (stops the battery overcharging if it is 'full') and turning on if the water level drops...

The tub is the battery bank itself (need to store more water- get a bigger tub (more Ah batteries) or add another tub next to it (batteries in parallel)- and you have another hose draining the tub (the load/inverter)...

You don't need to unplug the second hose and plug it into the first hose to use it (ie the 'not fond of tapping into the battery while it is being charged' thing) it just 'happens automagically'- if your second hose is pulling out less water than the first hose is putting in- your tub still fills until the float valve partially shuts off the flow to stop it overflowing... and then just keeps it 'slowly filling' at the exact same rate water is coming out the second hose... ie the tub is neither dropping nor overflowing...

Stop draining the tub with the second hose, and the float valve shuts off the first hose altogether (ie the battery is full and the charge controller stops the panels overcharging the battery)

And why you can end up with a 'flat battery' even if you are charging it if you have a big enough load on it.... you have a 'firehose' sucking water out (big load, big current)- and are filling it with a garden hose (smaller current) your float valve can be 'completely on' and flowing as much water as it can- yet the tub soon empties...

Got tired of waiting for the battery to reach full charge, so I disconnected it and now the battery barely reaches 5v... What did I do wrong ?

Ouch- if it is only at 5v after being on charge- you have severely overdischarged it or otherwise abused it, and your battery is now a 'Norwegian Blue' ie an ex-parrot...

Six months if abused could indeed see a battery almost at the end of its service life (I have seen many fail after only a month or two when severely abused by people who were massively overdischarging them (and yours is a SLA- they have charging current limits that can see them failing quickly if not followed as well)- most gel/SLA batteries have an initial maximum charging current (usually less than 30A for a 100Ah rated one) which limits the wattage of panels you can handle unless you have a quality charge controller that limits inrush current on SLA settings... and often have a relatively low output current (which limits the inverter size they can handle)

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This bit from before seems pertinent... and a bit predictive...
Sorry to say it, but that battery is probably toast...
(you can try to recover it wih a low powered mains charger (just in case your charge controller is also toasted) but even if it accepts a charge now, its capacity will have been dramatically reduced...)

corporal_Canada said:

so I disconnected it and now the battery barely reaches 5v.

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Sorry but a 12v battery at 5v is done.
could be a good door stop.
Back at post #1 you were describing the cheap SCC - the type "with only three buttons" and a "little picture of a light bulb" - ie for the load side.
I had one of those back in the day - I used it to charge up car batteries on a shelf while I did autobody work on the cars. I left it too long, and even though I had set all the parameters that POS charger killed a perfectly good car battery one day. I don't trust those little "wallet sized" SCC''s
and I should have known better since it was like $20 or less.
Cost me a $100 battery to learn that life lesson.