Solar panel controller - all the same? Recommendations?

[tabbypurr]

5w at 12v is 0.42A, not 10A. If a FET dissipates 1.8W doing that then you chose the wrong fet.

NT

[Paul]

I picked 10A because I don't know what the actual load is. It was an illustration, using a number picked from the air for the illustration.

When the designer tested his creation with the light bulb, that was for test purposes, and wasn't likely to be the actual load.

Obviously if the load is insignificant, the series element dissipation is likely to be insignificant as well.

In the illustration, wasting 1.8W compared to 120W isn't too bad. I have worse linear stuff running in the house right now, stuff that isn't even close to being that good.

Paul

[tabbypurr]

thing is you can pick whatever series dissipation you want. Naturally the lower it is the more you pay for your fets. But high current very low Rdson fets are readily available now.

NT

[T i m]

<snip>

Of course you do, because you have no idea what I actually know about this subject because you don't have the means. Stop digging! ;-(

No need to be sorry. You were the one suggesting a solution could be found with some 'basic electronics' and I was wondering why you weren't rich?

<snip>

You think you can mention some components and that forms a solution do you? How does your imagined solution compare with the internals of the devices the OP was referencing OOI?

Like you could! ;-)

<snip>

Yes, we know that ...

I know it, you don't realise I know it and try to suggest simple solutions without realising all the real world issues. eg, You 'simple diode' won't prevent the battery being ruined by being over discharged and that could be an expensive experiment.

At least a Charge controller will prevent that, even if it's not as good from a parasitic load POV.

<snip>

No, really ... that's what you hope is it ... ;-)

Now, as per the OP's request, what personal experience do you have of the charge controllers he was asking about and what models have you used for say, at least 1 year?

Cheers, T i m

[T i m]

;-)

A 12V 5W (~.5)A should provide enough wetting current to keep some relay contacts happy and a latching relay might be a 'simpler' solution to at least protect the battery from over discharge than anything then needs actively driving.

It could re designed to re-energise the load with a suitably large hysteresis, if 'battery care' is important.

I know the controller I have had on the panels in the Workshop for the last 10 years has a very low parasitic load but not insignificant, if running a battery that matches the rating of the panel and especially during the winter months.

The battery feeds some low power flouros (sorta emergency / convenience lighting) and I have left them on by mistake several times. 'Luckily', the charge controller has a LVD built in but it still take a log time to get the battery anything like charged again to be able to support the lights for any time.

Cheers, T i m

[T i m]

Don't worry, our NT is very literal. ;-)

;-)

Yup.

So, now we have ascertained that we will *have* to waste (valuable / solar generated) energy to prevent damage to the battery from over-discharge, the issue is how to do that.

Are the commercial charge controller solutions as 'good' when it comes to any parasitic load then we might be able to come up with ourselves?

If we had something that could sleep for say 5 mins (depending on the size of the load to the battery capacity (so rate of discharge), and given no solar charge) and only wake long enough to check the battery voltage and either toggle the output off or not before sleeping, as long as the total energy consumed during that cycle was less than the average of something more linear, then we may have a solution. ;-)

ESP32 / Deep sleep (10uA?)

Cheers, T i m

[tabbypurr]

what you might know about it is not my concern, and does not change the fact that a person competent in electonics can design something from my brief comment. If you can't I couldn't care less, and I'm not interested in your trolling nonsense. If you knew your stuff you would not be resorting to childishness.

I'm not seeing a connection between the 2, and you know jack about my finances.

I can and did. It is a solution for people that can do the rest. That ought to be obvious. For others, I've no interest in spending however long designing something for them for free. If you object to that go ahead & do it. Otherwise you're a pointless whiner.

It's pretty basic stuff. I've already given the outline. And I've written a enough EE teaching material before now.

You seem to have this wacko obsession with the idea that others must be pretending to be something they're not. Clue: I could not give one flying whatsit what you think. You talk so much rubbish that I mostly don't read your posts. What on earth does anyone gain by seeking approval for something they're not? The only sane answer is nothing. Only fools fail to realise that. If you disagree with that I don't care.

given the questions you ask it's not convincing. Who knows.

You've said that over & over. It's stating the bleeding obvious. The diode was never intended to be a low voltage cutoff, as you perfectly well know. It's all that's used in many cases. I don't care what you think about that, it just is.

'not as good' is one way to put it. What is the I_q of your proposed solution? What is the cost? Is it justified to get 5w peak some of the time? We don't even know the op's app or setup yet you seem very keen on your guess as to best solution! If I look at my current uses of lead acids, it would be the best solution for precisely none of them. Your confidence in your guessed opinion is unrealistic.

you're departing from sanity at this point

I've worked a fair bit with lead acids, but very little with solar pv. PV has enough issues to make it not a satisfactory solution in most cases. But that really does not address your issue with circuit choices, so is of limited relevance.

NT

[tabbypurr]

you have come nowhere remotely near establishing that. You are not a good engineer.

So are you actually proposing using an ESP32 to cut the battery off at low voltage?

"At the heart of the ESP32 chip is a Dual-Core 32-bit microprocessor along with 448 KB of ROM, 520 KB of SRAM and 4MB of Flash memory.

It also contains WiFi module, Bluetooth Module, Cryptographic Accelerator (a co-processor designed specifically to perform cryptographic operations), the RTC module, and lot of peripherals."

If so, you're lost in space.

NT

[T i m]

<snip crazy ranting>

Same here (ignoring the PEV I've had for 30 years that uses them). JOOI, I can probably lay my hands on 20+ lead acid batteries within 10 paces from here.

I guessed.

Agreed. But not the question raised here.

My 'circuit choices' (and by that your mean potentially the OP's, as he was asking about charge controllers and people who had *experience* of them) ... included full consideration of the OP's overall question, so it's *totally* relevant.

So, again, if *your* basic electronics suggestion can beat the parasitic drain of any of the charge controllers you are familiar with and are commercially available, I'm sure the OP (and electronics industry) would be interested to hear about them?

And why wouldn't you be happy to show the world how clever you were?

Cheers, T i m

[T i m]

<snip>

It's a fact mate. I'd stop digging if I were you.

I'm not 'an engineer', I'm an electronics / datacoms service tech (by training).

Nope, I'm considering the use of one to manage a latching relay to do that (and potentially many other things that could be handy in such circumstances).

Very good, at least you can copy and paste. Now, do you actually

*have* an ESP32 there OOI and if so, what have you used it for so far?

And you are still so literal / difficult / stubborn that you are missing the bigger picture.

How many uA would your proposed 'basic electronics' LVD solution draw? I mean, even if you don't want to show the schematic here (to help others) you could give us the value?

Answer that or STFU.

Cheers, T i m

[tabbypurr]

no, it's your choices I take issue with

not to the question of preventing discharge into the PV panel. You specifically objected to a diode not doing other things which were not requested, and which you clearly have no clue whether are wanted or needed.

If the op has been reading this thread they've already heard it.

With all due respect

1. A suggestion of a simple circuit has nothing to do with my level of cleverness
2. I've already made clear that I don't intend to spend a bunch of time for nothing
3. you're simply wasting time

NT

[tabbypurr]

It's nowhere remotely close to a fact. I've already explained why.

OK this explains some. I AM a qualified EE. And I would seriously hope I've come a very long way from the kind of 101 stuff we had to do for that degree.

so yes, you do want to use an ESP32 with the specs of yesterday's desktop computer to control a voltage threshold! That's just insanity.

And can see this is wildly far from what is appropriate or even relevant to use for a LV cutoff.

no, and that fact is of zero relevance. Don't pretend it is.

Lol. OK so you think parasitic draw or I_q is the bigger picture. What I_q what I proposed uses depends on the comparator (or opamp) used. Take your pick. I would however point out that whether a cutout circuit uses 1uA, 10uA or 100uA is utterly irrelevant in this situation.

NT