Question re Solar regulator

Here we go again.
A solar panel is a constant current device. Hooked to a battery the voltage will depend on the type of battery, state of charge of the battery, temperature etc. Under the circumstances it should never get to anything like 18volt.

If you have a battery that can take a continuous 6 amp charge without damage, and want to risk it, then go for it.

I'd use a regulator.

And to be correct your question should read.

If I'm running a fridge which draws on average 2 Amphours/hr and I have a solar panel producing again on average 6 Amphours/hr
We have....fridge 2 Amphours/hr for 24hrs=48 Amphours draw down
Solar panel.....6 Amphours/hr over say 7hrs=42 Amphours in
Therefore I will never overcharge battery (100 Amphour agm)
DO I REALLY NEED A REGULATOR??

Guys,

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Lex I think you have misunderstood the question and answer.

Most regulator will limit voltage and not current, an unregulated solar panel will deliver in excess of 18v at certain times, this is to high for safe battery charging.

A solar panel regulator will not regulate current but it will regulate voltage to an acceptable level for charging.

Of course a solar panel is a constant current variable voltage device and I don't know where you got the idea of it being any different in my post.

Lex do you understand what a regulator does?

I'm sorry if I mislead anybody and I would suggest not to take any notice of my post and ask it to be removed on the grounds I was incorrect and may of mislead someone.

I'm starting to get really sick of this forum again as the MOD SQUAD said!

Thanks to all for replys...........will get a reg

Cheers
Richard

Lex M is right.

If you connect a "48 volt" Solar Panel to a 12 volt Lead Acid battery it will start to charge it at exactly the same current as a "12 volt" panel would.

If you don't have a regulator connected and you don't disconnect the panel manually, a "12 volt" panel will overcharge the battery with exactly the same timing as a "48 volt" panel.

To understand that you can connect a Solar Panel directly to a battery, means you have to understand that Solar Panel is a constant-current source - unlike every other source of DC around us.

Thats what I said didn't I?

"A regulator regulates the charge (voltage) going into the battery from the solar panels.

Most deep cycle batteries like somewhere between 14.5v up to 15v with 14.5 to 14.7 being the average, solar panels will put out over 18v if unregulated.

If you put 18v in to any12v battery for a long period there would be a good chance of destroying it and causing injuries to anyone near by if it explodes."



The remark about the current was intended to show current has very little to do with charging a battery......as the original post by Richard L (WA) was only regarding current and not voltage.

What I said
"Amps have nothing to do with charging a battery with in reason, if you charged a battery with 1 amp it would be slower to charge then with 15 amps but what makes a battery charge is voltage. "

He made no mention about voltage only current, I made mention about voltage and remarked what more or less current will do regarding charging batteries.

The remarks I made about current had nothing to do with solar panels.



As I said
"A regulator regulates the charge (voltage) going into the battery from the solar panels."

Obviously I must be wrong so please tell me where I went wrong and what I don't understand?



So please don't twist things around to make me look stupid!

That would be right!

Guru's, I’m not questioning what you say but I'm not sure I understand it. We have 2/80w solar panels. In shade we get (about) 0.5 – 1.0 amps coming into our Steca regulator and in clear sun we might have 10 - 12 amps. So how can you call panels a constant current device when the current changes? Or do you mean "constant" is different from "varying"? As Pauline Hanson said, “please explain”. Cheers

jdwynn,
the Voltage is stated as 'constant' the Amps is 'varying'

Maîneÿ . . .

"So how can you call panels a constant current device when the current changes?"

If you connect a "24 volt" 160 watt panel in sunshine to a 24 volt battery it will put about 5 amps into it.

If you connect a "24 volt" 160 watt panel in sunshine to a 12 volt battery it will put about 5 amps into it.

If you connect a "24 volt" 160 watt panel in sunshine to a 6 volt battery it will put about 5 amps into it.

If you connect a "24 volt" 160 watt panel in sunshine to the 10 Amp terminals of a Multimeter (essentially a short circuit) it will put about 5 amps into it.

If you connect a "24 volt" 160 watt panel in sunshine to a 240 volt powerpoint - no, it won't put out 5 amps.

If you connect a "24 volt" 160 watt panel in moonlight to a 24 volt battery it won't put 5 amps into it.

This post has been read by the moderation team and has been moderated due to a breach of The Trolling Rule .

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This post has been read by the moderation team and has been moderated due to a breach of The Trolling Rule .

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Thanks Mainey & Mike, got it now I think - tricky stuff. I've only played with 12v so this beyond my experience. Cheers

So Mike the battery effectively regulates the voltage is that correct?

"the battery effectively regulates the voltage"

- if you're charging a battery of around 100 amphour from a constant-current source of around 5 to 10 amps, then yes. When the battery reaches full charge, that's when the voltage will start to rise above 14 volts.

Been stewing on this thru the day a bit. On top of what Bonz has asked, how does the battery handle bulk/float voltage differences from a charger?

hmm Mike, we need to shake hands I reckon and discuss this, I would love to know how the solar cells regulate the current if the voltage varies, as Ohms rule would suggest otherwise. This is very interesting.

"I would love to know how the solar cells regulate the current if the voltage varies"

The problem is every other DC source around us keeps the voltage fairly constant as you vary the load resistance.

A Solar Panel keeps the current fairly constant as you vary the load resistance - that's just the way it is. It's standard practice to test the current output of a solar panel by connecting an ampmeter (virtually a short-circuit) across the solar panel terminals.

Look up the data sheet for any solar panel and find the voltage-current curve - the current is fairly constant from 18 to zero volts.


"as Ohms rule would suggest"
- Ohms law tells you how much current will flow if you know the voltage and resistance - but a solar panels internal resistance is very high, so it doesn;t matter if you change the load resistance - it's swamped by the panel internal resistance.

Thanx Mike, I will go look that up. Very interesting.

Olcoolone, sorry for hijacking your reply mate!

quote
"Most regulator will limit voltage and not current, an unregulated solar panel will deliver in excess of 18v at certain times, this is to high for safe battery charging."

"A solar panel regulator will not regulate current but it will regulate voltage to an acceptable level for charging."

"Lex do you understand what a regulator does?"
end quote.

Yes I do. It regulates current while monitoring battery voltage.

So Lex a solar regulator is a current regulator and not a voltage regulator?

Why do the refer to them as solar voltage regulators and never solar current regulators?

Perhaps I was wrong and I apologise.

"Why do the refer to them as solar voltage regulators and never solar current regulators?"

They do occasionally. Also "Solar regulator" "Solar Controller" "Solar power regulator" "Solar charge controller" and on and on.

"Solar charge controller" makes sense to me.

Thanks Mainey.........My panel is 80 watt also

Richard

Thanks Robin

In my case we would be in a static setup for perhaps 2 weeks.....so with only the solar panel as source of charge I would probably run out of charge.....therefore my ?? for a regulator.......my panel would only give a peak of 6amps I think

Richard

Richard,
Yes, "peak" Amps - not 'average' as I commented on earlier :-)

Good to see you make the decision to get a regulator, now just get a good one

Maîneÿ . . .