Solar panel ....Do I really need a smart charger?

[BabaYaga]

The terminal I referred to is the one to which the charge warning light is connected.

As I understand it, when I turn the "ignition" on, +12v is supplied to the charge warning light and earthed through this terminal, providing a small current through the field coil. As the resistance of the coil is a lot less than that of the bulb, everything downstream of the light is at near enough 0v, so the relay stays asleep. When the engine starts and the alternator spins up, this small current provides a magnetic field to start the alternator generating current, at which point it's fed by the output from the alternator. The terminal is then at +12v, so the spilt charge relay wakes up and the warning light has +12v on both sides, so it goes out.

Sounds like a good explanation. Thank you.

 

[sailinglegend420]

Charles, you and several posters need to watch the video above from Maine Sail in the USA. He's one of the most respected posters on the whole internet..

How was that measured?

Your whole pointlessly pedantic post I didn't think was worthy of any reply, but I fear others reading such nonsense may think you have some good points.

You would learn a lot by going onto the Cruisers Forum website @ http://www.cruisersforum.com/forums/f14/

Maine Sail gets more thanks for his postings than anyone else on that exceptional site.

He demonstrates that even with a small 12 watt panel with no controller it will be putting over 15 volts into a fully charged 220 Ah Lifeline AGM.

Volts don't go into anything. Volts go across things. Amps go into things..

Pedantic!
Amps are the rate at which you put energy back into a battery.

The ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time, with 6.241×1018 electrons (or one coulomb) per second constituting one ampere.

It only puts in 0.7 amps because the battery limits how much current it will take, but it's the voltage that does the damage.

The only thing volts will damage is insulation, and even then it does the damage by pushing amps through..

This is really where you show your ignorance.
Voltage is everything - the battery decides how many amps it will accept based on the voltage and the battery state of charge. Too little voltage and the battery may never get fully charged, and may lead to pre-mature failure due to stratification. Too much voltage causes too much current. This is why we use multi-stage chargers that drop to a lower "Float" voltage that is below the batteries gassing voltage. This is all temperature dependant. Batteries at 40C gas at 14.0v.

Anything above 14.4v will cause excessive gassing when the battery is already fully charged.

Gassing is a direct result of current and only of current: it's electrons moving around which turn ions into gases.

Batteries need to gas to charge properly. Excessive gassing is the problem for batteries and is a result of too high a voltage, or as I said, maintaining its normal absorption voltage(14.4v) after the battery is fully charged. So a fully charged battery, as shown in the video, was still accepting 0.7 amps, and this "energy" has to do something so it causes excessive gassing.

 

[GHA]

Volts don't go into anything. Volts go across things. Amps go into things.



The only thing volts will damage is insulation, and even then it does the damage by pushing amps through.



Gassing is a direct result of current and only of current: it's electrons moving around which turn ions into gases.

Why would all those battery manufacturers recommend max charging voltage?

Unless, could there be some kind of relationship between volts and amps.........

 

[JumbleDuck]

Your whole pointlessly pedantic post I didn't think was worthy of any reply, but I fear others reading such nonsense may think you have some good points.

You would learn a lot by going onto the Cruisers Forum website @ http://www.cruisersforum.com/forums/f14/

Maine Sail gets more thanks for his postings than anyone else on that exceptional site.

I've had a look, but can't see those statistics. Do you have a link? In any case "Gets thanked a lot on one website" is not quite the same as "He's one of the most respected posters on the whole internet", is it?

https://yourlogicalfallacyis.com/appeal-to-authority

Amps are the rate at which you put energy back into a battery.

Wrong on two counts. First of all, the rate at which energy flows is volts x amps, not amps. Secondly, if the battery is gassing then the electrical energy supplied is not going back into the battery, at least not for long. Edit: Neither is it all coming out as gas. A significant proportion, particularly at the low current densities cited, turns into heat by recombination of gases in the cells.

The ampere is a measure of the amount of electric charge passing a point in an electric circuit per unit time, with 6.241×1018 electrons (or one coulomb) per second constituting one ampere.

Copied direct from Wikipedia (http://en.wikipedia.org/wiki/Ampere) I see. Still isn't energy flow.

Voltage is everything - the battery decides how many amps it will accept based on the voltage and the battery state of charge.

Nevertheless it is charge which batteries store, not volts, so - as I think you recognize - the point of the volts is to drive the amps.

 

[JumbleDuck]

Why would all those battery manufacturers recommend max charging voltage?

Mainly because it's a darn sight easier to make a controlled voltage supply than a controlled current one. They do exist, though - the gel cell charger I had for my glider used a series of current levels rather than voltages.

 

[GHA]

Mainly because it's a darn sight easier to make a controlled voltage supply than a controlled current one. They do exist, though - the gel cell charger I had for my glider used a series of current levels rather than voltages.

So maybe current and voltage are linked somehow

Back to batteries, the only way you´ll get the voltage up above the resting voltage of the battery is with a bit of current, get up above 15v and your batteries will be bubbling away , not good for them at all for any length of time.

Unlikely in the UK in winter but there is a video which shows it´s possible even with a small panel and a big bank.

 

[JumbleDuck]

]Unlikely in the UK in winter but there is a video which shows it´s possible even with a small panel and a big bank.

I think that's the one by One Of The Most Respected Posters On The Whole Internet (TM). Which is interesting, but not conclusive, since it basically says "Oh my god - milliamps. Hundreds and hundreds of milliamps. This baby's gonna blow" without any discussion of what happens inside the battery at those low current levels.

How many boat batteries have you heard of blowing up as a result of excessive input from a small, unregulated panel?

 

[GHA]

I think that's the one by One Of The Most Respected Posters On The Whole Internet (TM). Which is interesting, but not conclusive, since it basically says "Oh my god - milliamps. Hundreds and hundreds of milliamps. This baby's gonna blow" without any discussion of what happens inside the battery at those low current levels.

How many boat batteries have you heard of blowing up as a result of excessive input from a small, unregulated panel?

That´s not what was being talked about, the point being made is that you can boil your batteries with a much smaller panel than most people think. Might not happen in the UK if there´s any drain on the batts and might take a while if it does but it´s possible. A 12w panel can quietly part hydrogen and oxygen from their embrace then one day you go back to your boat and the plates are sticking out and you´ve done some bad damage to your wallet.
Get your batteries over 15v for a while and have a listen.

 

[JumbleDuck]

That´s not what was being talked about, the point being made is that you can boil your batteries with a much smaller panel than most people think. Might not happen in the UK if there´s any drain on the batts and might take a while if it does but it´s possible. A 12w panel can quietly part hydrogen and oxygen from their embrace then one day you go back to your boat and the plates are sticking out and you´ve done some bad damage to your wallet.
Get your batteries over 15v for a while and have a listen.

Is there any evidence that this actually happens? If it was such a risk, wouldn't we have tales of boiled batteries all over the place? even if there is gassing going on, how much of the gas recombines in the electrolyte?

There may be a problem, but it takes a little more than an amateur waving a multimeter around to convince me.

 

[William_H]

Just to make sure everyone understands that figure of number of electrons moving per second of 6.241 x 1018 is of course to the power 1018 not multiplied by 1018.
An aweful lot of electrons moving house from one atom to the next at one amp. Interesting Stephen Fry on his GI program calimed that electricity moves at quite slow speed.
The speed of electricity is usually described as 300000km per second. This is actually the speed of the effect of electron movement. ie if you put an electron in one end of a metre of wire another will pop ou the other end at the speed down the wire of 300000km per second. He claimed however that one electron in itself will move at just a few KM per hour. I thought this strange as I would imagine that the speed of an electron would depnd on the size of the wire and the current. ie with a lot of current and a small wire our particular electron would have to be shuffled along much faster than in a larger wire where there are more electrons to share the total movement. (and of course we are talking Dc not AC where the electrons may never move far at all.)
Just waffling. Our argumaent in this thread is to whether a 10w panel giving .5 amp can damage a large 200AH battery by over charge. To be honest I don't know but doubt it even in our fierce and long summer sun. (let alone UK) A panel without a regulator is near to a constant curent source due to high pushing voltage (20v).
I do know that it is common to leave a battery on trickle charge long term. How much current does a trickle charger give? If it were 200ma (1/5 amp) that would equate to about 12 watts of solar at 8hrs per day charging full power. Trickle chargers don't to my knowledge destroy batteries even smaller ones. olewill

 

[GHA]

I do know that it is common to leave a battery on trickle charge long term. How much current does a trickle charger give? If it were 200ma (1/5 amp) that would equate to about 12 watts of solar at 8hrs per day charging full power. Trickle chargers don't to my knowledge destroy batteries even smaller ones. olewill

.
Trickle chargers don't push the voltage up to above 15v though. Would you happily leave your batteries at 15 plus volts for 8 hours every day the sun shines? Seems a possibly expensive experiment. And not one many battery or charger manufacturers would recommend.

 

[William_H]

Another person who does not realise the relationship of terminal voltage to current. Both are interactive especially with a solar panel becuae it has a large internal resistance.
So if a battery is held at 15volts terminal voltage by any charger then it must take a large current either charging or cooking the battery. A solar panel might have 20volts (to start with) but this voltage as seen at the panel and battery terminals falls with current. So if solar panel can only supply .5 amp then this will be at a voltage somewhat lower than open circuit voltage however it will push much of this current into a battery at high terminal voltage.
The end result is that damage or charge to a battery is a result of current.
Yes a trickle charger may have a voltage set more like 14volts so that current will diminish as battery inherent voltage (charge) rises. However I think most trickle chargers are crude in that they feed the battery with half wave rectified AC. This means that peak voltage (doing the pushing or trying to reach that peak) is about 18 volts but this is only for a short period of time and average voltage hence average current is lower. It is all a bit complex. (variable)
I still claim that a 10w panel is unlikely even starting froma fully charged 200AH battery to get the voltage above 14v and so is unlikely to damage it.
IMHO Our expert on U tube in USA is either trying to sell regulators or trying to justify his own purchase of a regulator. Or just being over cautious. olewill

 

[GHA]

Nu

Another person who does not realise the relationship of terminal voltage to current. Both are interactive especially with a solar panel becuae it has a large internal resistance.
So if a battery is held at 15volts terminal voltage by any charger then it must take a large current either charging or cooking the battery. A solar panel might have 20volts (to start with) but this voltage as seen at the panel and battery terminals falls with current. So if solar panel can only supply .5 amp then this will be at a voltage somewhat lower than open circuit voltage however it will push much of this current into a battery at high terminal voltage.
The end result is that damage or charge to a battery is a result of current.
Yes a trickle charger may have a voltage set more like 14volts so that current will diminish as battery inherent voltage (charge) rises. However I think most trickle chargers are crude in that they feed the battery with half wave rectified AC. This means that peak voltage (doing the pushing or trying to reach that peak) is about 18 volts but this is only for a short period of time and average voltage hence average current is lower. It is all a bit complex. (variable)
I still claim that a 10w panel is unlikely even starting froma fully charged 200AH battery to get the voltage above 14v and so is unlikely to damage it.
IMHO Our expert on U tube in USA is either trying to sell regulators or trying to justify his own purchase of a regulator. Or just being over cautious. olewill

You think he faked the readings? 15 plus volts with 0.75a are obvious on the meters, if anyone else had some real data it would be helpful, claims don't mean a lot without data to back them up unfortunately.

Compass Marines YouTube channel is well worth a look through, there's a lot of useful info in there. Here's similar with a bench power supply..

 

[JumbleDuck]

An aweful lot of electrons moving house from one atom to the next at one amp. Interesting Stephen Fry on his GI program calimed that electricity moves at quite slow speed.

Correct. They shuffle along quite slowly though, as you say, the electrical signal goes much faster. Not quite at the speed of light, though - it can be as low is 0.6c, depending on the materials involved.