Questions About Wind / Solar Controller

[mbianka]

Originally Posted by Bash

Two good reasons to have a separate controller for each system:

1. Controllers get hot. The more amps you put through them, the hotter they get. Separate controllers spread the heat out.

2. If you're charging on both wind and solar, and the batteries are close to being topped off during the middle of the day, you may want to have the wind generator shut itself down while the solar takes care of the last bits of charging and/or trickle charging. I have my wind generator programmed to shut itself down .25v before the solar generator shuts down.

I agree with Bash. I don't like to have all the eggs in one basket. Separate systems allows for one to fail and still have the others for charging. I don't have an alternator on board because I installed electric propulsion in 2008. But, I do use a battery charger with a Honda 2000 generator from time to time to charge things up. In that case both my solar controller and wind generator disconnect once the charger voltage has reached a certain level. I don't have to do anything except turn the Morningstar solar controller back on when the charger has gone to float mode. The wind generator takes care of its self.

[edfoster]

Originally Posted by clayzone

edfoster what is the brand/model of the controller you are talking about?

This is a controller that I import from China. It is a wind/solar streetlight controller that has been in use for over five years and 1000's are in use. The model I use most often has internet network and grid connect features not needed for sailboats or offgrid cabins. The model for sailboat and cruisers lacks those options but I have added temp. compensation to adjust for boost and float curves.

It has a large heatsink and 2 10A progamable load outputs. Download the manual
http://www.foster-wills.com/hybrid_controller.pdf

[edfoster]

Originally Posted by cwyckham

Hi Ed,

I've just been asking questions about this very topic on another thread.

What conflicts are there that would cause problems with the alternator "doing its job" while the solar and/or wind is hooked up while the engine is running?

I have over time seen many problems usually caused from lack of knowledge or improper practices during installations. All the advise you have received in this blog is correct. The question is how much do you want to spend on advanced highend systems that will produce very little extra energy. Or do you want to keep it simple.

Since this is your first experience with an electrical system type that is known to have conflict issues please first contact a local PROFFESIONAL. Your money will be best spent and the results should come with a warrenty.

[cwyckham]

Originally Posted by edfoster

I have over time seen many problems usually caused from lack of knowledge or improper practices during installations. All the advise you have received in this blog is correct. The question is how much do you want to spend on advanced highend systems that will produce very little extra energy. Or do you want to keep it simple.

Since this is your first experience with an electrical system type that is known to have conflict issues please first contact a local PROFFESIONAL. Your money will be best spent and the results should come with a warrenty.

Ummm... Thanks, I think.

Actually, self sufficiency is important to cruisers and the electrical system is mission critical and, frankly, very simple. There are certainly a few subtleties to learn, and I am obviously new on the journey. However, the worst case scenario seems to be wasting something on the order of $1000 by buying the wrong widget or upgrading something that doesn't need to be. I'd spend about that much to get a local professional to put things together, and then I'd be left with a black box I don't understand.

The main problem I have right now is that I have limited funds at the moment and am trying to put together a system that is workable and cheap in the short term and scalable in a few years when I want to spend the cash to put together the long term cruising solution.

There are also a few subtle problems that I'm trying to get a grasp of. One of them is conflicting controllers and regulators. There is some debate amongst the professionals, it would seem, at least on this board and in some of the literature as to whether such conflicts exist, and if they do, what the mechanism of conflict is. Relays can fix the problem if it exists.

I would be grateful if you would explain to me and others here who might also be wondering, what the mechanism is that causes a conflict and what the consequences of said conflict are. Is it just a matter of multiple timers kicking in and out during float, or are there other issues during other phases too?

[Ex-Calif]

Originally Posted by cwyckham

.

I would be grateful if you would explain to me and others here who might also be wondering, what the mechanism is that causes a conflict and what the consequences of said conflict are. Is it just a matter of multiple timers kicking in and out during float, or are there other issues during other phases too?

At the very basic level any charge controller or regulator for solar wind or genny is going to "sense" battery voltage. A discharged 12v system is generally said to be discharged at around 10.5v. A 12v battery is made of cells that can produce about 2.2v fully charged so a 12v battery is really a 13.2v battery. If you consider voltage as potential or pressure than solar, wind or generator has to produce more than 13.2 volts to be able to charge the battery. When any charging system detects less than 13v the controller tells the unit to start producing amperage.

The concern here is that one generating system is producing >13.2v causing the other systems to go off line or regulate themselves out of action. Or a concern that one system will fry another system.

Your highest amperage system could be your 30-40 amp engine generator, followed by a 30amp wind generator followed by 80watts (5.15amp) solar. Ideally you would have every charging system operating in harmony producing the right amount of amps to charge the battery bank in a controlled manner. Each system has advantages and disadvantages.

The discussion gets quite complex when the nuances of charging batteries and battery types is added.

I think Bash said he likes to have his wind system cut out at 12.x volts - lower than the solar and top up the final charge with solar.

[noelex 77]

Originally Posted by Ex-Calif

. If you consider voltage as potential or pressure than solar, wind or generator has to produce more than 13.2 volts to be able to charge the battery..

Whenever its voltage of the charge source is above the battery voltage some current will flow into the batteries. Charging will often take place at voltages well below 13.2.

Originally Posted by Ex-Calif

When any charging system detects less than 13v the controller tells the unit to start producing amperage.

.

This is not how regulators work. The maximum Current possible will flow into the batteries until the regulation voltage points are reached .The regulation points are much higher than 13.2 even in float.

Originally Posted by Ex-Calif

The concern here is that one generating system is producing >13.2v causing the other systems to go off line or regulate themselves out of action..

They will only go offline when the voltage has risen above the regulation voltage. You want them to go offline at this stage.

Originally Posted by Ex-Calif

. Or a concern that one system will fry another system.

.

This will not happen.

[Ex-Calif]

Originally Posted by noelex 77

Whenever its voltage of the charge source is above the battery voltage some current will flow into the batteries. Charging will often take place at voltages well below 13.2.

Correct - Like I said this becomes complicated quickly. What was left untyped (this is an imperfect medium for instruction) is that solar will fall below 13v in the shade and effectively be useless as a charging source. When the wind dies and the rpm falls on the windgen it too effectively becomes useless.

The point is that if a battery has a potential of 13.2v the electrical charging system must be able to exceed that amount to float a battery.

Originally Posted by noelex 77

This is not how regulators work. The maximum Current possible will flow into the batteries until the regulation voltage points are reached .The regulation points are much higher than 13.2 even in float.

They will only go offline when the voltage has risen above the regulation voltage. You want them to go offline at this stage.

Again the point is the regulation voltage not neccisarily the amperage. When the battery voltage approaches full charge it si the battery voltage that triggers the charging device to down regulate.

Originally Posted by noelex 77

This will not happen.

I agree I was restating my understanding of other people's concerns.

[goboatingnow]

Edfoster. You mustn't have looked to hard blue skies do a proper marine wind and solar controller

Now let's return to this "mysterious" interaction between charging sources.

As a professional electronics engineer, it amazes me what put forward at times as electrical theory.

Let's look at a few facts.

The terminal voltage of a battery ( ie the voltage developed across its terminals ) is primarily determined by the battery and it's internal impedance and capacitance. It is not ( unless the charger is very very large ) determined by any of the charging sources. ( a function of the relationship between output and input impedances)

A charging source is typically a constant current followed by constant voltage regulation

So charge sources put out maximum current, up to the acceptance current level , of the battery once the terminal voltage is below a preset absorption point. Paralleled charging sources will contribute current as a function of their output impedance. Usually there is a lazy set and one or more sources contributes most of the current so it could be at any time say the wind unit, the solar unit or the alternator. But it matters not in reality which one is doing what.

It also matters not that each regulator is battery sensing. All that happens is that different regulators will decide what there absorption set point is and begin voltage regulation. The circuit effect is that regulators output impedance rises and it's current falls. Hence it plays less and less role in supplying charge. The other controllers will do the same in their own way. All regulators then usually exit absorption mode by current sensing. ( with a coarse timer protection in some systems) so each regulator sensing its own current will exit absorption mode and seek to drop to float mode. All that happens is absorption will actually end when the last regulator decides. Then all will see float mode. There is no mysterious interaction.

The only reason an integrated charge regulator ( actually taking control of all charge sources) on a boat is useful, is that it prevents the lazy charger syndrome, and ensures that where a charge source can contribute power it does so. ( basically there is impedance matching)

Unfortunately trying to understand electric circuit theory using water analogies as well as voodoo electrics (" I don't understand it but "feel" it's better using xx method) tends to build vast misunderstanding.

For example if your wind generator is charging the batteries and it's regulator is working properly, why " disconnect" it and finished the charge on solar, what's the science behind that. What's happens when it's DARK!..it you have multiple charging sources, and they are all online it's doesn't matter which one finishes charging the battery. All electrons look the same, rumour has it, the battery doesn't care.

Separate regulators will not interfere with each other, nor will any proper design fry itself as all regulators have to handle other sources ( like the battery) separate controllers isn't the most inefficient system but the inefficiencies rarely justify the cost of a full integrated system

A working knowledge of thevenins theorem, kirchoffs laws, linear circuit analysis helps in all this. It's while first year electronics engineers spend a lot of time on it.
Dave

[cwyckham]

Wow. Thank you, Dave, for a very detailed and informed post.

Is it not possible that the interaction that people talk about is the issue of impedance mismatch that you described? If I have two mismatched sources, will I get less into the battery than the sum of the contribution each would have independently?

Is it possible for the addition of a smaller current source to reduce the output of the larger source? If so, could it reduce it enough that the addition of a smaller source (say adding solar to the alternator's contribution) actually reduces the net input to the batteries instead of adding to it?

[Coachbolt61]

Brain. Hurting. The pain. Head. Swelling. Information. Overload. Aaaaarrrrrr.

Booooom Clunk. (head hits floor)
Dog will eat well tonight. Brain food.
Smiles.

[goboatingnow]

Originally Posted by cwyckham

Wow. Thank you, Dave, for a very detailed and informed post.

Is it not possible that the interaction that people talk about is the issue of impedance mismatch that you described? If I have two mismatched sources, will I get less into the battery than the sum of the contribution each would have independently?

No. You will at the minimum get the max output from the strongest, in general in bulk mode the input impedance of the battery is so low that most sources will be contributing current

Is it possible for the addition of a smaller current source to reduce the output of the larger source? If so, could it reduce it enough that the addition of a smaller source (say adding solar to the alternator's contribution) actually reduces the net input to the batteries instead of adding to it?

No. Again in bulk mode all the available charge is going into the battery. ( in general)

This source interaction myth, has tended to stem from (a) comments made by "experts" often with no supporting science. (b) may refer to a specific setup and is then taken out of context.

Assuming all charging sources have a reasonable regulator. Theres no need to worry about parallel charging sources.

Dave

[noelex 77]

Originally Posted by goboatingnow

All regulators then usually exit absorption mode by current sensing. ( with a coarse timer protection in some systems) so each regulator sensing its own current will exit absorption mode and seek to drop to float mode.

Very sensible advice overall Goboatingnow. The only comment I would make is that charge termination by current sensing for solar or wind regulators is very rare on boats.
To do this the net charge current into the batteries must be known by the controller. Very few systems incorporate this degree of sophistication and most have a simple, but generally perfectly adequate, timed absorption mode.
It is possible in fact my system will do this, but I have never seen this on any other boat, so it cannot be too common.

[goboatingnow]

Originally Posted by noelex 77

Very sensible advice overall Goboatingnow. The only comment I would make is that charge termination by current sensing for solar or wind regulators is very rare on boats.
To do this the net charge current into the batteries must be known by the controller. Very few systems incorporate this degree of sophistication and most have a simple, but generally perfectly adequate, timed absorption mode.
It is possible in fact my system will do this, but I have never seen this on any other boat, so it cannot be too common.

No so. All the individual controller has to do is sense ITS current, not the net current. Once it sees a low current it can assume absorption is over. That fact that it might be continued on by other controllers doesn't matter.

In addition determining absorption by time is extraordinary inaccurate, nor have I seen it being used other then a coarse protection.

The other thing worth bearing in mind is that many solar and wind are just two stage ( in fact one stage regulators) all they do is voltage regulation at a fixed, so called absorption point, typically these days set around 14.2-14.4 volts. These is no " exit" of absorption mode, no timers are running. Once you keep the battery voltage below the gas off point such batteries can withstand such voltages forever ( that's what happens in your car) .

People get constantly confused about bulk,absorption,float, IUU, IUI curves. The actual regulator just has a voltage regulator set at a set point, that's all, the little LEDs are then " frigged" to tell you the " stages" the regulator believes its in.

The vast majority of solar regulators are just that a voltage regulator set at a set point , nominally called the absorption voltage. Below that there is no regulation, the unit transfer as much power as possible within its limits at whatever voltage the battery is at. Above that there's voltage regulation which is achieved by controlling the current ( ie the effective output impedance) of the regulator. Float mode is merely further current limiting the regulator so that battery voltage isn't raised. With multiple charge sources and constant loads the typical marine lead acid never sees or needs "float mode" ( which was specified to merely replace self discharge losses)

Dave

[twistedtree]

Originally Posted by goboatingnow

The other thing worth bearing in mind is that many solar and wind are just two stage ( in fact one stage regulators) all they do is voltage regulation at a fixed, so called absorption point, typically these days set around 14.2-14.4 volts. These is no " exit" of absorption mode, no timers are running. Once you keep the battery voltage below the gas off point such batteries can withstand such voltages forever ( that's what happens in your car) Dave

Dave, thanks for sharing the nuts and bolts, but I'm confused by the above.

Are you saying that it's OK to maintain a battery indefinitely at 14.2-14.4V and that it's below the gassing voltage? I though the gassing voltage was around 13.6 or so which is also the voltage for a constant voltage charger like in a car or many/most boat engines.

Also, I think noelex 77's point is that many regulators, for better or worse, only time the absorption mode and don't look at their output current as a criteria for switching to float.

[noelex 77]

Originally Posted by goboatingnow

No so. All the individual controller has to do is sense ITS current, not the net current. Once it sees a low current it can assume absorption is over. That fact that it might be continued on by other controllers doesn't matter.

Dave that will not provide any regulation at all.
The controller has no way of knowing if part of the current the solar panels are producing is powering a load.

For example suppose the set point is greater than 14.2v with less than 5 amps into the batteries. When these parameters are reached the battery is close to fully charged and the controller drops back to float.

If there is no load and the parameters are just about to met. The solar controller is regulating just over 5a and the battery is above 14.2. If we turn the fridge on drawing 6a. The solar controller will adjust to now provide 11A. It will never reach the return current parameters with the fridge on.

If the system recognizes the net current into the battery turning the fridge on makes no difference. The system still recognizes that the battery is only receiving 5A so its very close to fully charged.

Return amps has to be net current into the battery. Some of the total current provided by the solar controller will go to driving the loads. The solar controller can be supplying a very large total current even if the battery is fully charged.
Only the net current (together with battery voltage and battery bank size) gives an accurate indication of the battery reaching close to a fully charged state.

Originally Posted by goboatingnow

In addition determining absorption by time is extraordinary inaccurate, nor have I seen it being used other then a coarse protection.

This timed method is the way all the better solar controllers use to determine when to drop back to float..
The cheaper controllers maintain one voltage only as you indicate and never drop on to a float voltage.

99% of solar regulators in boats use one of these 2 systems.
There are very few that can use return amps.
Even probably the most sophisticated controller used on boats the Outback FX80 will not use return amps unless you purchase 3 additional products (which cost as much as the regulator again)