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Old 09-04-2012, 14:33   #31
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Re: Wind Gen Excess to Where?

Quote:
Originally Posted by hellosailor View Post
Multiple charge controllers connected to a battery don't get confused. It's the battery that determines the charging voltage not the charge controllers. "
Dave, I've got to disagree with you here and ALL the charging company tech folks I've spoken to have said the same thing.
Whats techs, perhaps you mean salesmen. a big LA battery in effect sets the terminal voltage , a bit of DC circuit analysis, will show that

Quote:
Unless you've got a real dumb charger aka just a power supply, each of your voltage sources (charging sources) has some type of "voltage sense" that reads the "battery" voltage and makes decisions based on that.
All any charging source has is the ability to measure battery voltage and current flowing throw its charger output no more no less

Quote:
Now, what happens when your solar panel, or windgen, or MPPT controller, any of them, is happily putting out full power because the battery wasn't at 13.8 volts? Well, that source puts out full power, and if you turn on another source, like your engine and alternator, the alternator's sense lead (which should be conected to the battery but sometimes it turned back to the alternator output instead) is going to say "Oh, there's good voltage here, I'm shutting down"
well no thats not what happens,( its a current foldback system of regulation) but so what, at least one source is providing all the power at that time, the battery is getting charged, more sources cant charge the battery faster anyway( see charge acceptance) in absorption mode


Quote:
. Same thing with an MPPT, same thing with the dump switch on the windgen.
In practical terms, you are creating a crap shoot. Whichever device is set for a slightly higher or lower voltage output or voltage sense, one of them is going to beat all the others and trick them because they are now reading voltage from a chaging source--not from a battery alone.
They don't interfere, remember the input impedance of the battery generally overrides everything, hence the terminal voltage is set by the battery not the charging source. In you case all that happens is one source charges the other may contribute current based on a share of their output impedance, but its doesn't matter the battery is getting charged.

Quote:
If the battery is a large bank, sitting at 90-95% and what you'd really like is to quickly (or economically) push it to 100% for better long-term life...it would be nice to have the chargers play nicely, but they just don't know how.
now your in electric voodoo land. The charge source(s) will contribute as much current as they can or as the battery acceptance levels determine. Yes due to the fact that the output impedances are not the same, one charge source ( or several may predominate over the other(s) , but it doesn't matter. Unless its important to you to finish you charging with a particular source, its irrelevant. The rate that absorption mode is completed is determined by battery chemistry, attempting to push more current in just generates heats and loss of electrolyte. All of this is due to battery characteristics not the fact that you have multiple charge sources.

I never said that all the sources will always combine properly and share current. If you think about it it doesn't make sense anyway, that requires current steering error signals between each device. but the battery will get charged as quickly as it can.

My point wasn't that having multiple charging sources active during absorption mode, made sense, it doesn't you only need as many sources as necessary to provide sufficient absorption mode current. What I was saying was that charging sources don't interfere with each other. all that happens is some may stop contributing when the voltage rises. ( but thats not interference).

PS : I used to design power supplies and chargers for a living
Dave
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Old 09-04-2012, 14:48   #32
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Re: Wind Gen Excess to Where?

Thanks for the additional info on the DC heater element. Think I'll give it a miss. I already have two large dump resistors connected to the wind gen, so no worries on that score.
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Old 09-04-2012, 15:25   #33
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Re: Wind Gen Excess to Where?

Perhaps the usage of the word "interference" is confusing. The charge controllers will generally interact with one another, and not always in the most desirable ways.

My old AirMarine (predecessor to the AirX et al) with an external controller will tend to trip itself into float mode prematurely with a good gust (with or without a second solar controller). Of course this is a function of the current output vs. battery capacity, and so will happen later (at a higher state of charge) if the charge current is relatively lower or the battery capacity higher. At least in my installation this will also trip the solar controller into float mode as well - an undesirable outcome. Then after the gust both charge sources can be charging at lower rates than otherwise. My solution has been to turn off the wind gen at that point and reset the solar controller, but of course this means I lose the benefit of the wind for finishing the charge.

I had a smart regulator on the engine as well. When running the engine the solar controller cycled on/off every second or so, which caused the alternator output (and the load on the engine) to fall/rise to counter it. I would shut off the solar panels just to get it to stop. Very annoying.

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Old 09-04-2012, 15:46   #34
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Re: Wind Gen Excess to Where?

Thats a function of the ridiculous bang bang solar controllers, that control charge by connecting the panel directly to the panel and then releasing it. I abhor those.

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Old 09-04-2012, 16:54   #35
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Re: Wind Gen Excess to Where?

Right. But 30 years ago it was considered a decent solution. Times (or at least technology) change. I expect to get a new smart regulator for the new Volvo engine, and probably a new controller for the solar panels. But that still won't stop interaction between the controllers. Perhaps I should look into a combined solar/wind controller...
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Old 09-04-2012, 16:58   #36
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Re: Wind Gen Excess to Where?

All that happens with two "proper"controllers is that during absorption mode, one will be lazy and the other will be putting in the amps. during bulk mode both will be hard at work.

They "interact" because controllers set different set points from when to change from constant current to constant voltage but in reality it has little effect the battery still gets charged, its only if you want to "know or control" which one finishes the charge cycle that you need to select.


This seems to be very confusing for people. Leaving aside weird controllers like the bang bang solar regulators ( very inefficient as you need 12V nominal panels). during bulk mode the LA input impedance being so low, defines the terminal voltage and both charge sources will drive into it to their current limit. ( current foldback is employed) . As the battery SOC rises, the terminal voltage rises and the regulators come out of current limit, and into voltage limit, as current continues into the battery the terminal voltage rises, At some point each charge controller will decide it has reached the end of the absorption cycle and in effect throttle back its current (i.e. its output impedance in effect rises). What it is doing is detaching itself from the battery. The other charge controller will shoulder the remaining current.

Ive currently two independent alternators and a battery charger all connected I can see the interaction on my battery monitoring system. ( I had a wind unit as well but not now)

it is possible to design chargers with paralleling circuits ( in effect current error) but its not common in marine applications.
Dave
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Old 09-04-2012, 17:11   #37
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Re: Wind Gen Excess to Where?

Yes, actually the problem I stated is more an issue with a wind generator than multiple controllers. The surge current that occurs with a gust results in tripping into float mode prematurely, at least with this controller (Flexcharge 25A) and the AirMarine. Depending on conditions there can be substantial differences between the wind and solar charge current (favoring either source), but with gusting conditions the wind charger is the one to leave off even if the solar output is much smaller (in order to prevent early float). Again, depending on conditions, this loss of charge current from the wind gen can result in not topping off the batteries - especially in strong, gusty winds where one would think the wind gen would be best. I wonder if there is a better controller to use for the wind gen...
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Old 09-04-2012, 17:19   #38
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Re: Wind Gen Excess to Where?

why does the charger trip into float mode ( of all modes). must be a bit of dodgy thinking on the part of the designer. It must think the battery needs no current so it goes to float, but surely it returns to normal once the gust disappears.
I know of one or two so called smart chargers where the software is too smart for their own good and in one of them there is an annoying algorithm that prevents the charger from returning to absorption until a minimum of time has passed. somewhat useless.

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Old 09-04-2012, 19:13   #39
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Re: Wind Gen Excess to Where?

travler37, like you I have 450 AH from four 6v batteries, I made two banks out of them. +1 for the Eclectic Energy D-400, but unlike yours it does not have a built-in regulator. I purchased the D-400 from Trans Marine as a package deal that included a heat sink power dump. Here are pictures from the top and bottom, you can connect two sources to it.

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My system has two Kyocera 135s and the D 400 connected to a bus bar that feeds into the charge controller. I did extensive research before choosing all my equipment and decided against the Morningstar regulator and chose a Flexcharge. This charge controller does not care about what is connected to it, what matters is that its amp rating is not exceeded.

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As you can see the battery voltage is adjustable, and when the voltage is exceeded the excess is diverted to the power dump. Easy peasy. Here is a link to a picture of the full system and a description of my wiring and fusing. Solar Panel Circuit Breaker Wiring (post #8) When I installed the system I included switches downline so I can combine or disconnect the battery banks in any combination so I can work on or equalize one bank and still have house power from the other. I installed this system in 2009 and haven't touched it since.

DO NOT try to use a 120 v element to dump 12 v - there is so much resistance it is like you have no power dump at all.
Bummer to hear that the 12v water heater elements don't heat water, I disconnected the water heater heat exchanger from my engine to reduce wear on the water pump ... I was looking forward to having warm water again from a 12 v element someday. :-(

Here is the link for Trans Marine if you want more info about that power dump www.trans-marine.net, they live aboard and often anchor near West Palm Beach, FL.
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Old 09-04-2012, 20:03   #40
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Re: Wind Gen Excess to Where?

Instead of thanking you individually i will thank you all at once.
Am gathering parts and will be onboard....escaping work........the end of the month.Will update you.
Once again thank you for sharing what has worked and what has not.
Mark
PS..If you want a nightmare try working in the oil fields of ND without cell service and trying to get things together...
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Old 10-04-2012, 05:19   #41
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Re: Wind Gen Excess to Where?

Quote:
Originally Posted by CarinaPDX View Post
...The surge current that occurs with a gust results in tripping into float mode prematurely,..
Great explanation as to why wind generator controllers don't work with solar controllers - thanks for that.

It's a pity Dave (goboatingnow) can't see the logic of many postings here!!!

Now we know he was an engineer that explains a lot. He just doesn't seem to have the ability to explain himself clearly - or answer simple questions.

Let's finally clarify one of his statements:

"....the terminal voltage is set by the battery not the charging source..."

Many have disagreed with this.

His statement is partially true, but only up to the point that the battery reaches its absorption voltage. This voltage is set by the controller, maybe 14.1 for gels, 14.8 for open lead acid. Up to the absorption voltage the current is constant as the battery voltage rises - controlled by the charge acceptance of the battery. At this point the battery stays at this voltage and the charge acceptance of the battery then determines the rate of the falling charge current. After a set time and or current and or other parameters programmed in by the engineer that designed the system, the controller switches to a much lower float voltage.

Just to throw another spanner in the works - this float voltage does not mean the battery is 100% charged!!!
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Old 10-04-2012, 09:01   #42
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Re: Wind Gen Excess to Where?

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Originally Posted by sailinglegend View Post

Just to throw another spanner in the works - this float voltage does not mean the battery is 100% charged!!!
Good description. And yes, this is not another spanner, it's the truth. Many folks just don't get it.
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Old 10-04-2012, 11:40   #43
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Re: Wind Gen Excess to Where?

Dave, I don't know how long ago you worked with what type of power supplies or chargers. i do know that folks with porbably the same credentials (EE's and higher) who are currently employed full-time designing and integrating the latest modern equipment--and no, not salesmen but internal techs and management--tell me things are different today. There are many different types of logic used, there are time-constrained resets, microprocessors using lookup tables, different types of voltage sensors and comparators, some programmed to "know" that certian levels or times are proper based on the battery bank they have bene programmed to work with.
And the thing that ALL of these systems seem to share in common, is that they are designed to work in their own voodoo universe, without input from any conflicting controllers or unplanned extra power sources being hooked up to them.

Folks who make the stuff could easily say "Sure, take our wind controller and our solar controller and wire 'em both up" but they don't. The closest thing to a uniform answer is "We don't know, but it isn't designed to work that way."

Maybe that's just CYA but it seems honestly put as they just don't know, and they don't recommend having more than one "intelligent" charge controller running at the same time, because every controller has apparently been designed only to work SOLO. Ever see two intelligent dogs try to grab the same long stick and get it through one narrow doorway at the same time? Won't work, unless one of them lets go of the stick. Doesn't matter which one, just as long as one lets go and the other one can drag it through.
Does this apply to solar, wind, and engine alternator controllers? OK, you say it makes no difference. So in theory, you should be able to find at least one honest vendor who will say their products can and will integrate multiple charge sources, and do so in a beneficial manner. Just one is all we need.
And so far, none of those guys has put his hand up to say "We do it."

In a world where the "normal" charging source is one alternator with integral regulator, not too smart and with the voltage sense lead normally disabled by tying it back to the output...What was normal and acceptable even ten years ago, is just not the same as an integrated multi-source system optimized for full battery life and capacity.

Surely, they can't ALL be lying. They can't ALL be willing to give up product sales. You say I've been mislead by salesmen--but these guys are telling me they can't and won't sell me anything, because they don't have it.

And if you look at how the logic used by each "box" is running, from the viewpoint of a programmer not an EE, that makes sense. The programs are simply not designed to work in a melle. They're more like doggie brains: "Oh look a squirrell!" and they're gone.
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Old 10-04-2012, 18:16   #44
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Re: Wind Gen Excess to Where?

When my batteries are charged I rotate the wind generator 180 degrees until the blades stop spinning. Then I secure one blade to the pole with a bit of line. Saves wear on the genny and no worries about the excess electricity.
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Old 10-04-2012, 19:17   #45
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Re: Wind Gen Excess to Where?

Quote:
Originally Posted by ShipShape View Post
travler37, like you I have 450 AH from four 6v batteries, I made two banks out of them. +1 for the Eclectic Energy D-400, but unlike yours it does not have a built-in regulator. I purchased the D-400 from Trans Marine as a package deal that included a heat sink power dump. Here are pictures from the top and bottom, you can connect two sources to it.

Attachment 39735

Attachment 39736

My system has two Kyocera 135s and the D 400 connected to a bus bar that feeds into the charge controller. I did extensive research before choosing all my equipment and decided against the Morningstar regulator and chose a Flexcharge. This charge controller does not care about what is connected to it, what matters is that its amp rating is not exceeded.

Attachment 39737

Attachment 39738

As you can see the battery voltage is adjustable, and when the voltage is exceeded the excess is diverted to the power dump. Easy peasy. Here is a link to a picture of the full system and a description of my wiring and fusing. Solar Panel Circuit Breaker Wiring (post #8) When I installed the system I included switches downline so I can combine or disconnect the battery banks in any combination so I can work on or equalize one bank and still have house power from the other. I installed this system in 2009 and haven't touched it since.

DO NOT try to use a 120 v element to dump 12 v - there is so much resistance it is like you have no power dump at all.
Bummer to hear that the 12v water heater elements don't heat water, I disconnected the water heater heat exchanger from my engine to reduce wear on the water pump ... I was looking forward to having warm water again from a 12 v element someday. :-(

Here is the link for Trans Marine if you want more info about that power dump www.trans-marine.net, they live aboard and often anchor near West Palm Beach, FL.
We installed the same system on Trans Marine recommendations.
We are using a KISS wind turbine and 100 watt Solar Stik upgrading to another 160 watts of solar. We dump to a resistance bank since we switched to a instant propane water heater a couple of years ago.
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