Dump Controllers vs Charge controllers

[SamoaPower]

I don't think I misunderstood your points (or intentions) at all. You have been on my case (as well as others) in this same vein before, so I don't expect you to stop now. I'm sorry that this isn't Tom's board and people won't say just what you want to hear.

Aah, the master of innuendo strikes again!

"Just because some rich person buys 10 grand in RE doesn't make him / her an expert in RE."

Agreed. At the risk of seeming paranoid, do you really think this applies to me? If so, my bank account sure doesn't know it. That's amusing.

"Sorry that you asked a question that got you in the doodoo..."

Gee, I don't recall asking a question.

"DIY is not the same as "buy it and have it installed""

Also true. I consider myself an avid DIYer who designs and builds virtually everything that's practical for RE and have never employed an installer. Look, I really am one of the guys but what might separate me from some of the others is that I want to see it done right. "Right" comes from not only formal education but also from the school of hard knocks. I've been there, made the mistakes and learned the lessons. I may be a talker but I'm also very much a doer. Enough horn blowing.

"...it will not change the reality that your view is very narrow on what "we" need."

Perhaps so. Bob g makes some good points about our demography. The "we" get to make their own choices for their own reasons. It would be nice (for them) if they were informed choices.

One final point (back on topic) - the contention that a simple controller fills the gap between no controller and expensive ones isn't necessarily true. Actually,  manual control can do a better job of charging the batteries if one is willing to pay attention (as you know Tom).

I don't feel bad about going on like this since few wanted to talk about battery charging anyway.

[TomW]

Samoa;

Yes, I admit, you are one of a handful of posters to this site who I feel talk down to the other users regularly and are and simply too full of themselves for the common good. This is regardless of whether you or they are technically right or wrong. I offer this original thread starter as my proof of same.

If stating honest opinions is wrong, then I accept responsibility for being honest. I know it is not Politically Correct to call it like you see it but it is a disease I have.

There, I said it plain and simple, no innuendo. And, thats my final comment on it because you may still be struggling to understand plain English.

Happy now?

Now back to my elevation plan to find guy locations and dimensions for the 2 turbines I hope to add by fall and hopefully can double up a couple guy anchors to cut costs and labor.

Cheers.

TomW

[Volvo farmer]

Tom,

I just went back and read the original post, without bias. I think it is a fair comparison of a bang-bang circuit like ghurds, and a true three stage design, like a person can buy from Xantrex. I do not see a personal agenda against any particular person in this post.

I personally do not see a "talking down" to anyone. Samoa seems to subscribe to the theory that batteries should have a proper absorbtion charge daily, and is pointing out that these simple dump controllers will not automatically do an absorbtion charge. Assuming enough wind, with a bang-bang controller, you're either constantly boiling the crap out of batteries or chronically undercharging them, depending on where the voltage is set.  I think it is a good point, and one that should be discussed.

Let me give you an example. My first solar system was this little one I put on my garage, 160W of panels, 4 golf cart batteries at 12V and a cheap 1500W inverter. I chose for my first charge controller a BZ Products MPPT200. Back at that time MPPT was all the rage and I thought it would give me the best bang for the buck, it was about $50 if I remember correctly. Well, as time went on, I kept wondering why every three months, I could see the tops of my plates in the golf cart batteries. I had the charge controller set up to a good absorb setpoint, like 13.8V. Problem was, I hardly ever used any power out of the batteries and the water boiled out at an alarming rate. Luckily for me the charge controller died after about 18 months and I put a $80 C30 on it. I only realized afterward that this BZ Products POS was NOT a three stage controller. I could hold batteries at float, I could boil them all the time, but nothing in-between.

Now, if someone, like Samoa, had warned me about charge controllers and how it is important to go through a daily absorb cycle of 1-3 hours and then return to float so as not to use excessive amounts of water, I likely would have been grateful for that information. I think there are plenty of people reading this board who are in the same boat I was in years ago and can benefit from this lesson.

I think maybe you and Samoa are on the same team, and maybe just don't realize it, perhaps because of past grievances or something. I see your agenda as leading people away from the BS that they can get an earful of in investigating RE solutions. In this particular post, I think Samoa is doing the same thing.

I'm not saying that this nifty simple controller that ghurd has cooked up is not a useful device, or that it does not have an appropriate place in somebody's RE system. Maybe I'm just one of those rich guys who has ten grand into his system and wants his batteries to last fifteen years. I want the best available, affordable technology to achieve that aim.  Others might have different goals. A $100 charge controller on a $2000 battery bank is a good investment in my book. If I had a $20 battety bank, maybe my perspective would change.

And here I am, without even a single wind turbine in the air, talking about what I theoretically believe is the best charging profile for batteries. Guilty as charged for being a talker and not a doer, and I mean that seriously, as I think we see eye-to-eye on that subject.

 

[Bruce S]

SomaPower;

  Okay, I was just going let this go, but while you and Tom are having this on going spat.

I DID ask questions and it may be possible that you missed them, while name calling.

I am no drone, I am not rich and I certainly don't like seeing batteries burnt up or exploded. NOR did I attack your comments, I was actually trying to pull the whole discussion back on track, but didn't get answer.

Why?

I believe your statement about manual control to be partially incorrect with respect to those who cannot keep a continuous eye on the batteries , and would like for you to prove me wrong.

I have seen what incorrect charging will do to even NiCds, hence the picture I put up years past that shows why thermal sensing IS important. I also see daily what UPS's do to batteries when they aren't cared for correctly.

It is true, I put it out there for everyone to read, that I got the chance to HELP Ghurd work with this design. BUT I'm not a drone. Name calling is childish, Let's all get past that.

 I have formal education and I have practical hands-on. I can paste up in my diaries all the A+s,EEs, BMs, certificates and awards that I have from years past, but they aren't worth more than the paper they're printed on with regards to hands-on abilities and to use them towards helping others.

Since I have the technical knowledge to follow a real discussion on this, explain in further detail why you believe that manual beats a device that can be set to keep batteries from boiling ( Acid based batts) of exploding ( dry Chemical based batts).

Thoughts?

Bruce S

FWIW: I am both a doer and talker, but I especially like to be a planner & assister

[SamoaPower]

Bruce,

I must apologise for getting side-tracked by all the nonsense going on in this post and will try to answer your questions.

"What you're possibly trying to say is that if a person has a good expensive system then make the jump to an industry built controller that will ensure long life to those batteries. And make sure that the system can be used to keep the windmill from being destroyed by high winds and all the while keeping the batteries from smoking."

I don't see my contention only applying to expensive systems. No matter the size of the system or the source of components, it would seem that maximizing battery life is a worthwhile goal. Keeping the batteries from smoking is only half the battle. Just as significant or perhaps more so, is the need to prevent chronic undercharge.

"The amount of information that people learn from doing it themselves is enormous. Right or wrong."

Of course. However, I don't believe that if that effort is directed to a device that won't do the job, that it is time well spent.

"Not all of those units are set to dump the charges ( but when used as a diversion dump) are set at 14.4Vdc. It never would've entered my mind to set them at anything other than a full charge. The systems I help with, are surely way different than most.  I help build system with cast-off stuff Like Sub-C NiCd batteries, hundreds of them and they are all carefully set to maintain the voltage max of the batteries not a sub-charge."

My comments were directed to use of lead acid batteries, sealed or flooded. Other battery chemistry require a different approach. Perhaps I should have qualified that point, but I don't think other types are in wide use.

If one was to set a voltage-limited charger to 14.4V for lead acid (particularly sealed types), and the charge source has sufficient capacity, and the system is left unattended, overcharge (perhaps severe) is guarranteed.

"...dump controller shouldn't  be used to control the speed of the WT, that should be part of the design of the WT not the down stream electronics that take care of the batteries."

Although you attribute this to me, I totally disagree. The whole purpose of dump (or diversion) control, as opposed to series control, is to provide a continuous load to the WT to minimize overspeed due to running unloaded. The simple bang-bang dump controller does this adequately. Unfortunately, it doesn't charge batteries very well. Other schemes (furling, etc) are directed more to output power limiting.

Re: Manual control.

I qualified my statement by saying, "if one is willing to pay attention". Obviously, this doesn't apply to an unattended system. My point is that a human controller CAN do a better job of charging batteries than a bang-bang type.

[TomW]

Bruce;

Not sure if you wanted me to respond here but I have used a human powered control scheme for a long time so I am going to respond.

I think a person can make decisions no logic circuit or device can even come close to. Stuff like knowing that today I will vacuum the floors so I can let the batteries fill up a bit more. I can also predict future needs on the fly and that is important. I guess I work cheap. I am here so I just manipulate things in a comfortable range and I am not certain you could program that logic into a device of reasonable complexity. Nor am I certain I am doing it in an optimal manner.

I also tend to believe that folks can get hung up in a cycle of over thinking things and never just get around to doing them. I read a few hundred pages of information on lead acid batteries going back to the beginning of the technology. I think I have filtered it down to a few basics that I doubt I can relay to another person. That allows me to make decisions and predictions no simple device can.

It is obviously not for everyone. No solution would be. I also think of this as more hobby than power production so the decisions I made on my system reflect that. My original set of T-105 are over 5 years old and they seem to be fine but I don't keep detailed records that far back and my system voltage has changed from 12 to 24 volts. I should have gone with 48 volts in hindsight. Locked in with a decent Outback inverter I will not replace just to use what I now know to be a better voltage [for me].

Bottom line, I honestly believe, is that there is no cookie cutter solution fit for every need. Google's massive array will obviously need different controls than, say someone with a VW battery maintainer and an L-16 Trojan.

Please do not mistake me for any kind of "expert", except at ticking people off, but I do hold a couple of degrees myself in the Electronics and computer fields along with a few years experience in both. The value in those pieces of paper lies mostly in the few BTU it could release if burned. Not that an education is bad. Oh, well, I digress.

Another sad fact is that there is a good bit of bad information out there on how to treat batteries WRT charging. Who do you listen to to discover the most suitable algorithm?

Far from a simple task just discovering foolproof methods and values for any given situation. Maybe everyone is grossly over thinking this whole subject? I don't think so since battery life is a very important consideration for many.

If you are using up "end of life" recyclers you got nothing to lose but some efficiency if you mess up.

If you just dropped a couple grand or so on batteries you probably want to baby them into a healthy old age.

Plus all the in between options like my mixed bank of Trojans and Telco VRLA units.

And what do you do when your sources just cannot do what the batteries "need"?

This is far from a simple set of questions that I doubt any one knows the answer to for a broad spectrum of users.

I educated myself on batteries [lead acid] so I could chose what I felt was the correct information to follow. Not everyone will do that.

Right, wrong or indifferent, thats my story and I am sticking with it.

Cheers.

TomW

[Bruce S]

SomaPower;

  Its good to see we're back on track with this discussion.

Please continue>> about the wind part.

As I see it and I will base this on an unattended system and non-lead acid batteries.

My reasoning is this, I have 100's of NiCd batteries mostly sub-c in size all measuring 1.5Ahr minimum wired together so I can power 12,36 & 48 volt systems with no less than 36Ahr the two biggest units rated at 12Vdc 300Ahr, and mostly less than 3 years old some but a few that have batteries as old a 7 years. When properly wired I can get just as much power from them as a person can get from say a SLA rated 12Vdc & 18Ahr, plus I can run them down to a level of 25% left of the full charge and they come back with perfect usefullness each time. and they weigh 1/3rd of the SLA.

My current setup is able to power a 2000watt inverter when called for.

I do have to say that NTL is the guru on making different devices from these packs.

I have PVs and am beginning to try to sneak small 'mills into a city that doesn't allow them beyond "lawn" ornaments.

I cannot put up 10 footers or anything like that , but a lot of little ones makes up for one big one.

To me a dump/diversion controller is to be used to keep control over the incoming power that has exceeded its rating or need no matter where it comes from; i.e.>. a system that has incoming voltages exceeding that the batteries can handle OR the batteries are charged and the power can be used for something else. Heating water comes to mind.

It is very possible that a full discussion over in R/O should be made to iron these things out. Possibly even a FAQ entry to keep items in their correct respects.

To all others reading this: IF for some reason I have this completely wrong explain in detail

AND if I may ask. Let's not continue with the name calling it doesn't look good for the younger ones who might be trying to read this site for help too.

I personally have pointed 1/2 my neighborhood here for their questions and it'd not be good for their parents to want ME to explain why grown people are harping at each other.

Cheers

Bruce S

[SamoaPower]

Bruce,

I'm not sure what more you want to know about the "wind part", but I'll give it a try. A WT that's spinning without an electrical load is essentially free-wheeling and will rotate at a much higher (double?) rate than when loaded. This is probably not of much consequence at low wind speeds, but as the wind picks up, it can become destructive.

Charging batteries will place a load on the WT to keep it under control but as the batteries become full, that load typically decreases and if we were to simply disconnect the batteries when full, the WT would have potential for destructive runaway. The dump controller prevents this by switching the WT output to another load (in effect) so it always remains loaded.

"To me a dump/diversion controller is to be used to keep control over the incoming power that has exceeded its rating or need no matter where it comes from; i.e.>. a system that has incoming voltages exceeding that the batteries can handle OR the batteries are charged and the power can be used for something else. Heating water comes to mind."

Yes, but not quite. The operating voltage and current while charging is primarilly determined by the batteries themselves, not the sources (PV, WT). This is because the battery impedence is typically much lower than the sources and pulls the source voltage down.

For PV, the only reason to use a dump type controller, as opposed to a series type, is to be able to use the excess energy when batteries are full, as you point out. And, that's an excellent reason.

For WTs however, it's a different story. A dump load is necessary to protect the machine. For hybrid systems (PV and WT), the dump controller is the only reasonable choice.

Notice however, I haven't said anything yet about battery charging. That's really a separate function and is my main complaint about simple bang-bang controllers. This is why I suggested a separate charge controller to go along with a simple dump controller. Without a proper charge algorithm, battery life WILL be compromised.

[snowcrow]

Samoa, I can really see your point about the WT having it's own controls! If something happens that removes the load, most likely a blow fuse or tripped breaker, the WT would run out of control!

My WT site is 3 hours away and visited only one week every month in summer and a day or so every other month in winter, a snowshoe hike! I think some sort of dead man's switch or device is in order to insure the WT doesn't wear itself out.

My thought was to add a lever to catch and hold the tail if the furling goes beyond a given point, and have solenoid for the lever's release, controlled for the ground.

Any thoughts?

Blessings, Snow Crow