connecting batteries in parallel or series, myth and theory

In alt.engineering.electrical snipped-for-privacy@citlink.net wrote:
|>So, a basic rule for GC batteries is, if you put them in any system that
|>doesn't have at least 5 days of autonomy, then you are going to kill them. | | Baloney. Batteries can be well-maintained and last the maximum with | zero days autonomy. It's done all the time with grid-connected setups | that only have storage enough to last through short outages.
What about off-grid setups?
|>That is because the charging , and discharging rates are going to kill them. |>As for as GC batteries go, it's mainly the charging rates that get them. | | Nonsense. The #1 cause of premature failure of home-power batteries is | chronic undercharging.
Sounds like a design problem.
|>If you keep the charge/discharge rate in line with design specs then they |>will last for decades. | | No. Batteries have a finite life-rating usually stated as a number of | cycles at a particular discharge level.
Which is only a simplistic view of the usage patterns of batteries.
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 14 Aug 2008 17:01:28 GMT, snipped-for-privacy@ipal.net wrote:

Same difference. Whether it's 1 day or 10, ignore the need to get batteries fully charged regularly and it won't matter whether they're 5 or 20 year batteries, whether they're wired in series or parallel, charged fast or slow, etc.

It can be, but it's more often just life. For example, a setup can be well designed for say, 2 hours use of TV per day. But if the user buys a larger model and/or watches it longer then he's likely to have a problem. The key IMO is a proper battery monitor. That provides the user with a routine method of knowing his battery's true SOC, which gives him a chance to adjust habits or hardware if needed. DJ, a solar dealer who used to post here, once wrote that he wouldn't sell a setup anymore unless it included a battery monitor. Either the customer would pay for it or he'd include it free if necessary. I'll add that I'd question the business sense of any dealer who installs a whole-house setup without a proper battery monitor. Besides doing the customer a disservice, he's inviting call-backs that will eat up his profit margin. In my own experience with strongly encouraging friends and acquaintances to buy and use battery monitors for their home power installations, I've yet to have anyone regret their purchase. Most rave that they should have had one from the beginning, and some blame their dealer for not including it. The necessary $50 shunts are installed in the popular Outback power panels, so many owners need add little more than the meter itself, which only costs about $150.

Batteries are rated to supply a specific number of amp-hrs. The amount will vary with the number and depth of discharge cycles, and can certainly be less than spec if subjected to poor maintenance or bad habits. But it can't be more unless you've discovered something that's escaped everyone else.
Of course, that's the prevailing wisdom, and this being Usenet, there are certainly alternative theeries. For example: "A lead acid battery stores a chemical reaction. Therefor every time you charge/ discharge the battery you use up some of the chemicals involved. Also the greater the depth of discharge the more chemical used = fewer cycles. When the chemical is gone the battery is dead." http://groups.google.com/group/alt.solar.photovoltaic/msg/3142a005266414bd
According to the learned discussion in that thread, the leading candidate for the depleted chemical is "orgone". So you could try adding some of that and perhaps extend your battery's life indefinitely. :-)
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Explain to me this... How do you go from sub 50% State Of Charge to 100% SOC in one solar day?
Explain how that is suppose to work in a real life system.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Why? It's *your* contention that SOC routinely goes from sub 50% to 100% in one day, which makes it *your* job to show some examples of such systems.
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

All right. You stated "Whether it's 1 day or 10(days of autonomy)".
Lets look at one day of autonomy for the winter months. 5 hours sunshine. You have 19 hours between charging periods. To have exactly 1 day autonomy would mean that you have to ride through two dark periods and one cloudy charging period. Given an average power usage spread (lights at night and other stuff in the day) that will give you about 44% capacity usage between charging periods. So each charging day, you are starting from 56% SOC. (close to my original guess)
So I will refine that question.
How do you get from 56% SOC to 100% SOC in one charging period.
If it can't happen then it does mater if the system has 1 or 10 days of autonomy.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You're quoting out of context. Read it again in full, I was referring to the need for regular complete charges.

Says you. My own charging period is 24 hours per day. Perhaps you meant your hypothetical to be limited to fixed PV without any supplemental sources.

Even using your worst tortured example, the user is likely to compare extending charging time with a supplemental source against enlarging storage 5X.

I do see what you're getting at with these hypotheticals. The thing is, they're not practical issues for anybody that I've ever heard of. I for damned sure have never heard anybody say "my charging rate is too high, I'm going to enlarge my storage to cure it", and I bet you've never heard that or anything like it either. If you really believe it's an issue, then I suggest you post some examples of where folks are asking for help with the problem.
Wayne

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Um.. Lets look at the thread and context in detail.

Context, days of autonomy in an off grid system which it had been for most of the thread.

You changed it to days of autonomy for a grid tie systems.

He redirected it back to the subject that was in keeping with the rest of post in this part of the thread. That being days of autonomy for an off grid setup.

The subject and context of any general reply will be days of autonomy for an off grid system. AKA 1 to 10 days of autonomy. You made no mention of charging for that many days.

Subject, how do you do a proper recharge with 1 day of autonomy. I probably didn't make the context clear enough (sorry)

subject autonomy, in keeping with all the previous post.

Subject autonomy, in keeping with all the previous post. Context, autonomy in an off grid system.

How?
Lets look at that idea. To me, your original statement is stating that irrelevant of 1 to 10 days of autonomy, that if you "ignore the need to get batteries fully charged regularly and it won't matter whether they're 5 or 20 year batteries, whether they're wired in series or parallel, charged fast or slow, etc." that they are going to die.
You are stating that you were meaning to say irrelevant of 1 to 10 of charging that if you don't keep them fully charged, then they will die. That isn't in keeping with the subject of the post you are replying too, you didn't make any indication that that was the context and it don't really make logical sense for the post you are replying to.

You change the subject back to grid tie systems again!!!! Which has nothing to do with the conversation!!!

What does that have to do with the conversation? I am asking you how something could be done. Because you say it doesn't mater if it is did that way or not. If someone is doing it in the real world or not is irrelevant.
The only person that seems to be having problems staying on subject is you. How can people have a logical discussion when someone keeps changing the subject every time they speak? You are most likely just trying to mess with peoples minds. I am not going to carry on this stupidity any longer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I wrote exactly what I meant, but I will concede that I'm not willing to work at writing clearly enough for you.

No, you're misinterpreting again. I'm off-grid. Surely it can't be news to you that some people have charging sources that aren't as time-limited as you're used to.

In this case, debating hypotheticals is only useful if they're at least somewhat practical. It seems that you have *the* solution in search of a specific problem that you've never actually heard of.

Good idea! A word of advice - if someone offers to sell you cheap pot, don't bite, because you won't be able to cook a damned thing in it! Oh crap, now you're going to accuse me of suggesting that people bite each other.

Good. Chill dude.
PS. No ice cubes!
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
|> Why? It's *your* contention that SOC routinely goes from sub 50% to |> 100% in one day, which makes it *your* job to show some examples of |> such systems. | | All right. You stated "Whether it's 1 day or 10(days of autonomy)". | | Lets look at one day of autonomy for the winter months. 5 hours sunshine. | You have 19 hours between charging periods. To have exactly 1 day autonomy | would mean that you have to ride through two dark periods and one cloudy | charging period. Given an average power usage spread (lights at night and | other stuff in the day) that will give you about 44% capacity usage between | charging periods. So each charging day, you are starting from 56% SOC. | (close to my original guess) | | So I will refine that question. | | How do you get from 56% SOC to 100% SOC in one charging period. | | If it can't happen then it does mater if the system has 1 or 10 days of | autonomy.
After a few days of no available solar/wind energy, I would expect the SOC of a battery bank to be lower than usual (if less than a few days of no available solar/wind energy is usual). And I would expect that when the energy becomes available, again, it can take at least a few days to get back to 100% SOC.
So is the issue a matter of how _long_ the bank sits at below 100% SOC, even if it doesn't go below 50% SOC?
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If lead sulfate sits for enough time on the plates it will crystallize. It is hard for you to convert it back to spongy lead and sulfuric acid. Most of the time it is just lost capacity. It doesn't mater if the charge level is 80% or 20%. If the battery never gets close to 100% charge, and the sulfate isn't disturbed , it will start to crystallize. You could hold a battery bank on float at 90% SOC and the 10% that is locked up in sulfate will crystallize after a while.
It you get up to 95% regularly in a cyclic application, then usually all the sulfate will get cycled to acid once In a while. The thickness in sulfate and lead build up isn't exactly even across the working surface, so at 95% SOC all the sulfate on any one surface is sometimes consumed during charging, leaving a little more on a different part of the plate. During the next charging cycle there may be plenty left on that part of the plate but spot two that had some left last time is completely sulfate free. But if you only get to 85% charge or lower on a cyclic application then there is sufficient sulfate thickness that the lowest levels of sulfate will not get disturbed long enough to allow it to crystallize. And that capacity is permanently lost.
That is why you do a EQ charge once in a while to make sure you get all the sulfate converted to acid, down to the deepest levels, to prevent it from crystallizing.
It doesn't mater if the bank is cycled down to 10% SOC, as long as it is fully recharged in time enough to prevent any deeply locked up sulfate from crystallizing.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
|> After a few days of no available solar/wind energy, I would expect the SOC |> of a battery bank to be lower than usual (if less than a few days of no |> available solar/wind energy is usual). And I would expect that when the |> energy becomes available, again, it can take at least a few days to get |> back to 100% SOC. |> |> So is the issue a matter of how _long_ the bank sits at below 100% SOC, |> even |> if it doesn't go below 50% SOC? | | If lead sulfate sits for enough time on the plates it will crystallize. It | is hard for you to convert it back to spongy lead and sulfuric acid. Most of | the time it is just lost capacity. It doesn't mater if the charge level is | 80% or 20%. If the battery never gets close to 100% charge, and the sulfate | isn't disturbed , it will start to crystallize. You could hold a battery | bank on float at 90% SOC and the 10% that is locked up in sulfate will | crystallize after a while. | | It you get up to 95% regularly in a cyclic application, then usually all the | sulfate will get cycled to acid once In a while. The thickness in sulfate | and lead build up isn't exactly even across the working surface, so at 95% | SOC all the sulfate on any one surface is sometimes consumed during | charging, leaving a little more on a different part of the plate. During the | next charging cycle there may be plenty left on that part of the plate but | spot two that had some left last time is completely sulfate free. But if you | only get to 85% charge or lower on a cyclic application then there is | sufficient sulfate thickness that the lowest levels of sulfate will not get | disturbed long enough to allow it to crystallize. And that capacity is | permanently lost. | | That is why you do a EQ charge once in a while to make sure you get all the | sulfate converted to acid, down to the deepest levels, to prevent it from | crystallizing. | | It doesn't mater if the bank is cycled down to 10% SOC, as long as it is | fully recharged in time enough to prevent any deeply locked up sulfate from | crystallizing.
This is the kind of scientific info I want to learn about.
Would a system that at least tries, and periodically could achieve (when there are enough days of sun and wind and rain), 100% charge back on the batteries, because it is sized to have enough energy source to do it, be good enough to minimize the PbSO4 crystalization? How many days below 100% begins to give you concern?
Would anything like high voltage pulses be able to break into the crystals?
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Aug 18, 11:15 am, snipped-for-privacy@ipal.net wrote:

More to the point is how low the batteries charge is for a given time period. This is part of the calculation for days of autonomy. Personally I always charge my batteries if they get to 12V. Reason, it takes less time to bring them back up to better than 90%.

Run them up to 17V.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Again, that depends:
http://thesolar.biz/Battery_charging_article.htm
Notice the chart with the traditional three stage charging table.
In a number of cases the newer more sophisticated battery chargers will sense the condition of the battery/ battery string and apply their own charging algorithm. ( It can be a matter of trading a little money for a simpler more automatic maintenance requirement.)
Luck; Ken
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:>>> Would anything like high voltage pulses be able to break into the

P.S. There have been claims for battery desulfication schemes from day one. The high voltage pulse approach is often part of such efforts. I haven't heard of where anyone I would believe, has had any luck with such gadgets. Anything that actually works is/would be incorporated into the better chargers. (Some of them are pure snake oil, IMHO.)
http://www.batteryfaq.org /
http://jgdarden.com/batteryfaq/carfaq16.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yep, just what my regulator does.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 17 Aug 2008 20:24:06 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

It was *designed* to do a proper 3-stage charge, but you "subverted" that functionality in favor of single-stage. That was a dumb idea, although not quite as senseless as holding the record for dead batteries and pretending to be knowledgeable about battery maintenance.
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Aug 18, 11:48 pm, snipped-for-privacy@citlink.net wrote:

Again you are lying. Yes I changed the parameters of my programmable regulator. It's still a three stage regulator. It just does it to different voltages.
And again, you never designed your system and again you never built your house and yet again you said that increasing the daily load was the way to to reduce line losses.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 18 Aug 2008 16:25:49 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Why would a struckcheral editar choose the word "subvert" instead of "change" when he last described his modifications?

So the float voltage is 15, and the other stages, which are normally substantially higher, are what exactly?
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Aug 19, 10:41 am, snipped-for-privacy@citlink.net wrote:

Poetic license.

Your loads, time run, watt hours are what exactly?

You see, after ten+ years you are behind the game.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 18 Aug 2008 21:20:12 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

More like a Freudian slip.

A more appropriate question would be "what are your controller settings?". 28.8 bulk and absorption, 1 hour absorption (usually lasts longer due to interruptions by loads), and 27.2 float. See how easy that is? Apparently it's harder for quacks who are embarrassed by what their tinkering reveals.

I already get the bulk of my home energy needs from sun and wind, and have been doing so since day one. After a couple decades, you're still getting about 20X less. How much longer before you catch up? In particular, when do you plan to modify your infamous deezine so that loads over a few hundred watts, such as "cloths washing", don't require hiking out to the "workshop" to start a generator? And when can we expect to hear that you've stopped burning propane for refrigeration and water heating? Or is that stuff strictly for those who are "behind the game"?
Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.