Wiring In Series (pro vs con)

[ramblinrod]

PS, in this thread, other threads, and various articles I have read, the author states that Golf Car batteries last longer than Grp 24 to 31s because of plate thickness.

Everything else equal, I believe increased plate thickness contributes to longer life.

But everything is not equal in this comparison.

As shown in my prior post, everything else equal, the current within a 12 Vdc battery for a given load, is half that of a 6 Vdc battery. So the plates in a 12 Vdc battery only NEED to be half as thick, EVERYTHING ELSE BEING EQUAL.

[ka4wja]

Rod,
It appears that you are trying to bait me into joining your argument, which I will not do...


But, I'd like to offer you (and everyone here) a quick bit of info, that might help?? (Also, please forgive me if I'm misunderstanding you here)

Originally Posted by ramblinrod

PS, in this thread, other threads, and various articles I have read, the author states that Golf Car batteries last longer than Grp 24 to 31s because of plate thickness.

Everything else equal, I believe increased plate thickness contributes to longer life.

But everything is not equal in this comparison.

As shown in my prior post, everything else equal, the current within a 12 Vdc battery for a given load, is half that of a 6 Vdc battery. So the plates in a 12 Vdc battery only NEED to be half as thick, EVERYTHING ELSE BEING EQUAL.

The fact here (backed-up by science, not just my opinion) is that except for any differences / discrepancies in inter-cell connections (whether internal or external), and/or any variations of the health of each cell, the current thru a battery is the same for a given load, whether you use a "12-volt" battery, two "6-volt" batteries in series, or six "2-volt" cells in series....

120 watts / 10 amps drawn from a 12 volt battery is 10 amps drawn from each of its six cells....120 watts / 10 amps drawn from two 6 volt batteries in series is 10 amps drawn from each of these six cells....and 120 watts / 10 amps drawn from six 2 volt cells in series is 10 amps drawn from each of these six cells....

The load on the battery and the current drawn from it is the same, and the current drawn from each cell is the same....(again, except for any inter-cell connection differences, and/or any variations between the cells)
It matters not whether you are using one 12 volt battery, two 6 volt batteries, etc...the current is the same....

Now, if some wish to argue that....please do so without me....as I have no interest in getting involved...


But, what I find confusing is that you seem to be equating "plate thickness" with "current"???
And, stating that if you're drawing half the current thru a battery (or cell) then you need plates only half as thick???
Honestly, I'm not sure where you have come up with any of this...as this is actually contrary to the physics and chemistry of batteries...as well as contrary to the battery manufacturer's specs / marketing...
You are aware that high-current draws (like starters and bow thrusters) from batteries are best done by batteries with thin plates, not thick plates...yes???
It is long term / long time, low current draws (like Danfoss fridges, electronics, etc.) that are best done with batteries with thick plates...



But...
No worries here...
From time-to-time, we all make mistakes and end up stating something obviously wrong....heck, I've done it myself here on Cruisers Forum, so not a biggie....

I just wanted to be clear here that the "math" of current draw (and charging current going in), is not what you stated....

120 watts / 10 amps drawn from a 12 volt battery is 10 amps drawn from each of its six cells....120 watts / 10 amps drawn from two 6 volt batteries in series is 10 amps drawn from each of these six cells....and 120 watts / 10 amps drawn from six 2 volt cells in series is 10 amps drawn from each of these six cells...



I've tried to provide honest, factual info (back by science and published data)...as well as add some of my own real-world experiences....and I am not going to get involved in any on-line argument...as I continue to provide the facts...
Please be respectful of me and the facts....
If I've made an error...please let me know!! (heck, I'm not perfect! )
But, please just inform me and point to the factual error, do not try to argue a point / opinion, as I will not respond.
Thank you.


Fair winds...

John

[ramblinrod]

Originally Posted by ka4wja

Rod,
It appears that you are trying to bait me into joining your argument, which I will not do...

Nope, not trying to bait anyone, just stating facts and contradicting caca.

If you don't wish to argue there is a simple solution. Don't.

But, I'd like to offer you (and everyone here) a quick bit of info, that might help?? (Also, please forgive me if I'm misunderstanding you here)
The fact here (backed-up by science, not just my opinion) is that except for any differences / discrepancies in inter-cell connections (whether internal or external), and/or any variations of the health of each cell, the current thru a battery is the same for a given load, whether you use a "12-volt" battery, two "6-volt" batteries in series, or six "2-volt" cells in series....

120 watts / 10 amps drawn from a 12 volt battery is 10 amps drawn from each of its six cells....120 watts / 10 amps drawn from two 6 volt batteries in series is 10 amps drawn from each of these six cells....and 120 watts / 10 amps drawn from six 2 volt cells in series is 10 amps drawn from each of these six cells....

The load on the battery and the current drawn from it is the same, and the current drawn from each cell is the same....(again, except for any inter-cell connection differences, and/or any variations between the cells)
It matters not whether you are using one 12 volt battery, two 6 volt batteries, etc...the current is the same....

Now, if some wish to argue that....please do so without me....as I have no interest in getting involved...

Sure. Please note how I commonly state "everything else being equal".

So if one compares two equal scenarios:

a) 2 x 6Vdc batteries (say Golf car batteries) in a series string, weighing about 70 lbs each (140 lbs total) and having an A-hr rating of 200 A-hrs @ 12 Vdc, to...

b) 2 x 12 Vdc batteries (say Grp 27s) in a parallel bank, weighing about 70 lbs each (140 lbs total) and having an A-hr rating of 200 A-hrs @ 12Vdc

In this comparison, the volume and bulk density of the batteries are about equal.

For a 1.Kw load, each battery is delivering 0.5 kW each.

However, the 6 Vdc batteries are each passing 84 A, and the 12 Vdc batteries are passing 42 A each.

But, what I find confusing is that you seem to be equating "plate thickness" with "current"???
And, stating that if you're drawing half the current thru a battery (or cell) then you need plates only half as thick???
Honestly, I'm not sure where you have come up with any of this...as this is actually contrary to the physics and chemistry of batteries...as well as contrary to the battery manufacturer's specs / marketing...
You are aware that high-current draws (like starters and bow thrusters) from batteries are best done by batteries with thin plates, not thick plates...yes???

Again, everything else equal, the 6 Vdc battery plates need to be thicker, else the higher current will be detrimental to longevity.

It is long term / long time, low current draws (like Danfoss fridges, electronics, etc.) that are best done with batteries with thick plates...

Absolutely, and as I indicated above, absolutely no argument that for a given voltage and form factor, thicker plates are better for a deep cycle applications.

BUT, everything else equal (there's that phrase again), 6 Vdc batteries need to have thicker plates than 12 Vdc batteries just to be as good as them.

But...
No worries here...
From time-to-time, we all make mistakes and end up stating something obviously wrong....heck, I've done it myself here on Cruisers Forum, so not a biggie....

I am sorry for your error, I also have made errors, just not in this case.

I just wanted to be clear here that the "math" of current draw (and charging current going in), is not what you stated....

120 watts / 10 amps drawn from a 12 volt battery is 10 amps drawn from each of its six cells....120 watts / 10 amps drawn from two 6 volt batteries in series is 10 amps drawn from each of these six cells....and 120 watts / 10 amps drawn from six 2 volt cells in series is 10 amps drawn from each of these six cells...

Please see explanation above.

I've tried to provide honest, factual info (back by science and published data)...as well as add some of my own real-world experiences....

Same here.

and I am not going to get involved in any on-line argument...

OK? I see what you post, but aren't your actions contradicting them?

Please be respectful of me and the facts....

Likewise.

If I've made an error...please let me know!! (heck, I'm not perfect! )

Done, see above.

But, please just inform me and point to the factual error, do not try to argue a point / opinion, as I will not respond.

By very definition, pointing out an error in another's post, by presenting a conflicting position, or "alternate facts" is arguing a point.

I reserve the right to defend my position when it is challenged by another poster, and I don't care who the heck they are, or who they think they are.

Thank you.

Thank You for challenging me to defend my position, and You're Welcome to post as much or as little as you wish in response. It's a public forum.

[ka4wja]

Everyone please ignore my comments here about this ancillary discussion involving "golf carts", etc...
I was discussing boats and 12 volt systems...and I misunderstood, and thought that is what everyone else was talking about...
Oppsss..


Everyone does realize that this is rather ancillary to the original poster's (and everyone else's) query??
But...just so as we can all part as friends....please know that I did misunderstand you, Rod

Originally Posted by ramblinrod

PS, in this thread, other threads, and various articles I have read, the author states that Golf Car batteries last longer than Grp 24 to 31s because of plate thickness.

Everything else equal, I believe increased plate thickness contributes to longer life.

But everything is not equal in this comparison.

As shown in my prior post, everything else equal, the current within a 12 Vdc battery for a given load, is half that of a 6 Vdc battery. So the plates in a 12 Vdc battery only NEED to be half as thick, EVERYTHING ELSE BEING EQUAL.

1) Rod, I did misunderstand you....of course batteries in parallel share the current load...

I thought you were saying that if you used ONE 12 volt battery versus TWO 6 volt (or three 12 volt vs. six 6 volts, or four 12 volt vs. eight 6 volts, etc.), that the current would be less (half) in the cells, which of course it would not be...
(I thought I rambled on a lot....but, to be honest I didn't read the whole long earlier postings in their entirety, and just a quick read of this posting, above....

When you wrote: "the current within a 12 Vdc battery for a given load, is half that of a 6 Vdc battery."
I made the wrong assumption that you were taking into account that you'd need two 6 volt batteries to use in a 12 volt system....not that you were comparing current in a 12 volt system to that in a 6 volt system (doing the same work / same load)....
I now realize that you were still rambling about Golf Carts and 6 volt systems...
And, I was talking about boats and 12 volt systems....
(I probably should have just ignored all of this ancillary discussion...

So, no worries there....
We were talking about two different things...



2) But, sir, where you are misunderstanding is that the plates do NOT need to be thicker or " else the higher current will be detrimental to longevity"....that is contrary to battery physics / chemistry, as well as contrary to all manufactures data..

Originally Posted by ramblinrod

Again, everything else equal, the 6 Vdc battery plates need to be thicker, else the higher current will be detrimental to longevity.

(I understand that when handling high currents, "thicker" wire is needed to handle the currents without high resistance / heat / voltage drop, etc...but this is not what is happening inside as battery...and here, Rod is where you have gone completely off track)

It is certainly understandable that this misconception abounds, but doesn't change the fact that it is wrong...sorry about that...

"Thicker plates" in our boat batteries are not there to handle higher currents, they are there to give longer life-cycles, and provide what we all call "deep cycling"....

Now, I know that "big", "heavy" batteries, with "thick" plates, conjure up the common sense reason that there must be high current flowing there..
And, while in some applications (electric fork lifts, industrial floor scrubbers, etc.) there are quite high currents involved...but that is not why the batteries have thick plates....
And, certainly in our applications that's not a criteria at all...
(have you even looked at the spec'd 3500+ life cycles of some Rolls batteries with 0.260" thick positive plates....versus the 1500 life-cycles of Rolls batteries with 0.160" thick positive plates, etc...as well as the 10 year and 7 year warranties??)
The fact is that "real deep cycle" battery's thick positive plates (and their lead-antimony chemistry) are not thick so that they can "handle the high current", but rather so they can provide many more life-cycles...

I'm sorry if this fact is not to your liking....and I will not be responding further here...(I'm actually unsubscribing from this thread now, as I find the original poster has disappeared and there is nothing left for me to assist with...)




Fair winds...

John

[a64pilot]

I brought up golf carts, because there are tens of thousands of electric golf carts produced yearly, They are not a small manufacturing concern at all, and their use of a battery bank closely mimics our boating use, boats being a tiny fraction of battery consumption compared to golf carts.
Golf carts would use the most economically viable battery available consistent with long life period, and that is the abundant golf cart 6V battery.
For an idea of production volume
https://www.golfcartsforsale.com/blo...er-golf-carts/

[TeddyDiver]

Or forklifts with n x 2Vdc battery packs...

[ramblinrod]

Originally Posted by a64pilot

I brought up golf carts, because there are tens of thousands of electric golf carts produced yearly, They are not a small manufacturing concern at all, and their use of a battery bank closely mimics our boating use, boats being a tiny fraction of battery consumption compared to golf carts.
Golf carts would use the most economically viable battery available consistent with long life period, and that is the abundant golf cart 6V battery.
For an idea of production volume
https://www.golfcartsforsale.com/blo...er-golf-carts/

Golf cars absolutely pale in comparison to the number of boats built per year. Boats have standardized on 12 Vdc. Boats absolutely pale in comparison to RVs. Rvs standardized on 12 Vdc. Rvs absolutely pale in comparison to construction and farm machinery. Farm machinery standardized on 12 Vdc. Farm machinery absolutely pales in comparison to the automobile industry. The automobile industry standardized on 12 Vdc.

[ranger58sb]

Originally Posted by ramblinrod

Golf cars absolutely pale in comparison to the number of boats built per year. Boats have standardized on 12 Vdc. Boats absolutely pale in comparison to RVs. Rvs standardized on 12 Vdc. Rvs absolutely pale in comparison to construction and farm machinery. Farm machinery standardized on 12 Vdc. Farm machinery absolutely pales in comparison to the automobile industry. The automobile industry standardized on 12 Vdc.

What's the point, there?

Most of those are focused on starting applications, with a few systems usually only in use when the engine is running.

Golf carts and forklifts... and Duffy and Elco boats... and Teslas, I guess... differ in that the traction batteries are used to drive the vehicle, not just starting an engine and powering the clock and stereo. I don't think any ??? of those are using 12V systems...

??

-Chris

[john61ct]

Yes, any such discussion should isolate out any starter or "dual use" cases, focus on true deep cycle.

With propulsion the bigger/faster the vehicle, the more likely at 48+V right up into the hundreds, but built from many combinations of lower voltages.

DIY EV cars forums are a good resource.

In looking at the Rolls catalog in detail, for those willing to pay for the best they do have lots of 12V true cycle units.

I made a presales technical enquiry with the above specs and they came back with a recommendation for a 6V based foundation, single paralleled. They agreed lower is better for cooling than 12V but said 2V was overkill for such a small (~1500AH) bank.

The 6V cells were 120kg though.

[ramblinrod]

Originally Posted by a64pilot

I brought up golf carts, because there are tens of thousands of electric golf carts produced yearly, They are not a small manufacturing concern at all, and their use of a battery bank closely mimics our boating use, boats being a tiny fraction of battery consumption compared to golf carts.
Golf carts would use the most economically viable battery available consistent with long life period, and that is the abundant golf cart 6V battery.
For an idea of production volume
https://www.golfcartsforsale.com/blo...er-golf-carts/

When golf cars were first developed, 1950's, it was a fledgling industry. That is why the original designs would be based on 6 Vdc batteries.

For the first 20 years, the industry grew very slowly. When most other industries using FLA batteries switched and standardized on 12 Vdc, the golf car industry did not. Why? Some claim it is because 6 Vdc batteries are better. Others claim it is because the industry was too small at the time to change over the designs. Really, the golf car industry grew modestly until around 2000, at which time it really took off. Perhaps the reason for using 12 Vdc batteries is just because that is the way it started out, and nobody has seen a cost / benefit reason to change (which to change designs is very expensive for a larger manufacturer).

[ramblinrod]

Originally Posted by TeddyDiver

Or forklifts with n x 2Vdc battery packs...

Lots of tow motors, fork lifts, lift trucks (whatever one wishes to call them) use 12 Vdc batteries.

[ramblinrod]

Originally Posted by ka4wja

I was discussing boats and 12 volt systems...and I misunderstood, and thought that is what everyone else was talking about...
Oppsss..

No, I think you are still misunderstanding. The original post was questioning pros and cons of having marine house banks wired in series. The majority of the thread has been about this. That some propose using 6 Vdc batteries (commonly called golf car batteries) does not make it a golf car thread.

Everyone does realize that this is rather ancillary to the original poster's (and everyone else's) query??

Actually, no, it is quite directly related.

But...just so as we can all part as friends....please know that I did misunderstand you, Rod

Is this veiled apology? Based on your other posts, claiming to be taking the high road, but actually posting innuendo filled comments, I suspect it is.

1) Rod, I did misunderstand you....of course batteries in parallel share the current load...

Apology accepted.

I thought you were saying that if you used ONE 12 volt battery versus TWO 6 volt (or three 12 volt vs. six 6 volts, or four 12 volt vs. eight 6 volts, etc.), that the current would be less (half) in the cells, which of course it would not be...

No, the comparison was intended to be 2 x 12 Vdc batteries in parallel, compared to 2 x 6 Vdc batteries in series, everything else being equal.

(I thought I rambled on a lot....but, to be honest I didn't read the whole long earlier postings in their entirety, and just a quick read of this posting, above....

When you wrote: "the current within a 12 Vdc battery for a given load, is half that of a 6 Vdc battery."
I made the wrong assumption that you were taking into account that you'd need two 6 volt batteries to use in a 12 volt system....not that you were comparing current in a 12 volt system to that in a 6 volt system (doing the same work / same load)....

I now realize that you were still rambling about Golf Carts and 6 volt systems...

Nope, you still have it wrong, my comments are directly related to house banks on vessels.

And, I was talking about boats and 12 volt systems....
(I probably should have just ignored all of this ancillary discussion...

Me too.

So, no worries there....
We were talking about two different things...

Nope, still wrong.


2) But, sir, where you are misunderstanding is that the plates do NOT need to be thicker or " else the higher current will be detrimental to longevity"....that is contrary to battery physics / chemistry, as well as contrary to all manufactures data..

Incorrect. It is true that thin plates can produce and accept high amounts of current, FOR A VERY SHORT TIME. Run those current levels, either loading or charging for a long time, and it is very hard on the battery. Plate stress is directly proportional to the current passed. So again, everything else being equal, for the same amount of power for a 12 Vdc battery, or a 6 Vdc battery, the latter has to have thicker plates, to be able to handle the stress equally well.

(I understand that when handling high currents, "thicker" wire is needed to handle the currents without high resistance / heat / voltage drop, etc...but this is not what is happening inside as battery...and here, Rod is where you have gone completely off track)

It is certainly understandable that this misconception abounds, but doesn't change the fact that it is wrong...sorry about that...

Incorrect, see above.

"Thicker plates" in our boat batteries are not there to handle higher currents, they are there to give longer life-cycles, and provide what we all call "deep cycling"....

So YOU say. And I agree, everything else equal, thicker plates give longer life cycles. 6 Vdc batteries and 12 Vdc batteries are not equal. When you reduce the voltage, to perform the same amount of work (power in Watts) the plates in a 6 Vdc battery have to be proportionally larger to handle the stress EQUALLY as well as a 12 Vdc battery.

I'm sorry if this fact is not to your liking....and I will not be responding further here...(I'm actually unsubscribing from this thread now, as I find the original poster has disappeared and there is nothing left for me to assist with...)

It is not a matter of liking or disliking facts. It is a matter of correctness.

While anyone can state various facts, how they are related and applied to the subject that is the real issue.

[TeddyDiver]

Originally Posted by ramblinrod

Lots of tow motors, fork lifts, lift trucks (whatever one wishes to call them) use 12 Vdc batteries.

Only the small ones intended for occasional use. Dunno about tow motors, unknown to me. Been working with heavy industrial ones mostly.
You are writing too much to respond to all your mistakes..

BR Teddy

[john61ct]

Originally Posted by ramblinrod

.No, the comparison was intended to be 2 x 12 Vdc batteries in parallel, compared to 2 x 6 Vdc batteries in series, everything else being equal.

But as you say, redundancy can have value.

So to me, isolating the question at issue would mean a 12V system, equal total AHs, but comprising:

2x 12V (2P)

vs

4x 6V (2S2P)

and/or 12x 2V (6S2P) for very high AH banks


I will admit, for all my experience at the cheaper end of the true deep cycle market, I was not aware of just how many 12V units are available from high-end vendors. If it pleases you, I will apologize for my ignorance on that issue.

However I believe relatively few of these 12V are sold compared to 6V units - with the high-end true deep cycle qualifier.

Most boaters are deceived into thinking you can buy deep cycle batteries in 12V and automotive start form factors from big box retail and auto parts suppliers, and end up with only "dual use" pseudo DC, sometimes at a higher cost per AH than a true DC would have cost them.

And I still think at the low end of the true DC market, the 6V GC2s are better value for longevity.

[sparrowhawk1]

It's not a matter of "capacity to operate your largest loads", a small battery bank will operate a high load bow thrust or windlass just as well as a large battery bank. Only not for nearly as long.

It's a matter of "how long you can operate your average loads" given the battery bank's Amp hour availability.[/QUOTE] from StuM




I always thought there was a certain percentage of amps( or call it ratio) you could draw for a given amp hour battery . For example I have a 400 amp hour battery Bank and my induction Hot Plate uses 80 amps. I only use it for short periods of time on high so I'm not talking about deep discharges. But I do wonder if I'm putting excessive wear on my bank especially since it's not really necessary. I'm just using extra electricity from my solar and wind. Thank you