Wiring In Series (pro vs con)

[sstuller]

I have had a batttery fail in my RV that was on the tongue of the trailer. Apparently it was a shorted cell and the charger kept charging because the voltage never got high enough to turn it off. The battery was in a black battery box in the Florida sun and got hotter and hotter. It's amazing how much heat that lead can absorb. Once I realized what was happening and disconnected it, the battery took three days to cool off. I have since painted the battery box white. Why on earth do they make them black? Thanks.

[john61ct]

Originally Posted by ramblinrod

Ummmmm, careful.

According to East Penn (one of the largest manufacturers of FLA batteries in the USA), their Grp 27 "start" is a different design than their Grp 27 "dual purpose", is a different design than their Grp 27 "deep cycle".

Trojans (one of the better GC2s) may last longer than cheap Grp 27s, but they are more expensive too. On a cost / a-hr (real life) cycled analysis, I don't know if they actually represent better value for money.

Will a bank of cheap GC2 last any longer than a bank of cheap Grp27 "Deep Cycles", everything else equal? The jury is still out on that one.

No, if you look at the vendor's own "lifetime cycles vs DoD charts" the 6V in series versions even within the same line always have significantly longer lifetimes.

Yes a Deka/East Penn **branded** I would trust their deep cycle label.

By far the best value for money for people with normal charging and monitoring gear is the Duracell branded (mfg East Penn) GC2s sold by Batteries+ and Sam's Club.

The Cosco equivalent are Johnson Control mfg, not quite as robust.

I don't recommend spending more per AH unless required by special circumstances, until the user is certain their setup will ensure the extra longevity they're paying for.

[ramblinrod]

Originally Posted by john61ct

No, if you look at the vendor's own "lifetime cycles vs DoD charts" the 6V in series versions even within the same line always have significantly longer lifetimes.

Yes a Deka/East Penn **branded** I would trust their deep cycle label.

By far the best value for money for people with normal charging and monitoring gear is the Duracell branded (mfg East Penn) GC2s sold by Batteries+ and Sam's Club.

The Cosco equivalent are Johnson Control mfg, not quite as robust.

I don't recommend spending more per AH unless required by special circumstances, until the user is certain their setup will ensure the extra longevity they're paying for.

Mmmm, I'm a little more careful to separate fact from fiction.

While the difference in specified lab cycles between a Trojan T105 and their
12 Vdc models is significant, for other manufacturers, not so much.

What we do know is that lab cycles have little bearing on real life.

Is there a direct correlation between lab cycles and real cycles? I think this is a conclusion that many are jumping to, with little or no validation.

I haven't seen any evidence of it, with the exception that everything else
equal, a Rolls Grp 27 tends to last a lot longer than a cheap Grp 27, and a Trojan T105 tends to last slightly longer than a cheap GC2, and a cheap GC2 doesn't
appear to last any longer than a cheap Grp27.

So despite popular belief that GC2s in general are the end all and be all over Grp27s in general, I for one, am not convinced.

Just because it's on he internet, even in a Compass Marine article (which I trust more than some sources) doesn't make it true.

[Zil]

I use Duracell labeled, Deka/EastPenn golf cart batteries. Best bang for my buck. The secret is to have enough 20hr amp capacity to operate your largest loads, considering Peukert's law in your calculations. Then have the charging available to replace what is used.
I'm in favor of smaller batteries in series. Using proper sized cables and lugs will be as good or better than internal connections.

[Maine Sail]

Originally Posted by ramblinrod

Mmmm, I'm a little more careful to separate fact from fiction.

While the difference in specified lab cycles between a Trojan T105 and their
12 Vdc models is significant, for other manufacturers, not so much.

What we do know is that lab cycles have little bearing on real life.

Is there a direct correlation between lab cycles and real cycles? I think this is a conclusion that many are jumping to, with little or no validation.

I haven't seen any evidence of it, with the exception that everything else
equal, a Rolls Grp 27 tends to last a lot longer than a cheap Grp 27, and a Trojan T105 tends to last slightly longer than a cheap GC2, and a cheap GC2 doesn't
appear to last any longer than a cheap Grp27.

So despite popular belief that GC2s in general are the end all and be all over Grp27s in general, I for one, am not convinced.

Just because it's on he internet, even in a Compass Marine article (which I trust more than some sources) doesn't make it true.

Rod,

You may want to invest in the equipment to test these batteries for actual Ah capacity. What you will find is that the GC2 / GC12's & up hold up quite a bit better than their automotive-cased siblings, even in PSOC use and yes even the cheaper 210Ah to 215Ah "condo cart" GC2's still hold up better. The lab data within a brand is a starting point for comparisons sake within a brand.

My battery article stemmed from actual physical testing of used real world use batteries over the last 17-18 years. In the beginning my test equipment was crude but worked. Testing was tedious to say the least. Today it includes temp controlled water baths, two testing stations and lab grade equipment for repeatability and accuracy. With the pres of a few buttons I am underway.

I can't even begin to count the number of 20 hour tests I have performed over the years but it is a lot. There are two 20 hour tests being performed right now as I type this.

If you want to believe G-24, 27's and 31's can hold up as well as GC2's or GC12's or larger by all means go for it. In some cases it's all that will fit so you choose a premium product such as a Rolls, Trojan, Crown or move to a GEL or AGM. In some cases I just use the cheap Deka G-24, 27's or 31's because the owner does not mind the cost of replacement every few years and does not have the physical height to fit a golf or industrial battery..

If I have the height the customer will always get a battery that meets their budget and can deliver the longest cycle life based on what I have physically seen over 17+ years of testing used and new batteries. That G-24, 27 & 31 compare with golf car batteries and up is not at all what I see when I physically test batteries for actual SOH/capacity. East Penn, Crown & Trojan are all on the same page with this on the published lab data.

I actually started a PSOC test last year for one of the publications yet I could not get any of the G-27 or 31 flooded batteries to deliver their rating so that I could even begin the test. As you can imagine the hours it takes to even begin this testing is huge. The hit I take when my test machines are off line for this work is also frustrating. To then have products with stated capacities that can't even deliver, makes it really, really, really frustrating. The Crown GC12 I was using delivered full rated capacity in about 17 cycles.

[StuM]

Originally Posted by Zil

I use Duracell labeled, Deka/EastPenn golf cart batteries. Best bang for my buck. The secret is to have enough 20hr amp capacity to operate your largest loads, considering Peukert's law in your calculations. Then have the charging available to replace what is used.
I'm in favor of smaller batteries in series. Using proper sized cables and lugs will be as good or better than internal connections.

More misunderstanding and incorrect units which are likely to lead to confusion?

A battery's 20 hr rating is Amp hour capacity, not Amp capacity.

Other than CCA/HCA, which is irrelevant to typical boat house loads, there is no such thing as "Amp capacity" of a battery.

The concept of "Amp capacity" and "largest loads" only comes into play when considering wiring size or use of an inverter.

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.

[john61ct]

I believe all the above is in reference to FLA.

With regard to just the "12V vs 6V" distinction, does the same general rule follow with AGM true deep cycle, brands like Northstar, Lifeline & Odyssey?

[ramblinrod]

Originally Posted by Maine Sail

Rod,

You may want to invest in the equipment to test these batteries for actual Ah capacity. What you will find is that the GC2 / GC12's & up hold up quite a bit better than their automotive-cased siblings, even in PSOC use and yes even the cheaper 210Ah to 215Ah "condo cart" GC2's still hold up better. The lab data within a brand is a starting point for comparisons sake within a brand.

My battery article stemmed from actual physical testing of used real world use batteries over the last 17-18 years. In the beginning my test equipment was crude but worked. Testing was tedious to say the least. Today it includes temp controlled water baths, two testing stations and lab grade equipment for repeatability and accuracy. With the pres of a few buttons I am underway.

I can't even begin to count the number of 20 hour tests I have performed over the years but it is a lot. There are two 20 hour tests being performed right now as I type this.

If you want to believe G-24, 27's and 31's can hold up as well as GC2's or GC12's or larger by all means go for it. In some cases it's all that will fit so you choose a premium product such as a Rolls, Trojan, Crown or move to a GEL or AGM. In some cases I just use the cheap Deka G-24, 27's or 31's because the owner does not mind the cost of replacement every few years and does not have the physical height to fit a golf or industrial battery..

If I have the height the customer will always get a battery that meets their budget and can deliver the longest cycle life based on what I have physically seen over 17+ years of testing used and new batteries. That G-24, 27 & 31 compare with golf car batteries and up is not at all what I see when I physically test batteries for actual SOH/capacity. East Penn, Crown & Trojan are all on the same page with this on the published lab data.

I actually started a PSOC test last year for one of the publications yet I could not get any of the G-27 or 31 flooded batteries to deliver their rating so that I could even begin the test. As you can imagine the hours it takes to even begin this testing is huge. The hit I take when my test machines are off line for this work is also frustrating. To then have products with stated capacities that can't even deliver, makes it really, really, really frustrating. The Crown GC12 I was using delivered full rated capacity in about 17 cycles.

Hi Rod, I understand that you have done testing and conducted personal observations on which you have drawn these conclusions. I have not conducted similar testing, but based on observations over many years, I have drawn different conclusions. I have seen T105s fail in as little as 2 years, and have never seen GC2s last longer than I would have expected a similar sized bank of Grp 27 DCs to last.

I learned a long time ago, not to accept opinion at face value. I worked for many, many years in electrical, electronic, and electro-mechanical engineering new product development and learned the value of proper scientific experimentation.

Whenever I heard a supposed subject matter expert declare "I think...." it raised immediate red flags. How many times were SMEs proven wrong by scientific evaluation? Countless. This is why I now only trust my own opinion, based on my own experience, testing, and observations, unless I can adequately review testing methodologies, data, and conclusions drawn by others.

I will be the first to admit that my opinion that GC2s are no better than Grp 27 DCs in general, may be wrong. However, other than various opinions that I believe in at least some cases are flawed by bias and pre-disposition, I have no valid data to prove those conclusions accurate, so I don't accept them at face value. I just consider them to be another data point of questionable validity.

[john61ct]

Heresy. IMO your loss, a very inefficient path to electrical enlightenment, but of course up to you.

[ramblinrod]

Originally Posted by john61ct

Heresy. IMO your loss, a very inefficient path to electrical enlightenment, but of course up to you.

Currently, some have theorized that "golf car" batteries last longer than 12 Vdc DC batteries in marine house bank application conditions.

"Is this true?"

DOD (Depth of Discharge), frequency of discharge, duration at PSOC (Partial State of Charge), and proper watering maintenance, have a huge impact, which is confirmed by my personal and professional experience, and every single manufacturer.

6 Vdc batteries vs 12 Vdc batteries, everything else equal, very little if any difference.

In other words, on a given boat, if one changes a 230 A-hr 12Vdc DC FLA bank to a 230 A-hr 6 Vdc bank, I wouldn't expect the latter to last any longer, if they are used and abused identically to the previous bank.

What will happen for sure, without question, is if one of those 6Vdc batteries shorts, they now have lost the entire bank until repairs are made, whereas with 12 Vdc batteries, they can simply disconnect the defective battery, and use the remaining battery until repairs are made.

[TeddyDiver]

Originally Posted by ramblinrod

In other words, on a given boat, if one changes a 230 A-hr 12Vdc DC FLA bank to a 230 A-hr 6 Vdc bank, I wouldn't expect the latter to last any longer, if they are used and abused identically to the previous bank.

What will happen for sure, without question, is if one of those 6Vdc batteries shorts, they now have lost the entire bank until repairs are made, whereas with 12 Vdc batteries, they can simply disconnect the defective battery, and use the remaining battery until repairs are made.

Real battery banks are 2v batteries in series.. Just saying

[ramblinrod]

Originally Posted by TeddyDiver

Real battery banks are 2v batteries in series.. Just saying

As discussed earlier in the thread, a 12 Vdc house bank consisting of
6 x 2Vdc cells is not a great configuration because if one cell shorts the whole bank is kaput until the cell can be replaced, which may take quite some time depending on where one is. At that point ya woulda been better off with a pair
of Grp 24 deep cycles. ;-)

[john61ct]

Originally Posted by ramblinrod

Currently, some have theorized that "golf car" batteries last longer than 12 Vdc DC batteries in marine house bank application conditions.

"Is this true?"

DOD (Depth of Discharge), frequency of discharge, duration at PSOC (Partial State of Charge), and proper watering maintenance, have a huge impact, which is confirmed by my personal and professional experience, and every single manufacturer.

6 Vdc batteries vs 12 Vdc batteries, everything else equal, very little if any difference.

In other words, on a given boat, if one changes a 230 A-hr 12Vdc DC FLA bank to a 230 A-hr 6 Vdc bank, I wouldn't expect the latter to last any longer, if they are used and abused identically to the previous bank.

Sorry I have already clearly stated that I disagree, and accumulated a lot of evidence and clear statements from **many sources I respect** to the contrary.

Since you choose to ignore these and insist on collecting your own experience, supposedly before coming to a conclusion, I suggest you do just that if you have the time and equipment, and perhaps refrain in the meantime.

I'm not arguing the point further with you.

Originally Posted by ramblinrod

What will happen for sure, without question, is if one of those 6Vdc batteries shorts, they now have lost the entire bank until repairs are made, whereas with 12 Vdc batteries, they can simply disconnect the defective battery, and use the remaining battery until repairs are made.

Same with 6V configured as 2S2P, 2S3P, or with 2V, 3V, 4 V cells, nothing special about 12V there, they are just 6S 2V packaged in a case.

[ramblinrod]

Originally Posted by john61ct

Sorry I have already clearly stated that I disagree, and accumulated a lot of evidence and clear statements from **many sources I respect** to the contrary.

You have every right to disagree.

Since you choose to ignore these and insist on collecting your own experience, supposedly before coming to a conclusion, I suggest you do just that if you have the time and equipment...

I have not ignored your posts.

I responded directly to them.

I disagree with your conclusions though.

Same with 6V configured as 2S2P, 2S3P, or with 2V, 3V, 4 V cells, nothing special about 12V there, they are just 6S 2V packaged in a case.

Per my prior post in this thread, my opinion is that a single series string of batteries to produce 12 Vdc is poor design as it provides no redundancy, should any cell in that string fail.

e.g. 1

2 x 6 Vdc battery house bank. ~ 230 A-hrs at 12 Vdc.

Remaining capacity when failed cell is isolated. 0 A-hrs at 12 Vdc.

e.g. 2

2 x 12 Vdc Grp 24 DC house bank. ~ 170 A-hrs at 12 Vdc.

Remaining capacity when failed cell is isolated. ~ 85 A-hrs at 12 Vdc.

e.g. 3

2 x 12 Vdc grp 27 DC house bank. ~ 200 A-hrs at 12 Vdc.

Remaining capacity when failed cell is isolated. ~ 100 A-hrs at 12 Vdc.

e.g. 4

2 x 12 Vdc Grp 31 DC house bank. ~ 230 A-hrs at 12 Vdc.

Remaining capacity when failed cell is isolated. ~ 115 A-hrs at 12 Vdc.

In the case of configurations of less than 12 Vdc batteries connected in series, when one cell fails, more capacity is lost until a replacement is obtained, as the other cells in that series string to make 12Vdc must also be isolated.

[TeddyDiver]

Originally Posted by ramblinrod

As discussed earlier in the thread, a 12 Vdc house bank consisting of
6 x 2Vdc cells is not a great configuration because if one cell shorts the whole bank is kaput until the cell can be replaced, which may take quite some time depending on where one is. At that point ya woulda been better off with a pair
of Grp 24 deep cycles. ;-)

I didn't say 6 x 2Vdc. The principle of using 12vdc batteries has limited your options. Using 2v batteries, programmable loading devices and voltage regulators having 7 or 8 (or anything.. ) 2v batteries in series has redundancy enough.

Any parallel connected battery bank is far more vulnerable compared to pure series bank (even 6x2vdc) and includes the risk of destroying the whole bank in case of one shorted cell. In that case there's 0v 0Ah instead of something else. The risk of reduced battery bank life is also present if some of the batteries has any problems (poor connection, internal resistance differs, waterlevel...) you name it, anything that can be wrong with a battery affects to all other parallelly connected batteries..

BR Teddy