Wiring In Series (pro vs con)

[TeddyDiver]

Originally Posted by ramblinrod

No. That is not what I stated.

Yes it is. You have said it multiple times, not going to pickup quotes but your messege has been about "paralled batteries short is easy to detect becouse unknown current draw / series batteries will be boiled with charger becouse the voltage drop goes unnoticed".
You can read your own posts and feel free to correct your statements if they aren't what you really tried to say. It's just while trying to debate sometimes the consistency of our claims get's a bit blurred..

BR Teddy

[john61ct]

Bottom line for me is I'd be happy to have a big kahuna bank of 2V cells. 6V is better for smaller, more "normal" sized banks.

12V units are fine if you just need a few, and the fact that is enough for 99.99% of the mostly tiny fresh-water or shore-hugging stinkpots out there, has little to do with the needs of long-term cruisers and liveaboards.

[ramblinrod]

Originally Posted by TeddyDiver

Yes it is. You have said it multiple times, not going to pickup quotes but your messege has been about "paralled batteries short is easy to detect becouse unknown current draw / series batteries will be boiled with charger becouse the voltage drop goes unnoticed".
You can read your own posts and feel free to correct your statements if they aren't what you really tried to say. It's just while trying to debate sometimes the consistency of our claims get's a bit blurred..

BR Teddy

Again, you are wrong. That is not what I said.

In summary:

1. Banks in parallel provide inherent redundancy via battery or bank isolation, typically by the flick of a switch.

2. A series only string, does not provide inherent redundancy via battery isolation, and requires more complex measures, which may or may not be available, perhaps at the most inopportune time

3. Banks in parallel are the simplest to address when a shorted cell is detected.

4. Regardless parallel or series, if a cell shorts, and a charger is left on, bad things can happen.

5. High acceptance rate batteries, are much more dangerous in this situation than standard FLA batteries.

6. High output charging systems (to take advantage of high acceptance rate batteries) increase danger further, and require safety measures to reduce the higher risk of thermal runaway.

7. Standard FLA 12 Vdc DC batteries, configured in parallel house banks, and supplied by an appropriate sized charger (10 - 20% of total A-hr capacity), is a very safe system, that has been employed on millions of boats, and has likely crossed more oceans in recreational cruising yachts than any other house bank configuration.

8. Standard FLA 12 Vdc DC batteries with deeper reservoirs above the plates, are better suited to the marine environment (while heeling, listing, or carving a turn).

9. DC to DC converters and spare cells "floating" around, as required to address a shorted cell in a series only string, are very expensive dead weight and over complicate what can be a simple system, but are absolutely required for high acceptance rate batteries, such as those configured of 2 Vdc VRLA or Li-Ion cells.

10. All of the statements above are absolutely correct and accurately reflect my positions and statements throughout this thread.

[ramblinrod]

Originally Posted by john61ct

Bottom line for me is I'd be happy to have a big kahuna bank of 2V cells.

That's absolutely fine. Your boat, your money, your risks.

6V is better for smaller, more "normal" sized banks.

This is a matter of opinion.

I am glad you have finally declared that "normally", 6Vdc cells are better than 2Vdc cells. I absolutely concur.

In my opinion, "normally" 12 Vdc FLA DC batteries are "better" than 6 Vdc batteries, for all of the reasons stated.

I personally only start favouring 6 Vdc batteries for banks of 6 (series parallel) or greater, where the loss of one battery, does not have such a profound effect on bank capacity by requiring the isolation of 2.

I agree with a portion of your final paragraph if it was changed to, "12V units are enough for 95% of boaters, where ever they are."

[TeddyDiver]

Originally Posted by ramblinrod

Again, you are wrong. That is not what I said.

In summary:

1. Banks in parallel provide inherent redundancy via battery or bank isolation, typically by the flick of a switch.

2. A series only string, does not provide inherent redundancy via battery isolation, and requires more complex measures, which may or may not be available, perhaps at the most inopportune time

3. Banks in parallel are the simplest to address when a shorted cell is detected.

4. Regardless parallel or series, if a cell shorts, and a charger is left on, bad things can happen.

5. High acceptance rate batteries, are much more dangerous in this situation than standard FLA batteries.

6. High output charging systems (to take advantage of high acceptance rate batteries) increase danger further, and require safety measures to reduce the higher risk of thermal runaway.

7. Standard FLA 12 Vdc DC batteries, configured in parallel house banks, and supplied by an appropriate sized charger (10 - 20% of total A-hr capacity), is a very safe system, that has been employed on millions of boats, and has likely crossed more oceans in recreational cruising yachts than any other house bank configuration.

8. Standard FLA 12 Vdc DC batteries with deeper reservoirs above the plates, are better suited to the marine environment (while heeling, listing, or carving a turn).

9. DC to DC converters and spare cells "floating" around, as required to address a shorted cell in a series only string, are very expensive dead weight and over complicate what can be a simple system, but are absolutely required for high acceptance rate batteries, such as those configured of 2 Vdc VRLA or Li-Ion cells.

10. All of the statements above are absolutely correct and accurately reflect my positions and statements throughout this thread.

1. and 2. In both cases your have to identify the faulty unit before any measures. In the case of series measures can wait for a while without complications. Parallel can't.

3. When or if it is detected in time.

4. With parallel much sooner.

5 and 6. High acceptance as AGM don't have quite the same danger for internal shorts as FLA, but got to say I'm not so familiar with them so it's just IMHO. Anyone?

7. There are millions of smokers too and they live to the end of their lives..

8. True, but there should be a reservoir below the plates too.

9. Actually you need only one or another, besides with higher voltage bank as 24v it doesn't matter if you loose a cell or two. DC-DC converters cost today less than a quality battery switch.
Why would high acceptance be any different from VLA? As I said earlier I'm not familiar with them.

10. Alternate thruth..

BR Teddy

[s/v Jedi]

Originally Posted by ramblinrod

TI am glad you have finally declared that "normally", 6Vdc cells are better than 2Vdc cells. I absolutely concur.

He did not, you're trolling, not allowed on this forum BTW.

You are ignorant, 6Vdc cells don't exist, you're just rambling. And how could a 6V battery be better than 2V cells when it is made out of 2V cells?

This is true: when your capacity requirements have passed 600Ah then it is technically best to go for 6x a 2V cell of the exact required capacity. Lifeline sells them from 630 Ah to 1,200 Ah which is a very popular range for the house banks on cruising sailboats and these only cost a couple dollars more.

The only, -only- valid reasons to buy something else are:

- lack of budget
- opt for carbon foam batteries, i.e. Firefly. But soon these will be available in 4V and 2V versions as well.
- opt for LiFePO4 cells

And that's how it is. All of above reasons can be valid but 4V, 6V or 12V batteries for a 600Ah or more bank are a worse choice otherwise.

[john61ct]

Sorry for misusing terminology, you are right that lead cells are only 2V. I guess better to say "6V batteries" to make up a 12V "bank".

The "Industrial RE" line of Trojans have removable 2V cells in their 4V and 6V batteries.

A "string" is that series, parallel or either?

And what is the logic behind that 600AH boundary by the way?

[TeddyDiver]

Originally Posted by john61ct

And what is the logic behind that 600AH boundary by the way?

Size of individual batteries and to avoid too many paralled batteries.

BR Teddy

[Three Sisters]

And would the length of your boating season have any priority in the selection process. Say your area has a 6 month time frame for dockspace being available. Of those 6 months, is your boating centered around the 80-90 degree weather of July and August ? Kids in school till the end of June and start back in early September ? The Battery bank sitting unused 6 or 7 months out of the year ? There may be answers in these questions that dictate 12v in parallel, cheaper and it'll be good enough.

[ramblinrod]

RR: 1. Banks in parallel provide inherent redundancy via battery or bank isolation, typically by the flick of a switch.

2. A series only string, does not provide inherent redundancy via battery isolation, and requires more complex measures, which may or may not be available, perhaps at the most inopportune time

Originally Posted by TeddyDiver

1. and 2. In both cases your have to identify the faulty unit before any measures.

RR: Correct! Most people do not take corrective measures to address a fault, until they have detected a fault.

RR: 3. Banks in parallel are the simplest to address when a shorted cell is detected.

TD: In the case of series measures can wait for a while without complications. Parallel can't.

RR: Incorrect. If a 2 vdc cell shorts, and you do nothing, you immediately start cooking the remaining cells in the series string with the charging systems.

The cost of a cooked bank of 6 x 2Vdc cells is about $2500 (excluding labour).

RR: 3. Banks in parallel are the simplest to address when a shorted cell is detected.

TD: 3. When or if it is detected in time.

RR: Correct. So when one sees the bank voltage is dropping more rapidly than it should, and smells the excessive off-gassing of the defective battery (which may also set of a sniffer alarm) and sees the charge current is higher than it should be, the simply isolate the defective battery, problem solved.

Vastly superior to the measures that have to be taken with a series only string.

RR: 4. Regardless parallel or series, if a cell shorts, and a charger is left on, bad things can happen.

TD: 4. With parallel much sooner.

RR:Not typically.

If the vessel is unattended with a high capacity charger connected to any bank (dumb on any account), it doesn't matter, bad things are going to happen.

If the vessel is attended, it is so easy to correct a faulty battery in a parallel bank, it can be corrected faster, so damage is less likely to occur.

With a series string of high acceptance VRLA batteries, and the charger capacity that can benefit from them, bad things will happen very fast.

RR: 5. High acceptance rate batteries, are much more dangerous in this situation than standard FLA batteries.

6. High output charging systems (to take advantage of high acceptance rate batteries) increase danger further, and require safety measures to reduce the higher risk of thermal runaway.

TD: 5 and 6. High acceptance as AGM don't have quite the same danger for internal shorts as FLA, but got to say I'm not so familiar with them so it's just IMHO. Anyone?

RR: Absolutely incorrect. When a cell shorts, (especially a low impedance short) high acceptance rate VRLAs including AGM and Gel, are much more prone to thermal runaway than 12 Vdc standard FLAs. Li-ions, don't get me started....Samsung phones, Hoverboards, etc, etc, etc.

EEE (Everything Else Equal), the faster a battery can accept or discharge current, the more dangerous it is. This is why 12 Vdc standard FLAs are so inherently safe (in comparison). While any battery that stores a significant amount of energy can be dangerous, standard 12 Vdc FLAs are much less so.

Additionally, because standard FLAs have lower acceptance rates, the corresponding "right-sized" charger has a lower current output, and therefore is inherently safer in fault conditions.

RR:7. Standard FLA 12 Vdc DC batteries, configured in parallel house banks, and supplied by an appropriate sized charger (10 - 20% of total A-hr capacity), is a very safe system, that has been employed on millions of boats, and has likely crossed more oceans in recreational cruising yachts than any other house bank configuration.

TD: 7. There are millions of smokers too and they live to the end of their lives..

RR: Please.

RR: 8. Standard FLA 12 Vdc DC batteries with deeper reservoirs above the plates, are better suited to the marine environment (while heeling, listing, or carving a turn).

8. True, but there should be a reservoir below the plates too.

Thank you for acknowledging. But after the but, is merely your opinion. My opinion is, that the reservoir below the plates in a 12Vdc standard FLA is just fine. The plates do not shed as much as other batteries that really need deeper reservoirs below the plates, (so compromise the depth of reservoir above the plates). In practice, 12 Vdc batteries rarely suffer a shorted cell due to reservoir related issues, within their normal useful life. I would much prefer the manufacturers leave the reservoir above the plates, than compromise that to put more below.

RR: 9. DC to DC converters and spare cells "floating" around, as either is required to address a shorted cell in a series only string, are very expensive dead weight and over complicate what can be a simple system, but are absolutely required for high acceptance rate batteries, such as those configured of 2 Vdc VRLA or Li-Ion cells.

[QUOTE][COLOR="blue"]

TD: 9. Actually you need only one or another

RR:I'm aware. They are both expensive, but only one or the other solution is necessary to address a defective series string. My statement above would be less prone to misinterpretation, if revised as indicated in red above.

Nothing is required to isolate a parallel battery, just disconnect the terminal, (but most will have an isolation switch that will make it even faster and easier.

TD: besides with higher voltage bank as 24v it doesn't matter if you loose a cell or two.

I disagree. If the cells are shorted, the charging systems will cook the series bank, unless modifications are made.

TD: DC-DC converters cost today less than a quality battery switch.

RR: Please show me a quality programmable DC-DC converter, designed for the marine environment, with an output of say 200 A (as required to handle house loads that one would require a 900 A-hr bank for) that can be purchased for $50.

Why would high acceptance be any different from VLA? As I said earlier I'm not familiar with them.

RR:There is a flip side to the benefit of high acceptance (AGM, Gel, Li-ion, or virtually any technology other than standard FLA) for charging; you have a much more dangerous battery in the event of a fault. It's that pros and cons thing I mentioned. If you don't think you are compromising something when you purchase a battery with an acceptance rate of 40% capacity or higher, guess again. The higher the acceptance rate, the more safety is compromised and the greater the need to add in additional safety measures to prevent thermal runaway.

[ramblinrod]

Originally Posted by s/v Jedi

He did not, you're trolling, not allowed on this forum BTW..

Did you not read the quote?

You are ignorant, 6Vdc cells don't exist, you're just rambling.

Actually, wrong on all accounts.

I accidentally interchanged "cell" for "battery", once, in a thread referring to these terms incessantly, where I have demonstrated knowledge of the difference throughout.

I wasn't trolling. I am truly happy he acknowledged this.

Now your calling a poster "ignorant", that is against forum rules, so knock it off.

And how could a 6V battery be better than 2V cells when it is made out of 2V cells?

As I have stated so many times throughout this thread.

This is true: when your capacity requirements have passed 600Ah then it is technically best to go for 6x a 2V cell of the exact required capacity. Lifeline sells them from 630 Ah to 1,200 Ah which is a very popular range for the house banks on cruising sailboats and these only cost a couple dollars more.

I understand that this is your opinion. I disagree, for all reasons previously stated.

The only, -only- valid reasons to buy something else are:

- lack of budget
- opt for carbon foam batteries, i.e. Firefly. But soon these will be available in 4V and 2V versions as well.
- opt for LiFePO4 cells

And that's how it is. All of above reasons can be valid but 4V, 6V or 12V batteries for a 600Ah or more bank are a worse choice otherwise.

I understand that this is your opinion. I disagree, for all reasons previously stated.

[ramblinrod]

Originally Posted by Three Sisters

And would the length of your boating season have any priority in the selection process. Say your area has a 6 month time frame for dockspace being available. Of those 6 months, is your boating centered around the 80-90 degree weather of July and August ? Kids in school till the end of June and start back in early September ? The Battery bank sitting unused 6 or 7 months out of the year ? There may be answers in these questions that dictate 12v in parallel, cheaper and it'll be good enough.

How the boat will be used, is a very important consideration when configuring a house bank (as I stated very early on this thread).

I consult and outfit boaters who have from absolute minimum energy needs to those who are full time, year round, cruisers running a boat load of systems.

[john61ct]

I don't know of anyone using Lithium Ion chemistries that have thermal runaway problems for House banks.

LiFePO4 does not.

[ramblinrod]

Originally Posted by john61ct

I don't know of anyone using Lithium Ion chemistries that have thermal runaway problems for House banks.

LiFePO4 does not.

Here are some links for you.

Can a Lithium-Ion Battery Fire Be Put Out with a Conventional Fire Extinguisher? - boats.com

http://www.economist.com/blogs/econo...st-explains-19

Managing the lithium (ion) battery fire risk - Industrial Fire Journal - Fire & Rescue - Hemming Group Ltd

[ramblinrod]

Originally Posted by TeddyDiver

Yes it is. You have said it multiple times, not going to pickup quotes but your messege has been about "paralled batteries short is easy to detect becouse unknown current draw / series batteries will be boiled with charger becouse the voltage drop goes unnoticed".
You can read your own posts and feel free to correct your statements if they aren't what you really tried to say. It's just while trying to debate sometimes the consistency of our claims get's a bit blurred..

BR Teddy

What you have posted above in quotation marks are not my words.

1. My position, "A paralleled battery cell short is easy to detect".

This statement is absolutely true, and I included details how it is easily done, while countering another posters position that it is difficult.

2. My position, "A series string of cells may be boiled dry by the applied charger, if a shorted cell occurs."

This statement is absolutely true, as I posted in response to another posters position that cell shorts are serious concerns for parallel batteries, but not for series configurations.

I clearly and accurately posted that if a shorted cell occurs in either a series or parallel battery configuration, with a high output charger left on unattended, "bad things will happen".

If you wish to respectfully post a counter position to any of my posts (in original context), I'm fine with that. That makes for healthy debate and good clean fun, that I hope others find informative, thought provoking, and entertaining.