Wiring In Series (pro vs con)

[ramblinrod]

Originally Posted by GrowleyMonster

And I am talking about a house bank. Electric propulsion aside, a large series bank offers additional advantages as a house bank. Being able to loop a bad battery out of the system and still function normally, for instance. Electric propulsion is only the factor that made me realize this, getting me off the 12v or nothing mindset. It is not the only circumstance that makes it possible or practical or advantageous. Apparently I was unclear in my post.

I do concur that something other than Grp 27s or GC2s is called for when contemplating electric propulsion with any speed and range. (The reason I would personally never consider electric propulsion in a crushing yacht.)

But with this one has to introduce all kinds of additional safety measures that just aren't require for parallel configured 12Vdc FLA batteries in a typical house bank.

[ramblinrod]

Originally Posted by Tasso

Guess that you're stressed at the coffee shop - but your comments are a bit condensing.

We are not stupid. We just have a different opinion.

There are trade-offs for any configuration.

BTW - anyone with a 200 amp charger without temperature sensors for alarms and shut down is crazy!

Ok, that begs the question, what is the temperature of a high acceptance battery near dead, after 3 hours on the charger, compared to the temperature of a fully charged battery with a shorted cell after 3 hours on the charger?

Answer = about equal.

[ramblinrod]

Originally Posted by GrowleyMonster

And I am talking about a house bank. Electric propulsion aside, a large series bank offers additional advantages as a house bank. Being able to loop a bad battery out of the system and still function normally, for instance. Electric propulsion is only the factor that made me realize this, getting me off the 12v or nothing mindset. It is not the only circumstance that makes it possible or practical or advantageous. Apparently I was unclear in my post.

I hope by now, any following, understands that for a reasonable sized house bank on a typical cruising yacht there is nothing safer, more simple, and more cost effective, with more natural redundancy, than 2 or more 12 Vdc standard FLA Grp X batteries in parallel, EVERYTHING ELSE BEING EQUAL.

I simply can't state this any clearer. I'm sorry if it sounds condescending to those who disagree, not meant to be, but that is the way it is, in the real world we cruise in.

[Tasso]

Originally Posted by ramblinrod

I'm sorry if it sounds condescending to those who disagree, not meant to be, but that is the way it is, in the real world we cruise in.

Condescending means dismissing the opinions of others with sarcasm.

Your experience and opinions differ. That is the sum of it.

[GrowleyMonster]

Originally Posted by ramblinrod

I hope by now, any following, understands that for a reasonable sized house bank on a typical cruising yacht there is nothing safer, more simple, and more cost effective, with more natural redundancy, than 2 or more 12 Vdc standard FLA Grp X batteries in parallel, EVERYTHING ELSE BEING EQUAL.

I simply can't state this any clearer. I'm sorry if it sounds condescending to those who disagree, not meant to be, but that is the way it is, in the real world we cruise in.

I think your view might be in the minority, for good reason. And for the record, I disagree with it.

[ramblinrod]

Originally Posted by GrowleyMonster

I think your view might be in the minority, for good reason. And for the record, I disagree with it.

That may be, though I hope not for the well being of fellow boaters. But it really matters not to me. What matters to me is that after weighing all of
The evidence everyone has generously contributed, I still believe it
To be true.

[john61ct]

I also disagree with Rambling's most recent statement, but am open to be convinced if other authorities I trust confirm his reasoning.

I think more important that a smaller number of parallel strings are used, IMO ideally two, with cell weight being the limiting factor driving the use of lower-voltage cells.

But I admit, a big set of US-made Firefly Oases would be great, second only to a well-designed non-proprietary LFP bank.

[Pete7]

Originally Posted by GrowleyMonster

I think your view might be in the minority,

On CF or world wide?

Pete

[TeddyDiver]

Originally Posted by Pete7

On CF or world wide?

Pete

Doesn't matter as opinions are meaningless, the facts and science matters. Once we acknowledge the facts we can do educated desicions even if that means taking somekind of risks one way or another.. IMHO

BR Teddy

[Pete7]

Originally Posted by TeddyDiver

Doesn't matter as opinions are meaningless, the facts and science matters. Once we acknowledge the facts we can do educated desicions even if that means taking somekind of risks one way or another.. IMHO

BR Teddy

Agreed, which is why I hold the opinion that the vast majority of boats have a single or a couple of 12v batteries for use as a housebank. Why? cheap, simple and easy to replace. You could add profitable to the list as well

Pete

[john61ct]

What the average boater does, isn't necessarily the way to go if you need a big bank for large loads, much heavier usage than the avg, just keeping on multiplying what they do may not be the best course.

[Tasso]

Originally Posted by TeddyDiver

Doesn't matter as opinions are meaningless, the facts and science matters.

Some science - weak batteries typically have higher internal resistance. In parallel - most of the charging current goes to the strongest batteries. In series voltage across weakest battery is increased. Weaker batteries - will be automatically equalized in a series configuration. No expert - but guessing this is why anecdotal evidence suggests series cells last longer than equivalent parallel batteries.

Also batteries don't fail (unless it's catastrophic) - cells do. When one cell goes bad in a 12v battery you're trashing something which is still 80% serviceable.

I think the idea that 12v batteries are cheaper is a false economy...

Battery science is complicated and this thread has done little to enlighten. Too much noise. If you're crossing an ocean it's different than crossing Lake Ontario. On longer trips you should approach batteries and redundant charging system with great care and after consulting true experts.

[s/v Jedi]

This is the difference: when I read a post like this one from Tasso then I immediately recognize that he understands the science behind this. It is obvious he has studied or worked in this field, could show us the math for how a charge current divides over parallel batteries or how a charge voltage is divided over a series string of cells.

Some other posters write here with the same air of authority and knowledge while they are squarely wrong. They do not know the principles at that engineering level, but they bring it like they do. I know I'm always considered arrogant when it comes to this but I have been wrong on occasion and don't mind at all to admit that.

Do series if you can, fuse parallel strings if you need them

Originally Posted by Tasso

Some science - weak batteries typically have higher internal resistance. In parallel - most of the charging current goes to the strongest batteries. In series voltage across weakest battery is increased. Weaker batteries - will be automatically equalized in a series configuration. No expert - but guessing this is why anecdotal evidence suggests series cells last longer than equivalent parallel batteries.

Also batteries don't fail (unless it's catastrophic) - cells do. When one cell goes bad in a 12v battery you're trashing something which is still 80% serviceable.

I think the idea that 12v batteries are cheaper is a false economy...

Battery science is complicated and this thread has done little to enlighten. Too much noise. If you're crossing an ocean it's different than crossing Lake Ontario. On longer trips you should approach batteries and redundant charging system with great care and after consulting true experts.

[ramblinrod]

Originally Posted by s/v Jedi

This is the difference: when I read a post like this one from Tasso then I immediately recognize that he understands the science behind this. It is obvious he has studied or worked in this field, could show us the math for how a charge current divides over parallel batteries or how a charge voltage is divided over a series string of cells.

Some other posters write here with the same air of authority and knowledge while they are squarely wrong. They do not know the principles at that engineering level, but they bring it like they do. I know I'm always considered arrogant when it comes to this but I have been wrong on occasion and don't mind at all to admit that.

Do series if you can, fuse parallel strings if you need them

You have every right to believe who and whatever you want. You support the position of some posters because you agree with them and don't those you don't. Me too.

That you have ignored fact after fact that I have posted, so that you can continue to support opposing opinion is your prerogative, despite all of the evidence facing you.

That I have proven supposed facts posted by others false, and you have chosen to ignore that as well is also your prerogative.

In closing, whether I am an engineer (which in the US means little, or an electronic engineering technician, which in Canada means a fair bit, and I have held positions in various corporations where many Canadian Engineers reported to me, is completely a side issue, a complete distraction from the facts. As is weather one is in Lake Ontario, the Pacific Ocean, or a pond for that matter, the science and the facts remain the same; the user needs may be different, or not.

[Tasso]

Originally Posted by ramblinrod

That I have proven supposed facts posted by others false, and you have chosen to ignore that as well is also your prerogative.

Rod my concern is your level of confidence in your position - which in fairness several posters have issue with. I challenge to you refute the science in my last post. I agree that the parallel configuration is cheaper and much easier to set up, and for that reason may be best for some. But I have not read anything that has addressed the science I have presented.

I have a university degree is Physics and one in Electrical Engineering. I accept some of your points - the availability of replacements is the most compelling - but others point out that carrying a spare is not great burden. I would argue that my GC2's are widely available.

I'm not even trying to make anyone agree with me - I just want people to be safe and to seek out informed advise specific to their needs. If you are a service technician - you should appreciate that listening to the customer is good practice.