Depth of Discharge Myth?

[ramblinrod]

Originally Posted by evm1024

This is a fair enough statement. It does leave out that not all people are motivated or even care about the best value for money. People do things for their own reasons and are quite happy to pay more for things that they value. And they get pissed off when someone tells them what they should spend their money on.


Yes, you have. The error is that you left off average cruising sailboat that I have seen in my very small part of the world.

You assume that your observation are global and just not limited to you.

Great start, you do see that there might be cases where LiFePO4 is a good choice.

I'm not sure if you have actually watched Delos. They run their generator all the time. They run it to charge their batteries, they run it to power the AC and who knows what else. What they do not do is only use their solar and wind to meet their power needs


Gosh, corporate sponsorship. I wish I had corporate sponsorship. Corporations are tripping over themselves to get their products on SV Delos. I cannot fault them there.

Delos has what $200,000 plus coming in from their videos. They can afford to put in any technology they want. They could have used Thin plate, Firefly, fule cells, or Lithium et al. But they chose LiFePO4. Did they get a good deal? More than likely but do not make the mistake to think that they went to LiFePO4 because of corporate sponsorship. They went LiFePO4 because of the power that LiFePO4 gives them.

Special case? Duh.

11.34 g/cm3

Every boat (and boat owner) is a one off case. You are being bombarded because you have created a fiction where you say that everyone should use lead. And when presented with exceptions you make the one off statement.


If that were only true. Sigh....

It appears to me and IMHO you care very much. Not really about folks promoting LFP for average cases but that list members object to your proclamations. And ask for proof....



I agree with you fully and so do the other list members. But you did not stop there.

Pretty much everyone here agrees that there are no drop in LiFePO4 systems that can be run as if they were Lead Acid systems.

We all pretty much agree that LiFePO4 systems require a lot more understanding and hands on than the typical weekend cruiser has or wants.

We all pretty much agree that for the cruise willing to take the time and effort that LiFePO4 will give much better service than FLA (and LA in general).

But you did not stop there. You went far beyond. It appears to me that you required all of us to agree with your opinion and confuse your opinion with fact. Of course I could be wrong...

You obviously have a bone to pick.

I have stated my personal and professional opinions and recommendations that are very appropriate for the average sailboat cruiser.

In that opinion, one who relies on continuous relatively low current charging such as solar and wind is better off with evaporator plate or box based refrigeration over a holding plate; one of the reasons I removed the latter in preference of the former on my personal boat. If one relies solely or mostly on ICE charging a holding plate may be a better choice.

I choose not to be slave to ICE charging; being forced to start up when battery capacity is depleted (hence the need for reserve capacity with any battery technology) YMMV.

For these reasons, based on years and years of electrical education, design and practical experience I have developed the recommendations previously posted for an FLA battery based, balanced electrical system, that will serve the average cruising sailboat, affordable and reliably. I have done so free of my normal consultation fee, for the benefit of CF members.

There are pros and cons to everything related to boats. I trust this is not new to you.

You can launch as many counter arguments whether they have any merit or absolutely none. I don’t care. Trust me, you are not likely to tell me anything I didn’t know, long long ago, likely before you did.

IOW, if you have a differing opinion and wish to launch continuous counter arguments forever, well I have better things to do.

This doesn’t make my knowledge and experience, nor my recommendations any less valid, nor my opinions of lesser value than yours.

IMHO on subjective issues where it comes down to personal preference, there can be no right or wrong solution.

To argue otherwise, is just a waste of breath. Right now I am breathing fresh air while swinging on the hook, with my solar charging system happily charging my batteries to full by the end of the day. The beer is cold, the ICE is hard, and LFP would be zero “Benefit” for huge cost. I choose to spend my money more wisely.

Those who wish to throw money away, may certainly do so. No skin off my nose. I just hope those who may be convinced to spend their hard earned dollars on expensive products that don’t really do anything of significant value for them, based on the rah, rah postings if the few who ignore economic justification for boat maintenance and improvement.

For the very rare circumstances where LFP conversion is economically justifiable, I pick no bones. Where LFP conversions are performed without financial justification (because one thinks it’s cool) I could care less.

[weavis]

So.
ITs time to close this thread for a moderator discussion yet again.

[Pete7]

I have opened then thread in the hope that contributions will be civil.

Pete

[newhaul]

One question concerning the lvc on Lfp that I don't understand .people talk about it happening at inopportune critical times .
My question is when would be so critical that you would not have plenty of time to switch to backup systems?

[Dockhead]

Originally Posted by newhaul

One question concerning the lvc on Lfp that I don't understand .people talk about it happening at inopportune critical times .
My question is when would be so critical that you would not have plenty of time to switch to backup systems?

I guess everyone will have to decide that for himself.


Maybe it's so improbable that it's not a rational fear, but I would personally hate to give the BMS the authority to shut off all my electrical gear, including a chart plotter I might be using in the middle of a tricky channel, or my depth sounder, because it thinks, possibly erroneously, that there's a low voltage event.



Does anyone else think that this is a rational concern?

[a64pilot]

1.Having a back up system means you now have two systems to maintain, with more than likely different charging voltages etc.
2. Are you always aboard, never land travel? I’d rater not come back to a freezer / fridge of rotting food, have you ever smelled that? I have it smells like a dead animal, which it is, and the smell is extremely difficult to eradicate, may not be able to get it out of the plastic that the box is made from, to say nothing of the upholstery in the boat.

It has been brought up by an established professional that a second lead bank would be good to have for those times when you leave the boat, size, space and money wise, two banks of different chemistry gets expensive.

Anything can be accomplished, all it takes is enough money. We can literally build a nuclear powered wristwatch, but to what end?

[newhaul]

Originally Posted by Dockhead

I guess everyone will have to decide that for himself.


Maybe it's so improbable that it's not a rational fear, but I would personally hate to give the BMS the authority to shut off all my electrical gear, including a chart plotter I might be using in the middle of a tricky channel, or my depth sounder, because it thinks, possibly erroneously, that there's a low voltage event.



Does anyone else think that this is a rational concern?

in a tricky channel or entering an unfamiliar port? Wouldn't you as a prudent sailor have the engines running if for no other reason just in case therefore providing charging?
As far as all the fancy toys what did we ever do without them?
Each person has to as you say decide what is acceptable risk.

[newhaul]

Originally Posted by a64pilot

1.Having a back up system means you now have two systems to maintain, with more than likely different charging voltages etc.
2. Are you always aboard, never land travel? I’d rater not come back to a freezer / fridge of rotting food, have you ever smelled that? I have it smells like a dead animal, which it is, and the smell is extremely difficult to eradicate, may not be able to get it out of the plastic that the box is made from, to say nothing of the upholstery in the boat.

It has been brought up by an established professional that a second lead bank would be good to have for those times when you leave the boat, size, space and money wise, two banks of different chemistry gets expensive.

Anything can be accomplished, all it takes is enough money. We can literally build a nuclear powered wristwatch, but to what end?

refer shutdown when not onboard is a remote possibility imo and not really critical.
Also that can and does happen with Fla as well ( I have experienced that the cure is vinegar)

[Dockhead]

Originally Posted by newhaul

in a tricky channel or entering an unfamiliar port? Wouldn't you as a prudent sailor have the engines running if for no other reason just in case therefore providing charging?
As far as all the fancy toys what did we ever do without them?
Each person has to as you say decide what is acceptable risk.

You will need some kind of battery in the system to use alternator power to keep your systems on.

Originally Posted by a64pilot

1.Having a back up system means you now have two systems to maintain, with more than likely different charging voltages etc.
2. Are you always aboard, never land travel? I’d rater not come back to a freezer / fridge of rotting food, have you ever smelled that? I have it smells like a dead animal, which it is, and the smell is extremely difficult to eradicate, may not be able to get it out of the plastic that the box is made from, to say nothing of the upholstery in the boat.

It has been brought up by an established professional that a second lead bank would be good to have for those times when you leave the boat, size, space and money wise, two banks of different chemistry gets expensive.

Anything can be accomplished, all it takes is enough money. We can literally build a nuclear powered wristwatch, but to what end?

It's a valid point, and to my mind and for my use case a major disadvantage of lithium -- I mean the complexity of having another battery or another bank as backup or at least dump load.


I don't know what is the relevance of the freezer remark, however. I never leave refrigeration running when I'm off the boat for more than overnight in any case, which means I throw out tons of food. I was always afraid someone might kick the shorepower plug out and the reefers would kill my batteries. If they are being run off lithium with a LVC perhaps it could be worth the risk from time to time -- you risk the stink, but not ruining batteries. A backup bank would be useless in this case and irrelevant -- would just delay the inevitable by another day or whatever.



Same thing with bilge pumps -- there is no reason to set up the bilge pumps to be able to kill your batteries. If you have a leak with no one aboard, either someone will notice and do something, or if they don't, the batteries will die and your boat will sink. A few hours plus or minus is not going to make any difference. Even with uninterrupted shore power -- the pumps will clog or burn up and your boat will sink. This is why I NEVER leave the boat even overnight without closing all my through hulls.

[newhaul]

Originally Posted by Dockhead

You will need some kind of battery in the system to use alternator power to keep your systems on.


It's a valid point, and to my mind and for my use case a major disadvantage of lithium -- I mean the complexity of having another battery or another bank as backup or at least dump load.

.
.

as to the 2 separate systems what is your normally isolated starting battery for?

[Dockhead]

Originally Posted by newhaul

as to the 2 separate systems what is your normally isolated starting battery for?

Yes, that could work fine on many boats.


On mine not, though. Main engine and generator on my boat each have their own starting battery with separate dedicated alternators and separate dedicated mains chargers. Totally separate from house power, and can't be connected -- because house is 24v and the other banks are 12v.

[newhaul]

Originally Posted by Dockhead

Yes, that could work fine on many boats.


On mine not, though. Main engine and generator on my boat each have their own starting battery with separate dedicated alternators and separate dedicated mains chargers. Totally separate from house power, and can't be connected -- because house is 24v and the other banks are 12v.

ok fair enough you can start your generator and charge your house bank.
I would also assume your chart plotter and most of your navigational critical systems are also 12 volt?
If not well then you would just have to do it manually for a few minutes till gen set charges enough to reset the lvc safety.

[john61ct]

I have not seen anyone advocate for a single LFP bank only, no lead on the boat.

My Main / Reserve design, as opposed to House / Starter, adds no extra bank, little extra complexity.

Without an LVD the power's gone anyway, just a bit later and after the bank's been damaged.

LVDs are used more (not exclusively) with LFP because the damage from going dead flat is catastrophic and the up-front investment is higher.

Situational awareness wrt your banks' SoH and SoC on an ongoing basis is required no matter what chemistry they are. **No Surprises** a critical operational goal of the overall design, not just physical infrastructure, but checklisted and scheduled inspection, testing, maintenance, and proactive replacement protocols.

Finally, for me, anyone whose setup requires working electricity for their survival, is not doing it right.

[wsmurdoch]

Back a little closer to the original topic, I ran across this training material for a Canadian submarine. https://maritime.org/doc/oberon/electrical/index.htm Needless to say, their batteries are big, and they have a lot of them.

They have two periodic full chargings of their flooded lead acid batteries. There is a "normal charge" conducted once every two weeks which brings the batteries to their full state of charge, and there is an "equalizing charge" done no less than every two months. That lets me know their frequency of topping off the battery charge.

New to me was a "quarterly discharge" done to a specific gravity of no lower than 1.080. "...unless this is carried out at regular intervals the effective capacity may be temporarily reduced."

Do our flooded lead acid batteries need a similar "quarterly discharge"? Do we make a mistake always keeping our flooded lead acid batteries nearly fully charged?

Bill Murdoch

[Kenomac]

Originally Posted by Dockhead

You will need some kind of battery in the system to use alternator power to keep your systems on.







Same thing with bilge pumps -- there is no reason to set up the bilge pumps to be able to kill your batteries. If you have a leak with no one aboard, either someone will notice and do something, or if they don't, the batteries will die and your boat will sink. A few hours plus or minus is not going to make any difference. Even with uninterrupted shore power -- the pumps will clog or burn up and your boat will sink. This is why I NEVER leave the boat even overnight without closing all my through hulls.

How many through hull fittings do you have? How long does it take to do all that?