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Old 06-26-2022, 11:14 AM   #21
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Originally Posted by ranger58sb View Post
Yep. Lifeline publishes an Expected Life Cycle curve -- cycles versus DoD -- in the Technical Manual for their batteries, available on their site Page 40 in Rev G, 11/26/2019.

On the graph it looks like a little over 1000 cycles at 50% predicted. Eyeballs somewhere near 525-550 at 80% DoD.

Per Rod Collins: that's "lab conditions" though... not necessarily representative of reality.

-Chris
So the 50-80%'walking around figures are valid'

We dont deal in lab conditions, we deal in real life/on the boat conditions.
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Old 06-26-2022, 12:40 PM   #22
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So the 50-80%'walking around figures are valid'

We dont deal in lab conditions, we deal in real life/on the boat conditions.
Sure. And sure.

Probably not easy for a manufacturer to replicate real life, though -- custom fitted to a bazillion individual boats.

I reckon they give what info they can based on standardized criteria and users are allowed to wing-it based on all that to modify their own personal expectations given their own typical environment and behavior.

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Old 06-26-2022, 12:59 PM   #23
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Per Rod Collins: that's "lab conditions" though... not necessarily representative of reality. Chris
And this one statement pretty well sums it up. So best to follow the time tested common sense battery practices for oneís particular house setup, equipment and cruising style.
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Old 06-26-2022, 03:53 PM   #24
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Originally Posted by ranger58sb View Post
Yep. Lifeline publishes an Expected Life Cycle curve -- cycles versus DoD -- in the Technical Manual for their batteries, available on their site Page 40 in Rev G, 11/26/2019.

On the graph it looks like a little over 1000 cycles at 50% predicted. Eyeballs somewhere near 525-550 at 80% DoD.

Per Rod Collins: that's "lab conditions" though... not necessarily representative of reality.

-Chris

Very much so re "lab conditions". But that's the only way to compare apples to apples.


Regarding real-life conditions, I believe what Rod is referring to is the tendency for boaters, particularly sail boater, to run their batteries at partial state of charge for extended periods of time. That's what leads to permanent sulfation and consequent loss of capacity, and is why he says that most batteries are murdered, not worn out. This is less of an issue for power boats because you have all your under-way time to charge, and hopefully fully charge you batteries. Sailboats don't have that given intermittent engine use, so tend to be harder on batteries. They key is regularly returning them to full charge, one way or another. That can be via long engine runs, solar, long generator runs, or shore power. Every boat will be a bit different.
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Old 06-26-2022, 05:01 PM   #25
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It's the voltage sag when running big stuff that was a killer for us
As we got near 50%, if two or more 240v fridge freezers kicked on at the same time, voltage would drop well below 24v
Commonly, inverters have their cut-off voltage set at 10.5 or 21.0 volts. So are you saying your voltage would drop that low? That's really a dramatic discharge.
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Old 06-26-2022, 05:53 PM   #26
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I can tell you that in my camper van I had two new 6v golf cart FLA and 2000w PSW inverter. Voltage sag was enough that I couldn't run a small microwave for more than a couple mins, and couldn't run a 5000 Btu A/C at all. With two 105ah LiFePO4 batteries and same inverter/cabling, no problem at all running hi-draw appliances (separately - to capacity of inverter) including electric tea kettle, induction hot plate, instant pot, AC, microwave, etc.

With six 6v golf carts in Weebles, I could run microwave and such. But I could definitely see significant voltage drop. Huge difference in the usability of LiFePO4 vs FLA. I can't speak to AGMs as I have only run them on other people's boats. I'm sure they're an improvement. But LiFePO4 are life altering.

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Old 06-26-2022, 06:13 PM   #27
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Commonly, inverters have their cut-off voltage set at 10.5 or 21.0 volts. So are you saying your voltage would drop that low? That's really a dramatic discharge.
First few years seemed ok but in year 4 it started setting the low voltage alarm off fairly regularly and, I had to drop the setting to a lower voltage
End of year 4 start of year 5 we started getting occasional inverter shutdowns but we managed to hold them together with extra Genset hours until the new LFP arrived from China.

As Peter says, LFP are life changing
Now the low voltage alarm is set at 25v and even with everything running, including hot water system have yet to have it activate.

It's all running now, pulling around 90amps @ 24v.
Voltage has sagged to 26.2v with batts @ 55% capacity

Should add: I would NEVER have considered running loads like that on AGM, if we saw more than a few minutes at 40 amps I'd be shutting stuff down or firing up the Genset.
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Old 06-26-2022, 08:16 PM   #28
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We had such good luck with our Rolls. They were in the boat when we bought it, and according to the date of install on the batteries, they were already 6 years old. We got another 6 years out of them before having to replace them in Panama. ( Ouch, that hurt)
The Admiral called me the Power Nazi as I tried religiously to recharge at 60%. But as they got older the ole genny ran more often. Still great batteries to have onboard for the house bank.
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Old 06-27-2022, 12:19 AM   #29
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Before I found the knowledge of the internet, I charges my batteries when the inverter stopped working at 10.5 volts. Usually 3-4 days at anchor. 5-6 years before they dropped to 2-3 days.
In the PNW the batteries are not used more than 4 months on this cycle so they last the 6-7 years expected and die of old age.
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Old 06-27-2022, 07:46 AM   #30
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It seems to me that the life-changing experiences are those of extreme users, those who put inordinate demands on their systems. For most boaters, the issues talked about here simply do not exist, at least they do not for me.

I have eight flooded golf car batteries. We generally cruise from anchorage to anchorange. Occasionally, we stay two nights, rarely three, in one place. Our luddite house bank easily last 14-16 hours before reaching 50% DOD and that's with two 4.2 cf fridges, a 7 cf chest freezer, two TVs plugged in full-time, and a SAT-TV dome and receiver on full-time. And, yet, in the morning we can brew coffee and use the microwave or toaster with no discernible decrease in performance (the effects of voltage sag). At times we even plug in a portable induction cooktop to cook breakfast although not all of the 120VAC implements at the same time. My batteries are five years old and test to 97% of original capacity.

So, lithium battery proponents, please explain to me, and others similary situated, how lithium would be life-changing.

As for longevity of batteries, twistedtree has explained the science. All batteries have a limited ability to deliver electrons. Cycles are meaningless. What counts is the number of electrons utilized. The tank is of limited capacity. So, what does that mean for the heavier users who have adopted lithium. It means that your profligate use of electrons will result in a battery bank that will not last nearly as long as you think it will based on a flawed concept of battery life being determined by cycles.

The bottom line for me is that my dumb old flooded batteries give me everything I need, every day, every cruise with no compromise of utility and/or convenience. So, five years from now I will have to spend $1,300 at today's prices for a replacement bank of Trojan T-105s. Works for me.
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Old 06-27-2022, 07:56 AM   #31
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As the battery bank gets bigger, voltage sag becomes less of a problem. A 100 amp load won't sag a 1200ah bank nearly as badly as a 600ah one. So depending on factors like that and how often you can get the batteries topped off, the benefits of LiFePO4 will vary depending on the situation. In some cases, just the increased space and weight density makes them worthwhile, as you can fit more battery capacity (but that isn't a limiting concern on many boats).
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Old 06-27-2022, 08:44 AM   #32
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So, lithium battery proponents, please explain to me, and others similary situated, how lithium would be life-changing.
I do not pretend to believe you can be pursuaded (I note there is no question mark at the end of what seems to be a question). I respect your opinion and understand your position. All I can tell you is that the combination of solar and LiFePO4 has fundamentally changed my power calculus. Gone are concerns about usage, ability to recharge, etc. Much more even and consistent infrastructure. Worrying about DoD/SoC are now nerd-out things, not really a concern.

14-16 hours to 50% DoD is not even close to what I would be comfortable with - my goal is net-zero so power becomes a non-issue. At 50% DoD, with a standard alternator, it can take 6-10 hours to recharge a 6x6vGC FLA bank. So you need beefed-up alternators and/or a generator - suddenly the $1200 in 6V batteries is an incomplete expense.....unless running half the day to recharge the batteries is normal.

I'm not buying the argument that a FLA battery has a fixed number of AH to give, and that (within reason) how those AH are expended (i.e. many shallow discharges vs few deep discharges) have little effect on the overall reservoir of total AH available.

Peter
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Old 06-27-2022, 09:06 AM   #33
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Peter
For your cruising style of living on the hook in Mexico your battery setup sounds pretty ideal given todayís choices. CJ is in a different location with a different cruising regimen thus a sea change in ready electron thinking doesnít appeal to him.

We currently are in a large marina dominated by commercial fishing craft. Dollars to doughnuts not one of them has Li batteries or solar panels. But several cruising boats nearby have setups like yours. Even though necessity is the mother of invention, oneís requirements tends to seep in to this subject.
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Old 06-27-2022, 09:16 AM   #34
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It seems to me that the life-changing experiences are those of extreme users, those who put inordinate demands on their systems. For most boaters, the issues talked about here simply do not exist, at least they do not for me.

Inordinate is a relative term. There have been a number of discussions about when LFP is more/less beneficial, and not everyone's usage patterns benefit the same. Is my usage "inordinate"? Maybe to some, but I would call it "convenient".


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Originally Posted by catalinajack View Post
I have eight flooded golf car batteries. We generally cruise from anchorage to anchorange. Occasionally, we stay two nights, rarely three, in one place. Our luddite house bank easily last 14-16 hours before reaching 50% DOD and that's with two 4.2 cf fridges, a 7 cf chest freezer, two TVs plugged in full-time, and a SAT-TV dome and receiver on full-time. And, yet, in the morning we can brew coffee and use the microwave or toaster with no discernible decrease in performance (the effects of voltage sag). At times we even plug in a portable induction cooktop to cook breakfast although not all of the 120VAC implements at the same time. My batteries are five years old and test to 97% of original capacity.

You, and many others have run like this for decades.


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Originally Posted by catalinajack View Post
So, lithium battery proponents, please explain to me, and others similary situated, how lithium would be life-changing.

In your case, the benefit would be shorter generator run times. Does that matter to you? At this point it would seen not, which is fine.

Quote:
Originally Posted by catalinajack View Post
As for longevity of batteries, twistedtree has explained the science. All batteries have a limited ability to deliver electrons. Cycles are meaningless. What counts is the number of electrons utilized. The tank is of limited capacity. So, what does that mean for the heavier users who have adopted lithium. It means that your profligate use of electrons will result in a battery bank that will not last nearly as long as you think it will based on a flawed concept of battery life being determined by cycles.

Cycles aren't meaningless or a flowed concept. They are just an incomplete metric for lifespan. FLA/AGM published cycle life is always based on a DOD, typically 50%. More complete specs will plot cycle life vs DOD, and that's the more complete story showing the range of usage available, and showing that 50% DOD is just one usage pattern, not the only usage pattern.


LFP is no different. 2500 cycles at 100% DOD has been proven over and over again for about 20 years now. And that's under much more abusive operation that any house battery bank will ever see. That's already about 5x the lifespan of lead, and only grows with more gentle use.


Quote:
Originally Posted by catalinajack View Post
The bottom line for me is that my dumb old flooded batteries give me everything I need, every day, every cruise with no compromise of utility and/or convenience. So, five years from now I will have to spend $1,300 at today's prices for a replacement bank of Trojan T-105s. Works for me.

And that's all good.
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Old 06-27-2022, 09:19 AM   #35
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As for longevity of batteries, twistedtree has explained the science. All batteries have a limited ability to deliver electrons. Cycles are meaningless. What counts is the number of electrons utilized.
Lead acid chemistries WILL deliver less total AH over their life if deeply discharged. Just that the difference is not as precipitous as many have supposed. Lithium batteries too, but with lithium the difference is negligible. And the total AH delivered by lithium is many times that of any lead acid chemistry, more than recovering their extra cost. This was even true a few years ago, and with the drop in price of lithium, is doubly true now. So regardless of operational advantages, lithium is the cheap choice - if you are keeping the boat for very long.
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Old 06-27-2022, 09:38 AM   #36
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Peter
For your cruising style of living on the hook in Mexico your battery setup sounds pretty ideal given todayís choices. CJ is in a different location with a different cruising regimen thus a sea change in ready electron thinking doesnít appeal to him.

We currently are in a large marina dominated by commercial fishing craft. Dollars to doughnuts not one of them has Li batteries or solar panels. But several cruising boats nearby have setups like yours. Even though necessity is the mother of invention, oneís requirements tends to seep in to this subject.
Yes, my use-case is at the outer edges, but my guess is there are a lot of people that don't want to be awakened by low-voltage alarms in the morning. That said, LiFePO4 and solar would help a boat like CJs, but running multiple fridges, freezers, TVs, and electronics full-time is likely beyond the reach of even a robust energy system. He might be able to double/triple his off-grid time, but in the end, the power demands are just too high to view a battery bank as anything other than a temporary bridge between generator/engine run-time; or being connected to shore power. Going from 12-16 hours to 50% DoD on FLA to 36 hours to 80% DoD on LiFePO4 isn't going to move the needle much.

Peter
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Old 06-27-2022, 09:52 AM   #37
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I'm not buying the argument that a FLA battery has a fixed number of AH to give, and that (within reason) how those AH are expended (i.e. many shallow discharges vs few deep discharges) have little effect on the overall reservoir of total AH available.

Peter

This is probably a good time to talk about this some more, because although the fundamental concept is shown in battery specs, there are other factors at play. So let's talk about the warts and imperfections...



First, the whole concept of having a lifetime number of Ah that you can cycle through the battery is more like 90% true, not 100% true. Again, just look at the published specs. But the notion that there is exponential decline if you use more then 50% DOD is 100% untrue.


Second, the concept breaks down more if you operate at the DOD extremes. Again, look at the published specs. But house battery use seldom, if ever operates that way.


Third, heavy loads have a disproportionate impact on lead batteries via the Peukert effect. Heavy loads draw down more Ah than their face value. Linking this back to the notion of running a smaller battery bank harder, and for a shorter life, the Peukert effect will be more pronounced. With half the bank size, any given load is proportionally twice as large with a subsequent larger Peukert degradation. So for any given load, Peukert hits you harder with a small bank vs a big bank, and that one IS an exponential relationship. It's not a big exponent, but it's not one either.


Fourth is the human factor, primarily operating at partial SOC and consequent permanent sulfation buildup over time. The longer we own and operate a battery bank, the more likely we make our own contribution to shortening their life.
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Old 06-27-2022, 11:19 AM   #38
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Apologies in advance if this is common knowledge but I just figured it out.

I've got a house bank of 1000 Ah of Rolls AGM batteries which means 500 Ah usable. I don't let the batteries go below 50% but it is a pain when the batteries approach this figure at the end of a day. What to do? Run the generator a couple hours (most expensive electricity ever) or let the batteries go below 50% (and shorten their lives) and just charge them from the main on the next days run?

I stumbled on a post suggesting that pulling the batteries below 50% wasn't that big a deal - https://tab-rv.vanillacommunity.com/...ge-myth-busted I then dug into the Rolls data sheets.

My Rolls AGMs list an expected life of ~1200 cycles at 50% depth of discharge. That translates to 1000 * .5 * 1200 = 600K Ah. At a routine 80% DOD the expected cycles drop from ~1200 to ~675 cycles - almost a 50% decrease. However, the usable Ah in this case are 1000 * .8 * 675 = 540K Ah. That is just 10% less than the 50% DOD number. Looking at total Ah available rather than cycles suggests that going below 50% DOD occasionally - or maybe regularly - isn't that big a deal.

Another conclusion I've reached from this is I spend too much time worrying about the batteries. I'm just going to use them as I want (within limits) and replace them when needed.
The models they use for those projections are purely mathematical... that is why 50% seems to be the same throughput as lower DoD's..A once in a blue moon discharge to 80% DoD is ok but recharge to 100% ASAP..
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Old 06-27-2022, 11:23 AM   #39
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Ah, I miss the good o' days when I had a big bank of eight 8D's connected to a huge 3kW transformer inverter from (I'm guessing) either WW2 or the Crusades. I ran the heck out of it, barely watered them, and just had a ball.

Ignorance is so wonderful sometimes!
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Old 06-27-2022, 02:44 PM   #40
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West marine 4D batteries are made by West Penn mfg.
Opinion?
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