Depth of Discharge Myth?

[conachair]

Originally Posted by john61ct

Note that as a bank ages, SoH drops, and it gets harder and harder, longer and longer for trailing current to drop to your target endAmps.

It is possible bank SoH has by then dropped past the scrapping point, but if you want to keep going with it, redefine 100% Full to

"Current change over 1 hour period of less than 0.1A"

as Deka does, or something similar

so you don't drive yourself nuts

Might be a bit more difficult than we think at such low currents..

This from this morning, bit extreme as I know the LX needs a good refit, too much voltage drop from the charger even at low currents. So at just before 09:08 turn on a few things to pull a bit more power from the mains charger and the voltage at the battery terminals drops about 30mV (this ads1115 sensor is *very* accurate) , current drops about 0.2A. (not so accurate and calibration is a bit out but shows what's going on)

IMHO accurate voltage at the battery terminals is a vital piece of info

[john61ct]

And should be what the charge source sees.

Why a dedicated voltage sense wire is often used on quality sources.

[ramblinrod]

Originally Posted by newhaul

with my Lfp .wake up in morning see power being made for batteries go about my day enjoying the quiet Sailing. At lunch time look and see my battery monitor saying I'm at 85 to 90% start the watermaker if I need water if not flip refer stat override switch and run the holding plates deep frozen . By sunset I shut off the refer and see full batteries and a good cold freezer. Cook dinner . Enjoy a movie on the tv . Next day repeat as needed.

It sounds like we are doing pretty much the same thing except I charge with solar instead of Infernal Combustion Engine most days and FLA batteries don't cost nearly as much.

My beer is just as cold, ice is just as hard, TV reception is just as good, but my cabin is cooler and quieter, and the money I didn't blow on unnecessary LiFePO4 batteries can be added to the cruising kitty, so we can afford lobster instead of tube steaks.

[sailorboy1]

Originally Posted by a64pilot

I still disagree with the 80% number, I can and do get much better than that with Solar, the issue is that last 5% takes a long time, but I can and do get deep into the 90% percent charged every day on Solar alone.
One hour of generator, maybe two hours if I use the little Honda is all it takes to get to fully charged.
Do that a couple of times a week and your bank will last longer, likely much longer. If you don’t have a little Honda, consider one, I’d rather run it than my propulsion motor to charge.

Just don’t use it to top up the batteries before you go to bed, cause it’s being used very ineffectively then.

Far as this "how long does it take to fully charge" all I'm going to say is that after not having being plugged into shorepower for 10 months now I can say that if I start the morning at -85AH and motor for 9 hours, my 90 amp alternator will just get the batteries surely fully charged. If I am at anchor and run the generator in the morning to get the batteries to about -30-40AH on a sunny day my 290W solar will just manage get the batteries to full charge.

Full charge being less than 0.5% acceptance at absorption voltage.

[ramblinrod]

Originally Posted by Pizzazz

For me, the conclusions are:

1. Most people (including me) extrapolate from own experiences which should not be generalized as they are not scientific and suffer from bias.

Could be, but some are very good at looking at things logically and objectively.

For example...

I have zero experience wrestling an alligator out of a pool.

I know beyond a shadow of a doubt I don't want alligators in my pool.

Similarly...

FLA batteries are inexpensive and last about 5 years average in a properly designed system.

LiFePO4 do basically the same thing (store energy for future use) for about 9 times the purchase price of FLA.

Either will keep the beer cold and ice hard when connected to a properly designed charging system. [/QUOTE]

2. Most battery manufacturers recommend 50% DOD...

It's actually the FLA charging system designer that recommends this.

3. Most boat manufacturers advise boaters to accept the reality that batteries are unlikely to be charged above 80% SOC when away from dock. Solar helps but for most of us it is not worth the trouble to go above 80% SOC when away from dock.

Only those charging with ICE. Those with a properly selected and installed wind and/or solar charging system will get close to 100% most days, and to 100% frequently enough, that battery longevity is optimized.

4. Rare cases such as people living on the hook for month of a time are just rare cases. I know of very few people who actually do that.

Depends who you talk to. Of all cruising sailboat owners, correct. Of a much smaller group who do live on the hook a month at a time, all do.

Golf cart batteries are ideal in terms of size, weight, cost, ease of replacement around the world, etc. also a much bigger industry

Depends on the comparator. In some cases, 12 Vdc DC batteries can be a better choice than 6 Vdc batteries. I just changed back to 2 x 12 Vdc, a customer who had a 2 xT105 bank, and a single battery failure took out all house bank capacity, where he could have got by much more easily only isolating and using one 12 Vdc house battery, until a replacement was made.

6. Lithium is not cost effective today unless you have specific requirements such as min weight (racers) or excess money to burn.

Agreed.

But additionally, if one charges exclusively by ICE, does not wish wind and/or solar charging, and can justify the cost, LiFePO4 can be a good choice.

7. The best battery solution is to have two banks, house and starter and make sure that the batteries are of different vintage, so the chance of simultaneous failure is smaller.

I completely disagree.

For an FLA house bank, I recommend it be split into 2 banks, but always combined, except for testing and servicing.


Batteries can be of different vintage, (mine are 2 x 6 years, 1 x 4 years, and 1 x 3 years), but in general, older batteries will relinquish the majority of the work to new batteries. To equalize the load between all batteries in the bank, all batteries should be the same vintage.

This is not as big a deal as some believe.

Basically, I make a judgement call based on discarded battery cost, vs new battery life expectancy cost. If the older batteries are above 50% life expectancy, I tend to just add new, rather than recycle batteries that could still last several years, depending on use case.

While I don't recommend it for my customers, I have omitted a dedicated start battery, and run everything off the house bank.

I carry a L-Ion booster as a portable 12 Vdc power supply to troubleshoot electrical systems, and to start our engine in the unlikely event I ever drain the house bank too low. (Former happens a lot, latter hasn't happened in 3 years.)

I have used this system for 3 years now, and it works great. All batteries are getting regular exercise and maximizing my house bank capacity, instead of a start battery sitting idle and under-utilized most of the time.

For customers, I recommend a reserve battery for starting, which could be a dedicated start battery, or a house bank battery that is isolated from the house at a low voltage cut-off, until the charging system is applied, to ensure the house bank can start the engine, even if they mess up and deplete the house bank.

[newhaul]

Originally Posted by ramblinrod

It sounds like we are doing pretty much the same thing except I charge with solar instead of Infernal Combustion Engine most days and FLA batteries don't cost nearly as much.

My beer is just as cold, ice is just as hard, TV reception is just as good, but my cabin is cooler and quieter, and the money I didn't blow on unnecessary LiFePO4 batteries can be added to the cruising kitty, so we can afford lobster instead of tube steaks.

one question where did I ever say in my post you quoted that I run the iron wind?
Your own posted scenario requires some running of it to charge with your alternator.
But the price is not as far apart as you think it is.
Just got a quote from a possible supplier of $310 for 12v 100ah built prismatic pack with external bms that is plus $220 shipping to the US from the factory.
So you see a good part of the price difference is NA related. ( the shipping includes the import taxes.)

[ranger58sb]

Originally Posted by ramblinrod

FLA batteries are inexpensive and last about 5 years average in a properly designed system.

LiFePO4 do basically the same thing (store energy for future use) for about 9 times the purchase price of FLA.

Cost would be relative to longevity... .and should also include effort spent in replacement...

How long might the LiFiPO4 batteries last?

-Chris

[ramblinrod]

Originally Posted by newhaul

one question where did I ever say in my post you quoted that I run the iron wind?

You didn't, but if you were honest, you would.


For a properly designed charging system based on shorepower, ICE, solar and/or wind. The more time spent off shore power, and not running the engine or generator for other purposes, the more frequently alternative energy will not meet demand and ICE is required solely for charging.

Your own posted scenario requires some running of it to charge with your alternator.

Only when solar (I don't have wind due to my current location) and motive purpose engine operation will not produce sufficient energy to meet energy deficit, same as you.

But the price is not as far apart as you think it is.
Just got a quote from a possible supplier of $310 for 12v 100ah built prismatic pack with external bms that is plus $220 shipping to the US from the factory.
So you see a good part of the price difference is NA related. ( the shipping includes the import taxes.)

Rather than price, look at cost.

By the time you research, source, arrange delivery, attempt to read and discard the provided instructions, deal with non-existent customer service and tech support, finally figure out the BMS system, connect it up, screw up, trash the batteries, order the replacements, wait for delivery, and try again, they will likely cost you $C 36 /A-hr @ 12 Vdc capacity.

While you hope they will last you many years, I predict 10 +/-.

For a 200 A-hr bank this will represent an annual cost of $720/yr.

FLAs typically retail for $C 1.7/A-hr @ 12 Vdc capacity in Ontario.

In a properly designed system they last 6 +/-.

For the same size bank, this will represent an annual cost of $56/yr.

Annual savings by using FLA instead of LiFePO4 = $664.

In other words, the difference between an individual eating steak and lobster instead of hotdogs about every 5 dinners aboard, for a year round live-aboard.

I guess it is where one's priorities fall, spending more money on electrical devices that sit in the bowels of the boat, or other things, like better food, entertainment, more adventure, higher RRSP contribution (so not eating ALPO in final years).

[newhaul]

Originally Posted by ranger42c

Cost would be relative to longevity... .and should also include effort spent in replacement...

How long might the LiFiPO4 batteries last?

-Chris

as with Fla the longevity of Lfp is also dependant on usage
With the same usage of 50%DOD as Fla you get about 7,000 cycles which looks like about 20 years with daily cycling.( see attached chart) So just figuring the labor costs to replace the Fla every (lets go long) 5 years . 4 times the labor cost of one Lfp install. Now I don't know where the 9x cost per ah comes from. ( I'm sure it will be explained to us in detail)
I just received a quote for $ 530 for a 12 volt 100ah custom built bank ( includes shipping) for a $5.30 per ah cost.

[newhaul]

Originally Posted by ramblinrod

You didn't, but if you were honest, you would.


For a properly designed charging system based on shorepower, ICE, solar and/or wind. The more time spent off shore power, and not running the engine or generator for other purposes, the more frequently alternative energy will not meet demand and ICE is required solely for charging.



Only when solar (I don't have wind due to my current location) and motive purpose engine operation will not produce sufficient energy to meet energy deficit, same as you.



Rather than price, look at cost.

By the time you research, source, arrange delivery, attempt to read and discard the provided instructions, deal with non-existent customer service and tech support, finally figure out the BMS system, connect it up, screw up, trash the batteries, order the replacements, wait for delivery, and try again, they will likely cost you $C 36 /A-hr @ 12 Vdc capacity.

While you hope they will last you many years, I predict 10 +/-.

For a 200 A-hr bank this will represent an annual cost of $720/yr.

FLAs typically retail for $C 1.7/A-hr @ 12 Vdc capacity in Ontario.

In a properly designed system they last 6 +/-.

For the same size bank, this will represent an annual cost of $56/yr.

Annual savings by using FLA instead of LiFePO4 = $664.

In other words, the difference between an individual eating steak and lobster instead of hotdogs about every 5 dinners aboard, for a year round live-aboard.

I guess it is where one's priorities fall, spending more money on electrical devices that sit in the bowels of the boat, or other things, like better food, entertainment, more adventure, higher RRSP contribution (so not eating ALPO in final years).

well for you really seem to have it all figured out . Must be from all of the lifepo4 installs you have done.
Question how many have you done?


Also you must have missed the fact that on my sailboat I don't even have an alternator on my engine. How can I charge with something that doesn't exist?

[poiu]

Originally Posted by sailorboy1

Far as this "how long does it take to fully charge" all I'm going to say is that after not having being plugged into shorepower for 10 months now I can say that if I start the morning at -85AH and motor for 9 hours, my 90 amp alternator will just get the batteries surely fully charged. If I am at anchor and run the generator in the morning to get the batteries to about -30-40AH on a sunny day my 290W solar will just manage get the batteries to full charge.

Full charge being less than 0.5% acceptance at absorption voltage.

I’m sure that isn’t fully charging them. I did tests a few times to check this. I set the float voltage on my charger to the stipulated voltage for the ambient temperature and watched the settled voltage rise. It would take 24 to 48 hours to climb to a maximum settled voltage. My understanding is that voltage plateauing is an indication of maximum conversion in the battery chemistry process. We also know that to store at anything below fully charged reduces life, and it is probably somewhere in the care of batteries at below float charge state that we are going awry.

[ramblinrod]

Originally Posted by newhaul

well for you really seem to have it all figured out . Must be from all of the lifepo4 installs you have done.
Question how many have you done?


Also you must have missed the fact that on my sailboat I don't even have an alternator on my engine. How can I charge with something that doesn't exist?

Quite frankly, I could care less what is on your personal boat.

I do object to you posting misleading info to others.

The average 35’ +/- cruising sailboat has a house bank, a shore power charger and an alternator. Those who anchor out a lot, and want to minimize use of ICE for charging, will also have solar and/or wind charging systems.

Regardless of battery technology, if one experiences insufficient wind and/or solar to meet load demand and usable bank capacity, they will have to charge by alternate means, including you.

While your boat may be unique (to you) the laws of physics don’t change on it, just because you have chosen expensive LiFePO4 over inexpensive FLA.

[newhaul]

Originally Posted by ramblinrod

Quite frankly, I could care less what they is on your personal boat.

I do object to you posting misleading info to others.

The average 35’ +/- cruising sailboat has a house bank, a shore power charger and an alternator. Those who anchor out a lot, and want to minimize use of ICE for charging, will also have solar and/or wind charging systems.

Regardless of battery technology, if one experiences insufficient wind and/or solar to meet load demand and usable bank capacity, the will have to charge by alternate means, including you, while your bank at may be unique (to you) the laws of physics don’t change on it, just because you have chosen expensive LiFePO4 over inexpensive FLA.

if you don't care about my personal vessels system then why did you reference it and say I was lying ?
you are baseing your inflammatory statement about my information on what exactly.your extensive actual field knowledge gathered from years working on lifepo4 systems?

You still having answered the question what is your knowledge base for lifepo4 systems?
Mine is actual field work.

[SV THIRD DAY]

Originally Posted by ramblinrod

the laws of physics don’t change .

Ah....Amigo.
It's Internet Chat Room Advice, hence the laws of Physics and common sense don't apply. Might as well come from a Russian bot.

Originally Posted by newhaul

You still having answered the question what is your knowledge base for lifepo4 systems?
Mine is actual field work.

But if you are going to play the expert you at least should share with others your credentials for playing said expert. That's not an unreasonable request.

[evm1024]

A few thoughts that might need to be remembered.

First off - sailing/boating is not a zero sum game. If I choose to spend my hard earned dollars on Carbon Fiber sails that is my look out. It does not mean that I will be eating hot dogs rather than lobster. If someone says that I will be eating hot dogs if I spend my money in a way that they do not approve of then that person is trying to force their view on me.

Second off - It should be very obvious to everyone that sailing/boating cannot be justified economically. Basically it is a waste of money. You can get recreation many other ways that do not require you to plunk down wads of cash, endure hardship, get wet and risk drowning. As a means of transportation is is not efficient, it is slow, and generally takes a long time. Anyone who argues that we need to be efficient needs to get another hobby.

Lastly I would like to point out that this thread is 'Depth of Discharge Myth?' and not 'LiFePO4 vs FLA - The Real Deal' which was closed once again.