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Battery Type and Cost vs Benefit

15K views 159 replies 18 participants last post by  SanderO 
#1 ·
No one go crazy this is a real question and I am not looking for bent out of shape battles.

I need new house batteries and have 6 months to decide on them. I have been been pretty happy with my standard golf cart type of batteries. But will entertain improvements, which for me mostly is a true cost/life benefit. But here is what I am seeing as "advantages" given about changing to another type of battery.

Agms/Gels
- spillage/watering - not a problem to me to spend any money on
- faster charging - not that I can verify except at low state of charge and since my old golf cart T105s already accept as much power as my charger and solar can put out there isn't any advantage
- longer life - not that I can verify for the usage I do

LiPo/Lithium (whatever they are called)
- longer life - ok how much on a life amp-hour basis, do I have to plan on not getting a pay back for 5 years, 10 years, 15 years
- faster charging - well I already charge as fast as my charge sources can supply
- weight - my house batteries only weigh 250lbs, want difference to me is it if I could reduce it by half
- space - well yes if I freed up one of the battery storage spots that could be used, but I have lots of space on the boat still

sell me on a reason to upgrade from a $500 set of batteries that will last me 4 years at least, $10.40/mo, and not a hiuge cost
 
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#4 ·
LFP might get decades of use, but only if everything is right and nothing goes wrong.

Yes half the weight and space.

Yes much faster charging, down to 2 hours if you have the amps

even one, but that reduces lifespan.

At seven+ times the cost per usable Ah, likely more with infrastructure,

I'm not selling anything

again up to you if worth the cost / risk.
 
#5 ·
sell me on a reason to upgrade from a $500 set of batteries that will last me 4 years at least, $10.40/mo, and not a hiuge cost
You've laid out your usage profile and reasoning many times over the past few years, and none of it has been factually or logically wrong for you.

Given your criteria and expectations, I'd go with what you had before - golf cart FLA batteries.

The one reasoning you left out of the LFP analysis is if you plan to run heavier loads off the battery. LFP has little voltage drop under load, so running higher loads means nothing to them. I assume your future usage won't change from the past?

On the other hand, one tends to run more heavy loads when LFP is present. We switched our water heater over to the inverter circuit and run it off batteries. We changed to a 30gph 120V watermaker from a 6gph DC one. With our increased solar, we can run our stateroom A/C overnight off the batteries.

Mark
 
#8 ·
The one reasoning you left out of the LFP analysis is if you plan to run heavier loads off the battery. LFP has little voltage drop under load, so running higher loads means nothing to them. I assume your future usage won't change from the past?
Ok that may be a reasonable reason.

I can run my HW heater now off the house bank via the inverter. It takes 15 minutes at 130 amps to warm up enough for a comfortable shower. I have no plans to increase my house bank, and the solar to match it enough, to really run any inverter load more than this. I would think this is really not much load to a battery designed to run a golf cart.

I assume LFP is Lithium? How much would a 300AH total bank be? (yes I can look it up but bet someone just knows)*

* near as I tell from a quick search is that it would be $3k, at 3 years/$600 bank life that would take 15 years to break even
 
#7 ·
1C is much faster than I'd want any bank of mine charged, unless I really needed to for strong reasons.

Even if each such cycle only resulted in 0.001 reduced lifespan.

For those happy with only one decade and a few thousand cycles, if other care factors are coddled, then sure go for it, not very "damaging" I suppose.

But say an 800Ah bank

completely ignoring the bank itself or chemistry issues

800A infrastructure has its own safety challenges!
 
#11 ·
Don please read to the end. Just another way of thinking.
I want a pickup. Now have a new house and miss not having a pickup. Could get a beater fix or repair daily, or make use of the ridiculous deals on new vehicles. But decided to do nothing. Think the engineers are all over battery technology. Regardless of what this (USA) country does the rest of world is believers in man made climate change and doesn’t believe it’s in their national interest to be dependent on foreign countries for energy. The marine industry gets the spill over from truck/car tech.
I held off buying the latest and greatest thinking with prototypes and small run electric pickups already being made I’d wait for a electric pickup or at least a hybrid.
Think you should think the same. If you’re going to hang onto Hunter wait for an sale on AGMs. Good chance that’s coming soon as the economy continues to collapse or get a bunch of golfs if things go south sooner and you absolutely need batteries. If you are going to hang onto the boat for 5-10yrs. Fireflies then make some sense. If you’re going to hang on to the hunter until they throw dirt in your face or your Viking funeral go for the lithium if a good deal comes along.
If you think you’re going to move to another boat at some time in the future it’s real likely this conversation changes and a different battery chemistry will be available in a few years.
 
#15 ·
Don please read to the end.......
Thats not all of it
Charging requirements by type is a biggy...if you are on the hook for exrended times
Burn diesel/honda or not
Some batt types have strict charging demands

Not just cost of the batts
...and not just costs
The batts, chosen capacity, chosen charging...all dictate...your expected experience..and available options
 
#13 ·
I don't have any input for what someone should consider who is happy with what they have.

I can add a few things about the original pros/cons. Gels do not charge fast, in fact, they are slow in the upper ranges of charge. Their principal advantage is they are very durable and can take a occasional deep discharge cycle and bounce back, better than other lead chemistries.

Just because one's charger provides all the charge that a lead bank will accept, does not relate to other options. AGM will accept more charge, so you can get them refilled faster. All lead, however, lowers the amount of charge it will accept, as they approach higher states of charge. Lithium is the real leader here. It will take full throttle, until it nearly crosses the finish line. That mean one makes way more hay, while the sun shines.
 
#14 ·
Doesn't seem to me to matter if a battery COULD accept more if it is already accepting all that you can provide it.
 
#16 ·
If you're saying your current charging system(s) can't put out more than your current batteries will accept, I understand. Not totally clear. Some charging systems throttle throttle back for what the battery will accept.

Raises another point, I think you understand. Changing chemistries will require a change in charging voltages and the in the case of lithium, requires an additional management system (which often come integrated with battery, but not on home grown setups). Even AGM would likely require a temperature controller on your alternator, if you don't have one.

If you're happy with what you have, as it's clearly a cost effective choice, I don't see you volunteering for anything different.
 
#17 ·
If you’re living on the hook it’s your alt. energy production that permits you to avoid putting on the generator. Even in the tropics at noon with 20kts. blowing simple flooded Pb. will accept what you put out. It’s that last wee bit when the batteries are on float. However not a week goes by that you’re not on the boat for a day. Maybe off sightseeing or shopping or snorkeling. On that day you get the plates all the way up. You wake up with the house bank at 70-75%. By 10am you’re on float. By 2 pm on you’re conditioning the bank and getting rid of that last bit of sulfur. We typically show 13.4 when we come back to the boat. We leave some devices on so the boat is monitored (anchor alarm, other alarms, recording barometer, sometime AIS). Know people make a big deal abound rate of acceptance but in my personal experience it’s much to do about nothing. I can understand if you’re in a windless area with low sun angle and short days this calculus wouldn’t work. But Don’s in FLA so expect he sees the same thing. A more important advantage to Li or carbon foam is the abilities that draw down well past 50%. That is a biggie as Mark has pointed out. The second real advantage is weight. We have 1024 of lifelines I could half the weight if I got the lead out.
 
#18 ·
.....Know people make a big deal abound rate of acceptance but in my personal experience it's much to do about nothing.......
I agree that acceptance is unlikely much of a factor, when charging from wind or solar, as those sources are themselves typically limited. However, when you find the need to burn diesel to charge (alternator or generator), or simply want to get the maximum out of a short motoring passage, high acceptance rates of AGM or especially lithium, will be greatly more efficient than flooded or gel. Different cons apply, as have been disclosed already.

Lithium pricing is still an issue, unless you own long enough to amortize it back. However, it seems likely to be the future standard. Charge cceptance, weight, usable range of charge, cycle lifespan, etc.
 
#19 ·
Should also mention in our circumstances and for many others the AC v DC for watermakers is another non issue. At least once every two weeks or so you have a boat day. Maybe diving the bottom or doing stainless or oils changes. So that day after breakfast and coffee you turn on the low output watermaker (we have two pumps so do alright). By the end of the day tanks are full. Sure there’s a concession. No evening music or TV or SSB chatting. You don’t have a work day when it’s airless, humid and wicked hot so no AC that day isn’t a biggie. Find we only want AC when out of the wind in a slip which is rare and then on shore power and not making water.
People should think about how they actually live before spending big money on things they may not actually need. You can’t always get what you want...but get what you need. Try sometime you just might find.....
 
#20 ·
The ability to drawn down the LFP batteries lower than the FLA I feel isn't an advantage unless you are space limited and do so regularly on your FLA. The past 4 years my 440H FLA bank was only down to 50% a few times, and that isn't a problem.

Acceptance doesn't seem an advantage to me if to get it I need to spend an extra $500-1000 on batteries AND then $1000-2000 to increase my charging. But I have no need to charge my batteries faster anyway.
 
#23 ·
The ability to drawn down the LFP batteries lower than the FLA I feel isn't an advantage unless you are space limited and do so regularly on your FLA. The past 4 years my 440H FLA bank was only down to 50% a few times, and that isn't a problem.
If you never go below 50% DOD on FLA (which is a good way to use them), then you simply convert to less capacity of LFP so that 50% LA is equivalent to 80% LFP - less expense (and weight and space).

Or, when you wake up in the morning with the LFP at 50% SOC and it is cloudy with no wind, you simply go about your day and don't worry about charging them.

And, if they cycle between 30-50% SOC for a couple of weeks, or even months, you don't worry about their health.

The ability to draw down deeply over and over, and keep them at partial SOC almost indefinitely, is one of the biggest advantages of lithium batteries. Maybe even the primary advantage.

Mark
 
#21 · (Edited)
Minnie we turn on the northern lights once a month because it’s bad to not run a diesel. Those days use the vacuum cleaner, AC, and anything we can think of to increase loading on it. Run it until oil is hot. Again each boat and set of people are different but still see a lot of other couples living off alt energy using their gensets very rarely.
Know there’s a diversity here with some running their genset an hour twice a day because of their frig/freezer.
 
#22 ·
Minnie we turn on the northern lights once a month because it's bad to not run a diesel. .....
Agreed, but I'd run it once per week, for that reason, even if only up to temp for maybe 30 mins.

Our current form of cruising runs the generator daily, but I appreciate it's not a particularly long term model. 2 to 3 weeks is about it, at a time. As I said, acceptance is an advantage, when one is running the engine for any purpose, as they'll essentially get more free recharge, from power they're making for propulsion. Faster the better, when free.

No right and wrong, just pros and cons. The OP is not going to change their current set up.
 
#27 ·
It sounds like FLA meets your needs. Take some of the hypothetical money you are saving by not changing and get one of those watering systems for them. I refused to do so for the 13yrs we had FLA. Our current boat came with FLA and a watering system so I got to use one for a bit before we replaced with LFP again. It is great - I'd definitely get one now if we ever go FLA again.

On both boats, the batteries were extremely easy to access and maintain - trivial, actually - so watering wasn't any big deal. But that watering system is the bomb. Just squeeze a bulb whenever you think of it and all the cells instantly fill up with just the right amount of water each.

Mark
 
#28 · (Edited)
It sounds like FLA meets your needs. Take some of the hypothetical money you are saving by not changing and get one of those watering systems for them. I refused to do so for the 13yrs we had FLA. Our current boat came with FLA and a watering system so I got to use one for a bit before we replaced with LFP again. It is great - I'd definitely get one now if we ever go FLA again.

On both boats, the batteries were extremely easy to access and maintain - trivial, actually - so watering wasn't any big deal. But that watering system is the bomb. Just squeeze a bulb whenever you think of it and all the cells instantly fill up with just the right amount of water each.

Mark
I will look into that. I think there is a plus to having to physically open the boxes once/month or so for inspection, but still just squeezing a bulb sounds like a nice thing if low cost enough. I will have to apply the cost of beer equivalent test to it.

Off hand does the watering system add height to the batteries as I don't have any extra height room unless I redo the base shelves.
 
#29 ·
If you do want to investigate pricing, LFP's usually referred to as LiFePO4 chemistry.

There is a vast difference between preassembed "drop ins" and just buying the prismatic bare cells.

I recommend the latter for longevity, flexibility higher current rates.

But sounds to me another FLA bank will be satisfactory for you, at at least 1/7th the cost.
 
#33 ·
If you do want to investigate pricing, LFP's usually referred to as LiFePO4 chemistry.
.
I thought that earlier in thread it was said those are different things.

But i guess it doesn't matter if they are goin* to be 7x more money.
 
#32 ·
I prefer maintenance free and am using a pair of 8D @ 590 ah... which are in the 9th year. They cost around $900 and I will replace them with 6 AGM @ 600ah for under $1100 with will outlast me and my ownership of the boat. I can do 5 AGM for 500ah and around $950.

We're never over night on a dock using shore power... so the 110 watts of solar and the 120 amp alt are the charging sources. We don't have 12v refer... We do with engine drive and the batts, solar and alter config.
 
#43 ·
Unless you really want to make the investment not just money but time and attention, like getting a new hobby

or really have another compelling reason, e.g. actually **need** to save the weight

it sounds to me another round of FLA will suit you better for now.

Then in coming years, keep attuned to developments, do some research at your leisure, no stress, learn who to listen to (IMO those in line with MS' tips)

so when the time rolls around again you will have a clearer idea if you want to make the jump.
 
#45 · (Edited)
Well I got through Mainesail's article. Here are what I see as the Pro/Con of the LFP as it applies to me (not saying to someone else it is different):

Pros
- faster total charge time because there is no need to hold at absorption to get to 100% SOC
- that equals a reduction of 10-30% of TOTAL charge AH needed
- lighter weight
- more tolerant of partial charging (it is even a good thing)
- don't have to water or equalize
- higher life cycles

Cons
- at least 60% more expensive, but probably more like 100-200%
- complex
- easy to destroy
- need to made the rest of the boat system "fit"
- suppliers dependability questionable except at the high price range when maybe it is good
- the high cycles as used in a real world cruiser mode are questionable
- hard to source if failure in anything close to a remote location

Really the only usable Pro to me is that the batteries are good being at partial charge, but that is a huge plus. But overall the cons and risk just don't seem to offset this. In the end I would need to HOPE the LFP batteries would last 12+ years to even break even cost wise over my FLA that I know and which have performed great as fall as a cost/benefit goes.

At this point it doesn't seem a benefit to me to take any risk on changing battery type considering I have no real reason to "improve" it. Maybe in 4 years or so when next set of FLA die things will have changed.
 
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#52 ·
In the end I would need to HOPE the LFP batteries would last 12+ years to even break even cost wise over my FLA that I know and which have performed great as fall as a cost/benefit goes.
Well my 400Ah bank, that started as an experiment, just turned 11 and is still delivering in excess of its 400Ah rating... :wink
 
#48 ·
For a 360AH bank it would be $2072 for a useable 288AH, verse $500 for 440AH of FLA with a usable 220AH.

The cost/benefit/risk just doesn't work for me. I just don't need the "latest, greatess, best" battery as the "old, crappy, proven" battery is working fine for me.
 
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