LFP - Decline in charge acceptance rate with battery age

[a64pilot]

Why would you want 120 v lights and water?

[tanglewood]

Originally Posted by a64pilot

That and like the poster above who said we don’t want Solar.

Take away your Solar and only leave you with running the generator to charge, and you would think LFP was the second coming. Then throw in we don’t want use propane and you have the perfect use case.

Trying to say if you don’t have an LFP bank, well then you must be cruising like the Pardey’s is ridiculous.

I think this is really the key. If you have enough solar/wind to meet your daily needs, then LFP is much less compelling. When you are recharging from an engine of some sort, LFP is really compelling because there is no long drawn out acceptance phase, and early death due to partial state of charge.

[a64pilot]

With just Solar alone I usually can’t quite to to a real 100% SOC, but if I have a 30 min generator run in the morning, I can.
Those of us with high output watermakers (120VAC) are usually going to run a generator anyway at least once a week.
Propane is a pain getting the tanks refilled, but I don’t think it’s really that big a safety problem if it’s maintained.
We used to every now and again leave ours on, would forget then notice later.
Now I have an annoying bright red led on my power panel that makes it real hard to forget.

[CatNewBee]

... to answer your question, I have not run my generator at all since I have the LFP and the solar.

My GEL Batteries suffered after one day light usage (refrigeration only, no inverter) and need to be recharged one way or another either by shore power or by alternators or by the generator every day. I could not sail the boat using my on-board electronics and auto-pilot over 24hr when fridges were on without running either engines or generator for hours to re-charge. Well 2 out of 4 were dead, but that is not the point. Even if all were new, it would not be enough for passages, fridges only draw daily 250Ah, running navigation, radar and autopilot adds another 100Ah, so 12h sailing, then re-charging or running out of power / deep discharge.

I would have to replace all 4 old ones with 4 new Excide equipment GEL 120Ah, each for the price of 296€ so total cost almost 1200€. They would give me weak usable 240Ah with maximum continuous current draw of 48A (0.1C) and charge time of 10+ hours to full.

I chose to spent 5000€ (4 times more) for the cells and get nominal 1000Ah (but in reality 1200Ah) usable capacity and max continuous current up to 1000A. so for me a god deal to spent only 4 times more and get 5 times more capacity plus 20 times the current. And this using the same space and weight.

This opens completely different options.

And no, Winston cells are not more expensive than branded GEL batteries here for the same usable capacity.

And they live 5-8 times longer. So good spent money.

My situation is different than yours, I live in a different country and the resources available are also different. What works for me may not work for you.

[a64pilot]

IF we could get LFP for even close to the price of lead, that obviously changes things.
However here the price seems to be about four times as much for the same useable power.
I’d replace my 660 AH of lead with 400 LFP.

I still have I hope four years before a decision will be forced upon me.

I think it’s likely the future, just not ready for prime time, yet.
I almost bought a Nissan Leaf when I was still working, but glad I didn’t now.
I know sounds like a completely different thing, just I don’t think the infrastructure is mature enough yet for either for me.

[ontherocks83]

Originally Posted by a64pilot

IF we could get LFP for even close to the price of lead, that obviously changes things.
However here the price seems to be about four times as much for the same useable power.
I’d replace my 660 AH of lead with 400 LFP.

From what I understand (which could be wrong) a 400Ah LFP bank is roughly the equivalent to a 600Ah lead acid bank so pretty close to the same. 80% of 400LFP = 320Ah useable and 50% of a 600Ah Lead acid bank is 300Ah useable.

Edit: sorry I just realized that is basically what you just said in your post. Reading too fast.

[Jammer]

Originally Posted by ontherocks83

From what I understand (which could be wrong) a 400Ah LFP bank is roughly the equivalent to a 600Ah lead acid bank so pretty close to the same. 80% of 400LFP = 320Ah useable and 50% of a 600Ah Lead acid bank is 300Ah useable.

Edit: sorry I just realized that is basically what you just said in your post. Reading too fast.

The idea that a 400 ah LFP bank is equivalent to a 600 ah FLA bank is, well, Hollywood accounting.


Even assuming, arguendo, that an FLA bank cannot be routinely operated to 80% dod without an unacceptable loss of useful life while an LFP bank can be so operated, without an unacceptable loss of useful life, there is a difference in the amount of reserve power available in an emergency.


But in actual fact, if you really want to run your FLAs down to 80%, you can, and as long as they are recharged reasonably promptly they'll be fine, and in a marine application their useful life will be limited by factors other than the number of cycles, so the effect on battery life is negligible.

[tanglewood]

Originally Posted by a64pilot

IF we could get LFP for even close to the price of lead, that obviously changes things.
However here the price seems to be about four times as much for the same useable power.
I’d replace my 660 AH of lead with 400 LFP.

I still have I hope four years before a decision will be forced upon me.

I think it’s likely the future, just not ready for prime time, yet.
I almost bought a Nissan Leaf when I was still working, but glad I didn’t now.
I know sounds like a completely different thing, just I don’t think the infrastructure is mature enough yet for either for me.

Price and availability are indeed the key factors. And by "availability", I mean an easy path for Joe boater to retrofit with LFP, which means complete product offerings from a company that buyers have confidence in, and widely available technical skills to design and implement a retrofit. Or well engineered systems in new boat builds.


For price, right now only people who will get the most advantage from LFP will pay the premium. Cut the price in half and a bunch more people will find it makes sense for them. Get within 25% to 50% of the cost of AGMs, and it's all over.


But today, I agree that it's not ready for prime time. We just need to be thankful for the pioneers who are helping to push it along in the right direction.

[44'cruisingcat]

Originally Posted by Jammer

The idea that a 400 ah LFP bank is equivalent to a 600 ah FLA bank is, well, Hollywood accounting.

True. We replaced our 600 ah lead batteries with 400 ah lithiums, and the lithiums are much better.

After a couple of cloudy days with the lead, our inverter would be giving low voltage alarms every time the fridge or freezer started up, and I'd need to run the generator.

The lithiums keep everything working fine.

[john61ct]

If mostly-solar is not enough

**and** running your high-amp ICE charging for one hour 3-4 times a week is not a hardship

then LFP will eliminate any need for solar at all.

If you like solar of course you can choose to keep it, but now it's purely optional,

especially if you are already running ICE that much anyway.

Of course the issue of up-front acquisition costs remain, but that is insignificant for many owners.

[senormechanico]

Originally Posted by a64pilot

Propane is a pain getting the tanks refilled, but I don’t think it’s really that big a safety problem if it’s maintained.
We used to every now and again leave ours on, would forget then notice later.
Now I have an annoying bright red led on my power panel that makes it real hard to forget.

Our propane sniffer has two greens. Very calming.

[jram]

YALFP thread. (Yet Another LFP)

Someone wanted long-term data. I know a few people that have LFP and have had for some years. They're very happy as am I. They're so happy, they've moved on from batteries being the number one cruiser topic.

Just my 2c

[newhaul]

Originally Posted by jram

YALFP thread. (Yet Another LFP)

Someone wanted long-term data. I know a few people that have LFP and have had for some years. They're very happy as am I. They're so happy, they've moved on from batteries being the number one cruiser topic.

Just my 2c

question do you have Lfp? If so how long have you been using them ?
Have you noticed any reduction in capacity since install?

please allow us to improve our understanding of the technology.

[mark0978]

I'm regularly putting in 1100W on a good sunny day from my 4x325W panels. So around 91Amps.

[jram]

Originally Posted by newhaul

question do you have Lfp? If so how long have you been using them ?
Have you noticed any reduction in capacity since install?

please allow us to improve our understanding of the technology.

I do have LFP. 540Ah of them. Only a year so far but my friends have many more. I've not heard them talk of degradation of capacity.

I was trying to point out that its no big deal. Every technology has its downsides but also benefits.

The most important thing is that those (I know) who have made informed decisions and completed installations appropriate to their circumstances, are very happy. So content that they are out cruising, full time, part time, seasonal whatever.

I can't help you understand the technology. Amongst the threads here there is all the information required when sifted from opinion. (My opinion is above - 'its no big deal'

The important questions are these:
Do I have a long enough future on this boat to justify the investment?
Do I have the ability to unlearn Lead acid habits and learn LFP habits?
Am I flexible enough to adapt and adopt to these new things?
Do I want a 'fit and forget' system (and pay for it) (BTW - try that with lead acid and see what investment is required).
Am I happy to adapt my power management perspective to leverage the benefits of LFP?

From my side, I had the best time. My electrical systems ran flawlessly and more reliably than ever before.

My system isn't finished. I ran with an own design battery protection system - I'm just about to solder up V3 and install it.

I don't have a battery management system. On most boats, the operator manages the batteries. All the batteries require is protection from the manager. Its the same whatever battery technology is used.

I'm not going to go on since this is old-hat to most on here and there are some monster threads that discuss the ins and outs of all the dark corners depending on the persistence of the reader.

Remember though - its not a car where you're trying to eek the last mile of range out of it. Its a boat with an array of charging systems and loads over which you have control. Operating between the knees is the correct approach and that takes 90% of the problems away. But its way too easy to get carried away with trying to engineer perfection - It doesn't exist with lead acid and it doesn't exist with LFP.

LFP is just another choice but it does require a change in mindset.