LiFePO4 vs FLA - The Real Deal

[newhaul]

Originally Posted by ramblinrod

Is this one of your water maker installations?

Cruisers & Sailing Forums - newhaul's Album: Watermaker install - Picture

That Rod is if you were to actually read the thread associated with it one of the in progress upfits to my own personal vessel . Btw yes that is bolted to the bulkbead in my head .( initial mockup for fitment)
Do you have a critique of the partial install that i havnt had time to complete? Im all ears. Rob SV Stephen Ulysses
Btw here is the refit thread. http://www.cruisersforum.com/forums/...-a-187721.html

[john61ct]

Originally Posted by thinwater

Not sayin' it isn't solveable, just that it is a serious consideration in design and operation.

Yes, if you leave your expensive bank aboard operating unattended.

I would never do that, even with multiple layers of automated protections.

Isolating the bank while stored, no worries.

A cheap lead batt can take on whatever needs to be left operating while the boat's not in use.

I believe most cruising boats just stay in warmer climates.

[john61ct]

Originally Posted by Paul L

But that isn't the lithium battery chemistry that most people are using.

If you plan on cycling them when they might get that cold, then you should buy the right one for the job.

They are just like plain LFP otherwise anyway, not anything exotic, very well respected maker.

[evm1024]

Hey Rod, Thanks for the timely reply.

Let me see if I can summarize it.

*- You have significant experience with part-time cruisers on Lake Ontario and an unknown number of world cruisers.

*- You have not seen a case where you thought LiFePO4 was an economically justifiable solution but you do know that such cases exist, and will recommend LiFePO4 in those cases.

*- You have not installed or worked on any LiFePO4 systems at this time.

*- Your opinion of the LiFePO4/FLA cost - benifit trade offs is based on significant experience with FLA and no direct experience with LiFePO4. Your opinion of LiFePO4 is formed from your research and reading on the subject.

If I can't justify the cost of LiFePO4 to myself, I surely can't justify the cost to my customers with similar needs, unless I was some kind of con man salesman, which I am not.

I could install LiFePO4 on my boat, use it as a tax write-off, sell it to customers who won't really benefit from it, and make a boat load of money at their expense.

I could also do it to show others I'm cool because I have the latest technology on my boat. *

I don't operate that way.

I want my boat and my customer boats to serve the owners cruising needs efficiently and affordably.

FLA will do this.

At least at present, LiFePO4 won't.

Based on the above quote it appears that you think that LiFePO4 is not efficient or affordable. That only con man salesmen recommend LiFePO4 systems. That people who sell LiFePO4 solutions are making a boat load of money at their customers expence. And that owners who choose to install LiFePO4 systems are motivated to be cool in the eyes of other boaters.

OK, Fair enough. It is good to know where you are coming from.

Regards

[44'cruisingcat]

Originally Posted by ramblinrod

I don't agree with this.

Well you're wrong.

The fact is many cruisers DO stay away from marinas for long periods. Maybe not in the lake where you sail, but there's a whole world out there.

[john61ct]

Even those routinely installing LFP systems in NA boats say that most of their customers own racing yachts where the light weight energy density is what drives the purchase decision.

I think it's fair to say the remainder are not too worried about cost issues, and / or appreciate being on the cutting edge of new technology.

Then you have the more-technical enthusiasts that will design and cobble together their own setup from bare prismatic cells, research and purchase their BMS functionality independently.

In Europe and down under, since the cells are only a bit more expensive than quality FLA, they are serviced by a better local supply chain than is available in the NA market, so LFP has been penetrating their market much faster than here.

Even in what we call the RV market LFP is getting more commonplace, while here it's quite rare.

Grey scale priority factors, no black and white.

Your rig your call.

[john61ct]

Originally Posted by 44'cruisingcat

Well you're wrong.

The fact is many cruisers DO stay away from marinas for long periods. Maybe not in the lake where you sail, but there's a whole world out there.

And personally, land or marine, I will only design for off-grid use, whether shore power is regularly available or not.

For those able to plug into mains every few days, there is no challenge at all.

And even if mains is often available now, doesn't mean it always will be.

[44'cruisingcat]

Originally Posted by thinwater

If this is true--and no one has mentioned installing heat--then this is a major question. I'd bet half the boats see subfreezing temps for months and most probably leave the batteries on solar chargers in the off season, which will charge automatically whenever they see fit.


Not sayin' it isn't solveable, just that it is a serious consideration in design and operation.

You could disconnect the batteries from the charging system during the off season.

[Delfin]

Originally Posted by 44'cruisingcat

Well you're wrong.

The fact is many cruisers DO stay away from marinas for long periods. Maybe not in the lake where you sail, but there's a whole world out there.

Just returned from a couple of months in northern BC. Perhaps three days at docks with power. You're right, it's a big world out there.

[newhaul]

Originally Posted by 44'cruisingcat

You could disconnect the batteries from the charging system during the off season.

for many of us there is no off season for using our own boats.

[44'cruisingcat]

Originally Posted by newhaul

for many of us there is no off season for using our own boats.

Well yes, I know. I'm one of these people. We use our boat every day.

But the post was in response to someone talking about an off season.

Anyway the point is, with lithiums you could leave the batteries sitting disconnected for months or even years without hurting them.

That would kill lead.

[newhaul]

Originally Posted by 44'cruisingcat

Well yes, I know. I'm one of these people. We use our boat every day.

But the post was in response to someone talking about an off season.

Anyway the point is, with lithiums you could leave the batteries sitting disconnected for months or even years without hurting them.

That would kill lead.

there is one important part when leaving Lfp unused and "shelved" for extended periods they prefer to be at a partial charge in the 50% vicinity for the best longevity. FWIW

[Delfin]

Originally Posted by a64pilot

Reference the lead / Lithium hybrid.
I supposed the idea is use the Lithium’s better charge abilities and then discharge them into the lead so as to maintain a safety buffer if you will?
So do you charge them both when charging? If so then you only need enough lithium to cover both house loads and 15% of the leads capacity so that when discharged to a comfortable level the lead is 100%?
Run off of the lead until 50%, then crank the generator and charge both lead and Lithium?
I don’t see what that won’t work?

I have a lead 200 Ah starter bank and a 600 Ah LiFePO4 house bank. Managing this installation is a Balmar 624 regulator, the BMS for the Li bank and a Blue Seas ACR with a three position switch - no combine (never use), auto combine and manual combine.

When charging, the BMS is switched on to bring the Li bank online if it isn't already. The ACR is in auto combine, so when the Li bank reaches the ACR threshold voltage (I think around 27.5 v), both banks are charged. When the Li bank's acceptance rate drops to around 5% of capacity, the ACR is switched to manual combine and the BMS turned off. This results in just the lead starter bank being charged. As we putt along, we make water and the alternator supplies charge current and house loads. When we arrive at anchor, the ACR is switched to auto combine and the is BMS switched on. Since the Li bank is the primary bank feeding the house loads wired up to the always hot leg of the ACR, this, in effect, isolates the starter bank since the resting voltage of the Li bank is below the threshold to auto combine and we run off the Li bank until recharging is needed.

Been using this setup for a few months cruising now and it works just peachy. I did forget to bring the Li bank online yesterday after anchoring, so ran down the starter bank to 23.8 v since the BMS was switched off, isolating the Li bank from loads. No problem - just switched the ACR to manual combine and the lead bank was at 26.4 volts the next morning with its need for charge current just being another load for the Li bank.

This is, I think, a little different than the scenario you describe. I don't know why you would want to run house loads off of the lead bank, unless hooked up to shore power simply because one of the significant advantages of Li is that it delivers such a flat voltage curve under load - I never see less than 26.1 volts, and that is great for dc motors, control boards, etc.

Regarding control boards, I have a Kabola boiler that was powered by 24 vdc. Kabola doesn't offer a 24 vdc option any more because lead batteries can frequently show significant voltage drop under load and the boards get fried. A $3,500 conversion later, my Kabola is now 230 volts ac through a small 120 - 230 converter. Had I the Li bank, my guess is that the board wouldn't have fried since it never would have seen anything less than 26 volts. This, by the way, is another reason why suggestions that you run lead batteries down to less than 50% SOC are not a great idea. The voltage drop at that level of discharge can cause damage to sensitive electronics, as I found to my dismay.

[Delfin]

Originally Posted by newhaul

there is one important part when leaving Lfp unused and "shelved" for extended periods they prefer to be at a partial charge in the 50% vicinity for the best longevity. FWIW

True. The day we return to shore power for awhile, I don't bother to recharge the Li bank, so it rests at around 50% SOC, which as you say, is optimal.

[newhaul]

Originally Posted by Delfin

True. The day we return to shore power for awhile, I don't bother to recharge the Li bank, so it rests at around 50% SOC, which as you say, is optimal.

that data is what I have gleaned from many sources including several manufacturers technical reports.