Understanding Lead-Acid Battery Life

[a64pilot]

Originally Posted by john61ct

Not talking carrying even 5% of that.

Just for the long tail, last 3-4 hours at say under 10A, crazy to think about running ICE for that.

If impractical then the two remaining choices are LFP (even if just for the hybrid long tail) or frequent replacement of lead.

You have to carry the house load, plus the 10A to charge anything.
So if you have a house load of 20 amps, then of course you have to make 30 to charge, and 30 amps isn’t a couple of portable panels laid on deck.
20 amps on a big complex boat running Radar and autopilot etc., isn’t all that uncommon.

In truth he wouldn’t need to run the generator eight hours a day, doing so would guarantee him a full, absolute 100% charge though, every single day and he doesn’t need that. He could run it just a few hours a day, then once or twice a week a long run to get to 100%, then after the trip is over, equalize and leave on float until the next adventure.

[a64pilot]

What may be of interest would be to find out how the honest to God real expedition boats handle their electrical demands, I think you would find more have a lead acid bank and run a generator long hours, more than you think.
Reason I think that, even though I have zero experience with them, is that the most important thing for a Boat like that is reliability, and lead is a known issue, low risk.

[tanglewood]

Originally Posted by a64pilot

What may be of interest would be to find out how the honest to God real expedition boats handle their electrical demands, I think you would find more have a lead acid bank and run a generator long hours, more than you think.
Reason I think that, even though I have zero experience with them, is that the most important thing for a Boat like that is reliability, and lead is a known issue, low risk.

We are building what I would consider to be a small scale expedition boat, and you hit the nail on the head. Reliability and redundancy are super, super important. This was the hardest thing to get comfortable with in taking on LFP.

[john61ct]

My use case is sailing, rarely motoring, minimize any ICE hours to as few as possible, try not to be too dependent on electricity,

liveaboard off-grid, rarely on shore power, many would call camping lifestyle, no home-style mod cons.

So yes, not an "expedition boat".

[john61ct]

Originally Posted by Paul L

So you only need to set these up a few times a week

Well that's enough to prevent lead's PSOC problem.

Assuming no mounted solar, or sometimes more needed.

> and don't find it to be a hassle to do safely while cruising?

I don't see how safety comes into it, like putting out a little blanket, not big, not heavy, not breakable.

Not a rigid schedule, put it off for another day if you want

Remember not actually adding many AH, just getting the long tail down to endAmps.

[Paul L]

Originally Posted by john61ct

Well that's enough to prevent lead's PSOC problem.

Assuming no mounted solar, or sometimes more needed.

> and don't find it to be a hassle to do safely while cruising?

I don't see how safety comes into it, like putting out a little blanket, not big, not heavy, not breakable.

Not a rigid schedule, put it off for another day if you want

Remember not actually adding many AH, just getting the long tail down to endAmps.

Have you ever dealt with an anchoring CF during a thunderstorm or frontal passage. Securing the large deck items is important.
Good to know that it works for your cruising using them only occasionally. How long have you been doing this?

[Dockhead]

Originally Posted by tanglewood

I paid a little under $1000 for 180ah @12v CALB cells. So that’s within spitting distance of Firefly at $500 for 100ah @12v

And that's per NOMINAL a/h, right? I think lithium has a bit more usable/nominal doesn't it?

[tanglewood]

Originally Posted by Dockhead

And that's per NOMINAL a/h, right? I think lithium has a bit more usable/nominal doesn't it?

Right for the LFP. The 180ah is the nameplate rating, so figure you will effectively use 70% to 80% of that.


I assume the Firefly is also a nameplate rating, but I don't know what's practical to use on them. I gather it's more than the typical 50% one would plan for other LA types. But don't know if it can realistically go as high as 70% to 80%.


I think this was John's comment earlier, that comparing usable capacity, the LFP is cheaper. But to be fair, the LFP number is for cells only and doesn't include the cost of a BMS. So all-in I expect LFP is more expensive. But I have paid very little attention to CF since it seems an intermediate step. I'm working from a blank sheet of paper, so going straight to LFP with a power system designed for LFP I think makes more sense in my situation. For more of a retrofit, I can see the attraction to CF. But I am also a skeptic and they aren't proven out enough yet for my taste. LFP is quite proven at the cell level. BMSs are a moving target, but I can control that myself so willing to take on that risk/task.

[john61ct]

Sorry what is CF?

[tanglewood]

Originally Posted by john61ct

Sorry what is CF?

Carbon Foam, aka FireFly

[rgleason]

If not drop-in, a 4- or even 8- pack of CALBs fits in a Pelican case.

https://www.electriccarpartscompany....fied-Batteries

Nice idea well executed but 4 x $260 = $1040 plus the case and all the fixins.
Not cheap for 100ah.
40+ lb portable.

Deceptively simple statement. Not a real choice for most people


https://www.entropypool.de/2015/06/0...-battery-pack/
Cool, connect it to a cheap electric trolling motor.
Great diagram +$200 for the BMV 700

[rgleason]

LFP won't work in the cold climates you cruise.
Another post in response:
LFP, at least the Winston ones, work fine in Arctic conditions. It seems to me that a majority of the expedition boats I met are using them. Any LiFePo can be charged down to 0C, and the boat can't get colder than that unless you are overwintering and frozen into the ice. The Winston cells are supposed to be good down to -20C.

I don't know what to believe at this point.

I get the impression a lot of these comments are coming from users in relatively warm climates all year round.

Some of these elegant and highly technical lithium installations which look so beautiful, are not intended to be removed every fall. In fact they are relatively permanent installations. If these batteries are left in place over winter where it can get down to -10F + wind chill, what can be done if no shore power lines are allowed to the boats by the yard?

I suppose they are left at 50%SoC and then they have to be checked every week (not possible). I am not at all sure this is a practical situation.

[a64pilot]

Assumption is that LFP is primarily a full time cruising thing, if your way up North and haul every winter and allow the interior of the boat to go sub zero, that’s not full time cruising.

Other than having to work, which of course puts a hurt on the full time cruising, I can’t imagine voluntarily living where it gets below zero degrees?
But then I’m allergic to cold.

[hellosailor]

"I can’t imagine voluntarily living where it gets below zero degrees?"
No snakes, NO MILDEW, no mosquitoes, no zika or yellow fever, no gators, no lizards, once you zip up your parka, you are always comfortable and dry inside. Some folks complain about the cold, others have learned to dress for it. It does make changing your oil a bit inconvenient, true. And AFAIK there's no real way to keep a holding tank working once the water starts getting hard.

Compare and contrast to the folks who live in high heat and humidity (ugh!) with critters of all kinds, heavy rainfalls, lightning and thunderstorms almost daily, tornadoes...

There are reasons that so many of those "nice warm places" had lots of cheap real estate until well after air conditioning became common.

And, the downhill skiing in the Carolinas, Florida, the Carib, well, it tends to ...wait, i can't use that word here, can I?(G)

[tanglewood]

Originally Posted by rgleason

https://www.electriccarpartscompany....fied-Batteries

Nice idea well executed but 4 x $260 = $1040 plus the case and all the fixins.
Not cheap for 100ah.
40+ lb portable.

I'm not following. The 100ah cells in your link cost $129 each, so 4 of them is $516. It may still not be anything you want, but the cost is half what you said.