1400 Ah Lithium from cells

[travellerw]

Good article..

However.. I'm simply Gobsmacked by the size of you bank and power draw. You numbers just seem really big to me. Our family of five with tons of toys, doesn't come anywhere near those numbers.

[BambooSailor]

The difference is the lead batteries are very forgiving compared to LiFePO4.

It's the other way around. You can destroy most lead acid batteries with one single discharge below 50%, or sulfate them in a few months if not charged properly. It will take much more abuse than that to destroy LiFePO4 battery.

[CatNewBee]

Originally Posted by kmacdonald

The difference is the lead batteries are very forgiving compared to LiFePO4. Large commercially available LiFePO4 banks with BMS were well over $5k. I'm not sure anyone is still offering them. Too many failures.

Well lead acid are not so forgiving as you might think. if they stay deep discharged they sulfate, if the cell dry out on wet batteries they get irreversibly damages and they have a 10 times shorter life expectation / cycles. Regarding large commercially banks - that's the reason we build our own banks by the way. There are some - like the Tesla power wall - but this are LiPo's like the ones in your tablet / notebook - too dangerous for my taste. Also some cars use LiPo / LiFePO4 around the world, so there is commercial use of high capacity cells for energy storage and propulsion.

[Davidhoy]

Originally Posted by CatNewBee

...but this are LiPo's like the ones in your tablet / notebook - too dangerous for my taste...

LiFePO4 are not the same and the LiPo's using in tablets and phones. You're not going to have a Galaxy Note 7-style fire on your hands with LiFePO4 batteries, they are much safer than other lithium battery chemistries.

-David

[CatNewBee]

I know, the LiFeYPO4 are even safer (less Lithium) and they charge in sub-zero temp's (operation range -45 ...80°C)

[nebster]

Originally Posted by exitstrategy

I was actually very concerned about this potential hazard, so outside I experimented with very briefly shorting a terminal across a single cell, and across a 4s and even across a parallel.

Ha, that's great that you did this! A lot of LFP cells have pretty high IR, perhaps on the order of lead acid. Greater IR dramatically reduces the amount of energy that can be dumped per unit time.

My (small) issues have all come at 16s, and I suspect voltage is a contributor there. Bigger arcs, harder to quench.

In other words, I believe that kids are much more capable than modern society has normalized.

I completely agree. Except when there are members of the opposite sex around.

The relay in the background is the power hogging one for LVD. As it was upstream from all other instruments I could only hazard a guess of its consumption based on how quickly it drained the much smaller portion of the parallel net that it was wired into on the first wiring. But on the order of 10-15 Ah

Hmm, can't quite read a part number on that guy.

15Ah per what? Per day? If so, that's 180Wh per day or about 7W continuous, which is pretty high. You should be able to achieve about 2.5W for a single 500A continuous-rated. Your diagram shows a dual bus, which would double that of course.

If you're willing to forgo the safety factor of the contactor automatically opening the circuit if it loses power (true fail-safe), you can use a latching relay and get zero consumption.

Another option is FET switching, which is very low consumption but more expensive. Victron has a couple of (one-way) switches with a pack-level monitor on board as a a bonus. I think theirs only go up to about 200A, though.

Yes, you are correct using the active BMS, I thought that this would give me better daily performance and peace of mind, and pro-long the need for me to go and pull it all apart for a periodic re top-balance.

Especially given your dense matrix of parallelism, that might well be true. It would be great if you would keep us updated over the course of time.

[nebster]

Originally Posted by kmacdonald

The difference is the lead batteries are very forgiving compared to LiFePO4. Large commercially available LiFePO4 banks with BMS were well over $5k. I'm not sure anyone is still offering them. Too many failures.

There are still commercial LFP packs available. Check out Lithionics, for example.

[nebster]

Originally Posted by kmacdonald

Don't get me wrong, I love the light weight, fast charge, deep cycle ability, and being able to be stored at PSOC that LiFePO4 offers but is it really up for prime time to the average cruiser?

It's probably not ready for primetime for the average cruiser. The average cruiser can't justify the cost of an end-to-end engineered system, and the average cruiser just trying to drop an LFP pack into an existing system will have poor results.

[Davidhoy]

Originally Posted by nebster

It's probably not ready for primetime for the average cruiser. The average cruiser can't justify the cost of an end-to-end engineered system, and the average cruiser just trying to drop an LFP pack into an existing system will have poor results.

If you run the numbers, LiFePO4 batteries are actually cheaper in the long run. They can handle a lot more charge cycles than FLA or AGM batteries, and when you factor in that, and add the cost of semi-regular FLA/AGM replacement, LiFePO4 comes out cheaper. Yes, more expensive initially, and a little more complex than FLA/AGM, but there's always more to the story.

-David

[nebster]

Originally Posted by Davidhoy

If you run the numbers, LiFePO4 batteries are actually cheaper in the long run. They can handle a lot more charge cycles than FLA or AGM batteries, and when you factor in that, and add the cost of semi-regular FLA/AGM replacement, LiFePO4 comes out cheaper. Yes, more expensive initially, and a little more complex than FLA/AGM, but there's always more to the story.

Oh, I'm with you, David. They definitely crossed the chasm into sensible a while ago.

For an "average" cruiser who just wants to ignore their electrical system mostly, though, I don't see a clear path forward without an end-to-end circuit designed around them. This chemistry demands proper charge control, thermal management, disconnects, and the rest. I don't think anyone is offering a complete ecosystem of components to provide an install-and-forget experience for an "average" cruiser.

I suppose it is possible that my guess at "average" is shooting too low.

[Davidhoy]

Originally Posted by nebster

I suppose it is possible that my guess at "average" is shooting too low.

Is there any such creature as the "average" cruiser? ;-)

[CatNewBee]

Originally Posted by nebster

I don't think anyone is offering a complete ecosystem of components to provide an install-and-forget experience for an "average" cruiser.

I suppose it is possible that my guess at "average" is shooting too low.

The opposite is true, EVERYBODY is offering eco-systems, but they are not interchangeable / compatible to each other. Mastervolt has one, Victron too, then Lithionics, SuperB and all the others. They slice the market among them, you must bet on one system and then stick with it with all other components. All components talk to each other, are nicely integrated, but every company talks their own language, own protocols, own buses - no standards out there yet.

[kmacdonald]

Originally Posted by Davidhoy

If you run the numbers, LiFePO4 batteries are actually cheaper in the long run. They can handle a lot more charge cycles than FLA or AGM batteries, and when you factor in that, and add the cost of semi-regular FLA/AGM replacement, LiFePO4 comes out cheaper. Yes, more expensive initially, and a little more complex than FLA/AGM, but there's always more to the story.

-David

If nothing goes wrong but that hasn't been the case for most installs.

[kmacdonald]

Originally Posted by BambooSailor

It's the other way around. You can destroy most lead acid batteries with one single discharge below 50%, or sulfate them in a few months if not charged properly. It will take much more abuse than that to destroy LiFePO4 battery.

Interesting comment to say the least.

[Ip485]

While on Lithium generally and having had a few problems with my AGM I am considering replacing the house bank with Lithium. The house bank is 700Ah, and a Mastervolt Lithium charger seems a a good charger, rated 100AH at 14.4V with the ability to charge an engine and Bow Thruster conventional battery.

Two questions, running the Lithium perhaps down to 10% what would be the expected charge time,

and

I also have an Outback solar controller - could this be coupled directly to Lithium in same way as it is to my AGMs?