Best New House Battery

[seeker321]

Diving in here on the battery debate....

Imnsho, LiFePO4 is, by far, the most rational choice for storing energy. I've been running a 720Ah Genesun pack now for almost four years. I say that with one of my packs hard down -- so only have 360Ah useable at the moment. Why one of the packs is down isn't fully determined yet, but I do know that one of my cells was spewing yellow powder. So guessing I need a coupe or more replacement cells.

I'm not stressing because the (excellent) Genasun BMS has long ago cut this pack out from both charging and discharging.

Warranty/support? What's to warranty? It's no different, really, than 6-volt golf cart batteries, 'cept the LiFePO4 cells are 1/3 the wright -- and, therefore, 1/3 the shipping cost to get replacements.

Probably the only REAL hassle is that I'm in Guam, and the bloody USPS refuses to ship Lithium batteries, so will have to use UPS or FedEx to ship replacements at 3x the price <grrrr>

So, why LFP -- for ANY boat? Weight. The ONLY place for lead (at least on monohulls) is at the VERY bottom of the keel. Anywhere else, it's parasitic. I'm on a mid to high performance ocean catamaran (chris white Atlantic 55) -- and ANY excess weight is parasitic. The LFP program allows weight savings across a broad spectrum. First, obviously, is the actual weight of the batteries. But, that's the LEAST significant weight savings. Given that the LFPs can (theoretically) charge at somewhere between 2.5 and 3C -- 'till absolutely full -- I spend WAY less time burning hydrocarbons to charge. In my case, I have two x 270 amp alts -- so less than 1C charging capacity. When there's zero solar (rare), I MAY have to fire up the charging source every couple of days for about 45 minutes to an hour to keep the system topped up.... That means that I need to carry WAY less fuel -- and this saves WAY more weight than the actual batteries!

I'll NEVER go back to lead. I'll be replacing my starting batteries next -- and add in the stock alternators to the above 270s and echo charge the the start batteries off the house. Even less running time for the engines

By the way, I live aboard full time. In VERY remote places. No second thoughts about this technology.

It's simply the best choice.

Oh, lastly, economics. I don't know if I'll get 3,000 or 5,000 cycles -- or perhaps even more. I DO know that as I get closer to the end of this limit, I'll still have LOTS of capacity left Nd -- in the same time frame would likely be on my third or fourth set of AGM batteries -- so, are LFPs REALLY that much more expensive?

 

[Maine Sail]

One thing the jury is still out on regarding LFP is the life of the battery expressed in terms of years, rather than just cycles. There is no doubt they will do many many more cycles than lead, but over how many years? IE how much will the capacity shrink just due to ageing. If you do 1000 cycles in 2 years and they are still at 95% capacity, what would the capacity be in 10 years with 1000 cycles? S

I'm not sure how one could possibly do 1,000 cycles in two year.! Assuming you discharge your LFPs enough in 24 hours to justify charging (hard to do if you have a decent bank) -- 365 charges per year over two years is only 730 cycles..... Just sayin'!

I have been doing accelerated cycle testing now for over two yars and am only approaching cycle 600. This is hard work...

My four 400Ah Winston cells (Thundersky) were manufactured on September 6, 2009. I bought them knowing they were used and possibly used for testing purposes. I got a great deal and specifically bought them for my own education and experimentation, use on our boat was secondary.... I have no idea what was done with them before I got my hands on them nor how many cycles they were put through.

What I do know is that in 550+ cycles, since I got them, the capacity has not changed much and I can still exceed the as new 400Ah rating at .25C which is approx 9X more than our average on-board loads...

The last cycle test, using some new and more accurate equipment at cycle 550, yielded 419 Ah's until the lowest cell hit 2.8V. This is charged to 13.8V and less than 10A of accepted current at 13.8V. Some even go so far as to argue that 13.8V is not full.... I don't consider this too bad for 2009 batteries and 550 cycles, most to 80% DOD. Shelf life seems to have not impacted these cells too badly, but perhaps a little...

In over 550 cycles I've noticed no real meaningful capacity difference, perhaps a 10Ah change. Every 50 cycles they are fully capacity tested so that I can keep track of performance. Most of the cycles have been to 80% DOD with 11 to capacity tests to 0%. Each of the first ten capacity tests were done identically including temp, constant load, charge current and current taper cut off.. From cycle 550 on they are being tested with a lab grade DC constant load that very, very accurately can count Ah's and time.

Based on the claims of some on LFP shelf life I should be seeing approx a 200Ah's capacity based on age alone? I know a nuber of guys with these same cells and some have over 1000 cycles on them in off grid applications. I am still measuring and able to draw in excess of new rated Ah capacity with cells that are 5.5 years old. These cells were rated at a .5C rate newer ones are rated a 1C but the Peukert is so low it really only makes slight differnces capacity, other than the duration of the test...

I fully expected them to have fallen off the cliff by now, but they have not... Clearly I must be doing something wrong...

With all that said LFP is still not prime time ready for the masses, at least IMHO........

Capacity test #11 @ cycle 550 end of charge:

Completed test 419.2Ah's @ 30A constant load:

 

[DDW]

I say that with one of my packs hard down -- so only have 360Ah useable at the moment. Why one of the packs is down isn't fully determined yet, but I do know that one of my cells was spewing yellow powder. So guessing I need a coupe or more replacement cells.

....

Oh, lastly, economics. I don't know if I'll get 3,000 or 5,000 cycles -- or perhaps even more. I DO know that as I get closer to the end of this limit, I'll still have LOTS of capacity left Nd -- in the same time frame would likely be on my third or fourth set of AGM batteries -- so, are LFPs REALLY that much more expensive?

While I am becoming a fan of LFP's, I'll have to guess you aren't going to get 5000 cycles on the pack that is spewing yellow powder and cannot be charged. If you get 5000 on the other, that is 2500 average before failure.

 

[seeker321]

I say that with one of my packs hard down -- so only have 360Ah useable at the moment. Why one of the packs is down isn't fully determined yet, but I do know that one of my cells was spewing yellow powder. So guessing I need a coupe or more replacement cells.

....

Oh, lastly, economics. I don't know if I'll get 3,000 or 5,000 cycles -- or perhaps even more. I DO know that as I get closer to the end of this limit, I'll still have LOTS of capacity left Nd -- in the same time frame would likely be on my third or fourth set of AGM batteries -- so, are LFPs REALLY that much more expensive?

While I am becoming a fan of LFP's, I'll have to guess you aren't going to get 5000 cycles on the pack that is spewing yellow powder and cannot be charged. If you get 5000 on the other, that is 2500 average before failure.

Well, sort of. My system is comprised of 2 x banks of 8 x 180Ah 3v cells.

The whole point of a good BMS is protection. What's likely happened is that one cell has gone bad on one bank. There is one BMS per bank -- and it separately isolates input and output. So, I have one bad cell. That's no big deal. I still have a completely functional DC system. The BMS did it's job and shutoff the bad bank. Drop in one or two new cells, series connect them for a day or two to let them all equalize, and I'm back in business.

What happens if one cell in your AGM battery fails? You replace the whole darn thing!

Yeah, I'm a little grumpy, but this is HARDLY a catastrophic failure!

 

[Maine Sail]

I say that with one of my packs hard down -- so only have 360Ah useable at the moment. Why one of the packs is down isn't fully determined yet, but I do know that one of my cells was spewing yellow powder. So guessing I need a coupe or more replacement cells.

....

Oh, lastly, economics. I don't know if I'll get 3,000 or 5,000 cycles -- or perhaps even more. I DO know that as I get closer to the end of this limit, I'll still have LOTS of capacity left Nd -- in the same time frame would likely be on my third or fourth set of AGM batteries -- so, are LFPs REALLY that much more expensive?

While I am becoming a fan of LFP's, I'll have to guess you aren't going to get 5000 cycles on the pack that is spewing yellow powder and cannot be charged. If you get 5000 on the other, that is 2500 average before failure.

Well, sort of. My system is comprised of 2 x banks of 8 x 180Ah 3v cells.

The whole point of a good BMS is protection. What's likely happened is that one cell has gone bad on one bank. There is one BMS per bank -- and it separately isolates input and output. So, I have one bad cell. That's no big deal. I still have a completely functional DC system. The BMS did it's job and shutoff the bad bank. Drop in one or two new cells, series connect them for a day or two to let them all equalize, and I'm back in business.

What happens if one cell in your AGM battery fails? You replace the whole darn thing!

Yeah, I'm a little grumpy, but this is HARDLY a catastrophic failure!

Have you spoken to Alex about this?

 

[DDW]

What happens if one cell in your AGM battery fails? You replace the whole darn thing!

Not hard to build an AGM bank from single cells, with BMS, still costs a lot less than LFP. Nevertheless, my next battery replacement will be LFP, if the AGM bank every wears out. 9 years old now but still going strong.

 

[seeker321]

Have you spoken to Alex about this?

Absolutely. They're awesome. I'm one of their earliest customers -- and while I'm long out of warranty, Alex has put an offer on the table for a complete new battery pack -- at a phenomenal price. The issue is shipping. A complete pack must go surface and I'm cruising the Pacific and don't want to remain in one place while waiting for a ship to show up....
I'll probably take him up on his offer once we're stopped somewhere for a couple of months (likely Langkawi). 'Till then, it's easy enough to airfreight in a couple of cells to keep the current pack going.

....which brings us back to the best inherent advantages of LFP -- weight! 1/3 the weight is 1/3 the shipping cost!

 

[Dennisail]

One thing the jury is still out on regarding LFP is the life of the battery expressed in terms of years, rather than just cycles. There is no doubt they will do many many more cycles than lead, but over how many years? IE how much will the capacity shrink just due to ageing. If you do 1000 cycles in 2 years and they are still at 95% capacity, what would the capacity be in 10 years with 1000 cycles? S

I'm not sure how one could possibly do 1,000 cycles in two year.! Assuming you discharge your LFPs enough in 24 hours to justify charging (hard to do if you have a decent bank) -- 365 charges per year over two years is only 730 cycles..... Just sayin'!

The figure was purely academic. Maybe I should have said 730? The point is cycle numbers have been well established to be highly superior, but these tests have been done under accelerated conditions time frame wise. As time goes by we will see how many fail due to age even though the high cycles numbers have not been reached. So far it does look good.

I am a big fan of lithium by the way.

 

[solosailor]

Yes, you should be able to replace a bad cell in an existing pack as long as they are still in production.

 

[jerryj2me]

Plenty of boats, cars, RVs, planes burned down from lead acid batteries too. It's safest to stay in bed all day and don't touch anything with electrons in it.

good luck with that...

 

[SMBReno]

@Maine Sail: Having trouble reconciling your test results with your ending comment about LFP not being ready for prime time...

 

[Maine Sail]

@Maine Sail: Having trouble reconciling your test results with your ending comment about LFP not being ready for prime time...

Not ready in the sense that most owners are not ready for it or able to cope with its nuances.... It is a major undertaking to do right, fully understand, and there is no such thing as "drop in" LFP as much as some want to belive there is........ The technoligy is great but it is not your abusable lead acid.

 

[IStream]

Maine,

It seems to me that it's the function of the charge controller to make things simple for the owner. Assuming this is the case, is the issue that:
1. There's no charge controller yet sophisticated enough to make it simple for the owner,

2. Li technology is not understood well enough to design said controller,

3. Li technology is changing too fast to design said controller, or

4. Some combination of the above?

Thanks.

 

[Maine Sail]

Maine,

It seems to me that it's the function of the charge controller to make things simple for the owner. Assuming this is the case, is the issue that:

1. There's no charge controller yet sophisticated enough to make it simple for the owner,

2. Li technology is not understood well enough to design said controller,

3. Li technology is changing too fast to design said controller, or

4. Some combination of the above?

Thanks.

Really a combination of all the above.. The one most important aspect you left out is people want a Rolls Royce for the Kia price.. Very few are willing to invest in a properly executed LFP system yet they see that they can buy the cells for a similar price to AGM, but they don't want to invest in the rest of the system.

The Genasun system is done right yet everyone thinks they can build a system and use their existing equipment and beat the system if you will.. We've already seen numerous cells destroyed by DIY's who are trying to adapt lead acid mentatity to LFP. I have seen alternator fires on 7 figure vessels because even the boat builder did not get it.... LFP is an entirely differnt ball game.

Even some really, really smart guys have destoryed LFP by trying to adapt lead acid products to LFP, such as forgetting to turn off battery temp compensation on a solar charge controller and then not having a battery management system, wired properly, to actually do its job.

There is a lot that needs consideration:

A proper marine install requires a separate loads and charge bus, most baots are not wired this way

You don't "float" LFP

You never want to over charge LFP

You never want to over-discharge LFP

You never want to charge LFP above 115F or so

You can NOT charge LFP below 32F

You DO NOT temp compensate LFP for charging

The safe charge voltages for LFP are considerably lower than lead acid

LFP can throw tens of thosuands of amps into a dead short

LFP eats alternators for lunch

LFP is very votlage stable thus using votlage as an indicator of SOC is not useful

You need to ensure the cells remain in balance

You need to initially balance the cells

There is virtually no data for fractional "C" use

The list goes on and on but in short LFP needs to be done as a system approach and very, very few are willing to pay for that. I know this because I have stopped consulting on LFP builds due to owners insisitng on cutting corners. The only consult I did where the owner actually did it correctly & safely, is one of the smartest guys I know and perhaps the world best race boat navigator... He actually got it..... 1 success in approx 35 or 36 is not reason enough to continue consulting on LFP builds.....

For now if you want LFP I would stongly urge anyone to go Gensun. The system is well designed, beautifully executed and when installed, by a some one who knows how to install these systems, they are very, very good...

 

[Moonduster]

Maine Sail,

Come on, you know better than this.

LFP does not eat alternators for breakfast, lunch or dinner. There's no LFP installation that will do anything to an alternator that would not also happen to that same alternator used in conjunction with a very large flooded, gel or AGM bank.

The problem is with those alternators that are not designed to produce their full rated output for more than a few minutes. LFP is the symptom, the alternators are the problem.

And there are plenty of good alternators available that work just fine. Hint: none of them are painted white.

And to IStream:

You ask a general question about Li. There are many, many Lithium Ion battery chemistries. For a variety of reasons, mostly having to do with inherent safety, only LFP is in vogue for boats. And with LFP, none of those things you mention is true. There are suitable charge controllers and the chemistry is well understood and fairly stable in the supply chain.

There are at least two LFP solutions that work just fine off the shelf. The Genasun system - batteries, BMS and alternator regulator is pretty simple. The Mastervolt system is quite a bit more complicated and has more parts. Either system can be understood, installed and operated by a knowledgable cruiser. Both are beyond those who have a plug-n-play, out-of-sight-out-of-mind approach to life.

The real problems with any battery system (LFP, Flooded, Gel or AGM) is that there are myriad details and many components. The attention to detail and problems encountered with installation, commissioning and lifetime management are a bit beyond most boat owners. This is why we see so many dead batteries after so few cycles.

Fully integrated solutions cost a lot of bucks - but especially with LFP there's real return on investment if doing world cruising and/or long distance racing. Lots of people have saved a lot of money by cobbling together a reasonable solution from off-the-shelf parts. Lots more people have failed at that sport.

 

[Vincent DePillis]

Recently installed a 100AH Genasun battery, solar controller and BMS. Set up includes Victron battery monitor, and Solbian 120 watt solar panel, and a Pronautic 1220P charger. System designed, specced and wired by knowledgeable and certified marine electrician, who is the local Genasun distributor.

The lighter weight allowed me to install the battery in a different location. I think the system will be a great improvement in a bunch of ways. However, there is no doubt that the system is complex and eye-wateringly expensive.

I was a little surprised about the parasitic load of the various monitoring systems-- there is a steady .17 or so load just to keep the system going. There is some additional weight associated with the extensive control and safety gear. The relays in particular are kind of chunky. And the fancy programable charger is just over five pounds. And you need to find room for all that stuff.

I suspect that the parasitic load, weight, complexity and space requirements would be no larger for the 200 ah battery than they are for the 100ah unit. So the sweet spot is probably a 200 ah system.

It would be nice if there were a simpler and lighter set of integrated solutions for the 100 ah battery. One box that does the 120V charging, the battery management, and the solar panel control. They are all computer run-- seems like it would be more efficient to have one microprocessor do all three functions, with one display panel that can be remote mounted.

Pipe dreams.

slightly off-topic-- I installed one Alpenglow cabin light as part of this project, the one with a built in red light. SUCH an improvement over the OEM fluorescents--- a fraction of the draw, and MUCH nicer light quality.