LiFePo4 House Bank Using SmartHousePower BMS

[Whimsical]

Li-ion batteries are very well understood. The main problem seems to be that people cherry pick facts to support thier arguments either in support or against. There are many chemistries all with advantages and disadvantages.
Maybe listen to a specialist scientist before jumping to too many conclusions.
Robotics Institute: Videos

Warning it is 75 mins but highly informative

[goboatingnow]

Originally Posted by Pblais

Li-ion batteries start to degrade if you use them or you don't from date of manufacture. So for laptops the batteries are always toast in 2 years no matter what you do. The sad truth is there are multiple issues competing with multiple demands.

What we all want is a battery that can be abused beyond your imagination and have an acceptance so high you can charge it on a single bolt of lightning and cost less than nothing. With the issues of cost vs. performance both being argued there is still the final issue of the supply of the worlds Lithium. If Li based technology is the the key then the price will surely drive up the cost to very high levels. The known supply isn't all that great.

As long as electric cars are still a fad the price for Li based batteries is assured to skyrocket. This alone will spawn even more unfounded claims. There is no way to supply the charging required to fuel electric cars. Boats have no status in the overall issue of power in a world perspective. Cell phones use almost no power and in the areas of technology where minimal power use is key, Li technology has already been eclipsed yet still cost effective. The key is using less power to find better sources to supply more power. RV's using LiFePo batteries is the ultimate oxymoron. Boats are not far behind. It only really works if most users don't use them because there isn't enough to supply most applications. Even if some miracle should happen there is no way to charge them all. At best they offer the folks that can afford them the ability to be a lazy. Money can always buy that much.

This is a rather un-informed rant. Charging sources will improve as the need for them arises. EV is not a fad, we haven't many other choices.

LFP is not an oxymoron. Why not use a more efficient more robust and higher performing battery system.

Dave

[jlubimir]

Electric1-

Have followed all the threads (here and on the DIY EV circuit) for several years. I was one of the fortunate ones who did not get burned by EV Components (while David Kois was still there) when I bought my Thundersky batteries. I have the following installed:

(1) TS LFP 200Ah for the genset
(1) TS LFP 200Ah for the diesel
(3) TS LFP 200Ah for the house side (total 600Ah)

Charging system:

100A Balmar externally regulated alternator on Yanmar Diesel engine;
100A charger (Freedom 20) with Xantrex Link 2000 monitor powered either by shore connection or by 4Kw genset.

I adjusted the external regulator to max voltage at 15.1V. I had to "spoof" the Freedom 20 by changing the temp profile to 30 degrees for LA batts to get the LFP batts charged to 14.8V using that charging method. Batteries charge up to "max" under either method and then almost immediately settle to 14.4V with any load.

I initially had some inexpensive shuts installed on each cell but removed them when one failed and a cell died and had to be replaced (just when EV Components failed). Since then I have had NO BMS and have had no issues with the batteries.

I routinely leave all batteries connected together in parallel or if I am going to be extending the time between charging, isolate the engine battery just to be safe. I routinely put a multimeter on the cells to check for imbalance and have found no material differences (<= .15V). Max discharge rate (with electric winches or windlass) is about 40A for periods of 30 sec on winches and 90A for 2 min on anchor windlass, well under .5C rate. I NEVER let the battery voltage drop below 12.8V (3.2V per cell) since I understand that the quickest way to "kill" an LFP battery is to take them below 2.5-2.6V per cell.

Previous crusing profile was long weekends (up to 2 weeks) and occasional races ( up to 72 hours).

This year I did the Bermuda 1-2 Race from Newport to Bermuda and back and again the batteries performed flawlessly (Average of 90 hrs each way, using an ave of 14-18a per hour, depending upon how hard the autopilot was working). (Genset and engine batts were isolated from house side for the race). I charged only 3 times for 3 hrs each from genset.

Am now cruising full time (Maine this summer and points south this winter) and, although I watch my batteries very closely, I would like to accomplish two objectives:

1. Decrease charging time when using the genset, even though it burns only .45 gph; and

2. Add proper BMS for LVC protection (3.2V) and indiv cell HVC protection (3.75V)

Please send me details specs on your BMS. My alternative is the Manzanita boards David Kois is currently selling thru Current EV Tech. Also, do you have any recomendations on a brand of inverter/charger which puts out > 100A DC from a 120V/ 30A AC source to reduce Genset run times? (Charging time is not a problem when using shore power overnight or motoring for several hours.)

Lastly, do you think I should dial back my voltage regulator for my engine-driven alternator to say 14.8V since the batteries settle to 14.4 anyway?

I would be willing to share any other information on my 2 yrs of cruising experience using the TS LFP batts. that might be helpful.

[goboatingnow]

Great experience and backs up my own measurements as regards cell balancing and BMS on large format cells.

As to LVC there are several low voltage battery disconnect systems on the Market.
( mastervolt)

As to HVC in reality how can you generate HVCs

Dave

[s/v Thea]

I would reduce voltage, at 15.1v minimum voltage on cell is 3.775. I have mine set to 14.5 and highest cell is about 3.67.

Doug

[Marqus]

Originally Posted by jlubimir

I NEVER let the battery voltage drop below 12.8V (3.2V per cell) since I understand that the quickest way to "kill" an LFP battery is to take them below 2.5-2.6V per cell.

Thanks for the nice write-up jlubimir, very instructive.
I don't have LFP experience, but am keenly looking at the options.

Referring to my quote above, may I ask a very elementary question:

Hypothetically, given a 100AH LFP battery being cycled between 14.4volt and 12.8volt limits (as you seem to indicate you do), how does that translate into Amp-hours delivered by the battery?

For example, it could be that 14.4volt represents 90AH (let's say it was not 100% charged, or can you say that for LFPs?), and 12.8volt represents 20AH left over, thus it delivered 70AH with every cycle.
But these are just my imaginary numbers - can you please relate the "real" numbers for such cycling use just for forum member's education, if you know them? Or alternatively, just your best guess from experience?

Thanks

[Whimsical]

Sky energy 100AH
At .5c discharge rate and 25 degrees C there is bugger all left after 3.0V, under 10%. Thats what i will be setting mine at

Bugger the graph didn't paste, look here
http://www.thunder-sky.com/pdf/201121921736.pdf

[T1 Terry]

Originally Posted by Pblais

Li-ion batteries start to degrade if you use them or you don't from date of manufacture. So for laptops the batteries are always toast in 2 years no matter what you do. The sad truth is there are multiple issues competing with multiple demands.

What we all want is a battery that can be abused beyond your imagination and have an acceptance so high you can charge it on a single bolt of lightning and cost less than nothing. With the issues of cost vs. performance both being argued there is still the final issue of the supply of the worlds Lithium. If Li based technology is the the key then the price will surely drive up the cost to very high levels. The known supply isn't all that great.

As long as electric cars are still a fad the price for Li based batteries is assured to skyrocket. This alone will spawn even more unfounded claims. There is no way to supply the charging required to fuel electric cars. Boats have no status in the overall issue of power in a world perspective. Cell phones use almost no power and in the areas of technology where minimal power use is key, Li technology has already been eclipsed yet still cost effective. The key is using less power to find better sources to supply more power. RV's using LiFePo batteries is the ultimate oxymoron. Boats are not far behind. It only really works if most users don't use them because there isn't enough to supply most applications. Even if some miracle should happen there is no way to charge them all. At best they offer the folks that can afford them the ability to be a lazy. Money can always buy that much.

Hello,
I was lead to this forum from another forum in Australia, the caravanner forum. I have been conducting a number of tests on LiFeP04 batteries, in particular Winston LYP 90ah cells for house battery use in motorhomes, a similar use to what full time boat living is like I guess.
The claim above made me join and say something because it appears a few different chemical technologies are being thrown in one basket here. I have 80 LYP/LFP cells that I bought in one lot from an Australian supplier, nearly 1/3rd of them are date 03/07/2009, the rest production date 25/03/2011. Out of the packing case the terminal voltages are approx. 5 millivolts between the new cells and the older cells. They don't die if they aren't used, infact they don't self discharge below 50% capacity it appears. The manufactures appear to be well aware of this and they ship them with a 50% state of charge.
Another thing that has set off alarm bells is the voltages I see these cells are being charged to, too high and you will shorten their life.
LYP and LFP cells are fully charged at 3.4v per cell, after this point plating starts to occur on the cathode and anode seriously reducing their capacity to accept and release energy, this damage is not reversible. I have established that a safe charging voltage of 13.8v seems to work well for a 4 cell battery, this stops charging just as the rapid voltage rise begins to occur when the battery is fully charged. This requires a voltage control charging regulator, I'm using a Plasmatronic PL20 with solar panels but any voltage control regulator will do the same job. When the cells are full the current stops flowing but the rate of charge acceptance is much higher than with lead acid.
Price, I have no idea what quality AGM batteries sell for in other parts of the world but in Australia the quality stuff like Ritar, Lifeline, etc if a 50% DoD (depth of Discharge) useable capacity for decent cycle life is compared to the 80% DoD of LYP/LFP cells then the lithium battery is actually cheaper. For example a 150ah Ritar would have a 75ah useable capacity and costs AU$550, 4 X Winston LYP90ah cells would have a 72ah useable capacity and costs AU$504. I'm sure all the other advantages of LYP/LFP cells have been listed else where so there's no point in going back over that ground.
If anyone is interested there is a thread over here [url]http://www.caravanersforum.com/viewtopic.php?f=2&t=17128[/url] about the tests so far.

T1 Terry

[sytaniwha]

Jlubimir,

Regarding your question about inverter/chargers: I am using a Victron charger for my shore power charger for my 4* 400Ahr (12v nominal) CALB LiFePO4 battery. I find them to be very reliable, exceptionally well designed and made, and their charging characteristics are totally programmable (depending on the model).

I'm also using Victron inverters.

Regarding T1Terry's comments on the price, I am currently in SouthEast Asia, and I also found that buying the LiFePO4 cells was about the same price as buying good quality SLA batteries (Trojan, Rolls, etc), and as my post on another thread just said, I'm not finding any need for a BMS in my cruising yacht house battery application. (I'll also copy that post to here.)

Cheers,
Paul.

[sytaniwha]

This is a copy of my post on the "LiFePO4 Batteries - Okay Tear me Apart" thread. I notice that the video link is redundant as it has already been posted on this thread.

Hi,

Below is a description of my 400Ahr LiFePO4 bank using 4 * 400Ahr CALB cells for the house bank of our 46ft cruising yacht, plus a link to an interesting video on LiFePO4 charge/discharge characteristics.

McG you may find this link interesting of a video by a Carnegie Mellon Robotics Institute PhD talking to a group of electric car enthusiasts about LiFePO4 charging and conditioning.

Robotics Institute: Videos

He recommends an initial charge/discharge cycle with your cells all in parallel, and stopping at a well defined curve point (e.g. very near full charge or full discharge), to initially ensure all your cells are at a very similar SOC. This is a step further than the good advice offered to you by Electric1.

Also, some of the earlier posts recommend matching your cells for capacity and internal impedance very closely at the factory, and I also think that is critical.

I purchased 4 * 400AHr cells off CALB direct earlier this year, and asked them to match as closely as possible. When they arrived, with the equipment I have I couldn't measure a difference in capacity or impedance, and parallel charge/discharge showed no imbalance (by monitoring individual cell current).

I was also very impressed with CALB's customer service. The sales person still contacts me every few months to see how the cells are, and answers tech questions very quickly.

I run the cells as a 12V (nominal), 400 Ahr bank. They replaced a 600Ahr Trojan SLA pack, and provide more useful energy per discharge. Another side benefit is that I don't have to worry about self-discharge ruining the cells when I leave the boat for an extended period.

I'm currently charging using a 120A alternator through a Sterling Power regulator, and a Victron 50A galvanically isolated mains charger. Both can have their charge parameters changed to fit the ideal charge curve for whatever brand of LiFePO you're using (I note that different brands have some quite significantly different charging parameters).

I use a Vetus Battery Watch unit which controls low voltage cutoff at the pack level to the consumers. Combined with the high voltage cutoff provided by the charge sources, this produces the sensible separation between charge and discharge as suggested by OceanPlanet (i.e. after a low voltage cutoff, the cells can still be charged, whilst a high voltage cutoff doesn't remove the ability for the consumers to draw power from the battery).

I was originally going to add a cell-level BMS, but agreed with GoBoatingNow's comments back in Mar/Apr 2010 that cell level probably isn't necessary for a relatively low current situation (like a typical cruising house bank), especially when there are only a few closely matched cells (4 in my case). My usage thus far supports that view, so we'll see how it goes in future.

I figured that as worst case I might have to do a parallel charge/discharge cycle manually on an annual basis to realign the cells, but I can't detect any drift thus far, so that may not even be necessary.

Anyway, I hope that this info helps some people. Also, thanks to those of you (Gael & OceanPlanet spring to mind) for starting to put real user data on this post - I find it helpful, and gives me areas to think about. Actual user data and experience trumps manufacturers' propaganda and people's general conjecture every time.

Cheers,
Paul.

[sytaniwha]

Does anyone have an interest in moving the discussions from actual users of LiFePO4 cells to a new thread so that we don't have to bounce between this thread and the "LiFePO4 Batteries - Okay Tear me Apart" thread (I don't know which one to post real information and questions to any more)?

Also, both of those threads have been hijacked at times by people debating the merits (or not) of Li technology. To be honest, although some of those discussions are interesting to read, I can't be bothered wading through the "back & forth, back & forth, back & forth........", sometimes long winded hyperbole, which seems to become more vitriolic with each post (on both sides of the argument). Some of these exchanges feel more like boozy dinner party debates about religion or politics.

What I'm most interested in is having discussions with actual users of these batteries in sailing yacht applications on their observations and experiments, with a focus on real use situations and actual data.

It seems to me that there might now be enough of us actually using these cells in real life sailing situations to make a long running thread just for us.

Anyone interested?

Cheers,
Paul.

[sytaniwha]

Ok,

So I just started another thread for users of LiFePO4 cells. Hopefully enough of us who are actually using LiFePO4 will find it useful and it will precipitate some useful sharing of real data and findings.

http://www.cruisersforum.com/forums/...rum-65069.html

This is an exciting technology, and hopefully we can help each other work through our solutions.

Cheers,
Paul.

[electric1]

Originally Posted by T1 Terry

LYP and LFP cells are fully charged at 3.4v per cell, after this point plating starts to occur on the cathode and anode seriously reducing their capacity to accept and release energy, this damage is not reversible. I have established that a safe charging voltage of 13.8v seems to work well for a 4 cell battery, this stops charging just as the rapid voltage rise begins to occur when the battery is fully charged.

What makes discussions about Li batteries confusing is that people refer to voltages without relating to state of the battery at the time voltage is measured. Such states are - charging ( at what C rate? ), discharging ( at what C rate ? ), resting ( for how long since last charge/discharge? ). Without answering these questions your voltage reading is utterly useless.

For example, its true that 3.4V is a fully charged cell, but only if its resting voltage, several hours after charge is done and no load has been applied. Same 3.4v while charging indicates that cell is far from full, how far depends on C rate of charging.

Statement that plating occurs in the upper "knee" is plain false, I have never seen any data indicating such. In my experience, no LiFePO4 cell damage occurs under 4.0V, and even higher on yellow cells ( aka ThunderSky, or Winston, or Sinopoly , whichever name you prefer, they seem to like rebranding their product often ). While there is no point in reaching the top voltage regularly because there is no useful energy at the top, its not the same as saying that damage occurs. No one in their right mind would produce a datasheet stating 3.85V or 4.25V if there was ANY amount of plating at those levels.

[electric1]

For naysayers, while its not possible to convince you of anything since your mind is already made up, I attach NASA paper of using Li batteries in space application, which is probably most demanding ever.

Also, LiFePO4 has been around for over 15 years in the lab and over 10 years in production, its NOT bleeding edge anymore. Patent laws and corporate greed prevent large Lead Acid producers from switching to Li, which eventually will put nails in their coffin, while new suppliers, albeit unproven and not all honest, will keep growing and earning their reputation.

My own EV with TS cells produced in August of 2008 has been on the road since June 2009, used and charged daily, about 700 cycles so far. Cells behave today just as well as 2 years ago, despite my intentional abuse on a few occasions ( for learning purposes ). There seems to be virtually no degradation so far.

You can wait 10 more years for lab testing or you can just use them today and be your own tester. Those who wait for new stuff just around the corner, never actually experience new stuff, which is OK for most people. Just like any other aspect in life, you can take more or less risks, to each their own.

As for all the excitement in the news based on "breakthru" in battery technology, it takes 5-10 years to production and only few "breakthru"s turn out to be practical for production. So, by the time next thing is in store, my LiFePO4 pack will have enjoyed a nice life and be happily replaced.

I can't upload NASA's PDF, its too large, I'll try to find a link to it...

[electric1]

Found it

http://ntrs.nasa.gov/archive/nasa/ca...2009023573.pdf

I would say that any statement that any Li chemistry, including LiFePO4 is "poorly understood" is absurd. Small disagreements between vendors regarding charge/discharge management can be explained easily, since there are various Li chemistries , various applications and C rates, various environmental conditions. Management can be fine tuned to better adapt to those variations, but general approach is the same across the board. Its no different than variations in Lead Acid world ( FLA, SLA, VRLA, AGM, etc ), each one has unique flavors to better suite application. If you make poor choice of solution for your application, you end up with dead battery or worse. Same goes for Li.