Why not LiFePO4?

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  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: Why not LiFePO4?
    Reed wrote: »
    We have been cycling to 30 and 40% for a year now with a 720 amp-hour battery bank (12 V nominal). However, we seldom go below 20 or 30% unless we are running air conditioner or running. It is set as a 180 amp-hour 48 V nominal battery bank.

    Just so we don't get to confused, You have 4 - 4 cell batteries which are 12 volt (nominal) set up as a 48v nominal bank. I'm assuming this is what you mean? It's confusing to call represent them as 2 different "banks"
    Reed wrote: »
    Charge temperature 0 to 40 C, 32 to 102 F
    Discharge temperature -10 to 60C, 12 to 140 F

    My batteries live outside, but I think the pure size would allow me to find room inside.
    FWIW - The forklift Lead antimony batteries loose considerable capacity in the cold, for me it works out fine, since I use the large capacity during the summer, and need much less in winter.
    Reed wrote: »
    The battery box is 8" wide, 12.5" long, 13.5" tall (without lugs). Total weight with 180Ah cells is 63 lbs/ 28.5 kg. $1564

    So this is retail for a single 12 volt nominal battery made up of 4 cells?

    I understand where a single bank for RV use has lots of advantages, particularly if you often have 'shore power' or a generator if you exceed your capacity. Looks like it would take about 8 of these to match the usable capacity of a forklift battery of 800Ah at 24volt. Perhaps they make larger cells, if not they will some day. That and more use will drive the price down, the future looks bright. Love to consider them in 10-15 years when my lift battery gives up. I suspect the price will be half of what it is now and we will have some real feedback on the longevity of this innovative battery chemistry.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: Why not LiFePO4?

    Very nice article Swanney!

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • soylentgreensoylentgreen Solar Expert Posts: 111 ✭✭
    Re: Why not LiFePO4?
    feedhorn wrote: »
    You can only use about 25% of a GC-2's amp hour rating because the sun doesn't shine long enough to refill more than that amount so you should say they are more like $3/ah.
    Since LiFePO4 batteries last up to 5 time longer than GC-2's now they look more like $15/ah.
    I expect to make a $2000 profit by using LiFePO4 over its lifetime.


    I totally agree with you, and my next set will probably be LiFePO4s - the problem is (as I just experienced), brand new LeadAcids work great and are cheap:

    http://forum.solar-electric.com/showthread.php?24489-New-Lead-Acid-Batteries-Are-better-than-Old-ones-)

    Kind of a perfect bait n switch consumer product, no? ;-)
  • ReedReed Solar Expert Posts: 55 ✭✭
    Re: Why not LiFePO4?
    Photowhit wrote: »
    Just so we don't get to confused, You have 4 - 4 cell batteries which are 12 volt (nominal) set up as a 48v nominal bank. I'm assuming this is what you mean? It's confusing to call represent them as 2 different "banks"

    Each battery is made of 4 cells for a 12 volt (nominal). Four of these are set in series for a 48V nominal bank.

    So this is retail for a single 12 volt nominal battery made up of 4 cells?

    The price is for a single 12 volt nominal battery made up for 4 cells

    I understand where a single bank for RV use has lots of advantages, particularly if you often have 'shore power' or a generator if you exceed your capacity. Looks like it would take about 8 of these to match the usable capacity of a forklift battery of 800Ah at 24volt. Perhaps they make larger cells, if not they will some day. That and more use will drive the price down, the future looks bright. Love to consider them in 10-15 years when my lift battery gives up. I suspect the price will be half of what it is now and we will have some real feedback on the longevity of this innovative battery chemistry.

    800 Ah at 24 volt is 1600 Ah at 12 Volt. You do say you can get 80% DOD which seems excessive for long life but I am a physicist and not a battery engineer. I knew almost nothing about lead antimony batteries so I had to Google. I could find nothing that permitted thousands of cycles down 80% DOD for PbA. I require further investigation

    The work done by Liberty Coach and others shows that we can expect 2000 cycles to more than 80% DOD so we have just at 600 Ah that we can use at 256 pounds. Weight is critical in and RV. However, we do not plan to go further than 60% if possible
    Reed and Elaine
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: Why not LiFePO4?
    Reed wrote: »
    800 Ah at 24 volt is 1600 Ah at 12 Volt. You do say you can get 80% DOD which seems excessive for long life but I am a physicist and not a battery engineer. I knew almost nothing about lead antimony batteries so I had to Google. I could find nothing that permitted thousands of cycles down 80% DOD for PbA. I require further investigation

    I don't need 1000s of cycles to 80%DOD, but I do need to have the option, their warranty which I posed earlier is 1500 cycles to 80%DOD or 5 years. In their intended use they are regularly drawn down below 50%DOD. I had this situation just last week with a hot humid overcast day, running my A/C around the clock and fridge in the un A/C'd area. Typically we have heat only with sunny days (the rest of the last 10 days or so...lol) I have taken them down to around 80% a couple times, but mostly running my water heater in the winter, and accidently leaving it on. It's on a timer now and will have other situation, either it's own dedicated array or running as opportunity load via Midnite Classics switching.

    I'm leery of having such an over paneled system 6500watt array into the 800ah 24v bank... even with the classic's ability to limit amperage. This would work to your argument of the lithium's ability to fast charge and my argument that I want someone else to test the system/waters...lol.

    I make this distinction, because I can see if someone is willing to run a genny during those times when they need the added capacity, that you could compare a 800ah lead acid with a 400ah LFP, with actually better use in many instances. Others have made this argument earlier, but if I had a smaller LFP system, I'd have a shut down somewhere in the 2nd night.

    PS, not sure why you want to break things down to 12 volts? I don't have a 12 volt battery, just 12 - 2 volt cells as you have 16 3.2(?)volt cells, though it appears yours are built as 12 volt nominal units. I think it's easier to think of a battery bank, I don't mind calling it by a Watt hours, but that is somewhat misleading if your talking about smaller lead acid batteries.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Why not LiFePO4?
    Reed wrote: »
    PNJunction is apparently incorrect for once, the thread has continued

    Wow, you said it. Maybe it is a good thing we are getting this out in the open and out of our system. :)

    Thing is, all the very same arguments are rehashed over from about 4 years ago. We are spinning our wheels getting nowhere fast since most of us are very late to the party. :)

    Why not just save a LOT of time, and visit this forum's thread from our marine brethren who have already pioneered the large prismatics for us. We have it even easier than they do. Note that this 4-year old thread is still active! Fortunately, the crowd has matured, and there is very little antagonism or politics left - just tech info for those who do want to run them regardless:

    http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html

    Yes, inside you'll still find the bms / no-bms discussions, but they are civil for the most part. OH, but wait - you want the lead vs lifepo4 drama starting in 2010? Here you go - look familiar to what's going here?:
    http://www.cruisersforum.com/forums/f14/lifepo4-batteries-okay-tear-me-apart-36530.html

    If one wants to wait on the sidelines for 8 or more years for proof of performance, then that's fine too. For those battery geeks among us who want to DO instead of just speculate, I'll risk these direct links, instead of trying to obfuscate them.

    This is just a very small representative list. There are other vendors similar that carry CALB, Winston, Sinopoly, Hi-Power too. Quite frankly, I'd have preferred to get them from NAWS, but they just aren't carried.

    http://www.elitepowersolutions.com/
    GBS-cell specific with plenty of other stuff you may like.

    http://www.batteryspace.com/lifepbatterymodules.aspx
    For DIY'ers who know how to order what they want, most notably getting lifepo4 prismatics, and not some other chemistry! This is where I got my GBS cells from (bared naked, but strapped and banded). Note: it may seem like a small thing, but the fact that GBS includes cell-top covers alone might be a consideration for diy'ers when it comes to safety from dropping a wrench on them.

    https://minibms.mybigcommerce.com/products/HousePower-BMS.html
    An alternative bms if you don't want what's offered by your battery dealer.

    One of the most valuable things you'll read from these pioneers of 4-5 years ago, is that many of the voltages listed by distributor or retailers were taken from a crusty ancient spec-sheet showing cell voltages like 4 -4.2v at the top, and 2.5v at the bottom, and were proven to be too extreme or downright wrong, especially for our application! Yet somehow, this stuff just gets copied and pasted to this day. (3.6v is about the max, and 3.1v is a reasonable range in today's world!)

    I'm in the "no-bms" crowd, or more accurately the "no-extreme-balance crowd - I DO have an LVD) of simply running lower voltages, and not taking these cells wall-to-wall because I have a large operational cushion by only designing for a 50% DOD! (typically run from 10-60% DOD) Just a hint...

    Before spending anything, take some time to read the Cruisersforum thread. It may answer a lot of questions, and save our own host's bandwidth. :)
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: Why not LiFePO4?

    Well I took a peek, don't really want to wade through 100's of forum pages of boating, where the most cost effective for off grid homes is typically not an option. I really don't doubt that they can be charged and even used effectively. Really want to do a cost analysis. I just don't see it yet, and suspect it will be many years before I need to worry about replacement.

    PS, really have no problem with sail boats, heck I might have been a more avid sailor than cyclist if it wasn't for Chrysler engines.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    Photowhit wrote: »
    Well I took a peek, don't really want to wade through 100's of forum pages of boating, where the most cost effective for off grid homes is typically not an option. I really don't doubt that they can be charged and even used effectively. Really want to do a cost analysis. I just don't see it yet, and suspect it will be many years before I need to worry about replacement.

    PS, really have no problem with sail boats, heck I might have been a more avid sailor than cyclist if it wasn't for Chrysler engines.
    It is interesting to see people that can't care for a $150 battery trying to care for a $900 battery.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Why not LiFePO4?
    It is interesting to see people that can't care for a $150 battery trying to care for a $900 battery.

    Which was my thinking too. And while I don't think this comment was directed at me specifically, I suppose it could apply as I've now got 10 year batteries that have only lasted 5, for whatever reason which we're trying to determine.

    But, then I remember the many people who've been told about their PbA batteries, including me, "you killed them." Now thankfully all these don't apply to me, but the comments are; you undercharged them for years, you charged them to 58.3 instead of 58.6 in bulk mode, they weren't allowed in absorb mode long enough, you neglected them and let them get sulfated, you didn't equalize them enough, you equalized them too much, you didn't check the electrolyte level for six months and they're toast.

    And it starts to make sense that others decided to do something totally different. If you're failing over and over, why not try something different? If PbA in the real world environments is only lasting half as long as under the optimum conditions with a battery expert tending to their needs on a daily basis, how much is the true cost then?

    What would have happened to the Lithium batteries if they weren't checked for electrolyte level? Oh, they don't need to be checked. What happens if you undercharge them for years? They don't end up sulfated, they end up lasting longer.

    But oh yes, if you don't watch the voltages, they'll be destroyed in minutes. But apparently they can be maintained, and there's only 2/3 the number of cells to work on. Just that aspect has always been a large advantage in my opinion.

    But most people, including me, are of the Indiana Jones thinking, "Looks dangerous, you go first." And that's why I'd like to thank PNJunction and others who have gone first and are here telling what they've found. I think while the time has been going on the Lithium batteries have been improving, both in quality and in price.

    Oh, and I also have to thank Bill, in Post #87, for his excellent analysis of the situation.
  • PhotowhitPhotowhit Solar Expert Posts: 5,650 ✭✭✭✭✭
    Re: Why not LiFePO4?
    It is interesting to see people that can't care for a $150 battery trying to care for a $900 battery.

    Not sure what this means? Since I was quoted does this mean you think I can't care for my batteries?

    I'm not the guy who went through 5 sets in 12 years. I'm the guy who ran an A/C off 4 GC2's for 4 years of their 5 year life.

    It might be fair to say I have issues with gas engines! from the quote. I had the engine overhauled before a trip around Florida, and it failed the first night out, spent the night 12 miles out on 6 foot seas on a 19' sailboat(in the gulf, much shorter periods)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    Photowhit wrote: »
    Not sure what this means?
    No, I was reading some of the posts in the sailing forum that you didn't have time to read. Trying to run a bow thruster on a LiFePO4 battery mixed with AGM batteries. I guess you really have to have a 5 hp DC thruster that pulls 400 amps @ 24 volts to understand. It's amazing to see a 800 amp hr bank pulled from 25 V to 20 volts in about 2 seconds. It's not a place for LiFePO4 batteries. Ever hear of the right tool for the right job ??

    Unfortunately a lot of loads take place between 4:00 am and say 9:00 am when your batteries are at their lowest. All you need is a refrigerator in defrost, trying to make coffee, people showering and your out of business. Get my drift ??

    Can a system be built to get around some of the problems ?? Yeah if it all works and you have plenty of $$$ to throw at it.

    I have LiFePO4 batteries, I love them. I have 3 that my Dyson vacuum cleaners use, it will run for 20 minutes on low speed before it quits with no warning. The fall off is really dramatic with them.

    Attachment not found.
    .
  • ReedReed Solar Expert Posts: 55 ✭✭
    Re: Why not LiFePO4?

    Enjoyed Swanney's article.

    Am with sub3marathon man concerning the Indiana Jones quote "look's dangerous, you go first!" This time however, did a lot of reading, corresponded with Ron Jones on his experience, read up on Liberty Coaches, and listened to older son and we made the plunge to have the entire 5th wheel solar system based on LFP. We are extremely happy after 14 months or so. We also have a son who is an expert in solar and batteries and if things go wrong, he can fix it (we have been known to call from Yucatan when something seemed wrong. )My wife is the bold one here, I am more the cunning coward - which served me well on my tour as a LRRP team leader with 173rd Abn 45 years ago.

    PNJunction has the corporate memory and has been involved with and followed the threads over the years. I appreciate the knowledge he brings to varied fora. Most of us do not have his knowledge and "rehashing" is new to us. I would think that much of the discussion and polite argumentation of four years ago were based on new knowledge and a bit of it was skewed with incorrect data.

    Surprisingly, even though we are now up to post #103, information is still being presented (Swanney's article) and discussions are continuing.

    Reed and Elaine
  • PNjunctionPNjunction Solar Expert Posts: 762 ✭✭✭
    Re: Why not LiFePO4?

    The best thing to keep in mind is our application differs from others. Unlike EV'ers, Marine, or RV'ers, where weight and physical space limitations dictate the limit in capacity, land-locked house-bank users have even better options.

    The biggest of which, if one does their power-budget homework right, is the ability to run in a "deficit-charge" or psoc style of operation without penalty, aside from eventually walking down to the limits of capacity to get the job done, at least no more than 80% to be reasonable about it. Just like lead, I'd STILL design for no more than 50% DOD, but that window of operation can slide now.

    This differs from lead-acid, where eventually you HAVE to achieve 100% SOC to rebalance and desulfate. Not so with lifepo4. There is no need to EVER achieve 100% SOC, and of course no sulfation.

    This opens doors to almost unimaginable combinations of operational use. It was what got me most excited about them.

    Example: The beginner who runs the classic "too small a panel for too large a battery" syndrome. The only penalty here is that sooner or later he will walk down his capacity to an unusable level. BUT, make a change in a smaller load, a larger panel, or a longer amount of solar-insolation, and that installation could be considered a success, never once reaching 100% SOC, while never damaging the battery in that process. Not so with lead, where sulfation eventually catches up with you in deficit-charge or psoc unless you take steps to get back to 100% once in awhile.

    We are hard-wired to think in terms of using a battery from the 100% to some other value of DOD. You can still do this with lifepo4. But, if you don't short-change yourself on capacity, the doors open. Not only that, but it relieves a lot of obsessing over obtaining a "perfect" balance, since this won't show up until you reach the extreme top or bottom of charge. Of course cells need to be in *reasonably* close SOC to begin with to avoid problems.

    So a mistake in your power budget, solar insolation, array size, load, etc, won't penalize you if you are lucky enough to oversize your battery by accident. You'll just be wasting money. OR, if you look at it from this standpoint - you'll have PLENTY of autonomy by accident too, which is something often overlooked.

    Obviously, lucky accidents aren't something one should plan on. Just consider that the classic "45 watt HF Panel" attached to a 100ah deep cycle" is immediately red-flagged, but perhaps not so with lifepo4 depending on the factors above. That's an extreme example, but the point is, the battery won't suffer from this sort of miscalculation - just an operational one.

    It also eases charging. One could quite happily do nothing but bulk charge to say 13.8v (3.45 per cell), and call it quits each and every cycle. No obsessing over "end-amps" in absorb and the like. You certainly can, but if you have enough capacity, there is no NEED to. This vague-ness about what is considered a full-charge is what blows your mind and is so disruptive to our existing 100 year train of thought. It really is unsettling, at least it was for me.

    If you put your mind to it, you can see that without sulfation and no need to reach 100% SOC, some of the possibilities with solar are endless.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    This differs from lead-acid, where eventually you HAVE to achieve 100% SOC to rebalance and desulfate. Not so with lifepo4. There is no need to EVER achieve 100% SOC, and of course no sulfation.
    The one thing you forget is what you take out has to be returned at some point or you have no capacity, doesn't matter what kind of chemistry you have unless it has some self regeneration properties. What would be the purpose of buying a battery that has X number of amp hrs just to charge it less than 100% capacity, that just makes the ROI even worse than it is on these batteries.
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Why not LiFePO4?
    What would be the purpose of buying a battery that has X number of amp hrs just to charge it less than 100% capacity, that just makes the ROI even worse than it is on these batteries.
    The purpose would be to extend the cycle and calendar time life of the batteries before replacement is required. That has a definite effect on ROI and needs to be evaluated accordingly.
    Same type of decision we have in buying Sam's Club batteries versus Trojan. They both have the same AH, so why pay more. :)
    SMA SB 3000, old BP panels.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    inetdog wrote: »
    The purpose would be to extend the cycle and calendar time life of the batteries before replacement is required. That has a definite effect on ROI and needs to be evaluated accordingly.
    Same type of decision we have in buying Sam's Club batteries versus Trojan. They both have the same AH, so why pay more. :)
    That's fuzzy math, lol.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Why not LiFePO4?
    The one thing you forget is what you take out has to be returned at some point or you have no capacity, doesn't matter what kind of chemistry you have unless it has some self regeneration properties. What would be the purpose of buying a battery that has X number of amp hrs just to charge it less than 100% capacity, that just makes the ROI even worse than it is on these batteries.
    Bold added.

    inetdog wrote: »
    The purpose would be to extend the cycle and calendar time life of the batteries before replacement is required. That has a definite effect on ROI and needs to be evaluated accordingly.
    Same type of decision we have in buying Sam's Club batteries versus Trojan. They both have the same AH, so why pay more. :)

    That's fuzzy math, lol.
    Bold added.

    Oh really??

    Blackcherry04, Surrettes, Still Trying, 5/20/2014:
    Well, I removed 200 amp hrs ( 16% DOD ) today and started a recharge @ 175 amps, they went to Absorb @ 1.245 SG level. After 5 hrs of Absorb @ 15.2v ( 8-20 amps ) the SG level is up to 1.265. Based on this voltage ( 15.2v ) I can only raise the SG level .025-.030 per charging hour.

    This time I only pulled 200 amp hrs out of them, last time it was 560 amp hrs and they exited absorb with a SG of 1.220 because of ending amps, as you can see if I had to raise the SG .45 I'd be looking at 15-16 > + hours to recharge them back to where I started ( 1.265 SG ) .


    I think I have fooled around with these batteries long enough to say that I would not recommend them for off-grid solar. I don't think there are enough charging hours to be able to manage them. You could probably do it, but you have to use EQ voltage to off set their inability to accept a charge. I have no clue what it will diminish their longevity with this kind of charging regime, but for a $2,500 for set 6 of batteries I could of had a set of 10, GC-2's for $900 and get 3-5 years and at least be able to charge them.
    There is a danger for me with this setup, If I lose power for a short amount of time it will trigger a full charge cycle, with these high voltage charges ( 15.2 v and 6-9 hr absorbs set into the Inverter, I could do some real damage.
    (Bold added)

    And on 5/21/2014:
    In all fairness I am trying to find what it takes to get them back to 100% charge ( 1.265 ) while they are new . On a normal basis 80-90% ( 1.250-1.255 SG ) is a fine charge level and do a EQ once a month or so is Ok. Most of the time they will be in the 50-80% range during use. At 50-80% I still have plenty of working capacity to get through the night.

    One thing this does do is bring up the subject of Charge Efficiency and the use of a battery monitor. If a normal batteries are 95% these can't be more than 60-75%, if that. That is a base line I am still developing to come up with a setting. Anyone using SOC as a guide line for recharge should be wary, forget something with LED's on it.
    (Bold added again)

    And, just to clarify, I put these quotes together with the "Reply With Quote" command to the entry and pasted into Word, then recopied here. But each quote is 100% accurate.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Why not LiFePO4?

    I might suggest that the two situations aren't comparable. The Surrette saga is a tale of how he's managing with a set of batteries that do not perform up to snuff, but still have enough range to do the job. The evaluation of the LiFePo running constantly below 100% capacity as being the same as a smaller bank in comparison to a FLA brought up to 100% is in reference to a bank that works, not one that is defective.

    So if you only run your LiFePo up to 80% SOC you have a 20% smaller capacity than you bought. The idea that lead-acid batteries don't have any 'real capacity' above 90% or spend most of their time at 75-85% SOC is erroneous; a well-designed system will achieve 100% SOC on any sunny day and this capacity can be counted on as real capacity.

    The difference would be that the LiFePo is resistant to damage from being in less than fully charged whereas lead-acid will definitely suffer from this condition, especially if below 75% SOC for more than a few days straight (starts hard sulphating).

    This makes the LiFePo a good choice for systems where charging may be unreliable. What immediately comes to my mind is the many systems I've helped with that are used for power stability in places where the grid is unreliable but available for use. Lead-avid can and has been used in these systems but it has an adverse and not entirely predictable effect on their lifespan.

    BTW trivia note: the recent discussions of LiFePo here has attracted the first LiFePo spammer! No, you probably didn't even see it. :D
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    < snip >
    And your point is ?? Now you say I should buy 180 amp hr cells @ $ 235 and charge it like a $160 , 130 amp hr cell so it will cycle less and last longer ??
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Why not LiFePO4?
    <snip>

    And your point is ?? Now you say I should buy 180 amp hr cells @ $ 235 and charge it like a $160 , 130 amp hr cell so it will cycle less and last longer ??
    Ummm, I'm not saying it, you are. But obviously my understanding of the situation is incorrect.

    When Blackcherry04 said, "Most of the time they will be in the 50-80% range during use. At 50-80% I still have plenty of working capacity to get through the night," I thought that meant what Blackcherry04 said, that most of the time the batteries would be in the 50% to 80% range DURING USE. I didn't calculate the percentage of time they wouldn't be in use. Of course, if they're not in use, they're giving a 0% ROI, so that is the also same as buying a smaller battery and keeping it in use 100% of the time.

    But wait, as Cariboocoot says, "I might suggest the two situations are not comparable." It would be great if he could further explain, as it pertains to this debate, why they aren't comparable.

    It is a debate about Lithium vs Lead. Blackcherry04 has said, "It is interesting to see people that can't care for a $150 battery trying to care for a $900 battery." I'm just not as sure, and PNjunction sure seems happy, at least at the moment, and I'm thankful that he's endured the negative comments from some and has shared his experiences.

    Now the story about caring for Lead batteries seems to have changed. And their limited capacity use vs. lithium has been minimized in this debate.

    It was my understanding that some kept the batteries at float for years, using essentially 0% of the battery capacity. My understanding was that others cycled to 30% DOD, which decreased the cycle life but increased the ROI because some of the potential of the battery was used. It was my understanding that it was possible to go to 50% DOD, if the battery was maintained back to 100% SOC in as short a time as possible, but the cycle life was shorter than at 30% DOD, and the ROI was less because the increase in return from electricity out was more than offset by the decrease in battery life. It was my understanding that forklift batteries were so robust that they could take 80% DOD, but with a shortened cycle life of 1500 cycles instead of 7000 cycles.

    So I'm hoping that one of the battery experts here can set the record straight on how PbA batteries should be used. Is it 100% DOD so you get the full use, or does that decrease the cycle life? All the battery manufacturers say it does. Why are people saying now that PbA batteries should be operated in the 50% to 80% range with just an occasional return to 100%, which is supposed to prolong their life? And such advice is surprisingly similar to the advice for Lithium batteries, except the usable range for Lithium is about 60% of capacity instead of 30% capacity for Lead. And finally, should a 180 amp hr cell @ $235 be charged like a $160 , 130 amp hr cell so it will cycle less and last longer, or is the $160 lower capacity cell just as good cycling more and lasting just as long?
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    < snip >
    You obliviously don't have a 1300 amp hr battery bank and have never used 500 amp hrs a day and had the need to replace amp hrs, so you wouldn't understand the different charge regimens that are used.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Why not LiFePO4?

    I did in fact explain why they aren't comparable: in one situation he is coping with batteries that are giving trouble and not coming up to their full rated capacity, in the other there is a comparison between fully-charged lead acids and LiFePo's purposefully not brought up to their full capacity.

    You definitely do not take lead-acid or any other battery to 100% Depth Of Discharge.
    You definitely do take lead-acid batteries to 100% State Of Charge.

    The operational difference between the two battery types is not the charge level but how well they tolerate different charge levels. Lead-acid is not as forgiving of SOC below 75% for extended times as LiFePo is. Some argue that the latter is not as accepting of 100% SOC so you would be forced to use a larger bank to get the equivalent stored power expected from a smaller bank of the same type (but not necessarily of a different type).

    This is a case where the capacity must be compared as usable stored Watt hours, not just Amp hours, as the SOC range for each is different. As a demonstration:
    Lead-acid 100 Amp hours @ 12 Volts = 1200 Watt hours total, 600 maximum usable (SOC range 100% to 50%).
    LiFePo 100 Amp hours @ 12 Volts = 1200 Watt hours total, but if the maximum SOC is limited to a suggested 80% and the minimum is still 50% then the usable Watt hours becomes (30 * 12) 360 Watt hours. If the SOC can go lower than 50% the usable capacity is larger, and likewise if the SOC can be brought up to 100%. It's all in whose advice you want to follow here.

    This then would further affect the ROI because of the actual power range vs. price, and will not overcome the 3X capital outlay (but may make it worse). Nor does it influence the Peukart effect or cycle life, both of which are largely unknown for RE applications due to the limited install base (and both will vary depending on the actual battery involved and that includes for lead-acid as well).

    The lead-acid will suffer more from partial SOC so if the application is more likely to generate these conditions the LiFePo has the advantage there. Also if there is need/ability for higher current charging.

    As always it is not as simple as "this battery is better", it depends on how it will be used. I'd think by now people would have learned this just from the tales of terror in using inappropriate lead-acid types for RE. But apparently not: there seems to be a built-in contrariness in the human soul which causes them to constantly try to utilize things for purposes other than what they were intended. I've run up against this so often it just makes me sick now. Even my neighbour here thinks his system "works fine" and won't change it according to my recommendations; instead he buys new batteries every two years because he thinks that's normal. It isn't.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Why not LiFePO4?

    from post 26, sorry if this point gets mentioned later but reading this long post in drib's and drabs...
    Reed wrote: »
    , so I just let them go down till they are below -3000 W and then hook up the 15 amp power cord to battery charger and things are up to -1000 W in an hour and a half or so ...
    Reed

    Not sure of the bank Ahr size, that affects the battery charger choice, but I am thinking that a smaller than normally used charger might be possible here as 100% SoC does NOT have to be reached ie 20A vs 40A charger.

    ADD: I am coming at this from the issue of having a charger that will not run on a Honda 1000i unless I use a small 15A charger to start the cycle then switch chargers and continue (Truecharge 40A 12v). The 30A 24V is a no go from the start... needs a 2000w min.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • ReedReed Solar Expert Posts: 55 ✭✭
    Re: Why not LiFePO4?
    westbranch wrote: »
    from post 26, sorry if this point gets mentioned later but reading this long post in drib's and drabs...
    Not sure of the bank Ahr size, that affects the battery charger choice, but I am thinking that a smaller than normally used charger might be possible here as !000% SoC does NOT have to be reached ie 20A vs 40A charger.
    ADD: I am coming at this from the issue of having a charger that will not run on a Honda 1000i unless I use a small 15A charger to start the cycle then switch chargers and continue (Truecharge 40A 12v). The 30A 24V is a no go from the start... needs a 2000w min.

    We are full-time RV'ers with what amounts to solar autonomy more or less. Battery bank is about 9.6 kW-hr of LFP. We have both a 1 kW and a 0.5 kW battery chargers that can be used singularly or in parallel. The 0.5 kW charger is for when (if we ever do) the 1.0 kW Honda. I believe son placed the 0.5 kW charger in for the problems to which you allude above. They are used in parallel when we use a 15 amp outlet (which we seldom do). We are currently in an RV park (o' the shame and humiliation but younger son and wife are expecting second child in Fort Collins and boondocking is 70 miles and 90 minutes each way) and there is total shade. We hook up every third day or so for two or three hours when battery banks are down by 30 to 40% DOD.

    As noted in earlier post(s), son put chargers in for two reasons:
    1. Dirty power. Burned out one micro-wave in Baja and another in Yucatan. Nearly burned out an air conditioner at a good state park in Colorado. We were
    in RV park for the same reason as this year. They were expecting first child and her parents had the "mootchdocking" spot in back yard. We only go to
    RV parks when visiting relatives that live in large towns and boondocking is not a viable option.
    2. Gets rid of the heavy and bulky 50 amp cable.

    Reed and Elaine
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Why not LiFePO4?

    You definitely do not take lead-acid or any other battery to 100% Depth Of Discharge.
    You definitely do take lead-acid batteries to 100% State Of Charge.

    .......


    This is a case where the capacity must be compared as usable stored Watt hours, not just Amp hours, as the SOC range for each is different. As a demonstration:
    Lead-acid 100 Amp hours @ 12 Volts = 1200 Watt hours total, 600 maximum usable (SOC range 100% to 50%).
    LiFePo 100 Amp hours @ 12 Volts = 1200 Watt hours total, but if the maximum SOC is limited to a suggested 80% and the minimum is still 50% then the usable Watt hours becomes (30 * 12) 360 Watt hours. If the SOC can go lower than 50% the usable capacity is larger, and likewise if the SOC can be brought up to 100%. It's all in whose advice you want to follow here.


    The lead-acid will suffer more from partial SOC so if the application is more likely to generate these conditions the LiFePo has the advantage there. Also if there is need/ability for higher current charging.

    As always it is not as simple as "this battery is better", it depends on how it will be used. ....

    "Coot thanks for this good (partial) summary of the differences between the 2 technologies .

    I think the one word you left out in your comparison is "location" as you know our location has a lot to do with the winter temperature and that amount of 'good sunlight' hours we can get/use daily, coupled with multiple dark days, cloud, snow etc

    Other factors I can think f are the temperature of an unoccupied residence ... oops SWMBO want to go shop.

    back in a few hours.
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • ZoNiEZoNiE Solar Expert Posts: 100 ✭✭
    Re: Why not LiFePO4?
    Photowhit wrote: »
    I have looked through the thread, read it several times...

    All I see is pure Economics... If it's my money for my use... I want to save money... Save me money and I will buy your product!!!

    I have 804 Ah capacity, it cost me $2525 delivered and I can, from reasonable examples expect it to last 15-20 years. (you can use 15yrs, that's what I did even though I had heard of 30+ and NAWS 20+yrs. I stuck to known users experiences)

    Can you save me money?

    That works out to $168/yr or $14/month, given 15 years usage. Not bad, really, yeah annually the cost of two GC2's at Costco, but No maintenance. Buy once, very desirable.

    I decided to forge ahead on all 12 pages of this sitting in an airport, and glad I did, despite the early kibitzing.
    PNjunction wrote: »
    Yes. Unless you are solely grid-tie, then don't go solar at all since it already costs about 10x above what you are charged by the local poco. The choice of battery chemistry is almost a non-issue at this point. :)

    I'm afraid however that the signal to noise ratio is already so high in this thread, that any objective discussion about lifepo4 is moot, and lurkers have long since vanished.

    It happens not only here, but in nearly all other forums too. Sad really.

    Again, glad this kept going. This Lurker is still here and learning...
    It would be good to see someone step up and buy a 600-800 amp hr bank @ 24 v that is cycled to 50 % on a daily basis and let us all in watching it's progress. A 100 amp hr battery will hardly be realistic on the performance one could expect. There is chatter everywhere, but little hard facts other than the price.

    Go for it! :cool:


    Also, to Reed and Elaine, sounds like you have if figured out. Forgive me if I missed it, but what size is your bank? (AH/volts?) what charge controller do you use, or, if you have a blog somewhere with all of this, please redirect me.

    I'm looking at building something for basic short term boondocking with my TT. I have nowhere near the roof surface you probably have to fit 1,400+ watts, but our needs are more simple, and we have an onboard genny I'm not against using. This system will be transferred to the next RV or Cabin, so I am looking at long term, long lasting components, so cost is not such an issue.

    The gist of what I am reading is that I can live with a 100AH LiPo4 battery where a 208AH GC2 would also work. Is this correct? about half the battery need based on SOC and DOD range?

    As a 12V user, this information was very enlightening. Now to get it all bought, and sell the Sensata to buy a more appropriate inverter.
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Why not LiFePO4?
    It would be good to see someone step up and buy a 600-800 amp hr bank @ 24 v that is cycled to 50 % on a daily basis and let us all in watching it's progress. A 100 amp hr battery will hardly be realistic on the performance one could expect. There is chatter everywhere, but little hard facts other than the price.
    ZoNiE wrote: »
    Go for it! :cool:
    I am out of $$$$ and I'd rather have a set that are past their half life to see how the end of their useful life occurs. It's easy to extend a premium FLA past 15 years ( used Forklift batteries ) but there is a lot that no one knows thats talking on here, 2 months ago they were talking about AGM batteries.
  • ZoNiEZoNiE Solar Expert Posts: 100 ✭✭
    Re: Why not LiFePO4?
    I am out of $$$$ and I'd rather have a set that are past their half life to see how the end of their useful life occurs. It's easy to extend a premium FLA past 15 years ( used Forklift batteries ) but there is a lot that no one knows thats talking on here, 2 months ago they were talking about AGM batteries.

    Yeah, I was just kidding anyway. Your need for half life makes sense. you'll get your data twice as fast.

    As for my question to Reed, nevermind, I just found it on SPT.

    As for my question about how much less LFP than FLA, Found that too. 84%.

    Been a good day of reading...
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Why not LiFePO4?
    ZoNiE wrote: »
    As for my question about how much less LFP than FLA, Found that too. 84%.

    Been a good day of reading...
    That 84% is based on autonomy days alone, with the full autonomy period coming from cycling the LFP down from 80% to 20% while the FLA bank would go from 100% down to 50%.
    So if .5 FLA = .6 LFP, LFP = 5/6 FLA.
    You may want to change the autonomy assumptions based on other criteria such as maximum charge rate, generator supplement, etc.
    If your first concern is how high you can run the load current, the LFP has more of an advantage than that over FLA, not so much over AGM.
    SMA SB 3000, old BP panels.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Re: Why not LiFePO4?

    OK just so I get this right, I have a 21 W load x 24 hrs = 504 W hrs x 2 (50%, FLA no reserve) = 1008 Wh /12V = 84 Ah battery x .84 (Fla to LFP) = 70.56 Ah LFP battery is needed. Correct?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
This discussion has been closed.