 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Windmills : LiFePO4 vs Lead Acid
Page 1 of 3   |
|||||
| Author | Message | ||||
electrodacus Newbie  Joined: 30/03/2014 Location: CanadaPosts: 39 |
I made a youtube video just uploaded today about the cost benefit in using LiFePO4 vs the old and very common Lead Acid. The video was mostly to show that Lead Acid is a much more expensive option but also talk about the other benefits of LiFePO4. I was even quite generous with Lead Acid that was why is only 2x more expensive than LiFePO4 if I have included all the other parameters things will have been much worse and in real life I expect Lead Acid to be at least 3 to 5x more expensive over the life time of the battery when compared to LiFePO4. Of course I'm not the only one to notice this in fact there are people, organizations, and companies that knew this for quite some time over 10 years. Problem is the DIY community that is a bit slow to change. I hope that this video will at least make some people read more and get informed about this. Here is the Link to Battery video. If you do not want or can not watch the video here is a short resume 
OK let me explain the calculations in that table. You have the LiFePO4 that has a capacity of 64Wh and can be cycled 3000 times at 100% DOD that gets you in a simplified calculation at 64Wh x 3000 = 192kWh of energy that can be stored during the life time of the battery. On Trojan L16RE-A you have 1794Wh of energy at 10h rate and 800 cycles at 100% DOD so again simple calculation 1794Wh x 800 = 1435kWh during the life of the battery. Now the cost of the battery is divided by the amount of energy stored in the battery during the life time so LiFePO4 19$ / 192kWh = 0.099$/kWh Lead Acid 300$ / 1794kWh = 0.209$/kWh Now this is not a real number and there are other factors that need to be taken in to account like the battery degradation over time and charge discharge efficient just to name a few but all this will make the Lead Acid look even worse and is to complicated for some people. In real life I expect LiFePO4 in solar application to be about 3x to 5x less expensive over the life of the battery when compared to Lead Acid. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
norcold Guru  Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Interesting Maths. To complicated for me.  We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
:) What math ? there is none just simple addition and multiplication. I think a good analogy will be solar PV panels. Say monocrystalline PV panels are LiFePO4 and amorphous PV panels are Lead Acid. Say you can get amorphous PV panels at 0.5$/Watt or monocrystalline at 1$/Watt. At first you will say that is obvious amorphous are a better deal until you read the specifications Then you find that amorphous will degrade to the point they become unusable losing 50% of the initial capacity after 7 years. On the other hand the monocrystalline panels still retain 80% of the original capacity after 25 years. Now witch one will be your choice? If you know the amount of solar radiation at your location you can calculate how much energy each of them will produce during the life of the panel and how much will that cost considering the initial investment. Say each 1W of solar panel will produce 1.3kWh/year (this is a realistic number) 1W amorphous will produce 1.3kWh x 7 years (not considering that is only 50% of this in the last year) = 9.1kWh during the life of the panel for each Watt installed so cost is 0.5$/9.1kWh = 5.6 cents / kWh 1W of monocrystalline will produce the same 1.3kWh x 25years = 32.5kWh during the life of the panel so 1$/32.5kWh = 3 cent / kWh so in the end monocrystalline is a way better investment even if it look more expensive without looking at the spec and making this simple calculation. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
OK let me explain, You Quote LiPo4 has 3000 cycles at 100% DOD. Please show your source of this. Lead-Acid 800 cycles at 100% DOD. Again please show your source of this. Remember 100% DOD is 0% charge. 100% Depth of Discharge = 0% charge Check my past posts, in particular my system. Check the life of that system so far, check the % maximum discharge I have quoted and adhere to. Compute the cycles my system has had to date. When you`ve done that you`ll understand where I`m coming from when I say interesting maths We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Sorry all the data you requested is available in my youtube video description but I can add the links here. LiPo4 dose not exist is LiFePO4 and this is important since this is the best chemistry for energy storage not the same as LiCoO2 most commonly found on laptops and phones that is designed for high energy density and not good for energy storage. Is like using a car battery designed for starting in energy storage. A123 Systems LiFePO4 Trojan L16RE Lead Acid Then here are some independent laboratory tests done on different LiFePO4 and a VRLA(Valve Regulated Lead Acid) you can see LiFePO4 with just 10% DOD can last for 30000 to 40000 cycles and still retain over 85% of the initial capacity and how the Lead Acid performance is significantly worse around 5 to 10x LiFePO4 lab test And here you can read a report presented back in 2007 at International Renewable Energy Storage conference regarding the use of Lithium for energy storage. Lithium for energy storage Discharging the Lead Acid to 50% DOD will bring no benefit see the Trojan Data sheet it will last for 1600 cycles at 50% DOD and that is exactly double the 800 cycles at 100% DOD so no benefit in the energy stored during life time. (and yes I know what DOD is and SOC there is no mistake) http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Both LiFePo4 & Lead-acid figures you got from graphs off product glossies You noticed my typo in my last post "LiPo4" now did you read my past posts on my system and compute the cycles so far. From experience I have no confidence that a lead-acid system would last 800 cycles at 100% DOD and my experience with LiFePo4 is limited to a small 8000 Mah 12v battery I run portable power tools with, and so far I am very impressed. But 3000 cycles at 100% DOD It is a Real-life and working system and I feel before we get to the interesting maths it is important we separate working figures from glossy figures. Then we`ve got to find a working LiFePo4 system that has been around bit, that way we`ll be comparing apples to apples so to speak. Useful wattage to useful wattage at the same voltage would be nice too. Heh!!! lead-acid is old and tired tech, to really get solar up and running we need cost effective batteries, I`m with you there We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
I will need to check your battery but this L16RE from Trojan is a more industrial type battery with thicker plates so it will last close to 2x more than a smaller T105 battery. Anyway that is in ideal conditions in the lab and not sure they really tested at 100% DOD or they just extrapolate data. I cheeked the standard they used to test the batteries and there is no test that will test the life cycle directly. There are also the tests done payed by the US department of energy that I link to and they have tested some LiFePO4 from few manufacturers and they see over 40k cycles at just shallow 10% DOD and high discharge rates 2C or so and this tests are still running they still have over 85% of the original capacity after all this tests. There is no doubt that there is no better technology than Lithium at the moment for electrochemical energy storage. Most LiCoO2 are rated 300 to 800 cycles from reputable manufacturers. Sony, Panasonic, LG, Samsung, Sanyo. And the LiFePO4 are rated usually well over 2000 cycles and I see a few over 4000 cycles and this are only tested at 100% DOD LiFePO4 has lower energy density when compared to LiCoO2 mostly because lower voltage 3.2V nominal 3.6V max charge vs 3.6V nominal 4.2V charged So LiFePO4 is almost 2x heavier for the same capacity than LiCoO2 Now in some special applications usually long life military they use LiCoO2 but charge them at only 3.9V max this reduces the capacity at 60% compared to that at 4.2V but makes them last 8x longer so instead of 300 to 500 cycles they last 2400 to 4000 cycles similar to LiFePO4 So yes optimizing Lithium batteries for energy density works great in stationary applications but is not great for cars where weight is an important factor that is why most manufacturers still use usually LiCoO2 and not LiFePO4 except for the DIY people. I will need to test maybe next month my 100Ah LiFeMnPO4 battery form GBS is used since last year on my offgrid house so at least 300 cycles but usually around 50 to 80% DOD so I should not see almost any capacity loss from may initial test two years ago when I got them new. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
I`ve clocked up 7 years on my lead acid off grid system 48v 1080 Ahr, but they have never been below 70% capacity hardly below 80% capacity, am very fortunate live in a sunny part of the world. Thus 7 x 365 = 2555 cycles so far. But no way would I take them even once to 100% DOD to test their capacity. LiFePo4 looks the most promising for our application, the fact it can be taken down to 50% DOD or better without effecting cycles much, makes it appealing but not from my figures cheaper then lead-acid yet. You mention LiFeMnPo4 ? We come from the land downunder. Vic |
||||
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I dont think it matters at what state of discharge the cycles are calculated at. The total lifetime Kw for a battery are all reasonably close together from 25% to 95%. I had a little dig around for some prices 260ah LFP $351 battery management and accessories (for 16 batteries) $57ea 70% DOD 5000 cycles (13.7 yrs) in theory that is 9.2 Kw/day for $6528 45800 kw lifetime 14.2 cents/Kw 2 volt BAE secura 660's are on special at $435 532ah (10 hour rating)(24 batteries) 40% DOD 3750cycles (10.2 yrs) 10.7 Kw/day for $10500 40125 Kw lifetime 26 cents/Kw 6 volt trojan ind13 820 $1300 604ah 10 hr rate (8 batteries) 45% DOD 3000 cycles (8.2 yrs) 13.7Kw/day for $10400 41100Kw lifetime 25.3 cents/Kw I think in the field, risk of battery damage through poor installation, neglected maintenance or system component failure is the true cost. Sure the LFP's are the cheapest, if they make it to 13 years without a failure. I have seen two turbine controllers fail and short the internal dump load to the batteries and completely drain them. I would like to think a battery management system could fail or malfunction without damaging the cells, when I start asking some BMS sellers questions about the proper wiring schematics and the correct solar charge controller voltages and settings they can get a little vague, so in the past I have just given up. I'm confused, no wait... maybe I'm not... |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Any battery has the risk of damage do to poor installation. I build my own BMS designed for small solar application works with up to 8 cells so 24V see the link in my signature. That one will never fail and damage the battery. I do not have a good solution at the moment for wind but I will think about. I do have a wind turbine but I do not have a dump load it will just brake the turbine if the battery is full. They are vague because they do not know much if anything about battery charging. You can not use a Solar controller designed for Lead Acid and a BMS especially those stupid BMS that charge the cells up to 3.9V for LiFePO4. There is no solution that is why I spent 6 months designing my own BMS it is on Kickstarter now but is open source so someone maybe will build a 48V variant is not that hard just need to add an additional monitoring IC. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
I think Yahoo2 answered your question even if not directly. What I wanted to demonstrate in that video comparison is that price / kWh used from the battery is what is important. So you have 7 years on 48V 1080Ah battery but you used in average around 20% DOD at the top of the charge where the battery is least efficient at charging and discharging. Remember I did not used charge discharge efficiency in my calculation because will make the Lead Acid look way worse. So I will not used here but I can tell you that is about 50% so you need 400Ah from solar to top your 20% of your 1080Ah battery. So you need a solar array at least 2x larger that if you will have used a 98% efficient LiFePO4. Now let me calculate 2555 cycles at 20% DOD (probably 20% is a bit high for the daily average if you say you did not went under 70% SOC) 48V x 1080Ah = 51.84kWh installed capacity 2555 * 20% * 51.84 = 26490kWh used from battery in those 7 years. Say you used Trojan L16RE-A that I have in my calculation and know the price for. You needed 48V / 6V = 8 battery in series and 1080Ah / 325Ah = 3.32 batteries in parallel not an integer but you need about 26 of this batteries to get the same capacity so 300$ x 26 = 7800$ maybe you payed more or less 7 years ago I do not know. 7800$ / 26490kWh = 29.44 cent/kWh this is if you trow the battery today and buy another one if it lasts another 3.5 years then you get to that 20.9 cent/kWh I calculated for Trojan in that table. So you see now why price / kWh is the important one? http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Yes I understand where your coming from, price per kwh is important, I will know that price /Kwh only when mine are finished. Those no of cycles are the important bit, and regardless of what the product glossies say tis real life use that counts and until we have such figures from the different battery chemistries, we are only guessing. I feel one of the Lithium family is the hope there, with a proper charger they should be basically maintenance free, which will make them somewhat idiot proof, and that as Yahoo2 points out is a big cause of lead-acid premature failure. Hopefully I`ll get 15 to 20 years out of mine, because at 10 years their replacement will cost about as much as the power bill they`d saved in 10 years, and that is the bottom line. Your 400 AH to top up the 20% I question(the 20% itself is as I`ve said a very rough %), guessing I`d say your 2 times the real figure. I do know off top of head I use 5.2Kwhr/day on average. Currently I`m away from my system but I`ll be back by the weekend, or get my head blown off by a cyclone. I`ll check my logs then and tell you precisely the real life figures, then we`ll be getting closer to having the maths right for lead-acid, Lithium we can only guesstimate.
We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
I will say that price /kWh is the most important number. Say you will want to sell electricity to your neighbour then you will really need to know your cost of battery amortisation else you will go bankrupt :) If you really used 20% of their capacity as an average daily then I don't think they will last more than another 3 or 4 years. But if you only use 5.2kWh/day in average and that includes the use during the day then you actually only discharge the battery way less than 10% average / day and not 20% then your current cost is more than double what I calculated before so you need another 14 or 20 years of service to get to 20cent /kWh Batteries age also with time not just with cycling and no mater if they are Lead Acid or LiFePO4 you should select the battery bank for a 10 to 12 years amortisation more is not really feasible for the current batteries. Lead Acid battery manufacturers spec the end of life when battery has only 50% of the initial capacity. For lithium batteries the spec is for 80% of the original capacity as the end of life. During the day when you connect a load first you use the available power from the solar PV panels then the difference only is provided from the battery. Today I used 3.1kWh from the AC side and probably another 1kWh directly from DC and my system is way smaller. I have a 24V Battery 8 cell GBS LiFeMnPO4 3x240W solar panels + 2x85W solar panels. Now is spring and I have excess power so during the day I run the inverter and one 1000W small oven for around 3h inverter is 92% efficient so form the PV + battery I take around 3.4 - 3.5kWh in a sunny day. I also have a small 300W wind turbine but use that only in winter when is less sun. Most of the power that I use over 60% is used for cooking. My entire solar setup was probably less than just your battery. My battery was 1200$ 2.5kWh total capacity + about 500$ for the 2400W inverter Tripp-lite PV2400 then the solar panels where 1200$ for the 3x 240W including shipping but they are less now that was two years ago. Wind turbine was 400$ the smaller 2x85W panels I got even earlier at 3$/Watt I use some crap programmable solar controllers for now until my Solar BMS is ready so I need to manually monitor the battery not that great. My power consumption is around 60 to 90kWh/month and I can generate between 90KWh and 140kWh/ month Solar + Wind depending on season. My set-up is working now for about a year and had only two days where I was without power and used the smaller 0.5kWh A123 System backup battery. Those where from my fault not estimating how much I had left in the battery since at the moment I do not have an energy counter (it will be on my Solar BMS) and the discharge curve is extremely flat you can not say what capacity you have left only based on voltage. The only thing you know for sure is when is 100% full and when is completely empty :) so a state of charge indicator is extremely important. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Price per Kwh only the most important if your an accountant
Quality, reliability etc of supply much more important to the user, that is the essence of not just power but life. Already that is showing, my system is a tired old tech but it is proven. Have not had a single hour never mind day without power in those 7 years plus. Forget about analogies, selling to your neighbours etc etc. I`ll talk realities. Whilst my system will not compete with the grid on price per Kwhr, it licks it totally on reliability and going back to initial talks with the accredited installer( could not DYO and get the Govt subsidy that was being offered), it has achieved that objective and touch wood will continue. Initially I asked for a system not for what it cost in capital outlay but for what it would do reliably, for I have learnt in life only the rich can afford cheap unproven equipment. Or to look at it another way only the rich can afford to keep replacing cheap equipment. I have 18 x 130 watt solar panels which have the batteries floating by midday probably 80% of the year. The supposed luxury of excess solar and battery capacity are necessary for reliability from my point of view. Unfortunately for the masses your right, price per Kwh is of most importance that is why "the grid" will be around for many more years, the majority are not prepared to spend capital on power production they wish to pay as they use. Thus whether the industry comes up with battery and panel systems that produce power at even 1/2 of grid power, unless we can bring the capital outlay down to zero, the industry is not in the market. Different story when the industry can compete, the solar-battery system with the current grid power production (coal, gas, nuclear etc) then solar will be a serious grid power supply. I use both a manual hydrometer and my inverters logging ability connected to a PC to monitor battery condition. At a glance on the PC I know the batteries current state, not always do the hydrometer and the PC agree, the hydrometer being the accurate one which has lead me to fiddle with the software to get it to monitor more accurately. Presently have my battery efficiency set at 87 % and getting closer to total agreement. The maths of it all. We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
I need to agree with you on the reliability part that why I was looking on the Lithium batteries in the first place :) I do not find Lead Acid a reliable battery. Yes it is around since the 1800 and people know all that is to know about them but they need maintenance and complicated charging 3 stage. LiFePO4 need only one stage CC (constant current and at 3.4V you can stop the charging since is 95% SOC) So you have 18 x 130W panels that is 2340W it seems about right for 5.2kWh average/day I only have 890W total solar. It will depend also on location a bit. As we talk about location where do you store your batteries? Since they need venting and at least where I live it will have been impossible to use Lead Acid. Is there any winter where you live? and how do you protect them from cold air? assuming that the space they are in is vented to the outside. There is no reason for grid power to disappear they will always be needed. http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Winter in sunny north OZ is clear blue skies ambient gets down to 10deg C on occasions but only 20 deg C in battery box. Nothing special in my battery storage just a timber well vented enclosure. The complicated charging is no drama I have a Outback 60, that goes through the bulk, absorption to float each day totally automatic. With a 2 monthly 1 hour equalisation, rest is ensuring electrolyte level is maintained. Don`t knock the old tech, lithium is promising but not there yet. I agree grid power should be here forever, it took us from the unhealthy days of individual coal, peat etc fires (high localised pollution) to the distribution of cheap electric power. I am just an advocate for renewable energy but not a knocker of current energy production. We`ll develop better batteries etc etc and replace fossil fuel for power production in time. We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Yes you are lucky with that weather. But for me at -30C I do not see how will have been able to use them. Here is an interesting document Battery-lab-test from a large lab in US doing tests on different Lithium batteries for energy storage. Here is a screen shoot page 12 of a large LiFePO4 160Ah cell that after 27k cycles at top 10% DOD still has 85% of initial capacity. So my opinion is that Lithium is already here else I will not have been investing my money in a LiFePO4  http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
-30C now I understand your rejection of lead-acid. Yes lithium is here now for you ,hopefully it will be 7 or more years before I need to select new batteries, if the next 7 years are like the last in tech changes who knows what batteries are available then. Regardless it is good to correspond with people of similar interests but in such a variety of different living conditions, for that we have our 4M to thank. I cannot even imagine living in -30 C conditions, I`m freezing at 10 C give me +30 deg C any day.
Another bit of info from my area concerning solar radiance. 1000 watts of mono solar panels will average yearly to 8.1 Kwhr per day in my area, due to latitude and cloudless conditions. We come from the land downunder. Vic |
||||
| electrodacus Newbie Joined: 30/03/2014 Location: CanadaPosts: 39 |
Moderate weather will be great but I prefer -40C vs +40C it will be easier to heat a room that it will be to cool one. Less technology involved. As for solar radiance not sure I got your number right 8.1kWh average day from 1000W of panels sounds way to high. I get at my location 3.8kWh/day average over a year form 1000W of solar panels and is probably one of the sunniest places on earth and the cold temperatures help with solar panels. So something sounds wrong there how did you got that number? I use this calculator Select Canada SA Regina. And I get an average of 5.04kWh/m2 as an average / day over a year Minimum is 3.06kWh/m2/day in December and max is 6.25kWh/m2/day in the summer. If I use that default derate factor of 0.77% I get 1387kWh over a year divided by 365 days = 3.8kWh/day average over a year form 1000W of solar PV http://electrodacus.com/ https://www.youtube.com/user/electrodacus |
||||
| norcold Guru Joined: 06/02/2011 Location: AustraliaPosts: 670 |
Simply latitude, the closer you are to that equator with cloudless skies the higher the radiance. The sun is closer to me it is that simple. Check out NASA and its solar radiance figures for areas such as far north Australia. 3.8Kwhr from 1000 watt would be one of the lowest returns for OZ even way down south. Also I guess that is why in Australia especially north, sun cancer is a major problem. I mentioned this in my last post because I knew this would be to you a questionable figure. If you go to the Clean Energy Council Australia webpage, trawl through the pages you`ll find a pdf file that gives the projected solar returns from panels for cities throughout Australia, you will see what I mean with my observation above to your 3.8Kwhr/day figure. Whilst in the cold panels performance is increased but not any great amount as in our hot summers I have seen no noticeable decrease in performance. Oz is just begging out for solar it is the way of the future surely, storage we need power storage. It is not just about sunny skies, low latitude in combination does it. We come from the land downunder. Vic |
||||
| Page 1 of 3 |
|||||
 Print this page |
