Lithium Iron Phosphate Batteries; LFP; LiFePO4 discussions

higginshiggins Solar Expert Posts: 56 ✭✭✭✭
NOTE:

I have combined three different Lithium (LFP) Rechargeable Battery Threads into this one.

If this is a problem, I can split them back apart.

Please let me know if this does not work for your guys.

-Bill B. Moderator

PS: There is still another thread about an LPF Power Pack that one of the members here is building for sale... I have left that thread where it is currently to let everyone discuss that LFP product on its own merits.

Portable Solar Power
Reference is made on here about percentage of discharge in batteries,is this the opposite end of the SOC percentage?For example if my battery is 100% fully charged am i working down 10% discharged with a load from 12.70/12.80?On a SOC 10 % SHOWS at the lowest voltage level of a battery ,getting more confused the more i learn.LOL,
Higgins:blush:
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Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: which end DOD SCALE?

    they do not refer to voltage, but refer to the ah capacity of a battery. if you have a 200ah battery that is 100% soc then it is fully charged meaning that all 200ah is available and this can also be written as 0% dod or the opposite which you got right. to take away 10% of the capacity (represents 20ah drawn) the battery is then at 180ah and is written as either 90% soc or 10% dod.
    rough guesses on capacity can be made with the at rest voltage, but this varies somewhat for different batteries.
  • higginshiggins Solar Expert Posts: 56 ✭✭✭✭
    Re: which end DOD SCALE?

    Thanks Neil that clears up some confusion with the charts and people's discharge percentages:D
    Higgins
  • icarusicarus Solar Expert Posts: 5,115 ✭✭✭✭
    Re: which end DOD SCALE?

    Just to re-confuse you, there is depth of discharge (DOD) and State of charge (SOC).

    So a battery 50% discharged would have a SOC of ~50%, or a DOD of 50%.

    A battery 10% discharged would have a DOD of 10% and a SOC of 90%!

    I like batteries to never go below 80% SOC/20%DOD.

    Tony
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: which end DOD SCALE?

    Who's LFP batteries ar you useing, how many amp Hrs, what did they cost and where did you get them?
  • BB.BB. Super Moderators, Administrators Posts: 28,858 admin
    Re: which end DOD SCALE?

    I believe the LFP batteries are:

    Lithium iron phosphate battery

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: which end DOD SCALE?

    Yep, supposed to be wonderful, never heard them used outside of EV's & laptops etc.
  • audredgeraudredger Solar Expert Posts: 272 ✭✭
    Re: which end DOD SCALE?

    With the high voltage ( 2.8 v) per cell, are you using a 5 cell bank to make 12v?
  • mike95490mike95490 Solar Expert Posts: 8,206 ✭✭✭✭✭
    Re: which end DOD SCALE?

    So, what would be involved in making up a 48V household bank,
    15 cells
    15 balancer units
    can a regular 48V lead-acid charger feed them or do I need a charger to intergrate with the balancers ?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • momofgcmmomofgcm Solar Expert Posts: 35
    Lithium Iron Phosphate Batteries; LFP; LiFePO4 discussions

    What is the difference between and LTP battery and an LFP battery I see in a lot of posts? We are using LTP's.

    This is a GREAT forum by the way!

    Kim
  • RWBRWB Solar Expert Posts: 168 ✭✭✭✭✭
    Re: Gel Batteries

    http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

    Me and my partner are the fist to use LFP batteries in our portable solar power systems and we have been testing and using LFP Batteries over the last 7 Months and we are very very happy with them. We have decided to never by a Lead Acid Battery again to build a new system unless a customer specifically ask for Lead Acid.

    Not many people are using LFP Batteries in the Solar Field yet but they will come around soon enough once they see for themself's how much better they are vs the old Lead Acid Battery Tech.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Gel Batteries

    rwb,
    i know you have brought up these batteries in other threads, but i think you should expand upon the discussion of these batteries here. go into the needs of chargers and the batteries and compare with the other types as the op started into asking about. show what capacities are available and who may sell them for what costs too. lead acid batteries are not cheap and i resent the manufacturers keeping the costs high after metal prices went back down. it smacks like a bit of price fixing from them and not the retailers of the batteries.
  • momofgcmmomofgcm Solar Expert Posts: 35
    Re: Gel Batteries

    I see what type they are but my question really is what is the difference. Why would I want them?

    We are using gel LTP batteries (although I'm not sure the actual technology used here).
  • RWBRWB Solar Expert Posts: 168 ✭✭✭✭✭
    Re: Gel Batteries

    Well the main advantages I love about the LFP Batteries are:

    #1. Reduced Weight 40-50% less weight on average. A 160&200 Amp Hour 12V LFP Battery Pack weighs 64 Pounds. A 12V AGM Battery Weighs up to 160 pounds, so were talking a 100 pound weight difference which is HUGE! Especially if your working with portable solar power systems.

    #2. Much Longer Battery Life Span vs lead acid batteries. 5000 Cycles at a constant 70% DOD with LFP vs 300-400 cycles with a Lead Acid Battery constantly drained to 70% DOD. The Life cycle difference is just crazy.

    #3. Near 100% efficient charge and discharging. Put 100 Amp Hours into the battery and you get 100 Amp Hours out of it most of the time. The LFP Batteries by Tundersky do not suffer from Perkuet's Exponent or what ever its called like Lead Acid Batteries do so basically no power is lost in the charging and discharging process, at least very little is lost if there is a loss compared to Lead Acid Batteries.

    Even under 1C loads you still get the batteries rated output unlike Lead Acid Batteries which give you less amp hours when drained under higher loads.

    #4. A 200 Ah Battery is considerably smaller than a 200Ah Lead Acid Battery.


    A 200Ah LFP battery drained to 80% Daily will give you 160 Amp Hours and it is rated to do this for 3000 cycles. After 3000 cycles the capacity will simply start dropping down to 80% of its rated capacity and continue to work. 3000 cycles is 8 years.

    A 200ah Lead Acid battery will give you 3000 cycles if you only drain it down to 20-30% every day which is only 50 Amp Hours per day at 25% DOD vs the 160 Amp Hours a LFP Battery will give you, that's a 110 Amp Hour Difference.

    So you can see how you could easily use less LFP Batteries to achieve your Amp Hour requirements vs More Lead Acid Batteries to achieve the same Amp Hour Requirements.

    You can start to see how the longer life span of LFP along with being able to pull more amp hours out of them and still get a 8 year life span. If you only drain the LFP batteries to 70% your life cycles go up to 5000 cycles which gives you an extra 5 years for a total of 13.6 years. After that 13 years your LFP Battery packs rated capacity will/should drop to 80% of your rated capacity and continue to work into the future.

    When you lay it all out on paper LFP Battery Storage is probably cheaper over time and maybe cheaper up front compared to a lead acid battery bank.

    Anyways those are a few things I really like about the LFP Batteries.
  • mike95490mike95490 Solar Expert Posts: 8,206 ✭✭✭✭✭
    Re: Gel Batteries
    RWB wrote: »
    Well the main advantages I love about the LFP Batteries are:
    .....
    .....
    .....

    When you lay it all out on paper LFP Battery Storage is probably cheaper over time and maybe cheaper up front compared to a lead acid battery bank.

    Anyways those are a few things I really like about the LFP Batteries.

    Do they need different chargers, or can I just swap out my FLA for LFP's on my tristar MPPT?
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • RWBRWB Solar Expert Posts: 168 ✭✭✭✭✭
    Re: Gel Batteries

    I just program the Sunsaver MPPT's to Bulk Charge of 14.4V, and Float Voltage of 14V. Turn off Equalize, and I disable Temperature Compensation because after talking with some very knowledgeable EV Car guys who use tons of these batteries they see no need for temperature compensation unless your in a very cold environment.

    I also asked the manufacture of the correct Temperature compensation settings and there were none to be given.

    You can Program the Tristars the same as I can program the sunsaver MPPT.
  • boBboB Solar Expert Posts: 954 ✭✭✭✭
    Re: Gel Batteries

    What kind of LFP batteries are you using ??

    On temp comp, I would think it might be handy just to reduce the charge if the batteries get hot ? It sure seems these days though that Lithium battery manufacturers always seem to make their batteries "smart" in that you can't over charge them.

    boB
  • RWBRWB Solar Expert Posts: 168 ✭✭✭✭✭
    Re: Gel Batteries

    We are using Thundersky Batteries mainly.
  • BB.BB. Super Moderators, Administrators Posts: 28,858 admin
    Re: Gel Batteries

    I have a question... Perhaps "momofgcm" is talking about a different LTP Gel battery...

    gel LTP batteries from Connexa Energy
    or
    Deka LTP SLA (Sealed Lead Acid)

    These batteries appear to be standard Gel / Sealed Lead Acid type batteries. I do not know what LTP means (terminal type?)--but has nothing to do with Lithium (I believe).

    LTP is close to an abbreviation used by Lithium type--But does not match any type of Lithium cell that I can find.

    So--the comparison/question appears to be more what the difference is between a SLA/Gel (or AGM/Flooded Cell) Lead Acid battery and the specific LFP chemistry type battery.

    Lithium iron phosphate battery
    Gel/AGM type Lead Acid Battery
    Lithium disposable (Primary) Battery (many types)
    Lithium-ion battery (rechargable)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Gel Batteries

    Thundersky Batteries (China manf.) are Lithium iron phosphate.

    Interesting presentation, particularly the safety parts. They are recommending per cell monitoring during charging (keep every cell under 4.2v limit).

    http://evolveelectrics.com/PDF/Thundersky/TS%20manual.pdf
  • hamlet_joneshamlet_jones Registered Users Posts: 12
    LiFePO4 Battery? Anybody tried them?

    Hi folks, this is my first post.

    I am moving, and I'm NOT taking my L.A.B. Bank with me. I hate lead acid!

    I am thinking of these new batteries:

    http://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

    They are available on ebay and other online merchants.

    Their nominal voltage is different than lead-acid, so you would need a programmable charge controller, and charging thru your inverter probably wouldn't work. However, the cycle life and chronological lifespan is miles above lead acid.

    The one thing I really hate about lead-acid is that they die whether or not you cycle them or not, whether you float charge them, or not. About 7-8 years, max.

    Anyway, who has the best programmable charge controller? Outback?

    THanks!
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: LiFePO4 Battery? Anybody tried them?

    All MPPT controllers can be set with custom voltage, in your case it will be 3.6V * 4 = 14.4V (12V system). Question is, how are you going to keep Li-Fe batteries balanced? What are you going to use to monitor each cell to make sure it never dips below 2.5V ?
  • hamlet_joneshamlet_jones Registered Users Posts: 12
    Re: LiFePO4 Battery? Anybody tried them?

    I don't know how to keep them balanced. It doesn't seem to be a problem with lead acid. I suppose I could use a low voltage disconnect set at 11 volts to prevent the cells from getting too low.

    I'm going to have to think about the balance issue. Maybe build a custom detecter for each cell? Does anybody make a lead-acid monitor with adj. set points? Maybe the MFG has something on offer...
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Gel Batteries
    RWB wrote: »
    I just program the Sunsaver MPPT's to Bulk Charge of 14.4V, and Float Voltage of 14V. Turn off Equalize, and I disable Temperature Compensation because after talking with some very knowledgeable EV Car guys who use tons of these batteries they see no need for temperature compensation unless your in a very cold environment.

    I also asked the manufacture of the correct Temperature compensation settings and there were none to be given.

    You can Program the Tristars the same as I can program the sunsaver MPPT.

    These setting seem a bit strange. Assume you have four batteries in series?

    Full charge would be 16.8 vdc. (4.2 vdc per cell). A float of 14v would shut off charging above 3.5 vdc which is about fully discharged voltage at light to moderate loads. This amounts to no charging until battery is fully discharged. This would seem to be wasting a lot of solar power.

    A charge at 14.4v would be only 3.6 v per cell giving less then 50% capacity.

    Partially charging a battery is a characteristic of hybrid autos since they are constantly recharging from motor and brake system. They are not interested in getting maximum capacity from battery. The lower charge point maximizes battery longevity which is more of interest to auto manf.

    I believe the battery longevity 'knee' is about 3.85 vdc per cell. You should be able to set float to about 15.1v which will make more power from PV system available. Bulk set to 15.4 vdc if you want maximum battery longevity.
  • BB.BB. Super Moderators, Administrators Posts: 28,858 admin
    Re: LiFePO4 Battery? Anybody tried them?

    There are a couple recent threads with LFP discussions. Inculding one person that is making a product that contains LFP batteries. Google does a better job searching for short words/acronyms than our site's search engine:

    www.google.com/search?q=lfp+site%3Awind-sun.com

    In general, the LFP batteries sound great. Most cells would include their own individual electronic circuit to prevent over charging and over discharging... As many of the new technology rechargeable batteries are very sensitive if operated outside their design range.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • KamalaKamala Solar Expert Posts: 452 ✭✭
    Re: LiFePO4 Battery? Anybody tried them?

    Maybe something like this http://evolveelectrics.com/EVWorks%20BMS.html
  • momofgcmmomofgcm Solar Expert Posts: 35
    Re: Gel Batteries
    BB. wrote: »

    So--the comparison/question appears to be more what the difference is between a SLA/Gel (or AGM/Flooded Cell) Lead Acid battery and the specific LFP chemistry type battery.

    RIGHT!!!

    My batteries are Gel lead acid batteries. My MK batteries are 8G4D LTP. I will have to find out what the LTP stands for.

    Why is the LFP better than the gel lead acid? Some of it was answered below.

    Kim
  • RCinFLARCinFLA Solar Expert Posts: 1,280 ✭✭✭
    Re: Gel Batteries
    momofgcm wrote: »
    RIGHT!!!

    My batteries are Gel lead acid batteries. My MK batteries are 8G4D LTP. I will have to find out what the LTP stands for.

    Why is the LFP better than the gel lead acid? Some of it was answered below.

    Kim

    Comparision is almost apples vs. oranges. Beside obvious per cell voltage difference, Lithium Iron Phosphate runs in lower 70% of state of charge for max battery longevity where Lead Acid runs in upper 70% of state of charge for max battery longevity.

    Lithium Iron Phosphate are suppose to be safer then Lithium Cobalt. Probably should have per cell monitored to avoid over discharge and over charging when dealing with a series multi-cell voltage stack.
  • hamlet_joneshamlet_jones Registered Users Posts: 12
    Re: LiFePO4 Battery? Anybody tried them?

    I actually am getting good communication with the China mfg. that is licensing the tech from MIT. I have an email in asking if they supply a circuit for overvoltage, balencing. Mayby know more in the morning...
  • AntronXAntronX Solar Expert Posts: 462 ✭✭
    Re: LiFePO4 Battery? Anybody tried them?
    I actually am getting good communication with the China mfg. that is licensing the tech from MIT. I have an email in asking if they supply a circuit for overvoltage, balencing. Mayby know more in the morning...

    Talk to these guys instead: http://www.evcomponents.com/SearchResults.asp?Cat=34 They deal with Chinese directly.
  • john pjohn p Solar Expert Posts: 814 ✭✭✭
    Re: LiFePO4 Battery? Anybody tried them?

    BB Bill I have never seen one that fitted this Most cells would include their own individual electronic circuit to prevent over charging and over dischargingIf you do buy a complete 12 battery the ballencing board is built into the top part of the battery but if you using seperate cells you need to buy 1 of 2 types of ballancing circuit
    1 The cheapest is a circuit board that monitors each cell then povides warnng if under or over discharge. ie provides output to switch relay to turn on off charger or device using current from the battery/ies
    2 the best but most expensive is a controler that does all the above but connects across each cell dropping resistors and circuit to stop any cell being over charged.
    Below is from a suppliers site it explains it better

    Fom a lifepo4 supplier

    A VMS differs fundamentally from a BMS in that it will not disconnect a battery automatically from external devices connected to it during over-charge or over discharge conditions. It will only provide a signal output or some other visual or audible warning when approaching these conditions. This signal output is used by electric vehicle (EV) manufacturers to interface with their own external control systems in different ways. For example the signal generated by the VMS when the battery becomes fully discharged might be used to drive an external relay or contactor via suitable switching transistors. The relay contacts then disconnect the battery from its load thereby preventing further discharge which could lead to battery damage and thus maintaining long battery life. The signal outputs from the VMS can be used in many different ways and are only limited by the imagination of the EV designer.





    The BMI VMS is built into the HPS series of battery packs. We do however supply the VMS in kit form for those experienced battery constructors who would like to assemble their own custom battery. The complete VMS kit includes two circuit boards, interconnecting ribbon cables, temperature sensing thermistor and wiring loom to connect the VMS board to the individual cell terminals. There is no soldering required since all wiring and sensors are terminated with connectors and simply plug into the main VMS circuit board. The second circuit board is optional since it is required only for advanced applications but is useful to have due to the warnings it provides by indicator LED's and warning buzzer. This board is a display board and has two DB9 data connectors fitted so that batteries can be monitored on a computer via an RS-232 data link. A battery data converter and software is available which interfaces the VMS with a PC. Each VMS board connects to and monitors four cells and several VMS boards can be linked together "daisy chain" fashion to accommodate any number of cells. So for example if a 36V battery was to be assembled this would require twelve cells and three VMS boards.

    LiFePO4 Battery Balancers


    Lithium Batteries Australia supplies the world's highest quality battery balancer for those who do not want to use a BMS and would prefer to balance their cells via an external balancer rather than a BMS. This balancer is the highest quality unit on the market and is very fast and accurate in its balancing ability due to its high 1.5 amps shunt current while charging. These are a very high quality unit made in an extruded aluminium case. They are made in Europe exclusively for LBA by our european partners.

    Balancers are available in all the common battery voltages of 24V, 36V, and 48V. Custom units can be supplied for any quantity of cells upon special order. Please enquire if you have a special request.
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