LiFePO4 Battery

[SolarWatt]

Hello guys

Can you please review the attached datasheet ?
It is a 12V 150AH deep cycle battery and the spec claims this battery can do DOD=100% for 2000 cycles !!! (10V looks like DoD=100% to me)
All the talking here are about not more than DOD=20%
So what is so special in this battery ??
What is LiFePO4 Battery at all ??


The website is http://www.optimumchina.com

The only problem is that the part number in the datasheet is IFR32650 and I didnt find it in the website of the company....

the closest product I found is this: http://www.optimumchina.com/products...166564084.html


Thanks
SolarWatt

[inetdog]

Hello guys

Can you please review the attached datasheet ?
It is a 12V 150AH deep cycle battery and the spec claims this battery can do DOD=100% for 2000 cycles !!! (10V looks like DoD=100% to me)
All the talking here are about not more than DOD=20%
So what is so special in this battery ??
What is LiFePO4 Battery at all ??


The website is http://www.optimumchina.com

The only problem is that the part number in the datasheet is IFR32650 and I didnt find it in the website of the company....

the closest product I found is this: http://www.optimumchina.com/products...166564084.html


Thanks
SolarWatt

The advice about 20% DOD is specific to Lead-Acid chemistry, regardless of FLA, AGM or GEL.

Other battery types, such as NiMH, NiCad, etc. can tolerate deeper discharge.

Lithium chemistry batteries are destroyed by discharge below a certain level, but the battery packs usually have built-in circuitry to prevent that, so 100% DOD is just to the point where it is cut off to preserve the cells.

Even for these other battery types, there is a limit to the number of charge/discharge cycles that they are good for. But that number is not nearly as sensitive to DOD as it is for Lead-Acid.

LiFePO4 stands for Lithium/ Iron Phophate. One electrode is Lithium, the other is Iron Phosphate.
Lithium based batteries have extremely high energy density per volume and per pound. But with that high density comes danger from short circuits, overcharging, thermal runaway, etc. So Lithium batteries require special charging and handling care. The variant which uses IronPhosphate is slightly lower energy density, but inherently much safer to use, so it is the growing choice for computer battery packs and DIY electric vehicles, as well as for lightweight starting batteries for motorcycles.

[rreinha]

LiFePO4 Lithium Iron Phosphate

Hello guys

Can you please review the attached datasheet ?
It is a 12V 150AH deep cycle battery and the spec claims this battery can do DOD=100% for 2000 cycles !!! (10V looks like DoD=100% to me)
All the talking here are about not more than DOD=20%
So what is so special in this battery ??
What is LiFePO4 Battery at all ??


The website is http://www.optimumchina.com

The only problem is that the part number in the datasheet is IFR32650 and I didnt find it in the website of the company....

the closest product I found is this: http://www.optimumchina.com/products...166564084.html


Thanks
SolarWatt

LiFePO4 Lithium Iron Phosphate is the most common of the Lithium batteries.
LFP cell voltage is nominal 3.4 Volts per cell. The voltage range is generally 2.0 to 3.9 volts.
Most manufactures like to keep some head room for longer life, so as a good rule of thumb for LFP is 2.7 to 3.4 Volts.

This battery is grouping 4 cylindrical 32650-5Ah cells in series to get to 12.8 volts nominal and then that group is grouped into 30 parallel groups to get to 150Ah. (120 cells in all)
This battery should have some kind of Internal Cell control in it to keep the module balance internally
A typical Cycle life on this type of battery is warrantied at 1800 cycles
LFP needs to be above 0 degC to be charged to get max life and capacity below 0C is about 1/2 (75Ah in this case)

[Sunking]

LiFePO4 Lithium Iron Phosphate is the most common of the Lithium batteries.

No they are not. Lithium Cobalt is the most common type.

[rreinha]

No they are not. Lithium Cobalt is the most common type.

I come out of the Auto industry and was speaking to that Sorry if I confused anyone.
Cobalt is higher Energy and more volatile and needs a good management control to it.
LFP is the must safer answer for large battery systems.

[Sunking]

I come out of the Auto industry and was speaking to that Sorry if I confused anyone.

The LFP auto industry has died. A123 Systems went Belly up. You are in Ca and the only EV manufacture there is Tesla which uses Colbalt.

[rreinha]

The LFP auto industry has died. A123 Systems went Belly up. You are in Ca and the only EV manufacture there is Tesla which uses Cobalt.

There many start up EV manufactures in Calif, Fisker, Coda, Phoenix, along with imports like Toyota, Honda, Hyundai, KIA all Calif based, and other OEM's like Ford and GM also use LFP, Chrysler is using a polymer along with some Fords.
Freightliner and Eaton systems are LFP
In the late 90's Nissan used Colbalt, but moved away to LFP for safety reasons.
In larger Megawatts batteries are LFP, LTO, and Polymer, but no larger batteries are Cobalt

[SolarWatt]

Thanks !!

[T1 Terry]

LiFeP04 Battery

I see the Delorean is making a comeback with a lithium ferrous battery pack. The proto type is using a DC motor and controller, capable of 100mph, the production model will have an AC motor and regen capability.
http://www.engadget.com/2011/10/17/d...doc-browns-wh/ a google search some Drive show takes the demo one for a test drive.

Back on topic sort of, I have been running a large part of my house on a lithium ferrous battery pack and solar for about 18 mths now and it has been a great success. The batteries 720Ah @12v nom have been exhausted a few times including this morning after 3 days of rain and/or heavily overcast conditions but they simply recharge with no apparent side effects. Max discharge is 2.8v as the safe limit although a friend bought a bulk lot of discarded electric cycles cell with a some cells all the way down at 0.5v (the dreaded active BMS monster) and they recharged and are working fine 6 mths later.
The rate they can accept charge is incredible, the sun came out this morning and the solar has been belting in 100 amps plus for the last 4 hrs and the terminal voltage holds steady at 13.2v, the recovery from 11.7v this morning to 13v took less than an hr. They possibly won't make fully charged by sun down but that doesn't matter to these cells, apart from the initial cost they are the answer at the moment for home power batteries.
Maybe by the time these batteries reach the end of their life the salt water lithium batteries will be an off the shelf item.

T1 Terry

[Beanyboy57]

The rate they can accept charge is incredible, the sun came out this morning and the solar has been belting in 100 amps plus for the last 4 hrs and the terminal voltage holds steady at 13.2v, the recovery from 11.7v this morning to 13v took less than an hr. They possibly won't make fully charged by sun down but that doesn't matter to these cells, apart from the initial cost they are the answer at the moment for home power batteries.
Maybe by the time these batteries reach the end of their life the salt water lithium batteries will be an off the shelf item.

T1 Terry

I see that some manufacturers are selling Lithium-ion batteries coupled with a battery management system to to keep them operating within safety specifications. How do you manage your batteries and may I ask roughly how much did yours cost?

[T1 Terry]

I see that some manufacturers are selling Lithium-ion batteries coupled with a battery management system to to keep them operating within safety specifications. How do you manage your batteries and may I ask roughly how much did yours cost?

Cell manufacturers don't sell BMS units, it's the resellers that are pushing the BMS units as an added on. As far as I see it they are just up sizing, you only wanted the burger but you must buy the rest or they won't sell you a burger. The lame piece of B/S about the manufacturer not selling the cells with a BMS is nonsense, you can buy 4 cells in one case batteries from the likes of Winston Battery company, it doesn't have a BMS system from the factory, the manufacturer didn't think it needed one so it didn't fit one.
Once the cells are balanced they stay in balance, the extremes of top end charging and completely discharging are the only areas where the cells drift apart, other than that they sit between 13v @ 20% SOC and 13.3v @ 90% SOC, the last 9% sees a rise to 3.40v, the last 1% sees a rapid rise in voltage. As soon as the cell is full it's full, like water in a glass, you can't fill it past the top, it just overflows. If one cell is 0.1Ah ahead of the others it will start to run away. Stay away from the max and min voltages and there isn't a problem. 3.45v per cell is 99% full, who cares about the other 1%, with my 720Afh pack that represents 7.2Ah, if I ran that close to the wind that 7.2Ah was a live or die situation I would seriously need to rethink the system and add a bit more.
The more cells you add in parallel to build capacity at the 3.2v level the more the system stays in balance, the slight differences in manufacturing balances out across the group. String these groups together to build voltage, 4 sets builds a 12.8v battery that will operate between 13.8v 99% full and 11.2v fully discharged, the inverter shuts down at 10.8v which is 2.7v per cell or super cell, as soon as the load stops the cells bounce back to 3v, that creates a safe low voltage cut off.
I don't run without any sort of a safety net, I use a Junsi cell log 8, they have adjustable high cell voltage and low cell voltage alarm points and you get an LED screen readout of just what's going on. There is even a model with a data logger so you can record what's happening and then feed it into the laptop to create graphs etc, good for fault finding or looking for trends, set for a 30 sec sample rate it hold 7 days of data. When you see a cell pack getting a bit higher than the others at the end of the charge cycle a few days in a row a simple light bulb across that cell burns a bit out till it's back to same level as the others, I haven't had to do that for over 12 mths so they just don't drift out of balance much. For$28 from a hobby shop it’s cheap insurance.
Really, you know you are getting close to the bottom when the voltage drops below 13v, 3.25v per cell, there is still 20% or more of the capacity left to go if things are tight so a complete shut down isn't required but just being conservative will get you through to the next day, forgetting to look till the next morning is still covered by the inverter shut down.

T1 Terry

[Beanyboy57]

Really, you know you are getting close to the bottom when the voltage drops below 13v, 3.25v per cell, there is still 20% or more of the capacity left to go if things are tight so a complete shut down isn't required but just being conservative will get you through to the next day, forgetting to look till the next morning is still covered by the inverter shut down.

T1 Terry

Great info thanks. I will certainly take Lithium batteries into consideration when I need to replace my battery bank in a few years time! My CC is fully programmable as is my inverter so this would make life easier for using Lithium batteries if that is what I choose.

[T1 Terry]

Great info thanks. I will certainly take Lithium batteries into consideration when I need to replace my battery bank in a few years time! My CC is fully programmable as is my inverter so this would make life easier for using Lithium batteries if that is what I choose.

There is guy on another forum from over your way that is setting up a grid backed lithium ferrous set up. the plan is to feed his 2 x 200w 24v panels i series into the 48v battery bank and run the main house system on the batteries and pumping all the roof topsolar into the grid. The main aim is to run off batteries through the peak price power period, then in the off peak period the batteries are recharged. His original reason was as a back up for an unreliable grid allowing all his icecreams to melt, he does an out door cinema circuit but there was so much more potential he is trialing the grid backed method.

T1 Terry

[Beanyboy57]

There is guy on another forum from over your way that is setting up a grid backed lithium ferrous set up. the plan is to feed his 2 x 200w 24v panels i series into the 48v battery bank and run the main house system on the batteries and pumping all the roof topsolar into the grid. The main aim is to run off batteries through the peak price power period, then in the off peak period the batteries are recharged. His original reason was as a back up for an unreliable grid allowing all his icecreams to melt, he does an out door cinema circuit but there was so much more potential he is trialing the grid backed method.

T1 Terry

I am already doing something very similar to this although the difference is that I have FLA batteries, my off-grid system is only used (on a timer) during the peak solar hours of the day to pump power back to the house from my garage powering several appliances and supplementing the power from my grid tie system and thereby increase my rebate from the excess produced and sent back into the grid. The balancing factor is the lifespan of the FLA batteries. I know that the off-grid inverter is mostly using the power of the PV array and that the batteries are only being depleted less than 14% and less than 10% some days. but as my set up is only less than 1 year old I am not sure of the long term consequences of my plan. My gut feeling is that it will not be economical, so that is why I am very interested in getting as much information as I can about battery developments as battery lifespan and power to weight ratio (i I can use those terms) is the key.