Still deciding between LiFePO4 and AGM

[BackwoodsEE]

I'm 90% decided that I'm going with a bank of eight 6V Surrette AGMs, but remain intrigued with those relatively inexpensive CALB "chi-com" (as Sunking puts it) LiFePO4 cells. A 360 Ah battery could be constructed from them for around $7,300, about $3,000 more than the 415 Ah AGM battery. That's equivalent capacity if not more, with no inefficient absorption stage to take hours and hours to get the battery up to healthy resting state. On the other hand, I wonder if the LiFePO4 cells would make economic sense in a lightly cycled grid-tied application where the battery acts mostly as a short term repository of coulombs between the charge controllers and the Outback Radian inverter/charger.

Given how shallow the depth of discharge is likely to be in such case, would the AGMs be the better choice? The warranty (pro-rated of course) for the Surrette Rolls S6 series in a renewable energy application is 7 years. Would a bank of 32 LiFePO4 180Ah cells kept around 50% SOC be likely to last any longer? It seems unlikely, but I haven't seen anything that would provide much of a solid estimate.

During my reading, I came across this interesting article that discusses the LiFePO4 in an evenhanded, realistic manner. It's directed toward cruising sailboat owners, but a lot of their sort of usage applies to us as well. He begins with this warning:

Unless you want a big fat dent, where your wallet used to be, I do not believe LiFePO4 is ready for mass DIY prime time builds. Read with CAUTION!!! If you think you want LiFePO4 PLEASE READ VERY CAREFULLY! Once you are done reading this, and it makes sense to you, then please spend another 6-8 months reading everything you can including every single LiFePO4 white paper you can get your hands on.

It includes a comparison between top and bottom balancing, with warnings about both.

Right now I'm thinking I'm going to just order the thousand pounds of Canadian lead and hope that Lithium makes more sense as an alternative when I have to replace it in 5-7 years. Comments welcome.

[Mike90250]

If you are Grid Tie, why are you looking at batteries ? Get a back up generator and stock up on fuel. What is the longest outage you think you might have in your area?

Batteries are like a boat: a hole you keep trying to fill with money.

[Sunking]

I'm 90% decided that I'm going with a bank of eight 6V Surrette AGMs, but remain intrigued with those relatively inexpensive CALB "chi-com" (as Sunking puts it) LiFePO4 cells. A 360 Ah battery could be constructed from them for around $7,300, about $3,000 more than the 415 Ah AGM battery.

Tap the breaks there my friend. The AGM's will last longer with a real warranty.

Which Rolls AGM? S or R series?

S Series used for RE give you a 24 months full replacement plus 60 months prorated. That is 7 years
R Reries used for RE gives you 12 plus 12 or 2 years.

Chi-Com claims 1 year, but you will never get them to honor it.

Lastly do not make the mistake comparing AGM to FLA. AGM's charge efficiency is 90%, and thus like LFP spend a lot less time in Absorb. They can also be discharged deeper than FLA. I agree with Mike if you are going GT, forget batteries. A genny is a lot cheaper and will allow you to run everything in your house like nothing happened. Batteries you only get a couple of emergency circuits, and hybrid Inverters use Commercial AC Power and generator to recharge the batteries, not solar.

So if you go hybrid, the Inverters cost twice as much, you have to rewire your home for the Emergency Circuits, and still need a generator plus batteries you do not use.

WTF Over?

[Sunking]

During my reading, I came across this interesting article that discusses the LiFePO4 in an evenhanded, realistic manner. It's directed toward cruising sailboat owners, but a lot of their sort of usage applies to us as well. He begins with this warning:.

He speaks the truth, and I share that opinion. Now you may ask why I mess with them. Real simple I build Racing Golf Carts and help people build DIY EV's. I am also a RC Pilot with about 100 LiPo batteries.

10 years ago the only LFP battery (LiFeP04), really the only lithium battery available to custom and DIY builders, were Chi-Coms and it started with Thunder Sky which quickly went bankrupt due to a poor product and lawsuits on warranty claims. That company was split into 3 companies and each tweaked the battery . Sinopoly and Winston we still call Thunder Turds because there are almost as bad as the original Thunder Turd, The 3rd was China Aviation Lithium Battery aka CALB. They improved the battery so you can get at least 1 or 2 years out of them Today they cost roughly 40 to 50-cents per Watt Hour as you have discovered. Back then if you wanted quality Lithium batteries like A123 cost run $2 to $3 per watt hours and still cost about that today. That is a 1000% premium to a top end FLA or 500% premium to AGM. 10 years ago we had no choice. Pb batteries are just not acceptable for EV's

Well today all that has changed. Most commercial EV's out there today are leases, and when they get returned, no one wants them because they know the battery is expensive and do not want to get stuck buying new ones. That and there are a lot of salvaged EV's. We use either Salvaged or Used EV batteries. Salvaged or Used is superior to Chi-Coms and last longer, so not many using Chi-Coms any more.

I started with GBS. Worse LFP there is come to find out the hard way as they have the longest Short Discharge Time of any battery (translated highest internal resistance). Then I upgraded to CALB. Had the CALB's for about 6 months, then me and a friend got a fairly new Nissan Leaf salvaged battery which is the most preferred among DIY and Custom EV makers. Not much demand for Tesla and the Chevy Volt because they are almost impossible to manage.Leaf batteries are EASY. A used commercial EV battery is better than a new Chi-Com.

Anyway here is a wealth of info on Lithium Batteries. This LINK wil take you to Short Discharge Time with a graph so you can see where Chi-Coms fall, dead last even behind Pb. In Davids web site you can find any lithium battery, BMS, and Chip Sets with a ton of great info. David is one of the most knowledgeable in the USA and well known in the industry. Anything you want to know is on his web site. I interviewed with him about 4 years ago just before I retired for the 2nd time. If he lived anywhere other than Boulder CO, I would have gone to work for him. Not only does he make BMS and custom EV and battery packs, he is also one of the largest Ganja Farmers in the country and he samples all of his products. His company is called Elithion. Check it out as it is a great resource. Lots of math, calculators, even simulators.

Now if you want the best Lithium battery out there is Kokam. They are the worlds largest Lithium Ion battery manufacture located in South Korea.

[karrak]

I don't know where Sunking gets his lifespan data for Chinese prismatic LFP batteries from but it does not match anything that I am aware if.There are a number of people who post on the Energy Matters forum in Australia and the sailing Cruiser website who have LFP batteries made by Winston, CALB and GBS that are around the same age as mine whose batteries show little sign of capacity loss. The standout is steveg whose LFP battery is over seven years old now. It is worth looking at his posts. My estimate of capacity loss is between 1% and 2% PA, probably closer to 1%. There will be some who say that if the loss is 2% PA that the battery only has a lifespan of ten years. This might be true with LA batteries as the battery impedance when the battery has lost 20% of its capacity is so high as to make the battery unusable but this is not the case with LFP batteries. When mine and my friend's batteries have lost enough capacity to be annoying I intend buying some new cells and either adding to the existing batteries to make up the loss or maybe add his old cells to my battery and get him a new battery.

I actually agree with Sunking that if you have the necessary knowledge that is would be cheaper to buy a used EV battery and use that. On another forum a retired engineer is saying he can get new Panasonic, Samsung and LG NMC 18650 cells for less than $1 each which equates to around $0.10/Wh! At that price making a battery using 18650 cells would be the best bet.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger
Latronics 4kW Inverter, homemade MPPT controller

[Sunking]

If you are Grid Tie, why are you looking at batteries ? Get a back up generator and stock up on fuel. What is the longest outage you think you might have in your area?

Batteries are like a boat: a hole you keep trying to fill with money.

BOAT = Break Out Another Thousand

[Sunking]

I don't know where Sunking gets his lifespan data for Chinese prismatic LFP batteries

You start by looking at warranties. 1 Year, where they came from and who they are made by. Then throw in 10 years experience with EV's. Just about all custom and DIY EV builders have switched and quit using Chi-Com Prismatics because the quality is just flat out piss poor. Couple that with the crap coming out of OZ and you have pure junk.

Of the hundreds of folks I have met and worked with over the last ten years on EV's have the same similar experience. Your Chi-coms arrive, you get them balanced and installed. Things seen OK the first 6-months, and then you start to notice performance and range loss. A year passes, performance and range are significantly reduced, and you are left holding the bag. You get what you pay for.

[BackwoodsEE]

AGM it is, then, for my glorified science project and expensive hobby. Yes, I know it stands little chance of being more than that, and it's not a problem.

Hopefully the AGMs will last a bit longer not being cycled much, except I'll probably run them down once every month or two.

I remain intrigued by how much the cyclic current draw from the inverter contributes to battery aging; if the Outback Radian is running at 6 kW to sell everything the charge controllers are producing, the current flow is not constant but varies between pretty much zero and over 100 A at a rate of 120 Hz. With 15 mOhm or so in the battery circuit (eight cells plus cable and connectors), that works out to about 1.5 V of ripple, unless the charge controllers supply all the current variation. I don't like the idea of the battery micro-cycling at 120 Hz just to maintain a constant output on a sunny day.

[steveg]

I don't know where Sunking gets his lifespan data for Chinese prismatic LFP batteries from but it does not match anything that I am aware if.There are a number of people who post on the Energy Matters forum in Australia and the sailing Cruiser website who have LFP batteries made by Winston, CALB and GBS that are around the same age as mine whose batteries show little sign of capacity loss. The standout is steveg whose LFP battery is over seven years old now. It is worth looking at his posts. My estimate of capacity loss is between 1% and 2% PA, probably closer to 1%. There will be some who say that if the loss is 2% PA that the battery only has a lifespan of ten years. This might be true with LA batteries as the battery impedance when the battery has lost 20% of its capacity is so high as to make the battery unusable but this is not the case with LFP batteries. When mine and my friend's batteries have lost enough capacity to be annoying I intend buying some new cells and either adding to the existing batteries to make up the loss or maybe add his old cells to my battery and get him a new battery.

I actually agree with Sunking that if you have the necessary knowledge that is would be cheaper to buy a used EV battery and use that. On another forum a retired engineer is saying he can get new Panasonic, Samsung and LG NMC 18650 cells for less than $1 each which equates to around $0.10/Wh! At that price making a battery using 18650 cells would be the best bet.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger
Latronics 4kW Inverter, homemade MPPT controller

Yep still running, haven't noticed any problem with them so far (7yrs) - but comparing traction (EV) use case and a house is very different ... we peak at 7kw draw which is only .4C from my battery very rarely - I agree that the low cost LFP's from China may not do so well under regular high loads i.e. EV


Steve...

[Sunking]

Yep still running, haven't noticed any problem with them so far (7yrs) - but comparing traction (EV) use case and a house is very different ... we peak at 7kw draw which is only .4C from my battery very rarely - I agree that the low cost LFP's from China may not do so well under regular high loads i.e. EV.

With the exception of acceleration. EV loads do not exceed .4C. If you look at a commercial EV with 200 to 300 mile range we are talking about 0.16 to 0.25C. However you charge at a must faster rate than an EV. So not sure what you are talking about.

So don't let that fool you. You just do not notice you have lost a major portion of your capacity and internal resistance has doubled. That is quite significant, you just don't know it. I will take a product that comes with a 7 to 10 year warranty from a company that has been around and US made over a Chi-Com 1 year warranty with a poor track record every day of the week.

Don't forget everything you know and have came from EV's. We knew it and taught you everything about them. If not for EV's there would be no Chi-Coms. EV's proved they are junk and we moved on.

Currently the two best Lithium Ion batteries are made by Panasonic (aka Telsa), LG Chem, and Nissan which will be made by LG Chem. All are Asian, but not Chi-Com.

[Sunking]

AGM it is, then, for my glorified science project and expensive hobby. Yes, I know it stands little chance of being more than that, and it's not a problem.

Hopefully the AGMs will last a bit longer not being cycled much, except I'll probably run them down once every month or two.

OK so what you are saying is they will be FLOAT SERVICE. Not a problem, just pointing some things out you need to consider. Possible reconsider one Train Driver to another. In Float Service we are really talking Calendar Life, not Cycle Life. So how deep you discharge them say once a month is of no consequence. Either FLA or AGM is as good as the other. Agree?

I remain intrigued by how much the cyclic current draw from the inverter contributes to battery aging; if the Outback Radian is running at 6 kW to sell everything the charge controllers are producing, the current flow is not constant but varies between pretty much zero and over 100 A at a rate of 120 Hz. With 15 mOhm or so in the battery circuit (eight cells plus cable and connectors), that works out to about 1.5 V of ripple, unless the charge controllers supply all the current variation. I don't like the idea of the battery micro-cycling at 120 Hz just to maintain a constant output on a sunny day.

What current? Batteries will be in Float, thus neither charging or discharging. I am not 100% certain, perhaps Butch or Inetdog will jump in here and confirm or redirect, but the batteries are not even in the circuit and are using the Radian Internal AC Charger Floating the batteries. In effect the Radian is working as a pure Grid Tied Inverter. Any excess is going out, any shortage is coming in from POCO. Batteries do not come on line until there is an outage the way you will have it set up. Essentially you have a limited UPS.

OK my last point is more of a question. Why AGM over FLA?

I am a bit confused why you would go to that expense when you do not need the capabilities of AGM. The batteries are stationary, so spills are not a concern. I assume they will not be exposed to -40 C or F, so freezing is not an issue. No daily cycle so getting them fully charged is not an issue. Nor does it sound like you need the extremely high Charge/Discharge rates. FLA batteries in Float Service are just as Maintenance Free as AGM because they do not use water as they never at Gassing Voltages. So again why AGM?

Let's look at dollars comparing Apples to Apples. I presume you are looking at Rolls S6 460 AGM right? That is a S series and when used as RE is a 7 year battery. Those cost $530 to $580 per battery right? Not sure what voltage you are thinking but if 48 volts is a $4200 to $4600 battery right?

Why not a Rolls S550 a 4000 series spec battery. A little more capacity at 428 AH. and carries the same 7 year warranty for either Marine, RV, or RE which is telling you it is a better battery because the S6 460 AGM is 7 years for RE, but only a 5-Year battery for RV and Marine. Go look for yourself. Am I right? The Rolls S-550 goes for $320 to $350 per unit right? At 48 volts is a $2560 to $2800 right.

So why AGM? I forgot.

Now for *** since he is kind of slow and not to bright the numbers look like this.

• 48 volt 428 AH Rolls S-550 cost $2700 and carries a full 7 year warranty, made in the USA with many dealers to honor warranty and Rolls has been around for 60 years and not going out of biz.
• 48 volt 415 AH Rolls S6 460 AGM cost $4400, and carries a full 7 year warranty, made in the USA with many dealers to honor warranty and Rolls has been around for 60 years and not going out of biz.
• 48 volt 360 AH CALB LFP CA 180 16S2P cost $7,700 and carries a 1 year warranty made in China which makes it almost impossible to make a warranty claim. You also need to add about another $1000 in equipment and work around LFP weaknesses and charging parameters.

Numbers do not lie. *** lies.

[rememberthemagic]

He speaks the truth, and I share that opinion. Now you may ask why I mess with them. Real simple I build Racing Golf Carts and help people build DIY EV's. I am also a RC Pilot with about 100 LiPo batteries.

10 years ago the only LFP battery (LiFeP04), really the only lithium battery available to custom and DIY builders, were Chi-Coms and it started with Thunder Sky which quickly went bankrupt due to a poor product and lawsuits on warranty claims. That company was split into 3 companies and each tweaked the battery . Sinopoly and Winston we still call Thunder Turds because there are almost as bad as the original Thunder Turd, The 3rd was China Aviation Lithium Battery aka CALB. They improved the battery so you can get at least 1 or 2 years out of them Today they cost roughly 40 to 50-cents per Watt Hour as you have discovered. Back then if you wanted quality Lithium batteries like A123 cost run $2 to $3 per watt hours and still cost about that today. That is a 1000% premium to a top end FLA or 500% premium to AGM. 10 years ago we had no choice. Pb batteries are just not acceptable for EV's

Well today all that has changed. Most commercial EV's out there today are leases, and when they get returned, no one wants them because they know the battery is expensive and do not want to get stuck buying new ones. That and there are a lot of salvaged EV's. We use either Salvaged or Used EV batteries. Salvaged or Used is superior to Chi-Coms and last longer, so not many using Chi-Coms any more.

I started with GBS. Worse LFP there is come to find out the hard way as they have the longest Short Discharge Time of any battery (translated highest internal resistance). Then I upgraded to CALB. Had the CALB's for about 6 months, then me and a friend got a fairly new Nissan Leaf salvaged battery which is the most preferred among DIY and Custom EV makers. Not much demand for Tesla and the Chevy Volt because they are almost impossible to manage.Leaf batteries are EASY. A used commercial EV battery is better than a new Chi-Com.

Anyway here is a wealth of info on Lithium Batteries. This LINK wil take you to Short Discharge Time with a graph so you can see where Chi-Coms fall, dead last even behind Pb. In Davids web site you can find any lithium battery, BMS, and Chip Sets with a ton of great info. David is one of the most knowledgeable in the USA and well known in the industry. Anything you want to know is on his web site. I interviewed with him about 4 years ago just before I retired for the 2nd time. If he lived anywhere other than Boulder CO, I would have gone to work for him. Not only does he make BMS and custom EV and battery packs, he is also one of the largest Ganja Farmers in the country and he samples all of his products. His company is called Elithion. Check it out as it is a great resource. Lots of math, calculators, even simulators.

Now if you want the best Lithium battery out there is Kokam. They are the worlds largest Lithium Ion battery manufacture located in South Korea.

so what if you are interested in Grid assist where the goal is to be as self sufficient as possible creating as much solar power as needed to run the house and charge battery's that will in turn run the house at night using grid only when batteries are depleted? If that is the case what battery technology would you recommend (AGM, LifePo4), etc.. Safety is a big issue as these batteries will be indoors in a spare room (so FLA is out) and Lion seems to volatile.

[PNjunction]

I'm a big proponent of LiFeP04, but *in your proposed application*, they do not make sense at all. Go with the AGM.

LFP makes the most sense in a cyclic application. To over-purchase capacity to have them sit at 50% DOD all the time is a total waste of money, especially if they will only be called upon to do light-duty service when called upon.

rememberthemagic: study up on the differences between Lifepo4, and all the *other* lithium chemistries. LFP isn't volatile for a reason: ferrous-oxide is one greedy little molecule that holds on to oxygen like no tomorrow. You may mistakenly burn up your *infrastructure* wiring, or make them vent, but there is a very big difference between LFP venting, and all other lithium chemistries "venting with flame!". This is one reason why lithium motorocycle starting batteries that are 2-inches away from your butt are LFP, and NOT any other type of lithium for example. ...

But don't sweat it - most consumers, many hobbiests, and even the media don't know the difference.... to them there is only one type of lithium. Kind of like if in the lead-acid world, not knowing the difference between flooded, gel, or agm parameters....

[SunEagle]

BlueBell

Before you can post you must get approved by the Admin Solar Pete. Until then all of your posts will go to the Unapproved barrel. So try to stay calm and you will get to make posts soon.

[Sunking]

so what if you are interested in Grid assist where the goal is to be as self sufficient as possible creating as much solar power as needed to run the house and charge battery's that will in turn run the house at night using grid only when batteries are depleted? If that is the case what battery technology would you recommend (AGM, LifePo4), etc.. Safety is a big issue as these batteries will be indoors in a spare room (so FLA is out) and Lion seems to volatile.

If you have grid power, it would be very foolish to use any battery for power.

If you use FLA, your Kwh cost are going to be 4 to 10 time more than buying power.
AGM cost more than FLA and AGM only last half as long as FLA driving up the cost to 10 to 20 times more than buying power.
LFP is even more expensive than AGM with about the same short cycle life.

So if you have two gas station side by side. One station called utility sells gas for $2/gal for all the gas you want with no limits. The other station called battery sells gas for $20/gal and limits you to 3 gallons per day. Which gas station do you buy from?

Utility or Battery?