LiFeYPo4 questions

[PNjunction]

Chris - the good news is that we don't have to deal with China directly like we did 4-5 years ago. These large prismatics, like GBS, CALB, Winston, etc are available from a number of stateside EV and specialty battery outlets. I personally use GBS cells.

One you might want to look at is

Elite Power Solutions in Tempe, AZ. They specialize in the GBS cells, although I have no firsthand experience with them. I got mine from BatterySpace.

That being said, remember that the manufacturers and distributors are catering mostly to the EV market, and may have never heard of "solar insolation hours", nor the generic rule of not sizing your battery bank to go below 50% DOD. Since lifepo4 is usually taken down to 80-90% DOD by EV'ers and is the standard for rated cycle life, they may be grossly underestimating your capacity needs, even if the data you gave them was perfect.

For best results, we normally eschew "growing into" your battery needs, as this usually results in one or more complete rebuilds of most of the existing infrastructure, not to mention generally poor battery operations with batteries of different age and use patterns.

If you can give us an idea of how much power you are using now, or are planning to use, we can figure out probably much more accurately than a battery manufacturer or EV shop can - or if it is even within the range of reality.

Large prismatics like the GBS and CALBS can easily handle 1C of current, with 3C bursts (on average) but of course, your battery would last a little less than an hour, so that kind of pull, even though it can be done, is not realistic for a house-bank. Still good news for huge surge loads.

If you can give us a better idea of how much power you intend to pull, we can see if it can be done - on both the discharge AND solar recharge capability. Perhaps if this was restated in a fresh new thread we can keep a better handle on it.

[asheville solar]

Just wanted to thank the two of you for the help. I had a chance to look into those EV sites and you are right, the pricing is right in line with what I am getting from China. The Calb 400ah cells look like they are priced well. The GBS look really nice but expense wise, add up quickly.

I looked at my power bill history and maybe this will give you guys a better idea as to what I am running. I do have my workshop located at my house where on occasion I am running 220v heaters and a 220v compressor. However I am not expecting to run this off my battery bank at night. Most of my house now has LED lights in them and is 100% electricity. No gas, electric heat pump, GE hybrid water heater.

Looking at past electrical bills which include this cold winter: 77.3 KWh/day or 2319 KWh/month.

Most likely, I would only run my batteries 30-40% down to extend the life unless the community recommends more.

If I go with Calb 400ah cells, do you guys recommend any certain BMS system? Especially if I add a second 48v 400ah bank in about 6 months to 1 year?

Thanks for the help,
Chris

[PNjunction]

..The Calb 400ah cells look like they are priced well. The GBS look really nice but expense wise, add up quickly.

Just make sure you are looking at the price of individual cells, and not comparing bare cells to pre-built systems that may or may not have additional bms systems added on.

I looked at my power bill history and maybe this will give you guys a better idea as to what I am running.

You know that going off-grid with battery storage is currently about 10x the cost from the local power company right? So one does this for reasons other than savings. Just wanted to make sure.

Unfortunately, we still do not have any great idea of how much power you need to run, and for how long, to suggest any sort of battery capacity.

Most likely, I would only run my batteries 30-40% down to extend the life unless the community recommends more.

That's a lead-acid mindset. With lifepo4, instead of running from 100-70% SOC, you would actually do better running in a partial-state-of-charge scenario of perhaps 90-60% / 80-50% SOC. Since there is no need to actually charge lifepo4's fully, charging requirements are eased, and if run in a PSOC state, balance - especially in a somewhat low voltage / low current application like a house bank compared to EV use, is a non-issue assuming the cells were charged reasonably close by the distributor.

If I go with Calb 400ah cells, do you guys recommend any certain BMS system? Especially if I add a second 48v 400ah bank in about 6 months to 1 year?

Also take a look at Genasun and Mastervolt, although they concentrate mostly on marine racing.

While I have no personal experience with these guys, the "House Power BMS" from CleanPowerAuto LLC might be suitable. Note that I don't use any bms at all, except for low voltage disconnect, and a high voltage controlled by my charger. Balance under a house-bank scenario is not that big of an issue if you don't run these things wall-to-wall charge/discharge, which we don't by not purposely undersizing our battery. At this point I'm getting off track into the bms issue, which usually ruins good threads.

Truthfully, unless you really know your power requirements, there's not much for us to recommend. What I WILL recommend is that you consult a qualified systems installer / consultant - like that of our own forum host!

[Sunking]

PN FWIW sizing requirements for lithium are not much different that than FLA. With FLA minimum autonomy is 5 days, lithium minimum is 3 days to be equal in usable capacity. The big advantage of lithium can be Peukert losses and weight, but weight i snot really an issue for off-grid unless we are talking a boat or RV. Myself personally I would not use lithium a sit is just still too expensive and unproven. The cycle life claims for lithium thus far have proven to be false, and cold weather performance is very poor. Lots of stranded Leaf owners last winter.

[asheville solar]

PN FWIW sizing requirements for lithium are not much different that than FLA. With FLA minimum autonomy is 5 days, lithium minimum is 3 days to be equal in usable capacity. The big advantage of lithium can be Peukert losses and weight, but weight i snot really an issue for off-grid unless we are talking a boat or RV. Myself personally I would not use lithium a sit is just still too expensive and unproven. The cycle life claims for lithium thus far have proven to be false, and cold weather performance is very poor. Lots of stranded Leaf owners last winter.

PN & Sunking,
Thanks for the helpful insights. For clarification, I will be still tide to the grid with the hybrid inverters. With the battery bank, it will only be used to supplement my energy usage at night. I would love to go off the grid but like you said, the expend would be very high. I very well may manage my cells with the BMS system as you mentioned. Purely on the discharge minimum if I understood and the Outback charge controllers for the max cutoff.

Energy usage in the evening would be normal house hold of three usage. Fridge, oven/stove top, lights, possibly washer and dryer, heat & air. I know that does not help without looking at each component separately and see what it's drawing.

I have looked into two companies after finding them mentioned in a previous thread from this forum if I am correct. They are Alliance Renewable Energy Inc. and Electric Car Parts Company.
Possible choices would be Calb CA400FI new model at 400ah. $497/cell
Or similar Thundersky (Winston owned if I am correct) from Alliance Renewable Energy.

Does anyone have any thoughts on either company or cells?

Thanks,
Chris

[Sunking]

Energy usage in the evening would be normal house hold of three usage. Fridge, oven/stove top, lights, possibly washer and dryer, heat & air. I know that does not help without looking at each component separately and see what it's drawing.

OK I have not kept up with this thread, but you cannot run all that on battery. You can get the small stuff, but ovens, cook tops, dryers, air conditioning are very high wattage devices. Ovens pull 2500 to 4000 watts, cook tops 1500 to 4000 watts, electric dryers 4000 to 4500 watts, air conditioning can go even higher than all the others.

[PNjunction]

PN FWIW sizing requirements for lithium are not much different that than FLA. With FLA minimum autonomy is 5 days, lithium minimum is 3 days to be equal in usable capacity.

I'm with you on the sizing, although my needs are only 2-day autonomy, if that - but my needs are relatively small. Still, any solar user would be foolish to design to go past 50% DOD, even though lifepo4 will easily do 80% DOD at full performance. My GBS batteries continue to amaze me.

One very positive aspect about lifepo4 that is sometimes overlooked is that their ability to operate in a partial-state-of-charge, even their preference for that, and the ability to go to 80% DOD affords a wide headroom latitude for poor solar conditions, unexpected loads, or minor goofs in actual capacity calculations. Had it not been for this aspect, I wouldn't have been interested in getting my own batteries and verifying the claims.

The cycle life claims for lithium thus far have proven to be false, and cold weather performance is very poor. Lots of stranded Leaf owners last winter.

I don't know where you got those claims from. Most of what I've seen from house-bank users has been extremely positive, although they have only been commonly available for about 5 years now - still a few years ago to get the calendric-aging affect accounted for. Also remember that the Leaf, (like the Boeing incident that also gets brought up), are NOT USING lifepo4 chemistry. Neither are they operating in the same conditions a typical house bank user is. Add to that incidental things like thermal management, wiring infrastucture, charging details etc can easily distract one from the real usage we would put them to. That whole discussion is a red-herring.

You know we're going to laugh about this one day when I hunt you down, and hand-deliver a set of lifepo4 cells and run them through some cycles emulating house-bank duty. I'd like to bring my video camera so I can post it on the net - the look on your face will be priceless.

[PNjunction]

I have looked into two companies after finding them mentioned in a previous thread from this forum if I am correct. They are Alliance Renewable Energy Inc. and Electric Car Parts Company.
Possible choices would be Calb CA400FI new model at 400ah. $497/cell
Or similar Thundersky (Winston owned if I am correct) from Alliance Renewable Energy.

I was going to mention those guys, especially if you are dealing with USA stock. I can't speak personally for any of them. I just know I can get my hands on high quality Calb's and GBS rather quickly if needed.

Others commonly found:

elitepowersolutions
evsource
ev-power
electricautosports
gwl/power

CALB for most is considered top of the line, and the CA cells are great. However, don't go nuts over other models that offer higher and higher rates more applicable to the hardcore high-performance EV market - in other words, they have cells that can do 5-10C or more easily - but if you made say a 400ah bank of those, would you EVER draw 4KW continuously in a house-bank setup? No. So you'd be paying for a feature that you'd never use. Stick to the lower rate cells for house-bank duty.

This is a common mistake for those trying to adopt cylindrical high-rate cells for our "fractional C" application. They are paying through the nose for a current capability they will never achieve in either charge or discharge.

Unless you are a good DIY'er, I would definitely have them pre-built with all the necessary cell-links, banding straps, and the like. You don't want a large box of just individual cells showing up on your door unless you know how to deal with it.

[Sunking]

I'm with you on the sizing, although my needs are only 2-day autonomy, if that - but my needs are relatively small. Still, any solar user would be foolish to design to go past 50% DOD, even though lifepo4 will easily do 80% DOD at full performance. My GBS batteries continue to amaze me.

When it comes right down to it, there is not much difference in usable capacity between FLA and LiFePo4. If you cycle both at optimum cycle life SOC they are pretty close to each other. Example let's say 100 AH. Al FLA you cycle from 100 to 50% for 50 AH. LiFePo4 80 to 20% or 60 AH usable.

I don't know where you got those claims from.

From the EV side of the house where they are used extensively for some time with a track record.

[PNjunction]

From the EV side of the house where they are used extensively for some time with a track record.

Exactly my point - that is not the application we use them for, where EV'ers routinely run 0-90% DOD or more, have failing balancing circuitry and other infrastructure points-of-failure related to vehicle operations.

Our house-bank needs are entirely different, and will lead a very sheltered life in a "fractional C" environment.

[Sunking]

Exactly my point - that is not the application we use them for, where EV'ers routinely run 0-90% DOD or more,

I would debate that but get your point. From an EV POV especially DIY EV where they use the exact same cells you do run them more in the 90's to 100, down to 20-30% to hit the maximum cycle life. Users of commercial made EV's CPU will not let them drain them below a set point, but there are not many using LFP.

EV's charge differently than Solar. In Solar you have to use a Forced Charge Algorithm (basically the same as the BULK for FLA) to 90 to 95% SOC and terminate. EV's charge a bit slower, well sometimes slower, but they use Constant Voltage Current Taper Algorithm and charge terminates when current tapers down to 3 to 5% of C. That allows them to saturate from 95% where solar stops with EQ-Balance to full charge at 100%.

[PNjunction]

The amateur EV'ers have a nightmare on their hands - although it can be done.

Compared to us, they've got extremely high voltage / high current battery setups with oodles of interconnect wiring, sometimes the unnecessary use of balancing systems that fail or mask pending issues - the whole gamut.

It can be done - it took me a few years to somewhat agree with Jack Rickard on the basics, despite the entertainment.

Still, I always kept in mind the experiences of those in the marine crowd using lifepo4 house banks as a closer approximation to what we do. (ie, Cruisersforum, etc). And compared to them, we have it even easier than they do! Many are going on 5 years or more, but still we are watching out for real-world 10 year usage patterns. I'm on my way with my own.

[Sunking]

Compared to us, they've got extremely high voltage / high current battery setups

Maybe not as much as you think. One of the most popular motors used in the DIY arena is a TransWarp 9 motor made by netgain and it is a 72 volt motor. Other popular motor are based on 140 VDC platform of controllers and Open Source BMS. Most use a single string of 100 AH LFP from Calb CA100FI Cell 3.2V 100Ah. Now some of the big guys in R&D I know who work for GE and another electrical manufacture run AC motors with with VFD up to 400 and 500 volts use the exact same Calb cell in a single string. Once I think has gone with two parallel strings but that is an exception.

The only thing really different is very brief discharge rates of 5C on EV's from a standing start to standing on the accelerator until you hit cruise speed, then discharge rates drop dramatically to less than 1C. But the tech is the same.

--Mod Note: Something about this post got it automatically classified for moderation. Probably the direct links to product. Since Dereck (Sunking) is a regular with an established reputations for impartiality, I am allowing this post.

[Sunking]

Compared to us, they've got extremely high voltage / high current battery setups

Maybe not as much as you think. One of the most popular motors used in the DIY arena is a TransWarp 9 motor made by netgain and it is a 72 volt motor. Other popular motor are based on 140 VDC platform of controllers and Open Source BMS. Most use a single string of 100 AH LFP from Calb CA100FI Cell 3.2V 100Ah. Now some of the big guys in R&D I know who work for GE and another electrical manufacture run AC motors with with VFD up to 400 and 500 volts use the exact same Calb cell in a single string. Once I think has gone with two parallel strings but that is an exception.

The only thing really different is very brief discharge rates of 5C on EV's from a standing start to standing on the accelerator until you hit cruise speed, then discharge rates drop dramatically to less than 1C.

--Mod Note: Something about this post got it automatically classified for moderation. Probably the direct links to product. Since Dereck (Sunking) is a regular with an established reputations for impartiality, I am allowing this post.

[asheville solar]

PNJunction,
Thanks for the help. I will look into those companies that you mentioned. Being new to all this, I agree that EVers seem to have a lot more on their plate when it comes to the whole system setup and potential problems. This is purely coming from an outsider who is newly looking into all this. I will be having a friend who is an installer of a local solar company help me with the whole system install.

I did want to get your advice or anyone else's on batteries. I have looked into the Calb cells with a 400ah rating. Not a bad price. Then I stumbled across Thundersky 700ah cells (same yellow cells as Winston??). I can pick up these cells for $560/cell with 700ah from several different suppliers. Seems like one hell of a deal. Any thoughts on these?

I don't think I will have a problem assembling the individual cells with my friend who is in the solar industry. Do all battery cell banks need to be strapped to prevent expansion? Naturally I will be wiring the BMS system for these. I am thinking about the Orion Jr. which seems like a quality manufacturer.

Thanks,
Chris