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  • lownutHeib0
    replied
    Another update:

    In spring 2018 (3 years in) I noticed difficulty starting the fridge off of the pair of stacks. Looks like the power handling has degraded. Looking further into capacity, performed a charge/discharge test and got about 1.2kwh/stack when discharging at 75W/stack until 44V cutoff, then switching to 20W/stack and draining them further. Depending on the source (Aquion had a few capacity charts which contradicted each other) the S20 is somewhere between 2.3 and 2.6kWh per stack if currents are kept below 2A/ea. (about 90W/ea.). So this appears to be worse than the expected 30% degradation found in the documentation. As a workaround I wired up a small super-capacitor array and that did the trick to supply the startup draw.

    Suspecting a bad cell, I let them settle disconnected after a full charge and checked their individual voltages. There was no change in their voltage from when they were new.

    Perhaps this is the real sodium-ion behavior coming through as the additives which enhanced the capacity and power handling are wearing off? It is difficult finding documentation on sodium ion chemistry, for example some other chemistries have known tricks, such as running a few deep-cycles to bring a battery's capacity back, while other battery chemistries are destroyed that way. Aquion did mention in one piece of documentation that a deep cycle might improve them but it's unclear if that applies to older batteries or only for their break-in period.

    These batteries are in an environment with a lot of thermal swings, and they could have gotten too cold a few times.

    Anyway, I am now reaching the point where they start deviating from what was on paper: 50% degradation at 3 years given 50% DoD cycling. Subjectively, they don't seem to be degrading much after that. I could do another capacity test later in the year and we'll see what's happened.

    Leave a comment:


  • Sunking
    replied
    Originally posted by lownutHeib0 View Post
    • At 50% I can push about 5A into each stack, in correlation with the documentation. Beyond 80% the charge rate falls into the trickle range (0.5-1A).
    • Below 40F their charge resistance spikes. Below about 28F they don't present any usable charge or accept charge.
    • They have a high specific heat: I'm seeing about 2 days to adjust to a 20 degree change in air temperature, within 2 degrees. Reminder: They are encased in 3" foam insulation.
    • Overall they are working as I had expected.
    • We've had 3 outages (2hrs, 4hrs, 12hrs ), not including <1hr hiccups and the batteries/solar combo did their job. There is severe flicker when the fridge starts when on batteries alone.
    .
    These are significant issues which make the batteries useless for most applications. That is why they went bankrupt. It all revolves around very high Internal Resistance and extremely steep charge and discharge curves. About their only usable application is egress lighting for long periods.

    The very high resistance means they cannot be charged or discharged fast. That is why your lights flicker when the ridge starts, that cannot even handle a small load. In any Solar or Energy Storage you need to be able to charge/discharge at least at C/8 to C/6 in most locations, and some locations as high as C/2. As you mentioned C/40 is about all they can handle. That makes it extremely expensive to have any usable application.

    Example in a standard design you size the batteries for 5 day reserve capacity with 3 being usable. Using FLA batteries providing in winter you have at least 2.4 Sun Hours your charge rate will be at the maximum C/8 charge rate, Say you use 1 Kwh/day and with minimum 2.4 Sun Hours in winter requires a 630 watt panel, 52 Amp Charge Current, and a 12 volt 420 AH FLA battery. That will generate the max C/8 charge current for FLA batteries. If you were to do this with Aquion Batteries would require a 2000 AH battery with 20 day reserve capacity to handle a 50 amp charge current. Actually more than that because the charge efficiency is much lower than FLA.

    No dang wonder they failed. I knew it immediately because I knew what the numbers meant. Aquion batteries cast 3 times more than FLA and require 5 times more capacity. That makes them 15 times more expensive, To make matters worse the steep discharge curve means 40% of the capacity is not usable. No 12 volt Inverter works down to 8 volts and up to 16 volts. Unfortunately most consumers did not know this and learned the hard way. Between warranty claims and the news finally getting out doomed the company. The technology just will not work.

    That is why I scream Bloody Murder when folks come here touting them. Stay far away from them like NiFe batteries. Let some other sucker learn the hard way if they do not want to listen and learn.

    Leave a comment:


  • SunEagle
    replied
    Thanks for the update.

    Sounds like those batteries are at least doing what they claim they should. The real test is the total cycles and life span. I hope it works out for your considering your investment.

    Leave a comment:


  • lownutHeib0
    replied
    Update:
    • Both stacks functioning properly. No noticeable degradation in the performance.
    • I've been keeping them above 15% charge. There were some <5% DOD events, no noticeable effects.
    • Don't know exactly how many effective cycles have incurred - I don't have the data and I'm conservative about cycling. They are cycled by roughly 60% per day for 3/4 of the year.
    • At 50% I can push about 5A into each stack, in correlation with the documentation. Beyond 80% the charge rate falls into the trickle range (0.5-1A).
    • Spring of 2016, pushed the C40's float voltage to 57V. No adverse effects so far.
    • Below 40F their charge resistance spikes. Below about 28F they don't present any usable charge or accept charge.
    • Had them drop to around -3F, no damage (so far). Wouldn't recommend it.
    • They have a high specific heat: I'm seeing about 2 days to adjust to a 20 degree change in air temperature, within 2 degrees. Reminder: They are encased in 3" foam insulation.
    • I have temp/voltage CC current logs stored since fall 2015 but warn that the data is dirty due to sensor/communication errors. (I homebrewed with an rPI instead of using the expensive Aquion/Xantrex hardware). If there is interest I suppose I could try cleaning the data and presenting a few graphs.
    • Overall they are working as I had expected.
    • We've had 3 outages (2hrs, 4hrs, 12hrs ), not including <1hr hiccups and the batteries/solar combo did their job. There is severe flicker when the fridge starts when on batteries alone.

    Saw the news about Aquion bankuptcy. My main concern is the status of my warranty. Fortunately I only have a toe in the water with 2 stacks. I don't regret this (yet) - things are still working out.

    Have been watching the prices of the Aquion/Aspen over the years and was hoping they would fall by at least 30% but they did not. Then as the Powerwall II started hitting the market the Aquion/Aspen didn't appear that it could compete. Was happy to see that they were splitting them down into 24V stacks as they were not fun to move and install.

    Looking forward to seeing this technology again some way or another but the price really needs to fall. Perhaps the aftermarket has some promise, pending cost-effective shipping.

    Leave a comment:


  • Living Large
    replied
    Originally posted by lownutHeib0 View Post
    Yes. You may have gotten them mixed up like I did earlier.

    [ATTACH]8078[/ATTACH]
    Ah-ha. Thanks for the graph. You are correct - I was thinking backwards.

    Leave a comment:


  • lownutHeib0
    replied
    Originally posted by Living Large View Post
    The float is below the absorption voltage? Are you sure?
    Yes. You may have gotten them mixed up like I did earlier.

    aquion-pg17.jpg

    Leave a comment:


  • Living Large
    replied
    Originally posted by lownutHeib0 View Post
    I mistyped: I have the S20Ps in absorption at 57V, float at 54V.

    Also, the S30 is out now with a little more capacity, removed the fuse, and better warranty.
    The float is below the absorption voltage? Are you sure?

    Leave a comment:


  • lownutHeib0
    replied
    Correction

    I mistyped: I have the S20Ps in absorption at 57V, float at 54V.

    Also, the S30 is out now with a little more capacity, removed the fuse, and better warranty.

    Leave a comment:


  • Living Large
    replied
    Originally posted by lownutHeib0 View Post
    I have a small 1kw* install w/ a pair of Aquion S20P stacks which have been in steady use for about a month now. The purpose of the install is emergency power with the option of running day loads, during which the batteries work to buffer load mismatches.
    Cool. Tell us more as you learn it. I was looking at these for awhile. Good luck.

    Leave a comment:


  • SunEagle
    replied
    Originally posted by lownutHeib0 View Post
    I have a small 1kw* install w/ a pair of Aquion S20P stacks which have been in steady use for about a month now. The purpose of the install is emergency power with the option of running day loads, during which the batteries work to buffer load mismatches.

    *1kw STC / 780w NOCT. Even under full orthogonal sun and a few % from mpp I only get ~NOCT w/ full load.

    The stacks match well to my 48V system; by the time low voltage shutoff on my SK1500 kicks in at 42V there isn't much left in the stacks, as can be shown in the curves given in the Aquion literature. My CC is set to float them at 57V, the SK1500 throws a high voltage warning but has never shut off on me.

    The manual does not allow the 8-layer stacks to be disassembled; they are clamped so they are under constant pressure. I am not not yet sure what the procedure is for failed cells or the risk factor of a failed cell.

    They are rated to push a maximum of 450W each, though no voltage is given for that figure. They do not noticeably heat up under heavy load. I measured a trivial 2F degrees increase. They do dip a bit under load but not terribly. I am able to run a freezer, a fridge and fishtank with heater/lamp. I would expect a more serious install of 8+ stacks in parallel to be fine unless doing something out of the ordinary.

    I am using them with a Midnite Solar combiner; the Aquion manual wasn't very clear as to which direction to wire the DC breakers: Current could be flowing in either direction depending on charge state, which could compromise the arc-breaking mechanism of the DC breaker. I used fuses as cheap placeholders until I get a better picture of the situation in terms of bidirectional breakers. In the meantime I am in a potentially-awkward position if I ever have to disconnect-reconnect either of these stacks.

    The figures given by Aquion are based on accelerated tests. I understand that as a startup they need to get a product out ASAP and that there is some risk of accelerated tests vs real-world results. The fact that I only got two stacks is a response to this risk.

    There are a few concerns:
    The stacks are 260lb each, have a tilt limit of 15 degrees and cannot be disassembled.
    Min. operating temp is 24F, min storage temp is -4F. Manual says violating this limit could result in damage. The -4F figure is familiarly close to freezing point for brine.

    I live near Canada and have encapsulated the stacks in an insulated shell. They aren't supposed to casually vent like LA, but the manual states they can vent CO2, CO, and H in modest amounts. Needless to say, when I open the shell all doors and windows are wide open in preparation for concentrated vent gasses.
    First off welcome to Solar Panel Talk

    Thanks for posting data on your Aquion system. Yours is the second non commercial system that we are learning about. Hopefully it will perform for you as advertised.

    Keep us in the loop on how it does over the winter. Thanks

    Leave a comment:


  • lownutHeib0
    replied
    S20P stacks

    I have a small 1kw* install w/ a pair of Aquion S20P stacks which have been in steady use for about a month now. The purpose of the install is emergency power with the option of running day loads, during which the batteries work to buffer load mismatches.

    *1kw STC / 780w NOCT. Even under full orthogonal sun and a few % from mpp I only get ~NOCT w/ full load.

    The stacks match well to my 48V system; by the time low voltage shutoff on my SK1500 kicks in at 42V there isn't much left in the stacks, as can be shown in the curves given in the Aquion literature. My CC is set to float them at 57V, the SK1500 throws a high voltage warning but has never shut off on me.

    The manual does not allow the 8-layer stacks to be disassembled; they are clamped so they are under constant pressure. I am not not yet sure what the procedure is for failed cells or the risk factor of a failed cell.

    They are rated to push a maximum of 450W each, though no voltage is given for that figure. They do not noticeably heat up under heavy load. I measured a trivial 2F degrees increase. They do dip a bit under load but not terribly. I am able to run a freezer, a fridge and fishtank with heater/lamp. I would expect a more serious install of 8+ stacks in parallel to be fine unless doing something out of the ordinary.

    I am using them with a Midnite Solar combiner; the Aquion manual wasn't very clear as to which direction to wire the DC breakers: Current could be flowing in either direction depending on charge state, which could compromise the arc-breaking mechanism of the DC breaker. I used fuses as cheap placeholders until I get a better picture of the situation in terms of bidirectional breakers. In the meantime I am in a potentially-awkward position if I ever have to disconnect-reconnect either of these stacks.

    The figures given by Aquion are based on accelerated tests. I understand that as a startup they need to get a product out ASAP and that there is some risk of accelerated tests vs real-world results. The fact that I only got two stacks is a response to this risk.

    There are a few concerns:
    The stacks are 260lb each, have a tilt limit of 15 degrees and cannot be disassembled.
    Min. operating temp is 24F, min storage temp is -4F. Manual says violating this limit could result in damage. The -4F figure is familiarly close to freezing point for brine.

    I live near Canada and have encapsulated the stacks in an insulated shell. They aren't supposed to casually vent like LA, but the manual states they can vent CO2, CO, and H in modest amounts. Needless to say, when I open the shell all doors and windows are wide open in preparation for concentrated vent gasses.

    Leave a comment:


  • Sun Tzu
    replied
    Originally posted by Sunking View Post
    I have no problem with that. By limit I mean over gassing on charge side, or voltage sag on discharge side. Ri is the direct contributor to those two items. Bottom line is the Ri is way to high to be of any use other than running your cell phone. Imagine dragging around a 500 pound battery for your cell phone.



    I think you meant dishonest people??? Even battery companies that are trusted and been around 50 years lie like politicians and drunken sailors. Will say anything to get in your pants, err I meant pockets.



    I like you but you just crossed a line some folks here are not going to like one little bit. Users like Dan, Don, and Ian do not like facts or anything that shines a bad light on Renewable Energy. They believe anything Green they are told and could careless what is real or imagined. They believe batteries have 8000 cycles and have a positive EROI.
    I didn't even think about gassing. Yikes! Don't they claim to be self-balancing as well? Can anyone say electrolysis? I assume it is because they can overcharge their batteries like lead-acid. But yeah...gassing, good point.

    I am glad to hear that you appreciate where I am coming from guy. I hope the users you listed don't get too offended. But we have to be more critical about the companies that sell snake oil and that are more concerned with their next series of investment instead of being focused on making a product that works. They will do (have done) more harm to green tech than you or I pointing out technical concerns. That is the beauty of science. You and I could be 100% wrong (doubt it ) . All you have to do is show and explain the data that supports your claims...to people who understand it. Unfortunately, a lot of green tech enthusiast have more good intentions than technical understanding.

    And there is this:

    http://www.bizjournals.com/pittsburg...ittsburgh.html

    Leave a comment:


  • Sunking
    replied
    Originally posted by Sun Tzu View Post
    Not sure that I totally agree with the logic/math here Sun King. Internal resistance is a big deal, but what I do not believe that you can draw some of the conclusion that you are. Internal resistance directly correlates to how hot you can expect these puppies will get (i2r). I do not think that you can say that it will limit their C-rate. But it is really beside the point because I am in agreement about the practical use of these batteries. You will end up needing a huge of amount of these to do anything real.
    I have no problem with that. By limit I mean over gassing on charge side, or voltage sag on discharge side. Ri is the direct contributor to those two items. Bottom line is the Ri is way to high to be of any use other than running your cell phone. Imagine dragging around a 500 pound battery for your cell phone.

    Originally posted by Sun Tzu View Post
    Two things should stand out immediately with these guys, first, 3,000 cycle life claim from a company that is 4 years old? Really? Show me a startup battery company that doesn't claim 3,000+ cycles and I will show you honest people.
    I think you meant dishonest people??? Even battery companies that are trusted and been around 50 years lie like politicians and drunken sailors. Will say anything to get in your pants, err I meant pockets.

    Originally posted by Sun Tzu View Post
    It has become standard boilerplate for newbie battery companies wanting to get funding unfortunately. It hurts green tech and renewables when people make up outrageous claims and really grinds my gears. And the four years is the company's age, not their latest product. Which leads me to the second stand out, they have put out 3 products within one year of starting production, each obsolescing its predecessor. This is a huge red flag. Cell phones companies can't compete with this act of...marketing genius or "I'm not sure what I'm doing but as long as I tell you version 2.0 is better you should buy it". In today's society of throw away product, I don't blame them for trying. Seeing and handling the batteries in person and you walk away at best with the impression that these are early stage prototype. 12 gauge wire connected oddly to batteries in storage bin plastic? And I think there is a fuse for each stacking. Try finding the bad one when the lights go out!
    I like you but you just crossed a line some folks here are not going to like one little bit. Users like Dan, Don, and Ian do not like facts or anything that shines a bad light on Renewable Energy. They believe anything Green they are told and could careless what is real or imagined. They believe batteries have 8000 cycles and have a positive EROI.

    Leave a comment:


  • Sun Tzu
    replied
    Originally posted by Sunking View Post
    OK Amy here is my issue. Internal Resistance is way too high. Using the product sheet for the M100-L082 which is a 48 volt 540 AH battery we can determine Ri from the Voltage vs Capacity curve of 75 milli-ohms. I know to most folks that means nothing to them, but that is significant. For low voltage systems one of the design goals is to limit voltage sag at the battery post to 2% of less. Using a nominal voltage 48 volts and 540 AH capacity means you can only draw .96 volts / .075 ohms = 12.8 amps. On a 540 AH battery that is a miserable C/40 discharge. That is unusable. Basically means you got this huge battery that can only supply a 650 watt load.

    Now take something like a Rolls 4CS17PS a 4 volt 540 AH battery. It has a Ri of 1.03 milliohms. It would take 12 of them in series to equal 48 volts giving you a total of lets just say 13 millohms. Using the same 2% design goal you can draw .96 volts / .013 ohms = 74 amps or roughly C/7 discharge current. Using the Rolls equivalent you can supply a 3500 watt load.

    Now here is where it really gets ugly. If you can only discharge at a maximum of C/40 means you can only charge at a max of C/40. Again most folks are clueless what that means. But in essence makes it completely unusable because there is not enough Sun Hours in a day to recharge. Bare minimum winter sun hours for a FLA is 3 Sun hours before you exceed a C/8 charge current. For these batteries bare minimum is 16 sun hours. No place on the face of the planet gets 16 Sun Hours. In the lower 48 states Tuscon has the best in summer at 7 Sun Hours.

    Sorry I do not see any application these batteries can be used for other than extremely low power application for telemetry in extremely remote locations where is cost is not a factor. Good grief if ever fully discharged would take two full days of commercial power to recharge. On solar more than a week on the equator, 2 or 3 weeks anywhere else. Heck even FLA batteries are a challenge with their relatively high Ri, but these are outrageous now that I see the real data. No wonder they hide it.

    Not sure that I totally agree with the logic/math here Sun King. Internal resistance is a big deal, but what I do not believe that you can draw some of the conclusion that you are. Internal resistance directly correlates to how hot you can expect these puppies will get (i2r). I do not think that you can say that it will limit their C-rate. But it is really beside the point because I am in agreement about the practical use of these batteries. You will end up needing a huge of amount of these to do anything real. Two things should stand out immediately with these guys, first, 3,000 cycle life claim from a company that is 4 years old? Really? Show me a startup battery company that doesn't claim 3,000+ cycles and I will show you honest people. It has become standard boilerplate for newbie battery companies wanting to get funding unfortunately. It hurts green tech and renewables when people make up outrageous claims and really grinds my gears. And the four years is the company's age, not their latest product. Which leads me to the second stand out, they have put out 3 products within one year of starting production, each obsolescing its predecessor. This is a huge red flag. Cell phones companies can't compete with this act of...marketing genius or "I'm not sure what I'm doing but as long as I tell you version 2.0 is better you should buy it". In today's society of throw away product, I don't blame them for trying. Seeing and handling the batteries in person and you walk away at best with the impression that these are early stage prototype. 12 gauge wire connected oddly to batteries in storage bin plastic? And I think there is a fuse for each stacking. Try finding the bad one when the lights go out!

    Leave a comment:


  • RedDenver
    replied
    Originally posted by northerner View Post
    That makes sense, but I don't see any zero current lines on any of Aquion's discharge curves for the S20 stack. I guess one could try to estimate it by examining current discharges at 2,4,6,8, & 10 amps.

    It would also be interesting to see how the charge acceptance tapers off as the stack approaches full charge, and to see what the recommended "absorb" voltage is.
    Section 6.3 of the operations manuals for the L stack and M module have several figures that might be what you're looking for, including the recommended charging profile.

    Leave a comment:

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