Aquion Energy batteries

That's ok. I don't want to get you into any trouble here.

I was just looking for a ballpark price to see how it compares to a similar sized FLA or AGM system with the understanding there are limitations with those battery chemistry.

Amy while it is true they can deliver 12 amps, you neglected to say how much the voltage would drop would be incurred. That is the problem, they have very high resistance making them unusable. Manufactures are not going to make a major overhaul of their equipment line so customers can use a single vendors batteries. The high Ri and queer operating voltages make them pretty much useless with all equipment. I was excited to until the details came out. Manufactures would have to make equipment specifically for the batteries. Just like NiFe batteries queer voltages, that is not likely to happen. IMHO they got a dud that will go thud on the market. They will not be getting my investment dollars.

You can give a price if you are smart about it and give it $/wh capacity. That will trick the uninformed into thinking they are cheaper to use.

Again, I'm 2 days into my knowledge of the Aquions, so I'll answer questions as I get the answers.

1) Low voltage requirements. I checked the specs for the DC Voltage input range of the popular inverters we sell. They seem to be able to handle about 80% depth of discharge. I personally don't like to design any battery to its discharge limit anyways, so I would tend to oversize a little to extend the life of the system, regardless of the battery type. I'm comfortable with 80%, around 40V. All but the SMA can go at least to 40V.
a) Magnum PAE = 36V
b) Schneider XW+ = 40V
c) Outback GTFX = 40V
d) Outback Radian = 40V
e) SMA Sunny Island = 41V

2) High internal resistance. I believe that is only an issue with high current draws, which this battery is not designed for. If you have high current requirements, this is not the right battery for you. If you are trying to run your fridge, lights, laptop, and TV, which is the list most of my off-grid customers give me, I don't think voltage sag will be an issue. I have sent in a question to my tech contact there to confirm. I'm also checking on the surge of a well pump, although for off-gridders, we usually have them use a PV direct pump to a cistern, then a small DC pump on the battery bank for house pressurize.

3) Sizing/Pricing. Let's play with an off-grid cabin with 2.3kwh loads a day (pretty much the loads listed above), 3 days autonomy, 50F temp. Lead Acid math = 2300wh / .94 inverter efficiency / 50% DoD x 3 days x 1.19 temp deration / 48V = 364ah 48V. That's one string of 8 Trojan L16-RE-B 370ah 6V batteries for Flooded Lead Acid (FLA), or one string of Concorde PVX-4050HT 405ah 6V AGM batteries. I've got $2872 for the FLA and $5062 for the AGM. I can't do the math for you for the sizing of the Aquions, as I have a calculator tool they gave me, but I see needing between 3 and 4 stacks (depending on some variables) Let's say 4 stacks, 9792wh. That's $4620. So, more expensive than flooded, but less expensive than AGM. Cool.

I'll update posts as I get more details.

Amy

OK I assume you are talking about 48 volt inverters right. Under load a FLA battery is completely exhausted at 1.75 vpc. So with 24 cells is 42 volts on a 48 volt battery system. See any problem with that?


That is a show stopper. FLA battery systems are designed to handle a maximum C/8 load current because any higher is going to has voltage sag problems. Typical battery systems are designed for 5-day autonomy. Assuming you have the national average minimum sun hours in winter of 3 sun hours. Means your panel wattage is also going to equal C/8 charge current, which means panel wattage = inverter wattage. Well that alone is a huge problem for off grid folks because it means they have to oversize the battery to meet the Inverts maximum demands for those occasional loads like a Toaster, Microwave, ect... To get the same usable capacity and the ability to run an inverter at maximum capacity means a extremely over sized battery way beyond 5 day autonomy.

If I were going to spend that kind of money I want a battery that is compatible with all the equipment today and would look at using LFP.

I got a reply back from my contact at Aquion. He said" SEI growth is a phenomenon associated with organic electrolytes. We do not have an organic electrolyte, so there is no concern."

There are a couple of simultaneous post right now about the Aquions, but since I'm here, I'll answer questions from both. I'm not allowed to post links here, but I do have spec sheets for both the 51ah stack and 541ah module that may answer some questions. I'll attach to this post. Aquion M100-L082 Spec Sheet.pdf and Aquion S20-008F SpecSheet.pdf You can see on the Voltage vs Energy graph that at the lower amp draw, the voltage sag isn't as much as at the higher amperage, which is what they have been saying, the market is for lower wattage over a long period. If we consider 40V the lowest configurable low voltage cutoff for most 48V inverters, we can see that at 10A draw per stack, you can use about 800wh before hitting 40V, but at 6A, you can get about 1700wh before you cross that line. At 2A draw, you're up to about 2400wh before the inverter shuts off. Now this is per stack, so if you want to increase your power draw, you need to increase the number of stacks appropriately.

Keep in mind that only going down to 40V instead of 30V brings your depth of discharge from 100% to 80%, increasing the number of cycles from 3000 to 4000.

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.

Based on Sunking's post, and the discussions elsewhere here of my consideration of AHI, then FLA and finally LFP batteries for my off grid design, I decided to create a chart comparing the key statistics of these chemistries. Some of the data is estimated, some is a range for that particular chemistry if the spec was not available, etc, as noted. If you see errors, please comment. Personally, the data in this chart helped drive my decision to go with LFP from these three options for my needs. Your application may vary.

Good to have a definite answer. The AQ in aquion is basically water as the electrolyte, so no SEI growth like there is with LFP. Makes sense since Prof J. Whitacre moved beyond LFP, where the organic solvent is a highly guarded corporate secret in most other LFP batteries. Note that GBS says that their LFP electrolyte is the least toxic of all, what little there is of it in the cells.

Back to Aquion - from the start they never intended these batteries to be EV or even general purpose replacements. The major market seems to be grid-stabilization, and perhaps we are shoe-horning it into our application.

I think it is pretty neat - but like LFP, you've got to really understand and want those battery characteristics to fit your application.

But for grid stabilization you really need to be able to deliver a significant portion of the battery energy in a few hours, at most 12 hours, and recharge on that same time scale.
Unless the battery bank is so massive that you are only ever using 1/40 of its capacity per cycle, I do not see the point.

On the other hand, if you do not care much about cyclic energy efficiency, you could choose to pull higher current from the battery bank and accept as much as a 50% voltage drop provided you care most about short term stabilization and have output conversion equipment that can tolerate a wide range of input voltages.
That is, if you are willing to accept a voltage sag of 40% instead of 2%, you would be able to use a C/2 discharge rate. That is probably good enough for a voltage stabilization application. For the charging process you could limit it to C/12 or even C/20 and have a useful recharge in the stabilization application.

For comparison, I have seen statements that pumped water storage has a cyclic efficiency of 50% or lower, so there may be a place for a storage system that can be deployed anywhere, with the option of a relatively small and inexpensive system size.
Maybe.....

I am a newbie, but I think you are on the right track. northerner believes firmly that the AHI will fit his off-grid application. Just as firmly, I believe it will not fit mine.

I find the flat charge curve of LFP very attractive, but others don't. There isn't a lot to think about, other than staying away from the two ends. I need the fast charge time for my location. I like the low weight. The cost, as long as it isn't way out of whack, isn't so much a criteria for me. I agree totally with your statement of "understanding and wanting particular battery characteristics," and it applies across the board for all chemistries, from what I have seen so far. Of course, there is another route of just going out and buying large batteries at WalMart, if you like to fly by the seat of your pants.

The belief that it will work for me is based solely on specs that Aquion has released about their batteries. I have yet to see real feed back from users of this battery.

However, if all the specs they post hold true, especially considering cycle life and predicted cost reductions, then they may just be the best option. That is yet to be seen.

The best option is the one that costs less in the long run! At the same time the AHI batteries are environmentally friendly and require no maintenance.

I am concerned with more than predicted cost. Inhaling fumes from my backup generator and listening to it and maintaining it, for starters. I wouldn't be using solar electricity AT ALL if my decision was based solely on cost - I would find a location on grid.

Their specs have been a moving target. If you find the internal resistance published, please let us know. There was an Aquion person lurking here - maybe they would be kind enough to post it.

Easy to figure out, simple Ohm's Law from discharge curves.

I'll see if I can get the official specs from them. Stand by.

Hi Amy, could you also request specs with regards to charging if possible?