Aquion Energy up and coming battery....opinions please

[Living Large]

Remember that if you size for 7 kwh daily usage and take those 16 stacks down to close to 80% DOD, that has given you 3 days of battery supplied power. Any bank that size will take a significant amount of generator run time to bring it back up again.

Most days off grid, you will get some power in from your panels, which should also be factored in. There are times in mid winter when you may encounter heavy cloud cover for a period of days, however, I find that the sun can and often does shine, even in winter.

Most of the time, your solar should provide most of your power if the system is designed properly. Also, does depend on where you're located and how much sun you get?

Yes, part of the reason AHI will not work for my needs is where I am located and how much sun I get. That is precisely, 100% correct. We agree on this point. I am not in Arizona, I am in upstate New York. You do realize that. And a corollary to this is AHI will not work for all off-grid applications. It didn't for me, though we don't agree on that point.

I keep hearing I should redesign my system, yet amazingly, by dropping in LFP, everything is sized right, and I don't need to upgrade everything and take out a mortgage just to accommodate the latest flash in the pan that hasn't proven it is going to pan out yet. I don't need to upgrade anything, except adding an economical BMS. And my generator run time is a fraction of with AHI. I see this as a win-win. It is hard to explain, but this system was designed over several weeks, looking at using multiple chemistries. I started with AHI. Wanted in the worst way to use it, as people here saw. Sunking was respectful, in an intellectual exercise way - like "let's see if he sees where this goes". It took me a week, since it was my first time. As the design progressed, I saw at least one serious downside - generator sizing and run time. This was in addition to the fact I downsized the battery bank from the start due to cost, and that was nagging me in the back of my brain. This would result in even more gen run time. While fighting the generator problem and looking at larger generators and higher fuel costs and lower efficiencies, I thought to experiment with other chemistries. Went through a few more iterations and voila. Instead of feeling like I ended up with a big fat square peg in a round hole (AHI), it feels like everything fits. There is a lot to be said for that.

[Mike90250]

.....Most days off grid, you will get some power in from your panels, which should also be factored in. There are times in mid winter when you may encounter heavy cloud cover for a period of days, however, I find that the sun can and often does shine, even in winter......

Man, I wish I was there. Nov & Dec, was about 6 weeks of heavy clouds/storm in northern California. Burned a bunch of fuel. got nearly nothing from solar for 6 weeks

[northerner]

Not me smart money is just go with LFP. Cheaper and will last as long if not longer with none of the limitations. Originally these batteries were designed for EV's. That went down the tubes real fast with Ri and Energy Density. Now it is a battery trying to find an application.

My guess is one of two things will happen. They will go bankrupt, or what the owners would like is to be bought out by Exide or one of the big boys and bury the product.

Bottom line is overall cost, ie price per kwh over the batteries rated cycle life. If LFP's came down in price and the issues with cell balancing worked out, I would consider them. At this point, the AHI batteries are likely the most economical option (providing they put out as advertised), and price is expected to drop.

[northerner]

Decades ago, we used to call that switching in an end cell, adding more cells to bring the
usable battery voltage in range. Doubt its done anywhere today. But converters can be
built to run over a 2 to 1 voltage range; is this the project that will test that out? I would
start with a grid tie inverter, and reprogram it not to require such a stiff line voltage, and
be self starting with no line. Bruce Roe

I'm thinking another module could be added to the Aquion stack full time, no switching required.

One stack consists of 8 modules so:

at 59 volts/8 = 7.37 volts per module. 1 extra module would be 66.4 volts, well within the range of both my Outback inverter/charger and Midnite classic

at 40 volts/8 = 5 volts per module. 1 extra module would bring it in at 45 volts, well above the 42 volt cutoff, and equivalent to the 40 volt cutoff with 8 modules.

Problem with low voltage cutoff solved!

[Sunking]

Decades ago, we used to call that switching in an end cell, adding more cells to bring the
usable battery voltage in range.

Use to be common practice in Telecom with Step Switches. If site lost power an extra cell was switched in series, and it required its own dedicated 2 volt charger.

[Sunking]

I'm thrilled that the AHI will meet your needs.

For me, they will not. One stack is 51 Ah. Let's say I take it to 80% DOD. I need to put 40.8 Ah back in. That's 3.4 hours. If I need 16 stacks, to charge for 3.4 hours, I need 192 Amps. OK, that's at least a 10 and probably 12 kW generator. If I stick with my 6 kW generator, it means 7-8 hours. Plus I need to upsize the inverter/charger to handle all that current.

Now what about charging with my 4900 W PV array? This should be fun. Maybe I get 90-100 A on a good day. So that means 6.5 hours of full sun. I upsize my PV array, upsize my CC, upsize my battery cost, upsize my generator, upsize my fuel costs, upsize my maintenance, upsize the inverter/charger, upsize my wire. All to support AHI. I am living large, and so are the people who supply this stuff.

I simply do not have deep enough pockets for my needs.

LFP is essentially 100% efficient in terms of amp hours but do not be fooled because amp hours do not mean squat. Listen to this and wrap your head around it because it is important to understand.

What is 1 AH on AHI being charged up at 60 volts? 60 watt hours right? What is 1 AH at discharge when below charge voltage say at 48 volts or all the down toward 80% DOD of 33 volts? Could it be 33 to 48 watt hours? That round trip efficient Northern is speaking about is gobbely gupe Marketers use to make their crappy product sound good. AH efficiency don't mean squat. Even if AH efficiency were 100% like LFP, watt hour efficiency is not because charge voltage is higher than discharge voltages. Good thing about LFP is the flat charge/discharge curve makes the efficiency as high as you possible can get say compared to FLA or AHI.

[Sunking]

There is a solution to deal with heavier loads when the AHI batteries are below 60% DOD that I was considering. You could put in a small LFP battery that is engaged when bank voltage drops to near the 42 volt level.

Not me smart money is just go with LFP. Cheaper and will last as long if not longer with none of the limitations. Originally these batteries were designed for EV's. That went down the tubes real fast with Ri and Energy Density. Now it is a battery trying to find an application.

My guess is one of two things will happen. They will go bankrupt, or what the owners would like is to be bought out by Exide or one of the big boys and bury the product.

[bcroe]

There is a solution to deal with heavier loads when the AHI batteries are below 60% DOD that I was considering. You could put in a small LFP battery that is engaged when bank voltage drops to near the 42 volt level. In the case of my proposed system of 12 AHI stacks, a 100 ah LFP battery could provide temporary heavy load handling, if you really wanted to fully use the last 20% or so of capacity. In any case, you would be looking at recharging, if the bank is that low in the first place.

With my system, I have plenty of generator run time mid winter, but practically no run time from about mid February to mid October. So usually I either am running it on a regular basis or not, so such a back up would not be necessary. In fact, I had zero generator run time during that period this past year!

Another option to bring up battery voltage is add one more battery module per stack. Not sure if Aquion is considering this but I just checked my inverter charging limits and are between 42 and 68 volts, for the vfx3648? The current Aquion S20 stack has a voltage range of 30 to 59 volts.

Decades ago, we used to call that switching in an end cell, adding more cells to bring the
usable battery voltage in range. Doubt its done anywhere today. But converters can be
built to run over a 2 to 1 voltage range; is this the project that will test that out? I would
start with a grid tie inverter, and reprogram it not to require such a stiff line voltage, and
be self starting with no line. Bruce Roe

[northerner]

I'm thrilled that the AHI will meet your needs.

For me, they will not. One stack is 51 Ah. Let's say I take it to 80% DOD. I need to put 40.8 Ah back in. That's 3.4 hours. If I need 16 stacks, to charge for 3.4 hours, I need 192 Amps. OK, that's at least a 10 and probably 12 kW generator. If I stick with my 6 kW generator, it means 7-8 hours. Plus I need to upsize the inverter/charger to handle all that current.

Now what about charging with my 4900 W PV array? This should be fun. Maybe I get 90-100 A on a good day. So that means 6.5 hours of full sun. I upsize my PV array, upsize my CC, upsize my battery cost, upsize my generator, upsize my fuel costs, upsize my maintenance, upsize the inverter/charger, upsize my wire. All to support AHI. I am living large, and so are the people who supply this stuff.

I simply do not have deep enough pockets for my needs.

Remember that if you size for 7 kwh daily usage and take those 16 stacks down to close to 80% DOD, that has given you 3 days of battery supplied power. Any bank that size will take a significant amount of generator run time to bring it back up again.

Most days off grid, you will get some power in from your panels, which should also be factored in. There are times in mid winter when you may encounter heavy cloud cover for a period of days, however, I find that the sun can and often does shine, even in winter.

Most of the time, your solar should provide most of your power if the system is designed properly. Also, does depend on where you're located and how much sun you get?

[Living Large]

My current system using lead acid batteries is working fine for me now. If I decide to go with AHI batteries, there is no reason why Aquion AHI batteries would not work as well, as I know what my usage, loads and charging parameters are. Of course that is again dependent on the specs that Aquion has put out.

My current average use in winter is 7 kwh per day. I have a 2.8 kw array and a 3kw genset running on NG.

A battery of 12 Aquion S20 stacks (28.8 kwh total) would be more than sufficient to meet my needs, and equivalent to my current storage of lead acid batteries.

A rough estimate of 2800 watts of charging current is only somewhere between 4 and 5 amps per stack, and RTE (round trip efficiency) of the AHI stacks is about 85% at that current level. Less than 4 hours would be required to meet my daily needs, and that's in mid winter, worst case scenario. The Aquion stacks can accept up 12 amps per stack, over double my current requirements!

I'm thrilled that the AHI will meet your needs.

For me, they will not. One stack is 51 Ah. Let's say I take it to 80% DOD. I need to put 40.8 Ah back in. That's 3.4 hours. If I need 16 stacks, to charge for 3.4 hours, I need 192 Amps. OK, that's at least a 10 and probably 12 kW generator. If I stick with my 6 kW generator, it means 7-8 hours. Plus I need to upsize the inverter/charger to handle all that current.

Now what about charging with my 4900 W PV array? This should be fun. Maybe I get 90-100 A on a good day. So that means 6.5 hours of full sun. I upsize my PV array, upsize my CC, upsize my battery cost, upsize my generator, upsize my fuel costs, upsize my maintenance, upsize the inverter/charger, upsize my wire. All to support AHI. I am living large, and so are the people who supply this stuff.

I simply do not have deep enough pockets for my needs.

[northerner]

You cannot access the 40% of Aquion batteries because it is below 42 volts. Nothing can tap that down to 30 volts. When are you going to acknowledge that fact? It shoots all your capacity calculations to hell. It would take nearly twice the capacity of Aquion to equal the usable capacity of FLA.

There is a solution to deal with heavier loads when the AHI batteries are below 60% DOD that I was considering. You could put in a small LFP battery that is engaged when bank voltage drops to near the 42 volt level. In the case of my proposed system of 12 AHI stacks, a 100 ah LFP battery could provide temporary heavy load handling, if you really wanted to fully use the last 20% or so of capacity. In any case, you would be looking at recharging, if the bank is that low in the first place.

With my system, I have plenty of generator run time mid winter, but practically no run time from about mid February to mid October. So usually I either am running it on a regular basis or not, so such a back up would not be necessary. In fact, I had zero generator run time during that period this past year!

Another option to bring up battery voltage is add one more battery module per stack. Not sure if Aquion is considering this but I just checked my inverter charging limits and are between 42 and 68 volts, for the vfx3648? The current Aquion S20 stack has a voltage range of 30 to 59 volts.

[northerner]

Recharge time via generator is a major issue. With that high Ri comes very slow charge rates of greater than C/15. Totally unacceptable with both solar and generator. With a genny you want to charge with at least C/8 or higher to minimize fuel burn, fuel cost, and noise pollution. In northern climates with short days requires AGM batteries to take the very high charge rates of C/4 and higher required. No way is Aquion batteries a candidate for solar.

My current system using lead acid batteries is working fine for me now. If I decide to go with AHI batteries, there is no reason why Aquion AHI batteries would not work as well, as I know what my usage, loads and charging parameters are. Of course that is again dependent on the specs that Aquion has put out.

My current average use in winter is 7 kwh per day. I have a 2.8 kw array and a 3kw genset running on NG.

A battery of 12 Aquion S20 stacks (28.8 kwh total) would be more than sufficient to meet my needs, and equivalent to my current storage of lead acid batteries.

A rough estimate of 2800 watts of charging current is only somewhere between 4 and 5 amps per stack, and RTE (round trip efficiency) of the AHI stacks is about 85% at that current level. Less than 4 hours would be required to meet my daily needs, and that's in mid winter, worst case scenario. The Aquion stacks can accept up 12 amps per stack, over double my current requirements!

[northerner]

You cannot access the 40% of Aquion batteries because it is below 42 volts. Nothing can tap that down to 30 volts. When are you going to acknowledge that fact? It shoots all your capacity calculations to hell. It would take nearly twice the capacity of Aquion to equal the usable capacity of FLA.

Not entirely true sir, as, according to the specs given by Aquion, you can draw a lesser load of about 5 amps per stack at 60% DOD, and about 2.5 amps at 80% DOD. and stay at or above 42 volts.

So, for an example size of 12 stacks (size I'm thinking about and equivalent to my current FLA battery capacity) that would give you:

at 60% DOD: 2500 watt load

at 80% DOD: 1250 watt load

But you are right that a deeper depth of discharge with AHI batteries will limit the amount of power available.

[Living Large]

If i were in your shoes I would find land with utility. In areas where Winter sun hours fall below 3 hours you have to use AGM/LFP, or plan on running a genny a lot. Even with AGM or LFP you woul dstill need genny for those days and days of cloud cover. Given that i would look at LFP because you can hold off on genny until they get down to 20% vs 50% with AGM.

Keep up the research, you are doing very good.

That is exactly what I concluded - all of this. I am either doing good research, or listening to you.

[Living Large]

One comment on your spreadsheet. Cycle life for LFP you are using is based on 100% to 0% SOC. Normally only an EV would push those limits, no need to do that with solar. Run 10 to 90% and you can double that cycle life to 4000 cycles or roughly 10 years.. All lithium batteries are stressed if SOC is pushed to 100%. That is why manufactures only ship them at 60% SOC, and recommend storage at 60% SOC. Don't charge them fully. Even on your laptop you can extend battery life by setting SOC to 20/80.

Lastly LFP can be ran PSOC, so no need for genny until you get down to 10 to 20%.

Dereck - I took that cycle life from the electriccarparts website, which has a table of specifications for the 400Ah CALB - it specifies "Cycle Life (80% DOD)" = 2000. It does not address if SOC is assumed to be 100%. I trust your experience, however - and your comments were requested for that reason. I'll see if I can find further verification.

Yep, I was planning to run about 20-90%.

Edit I found a few "data sheets" on different sites. Charts. On a CALB site, it states "2000 cycles for the working conditions @80% DOD" One can only guess what that means. Another data sheet recommends staying within 10-90% to get 2000 cycles. I am going to guess conservatively they mean if you stay within 10-90% and typically go to 80% DOD, you get 2000 cycles. Then when you get more, you can be thrilled that you did better than expected (: