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

[dahur]

"Aquion Energy Wins Deal With Bakken Hale Off-Grid Residential Estate In Hawaii To Supply 1 MWh AHI Battery"

http://cleantechnica.com/2015/01/12/aquion-energy-wins-deal-bakken-hale-grid-residential-estate-hawaii-supply-1-mwh-ahi-battery/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+IM-cleantechnica+%28CleanTechnica%29

[Sunking]

If you size your bank accordingly then recharging won't be an issue. What is your daily usage expected to be and what will the highest load be on your proposed system?

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.

[SunEagle]

"Aquion Energy Wins Deal With Bakken Hale Off-Grid Residential Estate In Hawaii To Supply 1 MWh AHI Battery"



http://cleantechnica.com/2015/01/12/...eanTechnica%29

Not surprising that a private estate can afford to install not only a 176kw solar panel system but a 1MWh battery backup along with the required propane generators.

Looks like a win for Aguion but doesn't sound like something the average Joe can afford.

[Sunking]

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.

[Sunking]

I woke up today thinking about my attempt yesterday to explain why I don't believe AHI is feasible for my 7kwh per day application for a year-round off grid house with gen backup at a low winter insolation site. I do have some short term larger loads such as a well pump and microwave oven, but otherwise lower loads which don't include heating water or HVAC. This house I would like to be comfortable in, and not have to change my lifestyle substantially from my on-grid home. By that I mean having to go through multiple steps to do something that is now routine, each day. As an example, it would be nice to not have to crank up the generator every time I run some water. I do realize there will be regular monitoring and management.

One factor that really is important is not running my generator for lengthy periods of time to recharge the batteries. Maybe I am off-base, but when I saw the charge/discharge characteristics of LFP, and ability to charge at a wide range of currents, my eyes lit up. I will have stretches of cloudy/snowy weather, and insolation in Nov-Jan is low already. As readers here know, my objective from the start was to avoid the toxicity of FLA, if possible. Yes, it can be managed, but that was my preference.

I did a comparison chart of FLA, LFP and AHI to summarize some of the parameters I came across in the past few months as a newbie looking at these chemistries. I may have made some errors and improper estimations, and if so please kindly suggest corrections. Folks here live this stuff every day and rattle specs and rules off like second nature.

There are a couple of things that drove my thinking. For the amount of AHI I would need, to keep the charging time reasonable I would need to be near the 12A per stack max, which would require a generator of 10KW or more (I would need 18 stacks by northerner's estimate), and that would also make me upgrade the inverter/charger. Also, my solar array would have to be increased quite a bit for PV charging. Upgraded MPPT to handle more current. Initial cost and crossing my fingers and hoping for the best.

According to Dereck's estimate, the power I could draw out of the AHI is limited by its internal resistance and will be lower than I need for a well pump or microwave, I believe. More of everything but performance is what I was seeing for my particular application.

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%.

[Living Large]

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.

For my use, generator run time is a huge issue for the reasons you state, as well as maintaining the generator (oil, repairs, replacement). My idea of living isn't to have to listen to a generator run all day every few days. That is not an option. If that is what is required, I'll look for another place to live. AGM and LFP were both favorable for charge time for me by comparison.

[Sunking]

If that is what is required, I'll look for another place to live. AGM and LFP were both favorable for charge time for me by comparison.

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.

[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 (:

[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.

[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.

[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.

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.

[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]

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?

[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