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

[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.

[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]

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.

[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!

[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.

[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

[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.

[northerner]

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

I live in northern Alberta, and go through a period from about mid November through to about mid January, where I am heavily reliant on generator power. It basically requires daily generator run time as the sun is relatively low in the sky and only out for 7 to 8 hours. Even haze and high cloud reduces incoming power significantly. On a cold clear day in mid winter, I can receive up to 10 kwh in, from a 2.8 kwh solar array. A month on either side of that period is transitional, where only occasional generator runs are needed, and next to no generator run time beyond that. We do receive plenty of sun here though.

This winter has been cloudier than I've seen in the past. Had about 100 hours of generator run time in December.

[Living Large]

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.

Thank you for pointing out this nuance. A newbie like me can forget about efficiencies, not having worked with the hardware yet. When the rubber hits the road, a "little" thing like this will be huge.

[Living Large]

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!

This also increases the price, weight and size of a stack by 12.5%. It's an expensive band aid.

[Living Large]

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.

I do not agree that all things considered, AHI is "the most economical option". For my system, I need to upgrade everything just to charge them, and charging takes a long time. This all costs $$$. That is the downside to the discharge/charge characteristic that you argue lends itself to solar. As for absolute cost, for me there is a risk cost with AHI at this point. How do you put a price on that? You have people here still calling it vaporware.

As for cell balancing of LFP - that pretty much takes care of itself after initial balancing. Shunting will keep the cells in balance. It adds some complexity, small cost, and wastes a very small amount of energy.

An intangible is size and weight. The LFP is something like a pickup truck compared with AHI being a tractor trailer, IMO. Literally and figuratively. I like being able to move stuff around without a lot of effort.

[northerner]

I do not agree that all things considered, AHI is "the most economical option". For my system, I need to upgrade everything just to charge them, and charging takes a long time. This all costs $$$. That is the downside to the discharge/charge characteristic that you argue lends itself to solar. As for absolute cost, for me there is a risk cost with AHI at this point. How do you put a price on that? You have people here still calling it vaporware.

As for cell balancing of LFP - that pretty much takes care of itself after initial balancing. Shunting will keep the cells in balance. It adds some complexity, small cost, and wastes a very small amount of energy.

An intangible is size and weight. The LFP is something like a pickup truck compared with AHI being a tractor trailer, IMO. Literally and figuratively. I like being able to move stuff around without a lot of effort.

The only difference in charging will be in the difference of efficiency between AHI and LFP, which on average should only be about 10%. Actually having a larger bank, which is likely for a more efficiently designed AHI system, will reduce the amount of generator run time, allowing you to get through longer periods of cloudy weather. A properly designed solar system in conjunction with storage, will allow you to minimize generator run time.

The biggest expense with an off grid system by far, is batteries. They have a cycle life and need changing periodically. So savings here will have the biggest impact. Current price for LFP is over 20 cents per kwh, factoring in cycle life. Current price for AHI is 16 cents per kwh. This is more than a 10% savings, so is the better value. The big plus is if AHI drops down in price to 70% of what it is now, as expected by year's end, that would put it at just over 11 cents per kwh. There is nothing else out there that can even come close to competing with this! And the price is expected to continue dropping.

[russ]

There is nothing else out there that can even come close to competing with this! And the price is expected to continue dropping.

You are certainly a cheer leader for them! Do you work for their sales department or do you just make a habit of believing all the sales BS companies put out?

[northerner]

You are certainly a cheer leader for them! Do you work for their sales department or do you just make a habit of believing all the sales BS companies put out?

Russ, I don't work for their sales department. I'm hoping it's not sales BS, as I myself am looking to reduce battery expense. I'm sure others are as well.

[northerner]

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.

To consider efficiency, wouldn't one compare voltage levels for charge and discharge at a particular battery state of charge. For example if your charging at 1 amp at 50 volts, the difference in voltage would be not as significant if you now started discharging with 1 amp. The voltage for charge and discharge both go up as battery state of charge goes higher and vice versa.

I would think the efficiency of the AHI batteries that Aquion posts is referring to energy efficiency and not just AH???