Which battery is best for solar?

[n4zi]

    I currently have 8 12 volt flooded cell batteries and have been thinking about trying something different. I currently have
7 kw of panels and an XW6048 inverter- 3 Classic 150s for charging!. My 8 flooded batteries are 220 ah ea - so I have
440 ah of battery @ 48 VDC. I have been struggling with the idea of going to AGM type batteries and a 6V cell. Just wondering
what everyone recommends - I have US battery here in Memphis and they offer the L16 at 390 ah - was thinking minimum
16 or hopefully 24. The flooded cell are nice but it would be nice to have a sealed battery where I would have to vent?
Still working on the install here the 185XCHC are almost a year old I and I have maintained them with a PWM charger and (2) 80 watt panels. I dont have room in battery box for 4 more! Also I have heard that 3 strings is max!
Gentlemen - Your thoughts??

Bill  N4ZI Munford, TN

[mike90045]

with AGM, you do NOT want any parallel battery strings, they have very low internal resistance, and the subtle wire resistance differences will cause un-equal loading of the batteries.

If you need more battery amps, look into 4V or 2V cells, and use more in series.  Of course, the quantities are lower, and the price goes way up.

[n4zi]

Mike,

  That's good information - that's what I am after! I don't think 440 ah @ 48vdc is enough battery for a 7 kw system.
Originally I only planned to put out about 3 or 4 kw. Guess I kinda jumped before giving it a lot of thought! I have seen the
Edison batteries which are known for there long life, I see they are real expensive and some don't recommend them. I plan
to do grid-tie with battery backup for now. I would like to get another 3kw in panels and purchase a second 6kw XW. I am
not against buying (24) of the 2v batteries rated at 1100 ah in AGM. My usage here is horrific - last month I averaged
67 kwh per day- AC and pool pump causing biggest increase in summer Fall/Winter and Spring my usage is around 32KWH
per day here! I would like to hear from others. I hope to have system online by end of October if work allows! My brother
in-laws backhoe is broken down in back so I am waiting on a few parts for it to finish my undergrounds. I will use the
batteries I have for now - was surprised to see 100 ah @ 48 vdc listed as minimum for running the XW!

Thanks for your help!

   Bill N4ZI Munford, TN
ps I will surely post more questions a I see the need!

[RossW]

I don't think 440 ah @ 48vdc is enough battery for a 7 kw system.

I am not against buying (24) of the 2v batteries rated at 1100 ah in AGM. My usage here is horrific - last month I averaged
67 kwh per day

I would like to hear from others.

I (used to) have three parallel banks of 24 x 2V/500AH AGM


I have since replaced them with a single bank of 16 x 3V/300AH LFP with the intention of doubling that up later this year to make it a single bank of 32 x 3V/300AH LFP arranged as 16S2P.

[mike90045]

.... was surprised to see 100 ah @ 48 vdc listed as minimum for running the XW!...

That's to allow enough "capacitance" to let the inverter build a nice sine wave at 1Kw power.   100A needed for each 1Kw of load.  Otherwise, internal resistance (NiFe has lots) lets the voltage of a fully charged pack sag.

[carkifelek]

n4zi, If you had planned to used just 3kW, a single 440ah, 48V battery would’ve been enough. You can’t use two batteries in parallel since they both will have a different discharge rate based on their condition and even if one of the batteries drops a few millivolts, the complete battery pack becomes useless. You can however use a Zener with every voltage source so the batteries get only discharged when you’re taking power from the battery pack. These Zeners can be bypassed while charging.

[toothy]

Hello Bill

You seem like a fellow who might enjoy a crazy idea. Have a look at Aquion energy batteries if they work as touted I'd get some for my next set, time will tell. Also it seems their facebook page has more meat than their web site if you dig awhile.

We have a local expert on here but he is being extremely tight lipped about them, something about a non-disclosure agreement. I wish the company would let him tell us about them, if they are already on the market, what could he disclose that dollars couldn't find out, I'm just a big cheap chicken.

Of course what he may have to say could be ugly and then I understand the nda.

Good luck
Wade

[Halfcrazy]

I am testing the Aquions here but now that they are for sale I think I can talk a lot more about them.

The stacks we are actively testing right now are the older stacks the new ones are 40% more energy dense and 30-40% lower resistance.

Pros I can attest to:
*Do not need to be fully charged. Happy to never be above 50 or 60% SOC (Unlike Lead acid)
*Can be drawn down to 0% SOC with no side effects on the battery
*Environmentally friendly no harmful stuff in them
*Short circuit safe (You can short the battery out and walk away it doesnt care. When you un short it the voltage creeps back up and settles at about half what the SOC was prior)

Aquion claims (And I tend to believe them based on our testing but I will tell you more soon)
*The production battery is 40% more energy dense and 30-40% less internal resistance (This is key as the stacks we are testing now sag in voltage a little more than I like under a hard load but the production stacks are supposed to eliminate this and I will test this in a week)
*Extremely long cycle life especially when not "Fully" charged every day (Using Skip days on the Classic for instance)

Cons I have:
*Non production stacks have slightly more sag than I like in voltage under load, of course more stacks helps but our test location is an offgrid home with standard submersible well pump etc and 700 watts of PV using an SW2524 and 5 of the older non production stacks (To be fare they claim this is fixed now and I will make sure to give my opinion)
*Wiring, They use MC4 connectors and its a little harder to get used to. To be fare this really is not a con more than an older set in his ways installer needing to learn new ways. hat we do is use a Combiner box just like on PV and combine the Stacks. Of course if you buy 12 stacks on a pallet it is all wired for you so this is not really a con so much as an abservation.

Ryan

[n4zi]

   Guys,

   Don't know anything about the Aquions but will do a search and see what I come up with! I am still assembling
my system and have all my outside work complete for now. My batteries are US battery 185HC-XC 12 volt unit.
I currently have 2 banks for a total of 440 ah. I am thinking 2v and would prefer AGM type. My buddy across
town just purchased the Outback 200 amp hour units - he has 3 banks coming with 8 spare batteries. His rack
will hold 3 banks of 4 for 600 ah. I am currently thinking about the Enersys types - they are expensive but
within reason. If I was a rich man I would probably try the Iron Edisons but wow they are really expensive!
I would really like about 1100 to 1300 ah for lots of spare capacity(1 bank). I installed my second XW6048 and a hope
to purchase a minimum of 3 kw more of panels(for 10 kw total) The batteries are the quagmire. By the way
"n4zi" is my amateur radio callsign if your wondering - I get some real looks when they see that on the back
of my 93 mustang! Ryan think you still owe me an email on the XW firmware??  More thoughts?

  Thanks,

   Bill

[toothy]

Bill,

I can't speak to the AGM's but I can attest that a 1350 FLA bank is a quagmire that will eat all the joy from your life. Maybe not so much in the summer when we have plenty of sun but the whole early winter all I do is worry about hurting the batteries. You being grid connected have a distinct advantage in not having to hear the gen run while in late absorb.

Ryan,

Thanks, A LOT! You know I've been drooling about these for a while and am enthused that they are getting out there to the edge of main stream. I may be ready to jump in.

Good luck, Bill

Thanks, Ryan

[zoneblue]

I wonder when are they going to release charge / discharge curves / cycle life testing etc..

I am testing the Aquions here but now that they are for sale I think I can talk a lot more about them.

[dgd]

I wonder when are they going to release charge / discharge curves / cycle life testing etc..

I am testing the Aquions here but now that they are for sale I think I can talk a lot more about them.

I wonder when we will see Chinese copies of these swamping the battery market 

Dgd

[Westbranch]

I wonder when are they going to release charge / discharge curves / cycle life testing etc..

I am testing the Aquions here but now that they are for sale I think I can talk a lot more about them.

Not till Ryan has proved there is no magic smoke in them...

[inetdog]

I wonder when we will see Chinese copies of these swamping the battery market 

Dgd

A very good question, especially since there is an indication over on Candlepower that Panasonic is currently selling cheap Chinese copies of eneloops under the same part number as the Japanese made ones. 

[toothy]

My ineptitude show when I think about things electrical!

On the Aquion spec sheets  there is a single stack and a pallet of 12 combined stacks all wired together.

Why are the Ah spec's on the combined, wired 12 stack not a simple multiple of the  singles?

M- module = 541.5 Ah   http://www.aquionenergy.com/stationary-energy-storage-batteries#specifications

S- module = 51 Ah X 12 = 612 http://www.aquionenergy.com/energy-storage-battery#specifications

Thanks for your thoughts
Wade