best AGM

ws9876
ws9876 Solar Expert Posts: 448 ✭✭✭
in Off Grid Solar & Battery Systems #1
When I think of a good storage battery I always think 6 v or smaller for its durable plate construction. Considering you have to replace a bank every 8-10 years is a 12v set up an economic and realistic choice??what do you think..?
· Share on Twitter

Comments

  • ws9876
    ws9876 Solar Expert Posts: 448 ✭✭✭
    #2
    I mean 4 12vs for 48v
    · Share on Twitter
  • softdown
    softdown Solar Expert Posts: 3,901 ✭✭✭✭
    edited January 2018 #3
    One bad cell equals the death of a battery. For that reason alone, I recommend 6 volt batteries unless you are willing to buy very high quality 12 volt batteries. I have a number of retired 12 volt batteries that were perfectly fine....except for one bad cell next to the "charging" cell. 

    2 volt batteries would be even better though a lot of cabling is involved and a large bank is created....that costs money.

    There are also a lot more options in six volt batteries I think. 

    8-10 years may be wildly optimistic.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
    · Share on Twitter
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #4
    If 12v give you the capacity you need in a single string, there's no reason not to go that way. 48v is 24 cells, whether connected mostly internally using 12v batteries or externally with individual 2v cells. The main reason to use lower voltage would be to keep weight of components manageable.

    One thing to watch for in 12v AGMs though is, as you've alluded to, whether it's built as a true deep cycle. Many are dual use hybrids. If it gives a CCA and RC number, it might be in this category. A true deep cycle isn't particularly good at cranking amp applications, and will give amp-hours at ~20hr discharge rate, which is the application they're made for.

    For cost and longevity, it's hard to beat flooded. Is there a particular reason to use AGMs in your application?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
    · Share on Twitter
  • softdown
    softdown Solar Expert Posts: 3,901 ✭✭✭✭
    #5
    Estragon said:
    If 12v give you the capacity you need in a single string, there's no reason not to go that way. 
    Yes there is. One bad cell means the loss of six cells/battery instead of three cells/battery. 
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
    · Share on Twitter

Categories