1.28 vs 1.31 electrolyte density (for offgrid cycling)

liamg
liamg Registered Users Posts: 43 ✭✭
edited September 2017 in Off Grid Solar & Battery Systems #1
Hello,

I found two similar (in terms of weight) 6V traction batteries. One of them has a nominal electrolyte density of 1.28kg/l and the other one has a nominal density of 1.31kg/l. 

Like I've just said, they both weight approximatively the same but the former has an increased capacity (obvious).

As far as I know, a higher electrolyte density level could lead to an increased plate corrosion effect, as long as the battery stays in full charge/floating state (telecom, ups).

I want to use the batteries with my offgrid (solar) setup hence they will be cycled on daily basis. That means they won't be staying in full charge/floating state for too long (few hours per day only).

Is there a problem if I'll go with the higher electrolyte density ones? They are both golf cart batteries hence they are made for high cycling anyway.   
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Comments

  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #2
    Do they have the same recommended charging regimes?
    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
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  • Vic
    Vic Solar Expert Posts: 3,208 ✭✭✭✭
    #3

    If you absolutely do not need the small extra bit of Capacity of the 1.31 SG batteries,  would avoid those batteries.

    YES,   higher SG electrolyte does increase plate erosion,   increases self-discharge,   generally increases charge and EQ voltages,   and does shorten battery life,   all else being equal.

    1.31  SG electrolyte is very high,  1.280  is high  but common for GC-2 batteries  (1.277 - `.280 SG).
    Personally  I'd prefer 1.250 SG for my off-grid batteries  ...

    FWIW,   just opinions,   Good Luck,   Vic

    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
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  • liamg
    liamg Registered Users Posts: 43 ✭✭
    #4
    There's a common instruction manual for both models and the manufacturer do mention the EN 50272-3 standard for charging scheme (I could not find that document though).
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  • liamg
    liamg Registered Users Posts: 43 ✭✭
    #5
    @Vic:

    Sorry, I've missed your post. Yep, your explanations are legitimate and I just can't explain why the manufacturer claims the same parameter (life cycles) for both models.
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