Figuring out battery voltage values for programming inverter

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  • PG1959
    Junior Member
    • Jun 2020
    • 2
    #1

    Figuring out battery voltage values for programming inverter

    Hi there,
    I'm new at this and very much still learning- need a bit of help from you experienced guys...I have a used forklift battery powering my 7.5kW off-grid system. It is 48V, 1180Ah @C20. What values should I enter into the inverter (Victron Quattro 15kV) for absorbtion and float charge values and fully charged ? How do I figure this out? Thanks in advance and sorry if this seems a stupid question!
    Tags: None
    • Mike90250
      Moderator
      • May 2009
      • 16020
      #2
      The battery mfg will publish the specs for charging their battery. Absent that, use the generic Flooded setting on the charge controller and hope it's close enough

      your battery will need to receive about 10-15% of the C rating, so your charging sources need to be able to put about 100A into the battery. That will keep the tall forklift cells from becoming stratified and dying an early death.

      Getting a large battery bank, thinking you can recharge it slowly, condemns it to an early death by sulfation.
      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

      solar: http://tinyurl.com/LMR-Solar
      gen: http://tinyurl.com/LMR-Lister

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        • PG1959
          Junior Member
          • Jun 2020
          • 2
          #3
          Thanks for the reply Mike- I appreciate it. I don't think that should be an issue as I have two Victron 100amp mppts, fed by 6 strings of 5 260W panels and I live in a sunny country. So far it's all working great but the truth is I find going into the software and programming of the Victron inverter a challenge....I'm a semi-retired mechanical engineers and although (for my 60 something years!) I'm reasonably good with a laptop, I'm afraid of screwing sonething up in there, a wrong value, a box left unchecked etc. And it doesn't help that Victron are pretty unhelpful as they keep saying I shouldn't be doing this myself as I'm not a trained Victron installers etc etc. At first I did just leave the battery values at their default settings but it would never show the soc as more than 85%, even though I've oversized the system on purpose and it spends a lot of it's time in float. I believe the battery is in good shape as it was only 6 months old when I installed it last year. Anyway, I'm trying to track down a data sheet from the battery manufacturer and when I get it, I'll be asking for more advice, I'm sure!

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