How to tweak absorb

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Comments

  • FreewilleyFreewilley Solar Expert Posts: 223 ✭✭
    Yes, done and thanks.
    However, I do not feel bad about not having made this adjustment because (I think!) the same result is obtained by setting the float setpoint to absorb setting. As Steve says there is no reason not to do this, and my system rarely genuinely floats (so far) I will be leaving both of those where they are.
    When I leave in 6 weeks for AZ I will set things different of course.

    I feel really good about these changes and seeing BOTH strings at higher levels than I have ever seen them...and this is declining solar days for me.
    Mate, VFX 2812, FM 60 & MX 60, 2 Full River AGM 400 6v, 1400 watt Solar Array, Yamaha 3000iSEB inverter gen
    12 volt Flojet water pump
    off grid summer home in northern Ontario
  • EstragonEstragon Registered Users Posts: 4,303 ✭✭✭✭✭
    Sounds like you're well on the way to a healthy bank. Sometimes takes a while to get things dialed in. Good job!

    Doing a long absorb isn't quite the same as periodic EQing. Current eventually drops to next to nothing with a long absorb, and all that's happening is a bit of heating and bubbling. Doing the EQ at a higher voltage for a time means higher current to get to and hold Veq.

    You may want to move from the high Vfloat / long absorb regime well before leaving so you can establish what absorb voltage/time/end amps works best for your situation.
    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
  • FreewilleyFreewilley Solar Expert Posts: 223 ✭✭
    Curious as to why we can get varied heat when EQing.
    My new string has EQd for 4 hours and is right on 80 degrees. It is 1.275 SG.
    Is the lack of heat any indication how badly sulphated the plates are? '

    Also, should I be continuing to EQ when the SG is as high as it can go....earlier the advice was to EQ until the SG had not risen in an hour or two.
    I was figuring the continue that EQ on these through tomorrow (sunny until tomorrow night) and then cycle them and see how the absorb cycle goes after that...
    Mate, VFX 2812, FM 60 & MX 60, 2 Full River AGM 400 6v, 1400 watt Solar Array, Yamaha 3000iSEB inverter gen
    12 volt Flojet water pump
    off grid summer home in northern Ontario
  • EstragonEstragon Registered Users Posts: 4,303 ✭✭✭✭✭
    Older batteries apparently tend to gas and heat more. I'm not sure if that's a function of sulfation, or other age related factors. Mine rarely get much above 20°C (~65°F).

    I would stop EQ when; SG stops rising AND SGs are consistent between cells, OR batteries get above 115°f or so. I've never seen my bank get near that temp, but worth watching anyway - crud off the plates could short and make for a really bad day if not watched.
    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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