battery charge and discharge

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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #32
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    Re: battery charge and discharge
    Cariboocoot wrote: »
    When the real capacity reaches 0.75X you're down a day and have no reserve. By this point previous experience should tell you if you can continue operating with one day's capacity or if you'd better stick a crowbar in your wallet and buy new batteries. :D

    I know if I had it to do over I'd just buy a GB or Crown 900ah forklift battery and cycle it to 70-80% DoD instead of buying 1,200ah of little ones that can only be cycled to 50%.
    --
    Chris
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #33
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    Re: battery charge and discharge
    ChrisOlson wrote: »
    I know if I had it to do over I'd just buy a GB or Crown 900ah forklift battery and cycle it to 70-80% DoD instead of buying 1,200ah of little ones that can only be cycled to 50%.
    --
    Chris
    I hear you, Go big and go bold and get longevity or go cheap and small and dump them often. In my case, I break even ( if there is such a thing ) after the 3rd year and after that if I get a extra year I am happy. There is something about a new set that puts a smile on your face.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #34
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    Re: battery charge and discharge

    Yep. When you need big power capacity buying lots of little batteries to build a bank full of interconnecting wires and extra cells to look at doesn't make any sense.

    That concept usually gets lost when explaining about why to go up in system Voltage. People come away with the idea that once you hit 48 Volts you can only add more strings of GC2's. Got to try and disabuse them of the notion.
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #35
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    Re: battery charge and discharge
    stephendv wrote: »
    Pure gold! The interesting conclusion was that high voltage absorbs (2.58V) resulted in longer battery life than normal absorbs (2.4V).

    I couldn't find it on the page linked to from the BC's post. Could you post a link to the source?
    stephendv wrote: »
    I wonder if the results would still hold for RE applications, where batteries can sit at > 80% SoC for many months in summer? Maybe then the corrosion from overcharge would outweigh the anti-sulfation benefits of a high voltage charge?

    I think that the charging routines should change as DoD changes during the season so that the ratio of overcharge to DoD is kept relatively constant. However, that's easier said than done.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #36
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    Re: battery charge and discharge

    I think Blackcherry changed the link or I clicked on a different link somewhere... the one I read was here: http://batteryperformancereports.com/24.html
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #37
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    Re: battery charge and discharge
    stephendv wrote: »
    I think Blackcherry changed the link or I clicked on a different link somewhere... the one I read was here: http://batteryperformancereports.com/24.html
    Your right, I did change the link, I thought the first one wasn't as good, sorry for the confusion. In fact I deleted that whole post.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #38
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    Re: battery charge and discharge
    stephendv wrote: »
    Pure gold! The interesting conclusion was that high voltage absorbs (2.58V) resulted in longer battery life than normal absorbs (2.4V).

    Keep in mind that industrial constant-current IUIa profile chargers are much different than what we have in the RE world. That 2.58VPC is the termination voltage for the constant-current finish stage of absorb - something that RE chargers don't have.

    boB at MidNite Solar indicated to me that in the future they may add IUIa and "boost charging" profiles to the Classic's menu charging options. But not enough people even know what they are, or have adequate RE generating capacity to make them useful, so it's not a top priority at this point.
    --
    Chris
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #39
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    Re: battery charge and discharge
    stephendv wrote: »
    I think Blackcherry changed the link or I clicked on a different link somewhere... the one I read was here: http://batteryperformancereports.com/24.html

    Ha ha!

    I've seen that before.

    I think there are muliple ways the batteries can die. You need the determine the way your batteries are going to day, and then direct your charging to prevention of this particular cause of death.

    If you discharge to 80% DoD every day, sulphation is probably the worst peril.
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  • stephendv
    stephendv Solar Expert Posts: 1,571 ✭✭
    #40
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    Re: battery charge and discharge
    ChrisOlson wrote: »
    boB at MidNite Solar indicated to me that in the future they may add IUIa and "boost charging" profiles to the Classic's menu charging options. But not enough people even know what they are, or have adequate RE generating capacity to make them useful, so it's not a top priority at this point.

    Yeah, I've implemented IUIa charging every 20 days using an rpi. Daily DoD is only 10-20% and the controller will go straight to float most days, only doing an absorb every 4 days. So not sure whether every 20 days is too much or too little for a long absorb + finishing high voltage charge.
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  • Shadowcatcher
    Shadowcatcher Solar Expert Posts: 228 ✭✭✭
    #41
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    Re: battery charge and discharge

    I was intending to ask a similar question. The teardrop has a185W panel feeding into Morningstar MPPT and then into a Lifeline 150 AH AGM. I keep it for the most part at 100% SOC. This also what many/most RV owners do leaving it plugged in and the converter on float.
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