"Cycle Use Voltage" - unusual set point(s)

NicaSol
NicaSol Registered Users Posts: 32 ✭✭
in Advanced Solar Electric Technical Forum #1
No reply from the manufacturer, vendor does not know, and an incomplete answer from Google and the forum, thought I'd try posting.

The specs for Ritar DC12-200C (12v, 200Ah, lead carbon) batteries only makes reference to a Cycle Use Voltage set point of 13.8-14.0 V @ 25C. They are AGM batteries and most specs for AGMs that I have seen list a Bulk/Absorption and Float set point.

Internet and forum searches for "Cycle Use Voltage" have returned only that batteries generally serve one of two purposes: stand-by use - batteries generally maintained on float with occasional emergency use; and cycle use - regularly cycled (discharged and charged - repeated bulk/absorb, float stages) on a daily basis. Even the vendor, for this particular battery, said the set points were 14.4 for Absorption and 13.7 for Float. Any thoughts on what the manufacturer was referring to with what appears to be a single set point? Thanks.

Spec screenshot below:


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Comments

  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    edited March 2020 #2
    It has been my experience that this manufacturer's datasheets can be a moving target.
    You will have to look at these and make your choice.Presumably your supplier will back you up on this.
    Marc
    I always have more questions than answers. That's the nature of life.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #3
    Wow, those data sheets are all over the place... The first one appears to be the latest spec. sheet and more self consistent numbers.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    edited March 2020 #4
    Bill, this has been my experience with a few manufacturers - including some in the USA. For example, it is troublesome for me to see DOD-Lifecycle curves that suddenly double overnight without any other changes or explanations.
    I am forced to ask: "Really? You just now discovered that your batteries outperform others, after all of these years of sagging sales?"
    Sadly, it is like so much of today's information stream via social and news media: "Am I actually wrong if nobody proves it?" Tell me who has actually cycled tested the batteries in their system at home? Yes, I have seen it done - but it is rare!

    I always have more questions than answers. That's the nature of life.
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  • NicaSol
    NicaSol Registered Users Posts: 32 ✭✭
    #5
    Thanks BB, Mark - and for finding the 2017 version of the spec sheet. I also found these:



    To get back to my question about what the manufacturer was specifying with what looks like a single set point, and to wrap up this post, could it simply be that the Ritar 2019 spec sheet is screwed up? My vendor, the 2017 Ritar spec sheet, Enertik's Ritar spec sheet and Victron's lead carbon spec sheet all list absorption stage set points of 14.10 to 14.80 and float set points of 13.50 to 13.80. At a guess, the term "Cycle Use Voltage" or "Cycle Service" voltage is just another term for the Bulk/Absorption stage (correct me if wrong). In the case of the 2019 Ritar spec sheet they simply omitted listing two set points and, to boot, listed a set point (13.8 - 14.0) incorrectly for Cycle Use/Absorption that looks more like a float set point. Just my guess/thoughts.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,631 admin
    #6
    Here is a English translation of the first link (no drawings):

    https://translate.google.com/translate?sl=auto&tl=en&u=https%3A%2F%2Fenertik.com.ar%2Ffolletos%2Fritar%2Ffolleto_dc12-200c.pdf

    The charging voltages look to be more like typical flooded cell lead acid batteries. And they are sealed (VRLA--valve regulated lead acid--Sealed). 

    Since they are sealed, they probably will not do well if "over charged".... So making sure that the battery is not held at set point too long is probably important (so that they don't gas and vent).

    And given that they have a specification for constant power discharge--Typical for UPS (uninterruptible power supply) systems--And their long life--I do wonder if these are more designed for UPS usage (a few cycles during power outages) vs long term deep cycling (25% to 50% depth of discharge for solar solar power systems).

    The Victron data sheet has lower charging voltage (for cycling)--Which is what I would expect for a sealed type lead acid battery (as well as lower voltage voltage--Which I would also expect).

    And the usual Lead Acid battery charging requirement... 40% discharge (to 60% state of charge) and immediately recharging battery at 0.2C until recharged (over 8 hours) for 1,400 cycle life (daily cycle life of 3.8 years.

    Certainly looks good when compared to other UPS batteries... Longer float life, and relatively good cycle life for UPS applications (which could be down to 10-100 cycle life for deep discharge use in a typical UPS installation).

    Would ask the vendor about warranty details and if would be warranted for Off Grid Solar application.

    I am certainly not the expert here--Just from what I have read in the specs. and elsewhere.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    #7
    Carbon or not, I cannot help but be skeptical of their claim of:
    2,000 cycles @ 80% DoD
    3,000 cycles @ 50% DoD
    5,000 cycles @ 30% DoD
    I always have more questions than answers. That's the nature of life.
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  • NicaSol
    NicaSol Registered Users Posts: 32 ✭✭
    #8
    A new development, and getting back to the single charging set point thingy. The screenshot in my OP was from a spec sheet I originally downloaded from Ritar dated sometime in 2019 as Version 19A.0. It is also the spec sheet my vendor gave me. I just went back into Ritar's site and downloaded the spec sheet for the same battery, now Version 19B.0. (http://www.ritarpower.com/upimg/20191230111910838.pdf)

    The only thing that has changed is the "Feature" paragraph. The following three sentences have been added/modified:
     "...It is specially designed for daily heavy cyclic discharge use, with feature low boost charge voltage, it should not be used under float charge, it must be charged and discharged daily for cyclic use. Especially suitable for  the application of PSOC."

    The reason for my OP was how to program set points (bulk, absorption, float) if only one is listed. Other searches led to several articles in Solar Panel Talk, particularly posts made by Sunking. His reasoning is that solar does not provide the sustained power (in many systems) over the course of a day to properly charge batteries (and most battery manufactures changing their charging algorithms due to chronic solar battery undercharging). Very quickly, he advocates setting Bulk=Absorb=Float to force controllers to stay in constant current mode to maximize the charging of batteries during available daylight hours (along with very close monitoring with a hydrometer).

    Considering Sunking's reasoning, and looking at the revised Ritar specs with one set point, and featuring "... low boost charge voltage (AGMs - SG testing not possible), ...not to be used under float charge, ... charged and discharged daily for cyclic use. Especially suitable for  the application of PSOC", could it be that the spec sheet is not a mis-print and Ritar is advocating one value for all set points? Ritar still has not responded and I'm waiting member approval from Solar Panel Talk to post in their forum but I thought I'd pass this by here as well.

    Again, thanks for your comments.
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  • Marc Kurth
    Marc Kurth Solar Expert Posts: 1,174 ✭✭✭✭
    #9
    NicaSol said:


    .................. particularly posts made by Sunking. His reasoning is that solar does not provide the sustained power (in many systems) over the course of a day to properly charge batteries (and most battery manufactures changing their charging algorithms due to chronic solar battery undercharging). ......................................




    A couple of comments.
    - If there typically isn't enough solar to charge the battery bank in a system, the system has a basic design deficiency. Fix the deficiency. An occasional "catch up" period caused by lousy weather is normal. Yes, there are many poorly designed systems.
    - I have not seen most battery manufacturers changing their required algorithms. Yes, some of the better manufacturers suggest a constant current spec as a bandaid for deficient systems.
    Marc
    I always have more questions than answers. That's the nature of life.
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,113 ✭✭✭✭✭
    #10
    Undersized systems that are being over discharged on a regular basis require longer absorption times. Underpowered PV arrays will struggle to get to and through long absorb times.  As Marc stated basic design deficiencies will cause problems, especially in the lean winter hours. If your system is properly designed all parameters are covered in the design process starting with daily loads> battery bank size> Inverter size>location> PV array size and even generator size.

    On any sunny day, even in the winter, with a properly designed system, you should expect to be going into absorb by or before noon and most days into float before the end of the day. This has been my experience so far and I have yet needed to fire up the dusty old generator that came with my place in Baja.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • mito
    mito Registered Users Posts: 1 ✭
    #11
    I was browsing this issue about this Ritar DC12-200C a year ago, but I don`t see any extra information or updates about setting points and even Ritar has this battery out of their web. 
    Have any of you any experience on this batteries and if Ritar still continue to sell or promote  these large lifetime cycling batteries?

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