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Float or higher charge voltage for value regulated sealed lead acid battery

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  • #16
    Originally posted by tombarton View Post
    Thanks Mike. So am I correct in assuming that almost all AGM type batteries are inappropriate for solar storage?

    My seller is offering to replace what I've bought, but I think all of his used stock is AGM (which makes sense, as it seems the 'used' industry is just on-selling trash UPS storage that's been mandated to be replaced by govt/industry policy every 5 years).

    He's offering the Lion HZB-12-100 (100ah C20) AGM VRLA. Is this any better? Thanks again for the assistance - I'll give back to the forum where I can in future. Specs look to be:

    Float: 2.27-2.30 VPC @20 C
    Cycling: 2.34 @20 C
    Max. 2.4 VPC Max ripple 3.5% charging V
    There are AGM batteries that are truly designed for cyclical applications... but that is not what he is offering you.
    CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

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    • #17
      Originally posted by tombarton View Post
      Thanks Mike. So am I correct in assuming that almost all AGM type batteries are inappropriate for solar storage? .....
      Not at all. Your batteries are for Backup/Standby use and only designed for a couple dozen cycles and then discarded. There are also Deep Cycle SLA/VRLA batteries rated for 1500 or more deep cycles

      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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      • #18
        Thanks, I understand now. So the specs of these replace options are no better than the supersafe then? These replacements are described in sales brochures as deep cycle AGM.

        *Noone able to advise on this?
        Last edited by tombarton; 09-09-2017, 12:40 AM.

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        • #19
          The LION agm is better for your application than the original battery.

          Where you may only get 10 cycles or less from your first batteries, if the Lion agm's aren't discharged much past 50% of their capacity, then you'll get about 300-400 cycles out of them. So yes, these last ones are better.

          The LION brand of agm you show is basically just a garden-variety general-purpose caravan agm. 14.4v max absorb. And yes, you can deep-cycle them beyond 50% DOD, but that will just cut down on your available cycles. Still, that is better than the UPS type you have now, which will quickly die in 10!

          And those Lion's will charge quicker too! Since you aren't limited to only float-charge, but you can crank up the absorb to 14.4v max, you'll be able to get more into them faster. Don't exceed 0.25C charge current. It's on the label basically. Just don't buy old stock, which usually means that if you are nerdy enough like me to take your voltmeter with you to the battery depot, don't buy any with a terminal voltage less than 12.4v. That indicates old-stock, or storage in high-heat warehouse conditions where your battery is already sulfated to a major degree.

          Don't feel bad! Those entering the world of batteries is hit by an onslaught of information, mis-information, and marketing - ever since lead-acid was introduced to the world apparently. We've all had our costly mistakes, believe me.

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          • #20
            PNjunction thanks so much for the reply and info. I feel way better about these replacements now. Will never buy used UPS again! These Lion AGMs are over 13V after sitting overnight, and three years old. So hopefully they'll deal with a few visits to the bush property per year, and the rest of the time will be kept floating high. Thanks for your help - the battery world is indeed filled with information and misinformation. Hard to dive in and keep up!

            *EDIT: I should ask: is the float voltage the same as the 14.4 max absorb? I heard that I should also disable equalisation in the CC, so as to not exceed max and vent gas.

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            • #21
              Charging my current battery bank with my regular PWM charge controller how long should I let the battery bank stay at the bulk/ absorb voltage of 28.8v before I cut it down to 27v for float charge?

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              • #22
                Until your batteries are only accepting 1% - 2% of their ah rating
                2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                • #23
                  Will Regular(most) pwm controllers terminate the Pv cutoff voltage that you set for eg.28.8v and then switch to a lower voltage setting automatically for eg.27.4v and then commence float charging at that lower voltage or will still maintain the high voltage setting that you set but then switch to a lower current charging?

                  My controller just has one setting in which i set the cutoff voltage and whenever it reaches that voltage setting it remains at that voltage setting and then the current decrease gradually as the battery starts to get closer to the full charge level so in my case the controller won't decrease the high voltage setting once the battery gets full charge and then switch to a float charge voltage for eg. 27.4v unless i manually adjust it at every charge cycle. It just has one cutoff setting which it floats at that same setting.

                  Is there a way for me to let the controller automatically switch from that high bulk charge/absorb voltage after a certain length of time and then switch to a lower voltage setting to float charge at?

                  Or suppose i use a temp sensor (BTS) which attaches to the battery bank will the regular pwm controller ignore the voltage setting that i set and auto adjust the voltage/current once the battery starts to get too warm or too hot or pass the safe temp range?

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                  • #24
                    Originally posted by fabieville View Post
                    Will Regular(most) pwm controllers terminate the Pv cutoff voltage that you set .....
                    There are so many knock offs and fly by nights, I cannot comment. The good units have comprehensive manuals that detail the charge sequence.

                    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

                    Comment


                    • #25
                      If i install a BTS between my current VRLA battery bank which are factory default to float at 27.4v and set my one setting controller to cut the bulk charge at 28.8v which it will begin to float at that same voltage, will the BTS prevent the battery from getting too warm or pass the safe temp range by reducing the current or the voltage or both to a very minimal amount that will prevent the battery from gassing too much and prevent water loss or go into thermal runnaway at that 28.8v setting?

                      My controller has a Temp compensation of 4mV/Cell/'C does that indicate that once a certain battery temp is reach, the controller will decrease the charging voltage according to the temp reading and it will even reduce it more if the temp increase again?

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                      • #26
                        The absorb phase of the charging regimen holds the voltage at the preset voltage while the current being accepted slowly decreases. Once the controller is satisfied the absorb phase is complete it will transition to float. You may be overthinking this but if you have a BTS, by all means, use it.
                        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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