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  • #16
    Pumping air through the batteries really is good for batteries used in a forklift but you lose some of the advantages is solar panel charged batteries.

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    • #17
      Originally posted by inetdog View Post
      And that is specifically what Dereck cited in his statement about C/12.
      Keep in mind I am only referring to Flooded Lead Acid batteries. There is only one battery type I know that has a C/20 limit, well it depends on the manufacture, but the max charge rate for most Gel batteries is C/20 which is why gel batteries should never be used.

      Fork lift batteries are special purpose batteries designed specifically for fork lift use. Go to the Battery Bible for details. Since Electric Vehicles and Solar PV systems became marketable has changed the face of battery construction considerable and is still changing today. You simple Flooded Lead Acid battery is not so simple anymore as they can be made for SLI (starting lighting ignition aka cranking batteries) A hybrid used in Marine and golf carts applications where you do get cycle use but still need high current for starting or electric motors, Traction batteries for fork lifts and EV's, and Renewable Energy. Each is designed differently. This is why say just 10 years ago about the only batteries avaialbe for solar was the golf cart type like T-105, or floor machines batteries like L-16. Those are very poor choices today.
      MSEE, PE

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      • #18
        Something really good about the thread is that when I investigated stratification, most of it was in regards to elevated voltages during absorb to get the gassing / mixing - but if I read between the lines, that is mainly a remedial cure for stationary batteries or long-term occasional maintenance.

        The C/12 minimum for FLA seems to address the anti-stratification needs under normal usage, which would be very important for a stationary battery. Love it.....

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        • #19
          Originally posted by Sunking View Post
          Each is designed differently. This is why say just 10 years ago about the only batteries avaialbe for solar was the golf cart type like T-105, or floor machines batteries like L-16. Those are very poor choices today.
          I see this recommended / used a lot. Obviously one has to take into account their usage patterns when deciding, but what makes them less desirable - or basically what would be a smarter choice today?

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          • #20
            I know they are not yet prevalent but what do you guys think of LiFEPO4 batteries for such situations? They can be charged slow or fast (from C/12? to 3+C) and don't have the deep discharge issues of the lead acids. Is the price too high for them to start to be used in place of what is commonplace now? It sounds like LiFEPO4 are growing in use over in Asia due to the manufacturing of them for various industries.
            PowerOne 3.6 x 2, 32 SolarWorld 255W mono

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            • #21
              Originally posted by bonaire View Post
              I know they are not yet prevalent but what do you guys think of LiFEPO4 batteries for such situations? They can be charged slow or fast (from C/12? to 3+C) and don't have the deep discharge issues of the lead acids. Is the price too high for them to start to be used in place of what is commonplace now? It sounds like LiFEPO4 are growing in use over in Asia due to the manufacturing of them for various industries.
              They are arguably the safest and most consumer friendly of the Lithium battery options, but they still have a very high energy density and need to be managed with care. AFAIK any Lithium chemistry battery will suffer an irreversible loss of capacity if discharged below their LVC point, so some special care is needed there. Unlike FLA, AGM and other lead based chemistries, the voltage of any Lithium battery goes down significantly with SOC, (roughly from 4 volts to 3 volts, comparable to a 12 volt battery going down to 9 volts without taking into account resistance) so the loads need to be designed to accommodate that characteristic.
              But the current gating factor is the cost! The type of use (typically portable/mobile) has to justify their use instead of heavier but less demanding and cheaper alternatives.
              SunnyBoy 3000 US, 18 BP Solar 175B panels.

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              • #22
                Originally posted by bonaire View Post
                I know they are not yet prevalent but what do you guys think of LiFEPO4 batteries for such situations?
                Cost is the biggest road block followed by test of time. Lithium holds a lot of promise but there is one major problem with lithium aside for the safety issues. There are only 13 million tonnes of known reserve so it is a rare earth type material. Bolivia, Russia, and China hold the largest known reserves. USA does have a brine pool in NV with some but it is not mined currently in the USA as it is less expensive to buy elsewhere. It will be the EV market that develops lithium ion battery chemistry.
                MSEE, PE

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                • #23
                  Yes, the EV market is growing the Li development, for sure. (I drive a Volt, so I'm familiar). I also like the Li-Ti cells found in the new Honda Fit EV for their stability, however they have a low voltage of something like 2.7V nominal.

                  The safety factor of the Iron Phosphate material in LiFEPO4 seems to make it safer for home use for off-grid storage plus you can full-cycle the batteries quite a bit more than Lead Acid and all you need is a good battery management system. Cost of scale could possibly help lower the costs as well. Cars like the Volt have a sizeable battery in them and once they have completed life as a transportation battery, the plan is for grids to tie spent packs together in grid-storage arrays for some substations or whatever. I see that they could possibly also serve as home-storage, however I don't think I want a Li-Poly pack in my basement. I'd trust LiFEPO4 over Li-Poly even if the Volt pack has stabilizers in it (as it does) of magnesium spinel.

                  Li is quite a prevalent in some of those brines, as you mentioned, and I hope they can mine some in Utah or other states with Geology that is useful for it. Like Oil, it also will have a limited lifespan of availability.

                  Topical and timely: http://www.renewableenergyworld.com/...eptember5-2012
                  PowerOne 3.6 x 2, 32 SolarWorld 255W mono

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                  • #24
                    Aside from the high maintenance and low efficiency issues of NiFE, they have a serious compatibility issue with respect to steep voltage curve from full charge to discharged and high internal resistance.

                    For a 12 volt system requires 10 cells. At full charge is 1.4 volt (14 volt open circuit) at 100% SOC, and .7 volts (7 volts). When at full charge and a light load of about C/20 is applied the voltage drops to 12 volts. Apply a load in the area of C/10 to C/8 and the voltage drops to 10 volts even when the battery is fully charged. Just about any 12 volt inverter will shut down at 10.5 to 11 volts. You cannot use th efull cpacity of the battery, nor can they supply large discharge currents. Here is the kicker when the NiFe reaches 60% SOC the open circuit voltage is 10 to 10.5 volts. No inverter will run at that low of a voltage. An inverter can be designed to work at the low voltages, but none on the market.
                    MSEE, PE

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                    • #25
                      Got it, want to use it.

                      So here we are 2 years after this thread started.
                      I too purchased one of these, expecting a good starter kit.
                      Got the biggest deep-cycle I could, and upgraded the controller to a 10amp model to support 6 panels. (Only have 3 installed as of now)
                      I get it. This was a mistake. But we all make them, right?

                      I, like the thread author now have the stuff. Understanding that the panels as set up won't charge the honkin' battery (845 CA 114Ah) I have, what is best battery to buy to make "some" use of this kit, and what could he/I expect to be able to do with it?

                      My intention was to power my RV (travel trailer) and keep battery charged.
                      Most draw would be 12v (I changed most bulbs to LED) so we are talking occasional water pump use, lighting, 2 12v fans, 12v range hood, and I have a 400w inverter which powers my AC only fridge.

                      Thoughts?

                      And if any of the "experts" respond with condescending insults, i feel sorry for you and hope a teradactyl craps on your panels and block out the sun.
                      Last edited by TomWatts; 05-14-2014, 07:23 PM. Reason: Added battery specs

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