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  • #46
    Originally posted by BeRight View Post
    In using ultracaps - i find just the opposite of what one might think (different technology)-discharge is slow.

    The challenges: slow to charge and dc to ac converters cut out close to 10V. So, yes one needs to keep lots of Amps coming in to keep them charged. The 2600F ultra cap I am using is really small and light(compared to caps of the past)__ lots of folks doing work to shorten charge time.
    Beright there is nothing about Supercaps that make them slow to charge. They charge and discharge just as fast as any capacitor. You can charge then in a microsecond if the source is capable of supplying the charged. All caps charge in 5 Time Constants, and TC = Resistance x Capacitance. The time element is dictated by the amount resistance and capacitance in the circuit.

    Supercaps were developed for two primary applications; Energy weapons and regenerative braking in electric vehicles.
    MSEE, PE

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    • #47
      Originally posted by Sunking View Post
      Beright there is nothing about Supercaps that make them slow to charge. They charge and discharge just as fast as any capacitor. You can charge then in a microsecond if the source is capable of supplying the charged. All caps charge in 5 Time Constants, and TC = Resistance x Capacitance. The time element is dictated by the amount resistance and capacitance in the circuit.

      Supercaps were developed for two primary applications; Energy weapons and regenerative braking in electric vehicles.

      You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? Disappeared after they collected all the money they could and never even gave a sniff of a product.
      [SIGPIC][/SIGPIC]

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      • #48
        Originally posted by russ View Post
        You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? .
        That was EESTOR. They even caused a Canadian EV manufacture called Zenn Motors to go bankrupt waiting for the product to be released. Ironically Lockheed Martin reportable bought all rights for energy weapons use for $10 million share of the company.
        MSEE, PE

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        • #49
          Originally posted by russ View Post
          You forgot one Sunking - Scams - what was that company who would turn the world on it's ear using supercaps for EVs? Disappeared after they collected all the money they could and never even gave a sniff of a product.
          The other large application for supercaps (regardless of why they were first developed) is for very-low-power maintenance needs for electronics that get external power intermittently but dependably and have to ride through the time in between. A properly designed supercap will have a longer shelf and service life than just about any chemical battery system, and *can* (not necessarily all will) tolerate higher temperature extremes.

          But that does not make them suitable for storage of larger amounts of energy for long term needs. Batteries still own that market.

          PS: I got one of those "eternal" moving magnet generator flashlights about 15 years ago, and the capacitor died about five years ago. It still makes lots of light, but just in pulses as I shake it. <sigh>
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

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          • #50
            Originally posted by inetdog View Post
            PS: I got one of those "eternal" moving magnet generator flashlights about 15 years ago, and the capacitor died about five years ago. It still makes lots of light, but just in pulses as I shake it. <sigh>
            You can get one that you wind up instead of shake now....maybe when the cap dies it would still be ok in a pinch.


            I think that powering SOME things without a battery from solar will be the norm in years ahead.

            Only things that require power for short periods and that do not have voltage sensitive electronics but for resistive loads will be good....and especially if a panel is made to fit a load (or particular common power requirement).

            Works for me for somethings at least.

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            • #51
              Why I to want to use a load without a battery

              It's been thirty plus years since my electrical engineering classes, so I don't pretend to be an expert on this. I am planning on installing a 6 kw grid tie system without battery backup. I live in Southern California so the specter of several days without power haunts me. I have a multi fuel backup generator and enough gas for a week, and propane for a few days and natural gas for as long is it comes out of the meter. BUT what do I do after that? I have the potential for 6000 watts of solar power at high noon that I could use to cool my freezer but I cannot use it because my inverter shuts off when doesn't see a sine wave from the utility. I could install a battery backup with associated charger, charge controller etc and spend a considerable amount of time and money maintaining and replacing batteries that I don't need or use for years on end waiting for the big quake. I was in the satellite transmission industry for many years. I was around 100 kw UPS systems with huge battery banks. They scare the stuffing out of me.

              I wanted to use an Outback or Xantrex 48 volt inverter-charger tied to the grid and have a small battery bank for "load smoothing" but I agree the high current and cycling would destroy the batteries in short order. I thought about using the inverter as a straight grid-tie unit and reconfiguring it with batteries and charge controller only if the power was down for several days. Both Outback and Xantrex manuals are pretty adamant that they cannot be used without a battery bank.

              I may use a grid-tie Sunny Boy 6000 with my panel strings in series to deliver 300 volt DC to the inverter and have the capability to re-configure for 60 volt DC to feed a separate Aims 7000 watt 48volt inverter. I could plug it in at mid day and run some loads, but I doubt it would have the capacity to start the freezer compressor. Contrary to some things that have been said on this thread, you can run some loads off the PV's without a battery. Obviously the lower the load as a percentage of the PV array capacity and the more linear the load the better, let's say 1.5 kw on a 6 kw system. Cloud goes over, voltage drops below inverter minimum and switches off, better than nothing. There are also some other problems such as the inverter input voltage being exceeded when there is no load, but I think that could be solved with a simple circuit and a "shunt" or bypass load resistor. I could even use a water heater as the bypass load. Hot water equals happy wife.

              I saw a system in Northern Africa that used a huge flywheel instead of batteries to supply backup power for 60 seconds while the backup generator fired up and stabilized. I just might build one of those instead of spending 5k on batteries. No power at night but my beer will be cold and my wife will be showered and happy.

              Think outside the box a little.

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              • #52
                Originally posted by duncangalt View Post
                I wanted to use an Outback or Xantrex 48 volt inverter-charger tied to the grid and have a small battery bank for "load smoothing" but I agree the high current and cycling would destroy the batteries in short order.
                So use UPS batteries and don't cycle them unless there is an outage.

                I thought about using the inverter as a straight grid-tie unit and reconfiguring it with batteries and charge controller only if the power was down for several days. Both Outback and Xantrex manuals are pretty adamant that they cannot be used without a battery bank.
                Correct. You could go with an ultracapacitor bank; they last for decades and have VERY low ESR, allowing high peak powers from small amounts of energy storage. But you are going to spend a lot more for an ultracap bank than for a lead-acid bank.

                I may use a grid-tie Sunny Boy 6000 with my panel strings in series to deliver 300 volt DC to the inverter and have the capability to re-configure for 60 volt DC to feed a separate Aims 7000 watt 48volt inverter.
                You'd still need a battery. The impedance of even huge arrays isn't low enough to start large loads.

                Contrary to some things that have been said on this thread, you can run some loads off the PV's without a battery.
                Absolutely; you can run anything that can run on DC over the range that the panels will produce, and that has a higher minimum impedance than the PV array does.

                There are also some other problems such as the inverter input voltage being exceeded when there is no load, but I think that could be solved with a simple circuit and a "shunt" or bypass load resistor. I could even use a water heater as the bypass load. Hot water equals happy wife.
                Be very careful with this. I've blown inverters trying to do the same thing. The problem is that without storage your diverter load controller has to be very fast; faster than anything on the market right now. You'd need a closed loop high frequency PWM controller that accurately regulates voltage, and they are not trivial to build.

                I saw a system in Northern Africa that used a huge flywheel instead of batteries to supply backup power for 60 seconds while the backup generator fired up and stabilized. I just might build one of those instead of spending 5k on batteries.
                Warning. Flywheel containment problem = unhappy wife. Releasing all that energy at once will not be a good thing whether the storage is via battery or flywheel.

                Think outside the box a little.
                Ultracaps. As an example, 10 BMOD0058's from Maxwell will give you about 200 watt-hours of energy storage at something like 30kW max power output. Cost you around $1500. Warning - you will be quite far into experimental territory with this, and thus any such experiments should be kept well separate from wives who do not enjoy large thermal or rapid disassembly events.

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                • #53
                  Originally posted by billvon View Post
                  any such experiments should be kept well separate from wives who do not enjoy large thermal or rapid disassembly events.
                  A subset of the "Magic Smoke" department.
                  2 x 240w solar > Midnite Classic 150 > 380 Ah 12v

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                  • #54
                    Originally posted by Vern Faulkner View Post
                    A subset of the "Magic Smoke" department.
                    Or, as the lithium battery powered light enthusiasts love to say, "venting with flame."
                    Still not quite an explosion, but much more entertaining than simple "venting".

                    A key component of the flywheel designs for vehicle energy storage is a very strong casing (containment vessel?) to hold in the shrapnel when the flywheel overspeeds or suffers a heavy G shock.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                    • #55
                      Batteries only for the Zombie Apocalypse

                      Great feedback. Thanks.

                      You seem to get the point (s)

                      Big PV array that's useless after the grid goes down.
                      Desire not to purchase and maintain a large (scary) battery bank.
                      Years of lower efficiency conversion for sale to the grid. 85% vs 94%

                      What I may have to do is build my 6 kw grid tie system and have a separate charge controller, off grid 4 kw inverter and a bank of 4 12 volt batteries. Reconfigure the DC strings and operate the whole thing sort of manually after the apocalypse.

                      What's the short answer to keeping the 12 volt batteries from going bad while they wait three years to be called to action. Trickle charge for an hour per week? Discharge 25% once a month?

                      Capacitors will probably be part of the eventual technology solution. I'm not a big environmentalist but lead acid batteries as part of the "Green Energy" solution is kind of comical.

                      I still want to build the flywheel. Something with lots of mass and low RPM like a big tractor wheel or a merry-go-round.

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                      • #56
                        Originally posted by duncangalt View Post
                        Great feedback. Thanks.

                        You seem to get the point (s)

                        Big PV array that's useless after the grid goes down.
                        Desire not to purchase and maintain a large (scary) battery bank.
                        Years of lower efficiency conversion for sale to the grid. 85% vs 94%

                        A. What I may have to do is build my 6 kw grid tie system and have a separate charge controller, off grid 4 kw inverter and a bank of 4 12 volt batteries. Reconfigure the DC strings and operate the whole thing sort of manually after the apocalypse.

                        B. What's the short answer to keeping the 12 volt batteries from going bad while they wait three years to be called to action. Trickle charge for an hour per week? Discharge 25% once a month?

                        Capacitors will probably be part of the eventual technology solution. I'm not a big environmentalist but lead acid batteries as part of the "Green Energy" solution is kind of comical.

                        C. I still want to build the flywheel. Something with lots of mass and low RPM like a big tractor wheel or a merry-go-round.
                        A: You can look at hybrid systems that let you get a smaller amount of totally off grid power from a panel and battery combination and then add in extra power from straight panel to inverter components normally used for grid-tie, but now under the control of the battery powered inverter.


                        B: Trickle charge (in the automotive battery world) usually refers to a contant current charge that may or may not be safe for long term continuous connection to a battery. For Lead Acid batteries, what you want is a Float charge, which is a constant voltage charge that lets the battery take in just what it needs to make up for its self-discharge. The exact voltage to use will depend to some extent on the battery type and will in any case need to be temperature compensated.

                        C: Go for it! But do some calculations of how much energy is actually stored in such a high mass, low speed system, and more importantly, look at how you will be able to extract constant-frequency AC from the flywheel as it slows down. It can be done, but it takes more than just gearing a generator head to the flywheel.

                        PS: If you are not in a hurry and are seriously looking at Sunny Boy, do a google search ("Sunny Boy TL-US"), including this link, and also look on this forum for discussions and speculation about the not-yet-shipping Sunny Boy 2000/3000/4000 TL-US series.
                        SunnyBoy 3000 US, 18 BP Solar 175B panels.

                        Comment


                        • #57
                          Originally posted by inetdog View Post
                          A: You can look at hybrid systems that let you get a smaller amount of totally off grid power from a panel and battery combination and then add in extra power from straight panel to inverter components normally used for grid-tie, but now under the control of the battery powered inverter.


                          B: Trickle charge (in the automotive battery world) usually refers to a contant current charge that may or may not be safe for long term continuous connection to a battery. For Lead Acid batteries, what you want is a Float charge, which is a constant voltage charge that lets the battery take in just what it needs to make up for its self-discharge. The exact voltage to use will depend to some extent on the battery type and will in any case need to be temperature compensated.

                          C: Go for it! But do some calculations of how much energy is actually stored in such a high mass, low speed system, and more importantly, look at how you will be able to extract constant-frequency AC from the flywheel as it slows down. It can be done, but it takes more than just gearing a generator head to the flywheel.

                          PS: If you are not in a hurry and are seriously looking at Sunny Boy, do a google search ("Sunny Boy TL-US"), including this link, and also look on this forum for discussions and speculation about the not-yet-shipping Sunny Boy 2000/3000/4000 TL-US series.
                          Thanks,

                          I feel like I'm monopolizing your time.

                          Tractor wheel. Just enough energy to start the freezer compressor motor.

                          Option A sounds very interesting. Will the straight grid tie type inverter see the output of the battery backup inverter as the nice stable utility so it will agree to stay hot? What is the interface? Just tie them together at the load side of the AC panel and the slave (conventional grid tie) syncs to the master (off grid battery backup inverter) and shuts it self off if the master goes down because of low battery voltage?

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                          • #58
                            Originally posted by duncangalt View Post
                            Thanks,

                            I feel like I'm monopolizing your time.

                            Tractor wheel. Just enough energy to start the freezer compressor motor.

                            Option A sounds very interesting. Will the straight grid tie type inverter see the output of the battery backup inverter as the nice stable utility so it will agree to stay hot? What is the interface? Just tie them together at the load side of the AC panel and the slave (conventional grid tie) syncs to the master (off grid battery backup inverter) and shuts it self off if the master goes down because of low battery voltage?
                            Whoa slow down
                            there is a lot more to it than that.
                            NABCEP certified Technical Sales Professional

                            [URL="http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design"]http://www.solarpaneltalk.com/showth...Battery-Design[/URL]

                            [URL]http://www.calculator.net/voltage-drop-calculator.html[/URL] (Voltage drop Calculator among others)

                            [URL="http://www.gaisma.com"]www.gaisma.com[/URL]

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                            • #59
                              thing sort of manually after the apocalypse.

                              That says it all - dead end
                              [SIGPIC][/SIGPIC]

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                              • #60
                                Originally posted by duncangalt View Post
                                Desire not to purchase and maintain a large (scary) battery bank.
                                While I understand that desire, you should know that all the other solutions you are considering (especially flywheels) are far scarier.

                                Years of lower efficiency conversion for sale to the grid. 85% vs 94%
                                With an Outback system you'd be above 90% even with batteries.

                                What I may have to do is build my 6 kw grid tie system and have a separate charge controller, off grid 4 kw inverter and a bank of 4 12 volt batteries. Reconfigure the DC strings and operate the whole thing sort of manually after the apocalypse.
                                If the apocalypse is the issue, just buy the parts and have them on hand so you can convert over in a few days. Batteries will be the one thing you can't "stockpile" so best live near a battery distributor and hightail it over there as soon as the first (zombie/looter/secessionist) shows up.

                                What's the short answer to keeping the 12 volt batteries from going bad while they wait three years to be called to action. Trickle charge for an hour per week? Discharge 25% once a month?
                                Floating them at a high state of charge.

                                I still want to build the flywheel. Something with lots of mass and low RPM like a big tractor wheel or a merry-go-round.
                                A 220 pound tractor wheel spinning at 5000 RPM (all the mass in the rim) can store about 3 kilowatt-hours if you can extract almost every joule from its motion. Again, though, if it gets loose (or even has a minor tread problem) it's not going to be pretty. And your house will shake a fair amount . . .

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