Bargain AGMs

BruceMBruceM Posts: 23Registered Users
I noticed Gruber Power Services in Phoenix is selling 100 amp hr 12V AGMs at around $100 on ebay.
I called and they say these are 300 cycle at 50% DOD batteries.

That's more like a marine battery - Johnson Controls has about the same 300 cycle to 50% DOD at 80F spec on their size 27 (about 100 AH- this size I need) sold through Autozone on the cheap. ($56 plus core charge)

Concorde is twice the price and while they don't have cycle life data on their web site their tech rep for the Sun Extenders (very nice fellow) says they have 1050 cycles at 50% (77F). My only beef with the Concorde batts is the price. Ouch!

My application will have 25% depth of discharge on average for a 100 amp hr. bank of 10 batteries in series, with my own design charger and inverter.

Any thoughts on any bargains out there?

Bruce M




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Comments

  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    I think East Penn AGM Batteries (Deka and MK brands) appear to a good value. My Deka 8A4D batteries (size 4D, 12 V x ~200 Ah) were $220 each and are rated at 500 cycles @ 50% DOD and 3200 cycles # 10% DOD. For my typical max discharge of 25%, they're rated for 1200 cycles. Frankly, I expect they'll do better.

    See: http://www.eastpenn-deka.com/
    and: http://www.mkbattery.com/search.php?application=AGM&Submit=CLICK+TO+SEARCH
    and: http://www.eastpenn-deka.com/assets/base/0139.pdf

    Trojan also makes AGM batteries, but I don't know anything about their prices.

    See: http://www.trojanbattery.com/Products/RenewableEnergy.aspx

    Note that regular ol' flooded-cell batteries are ~80% efficient (Wh out / Wh in), but that AGM batteries are about 90% efficient. Everything else being equal, this means that a smaller PV array is required when using AGM batteries, and that helps offset their cost. Also note that AGM batteries don't require active ventilation or much maintenance.

    HTH,
    Jim / crewzer
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Thanks for the report on the Deka, Jim. Do you know a good source for these in N. AZ or Phx? I'm near Snowflake.

    I talked to my rep at Gruber- I might have been wrong about the cycle data- he no said it was 500 cycles at 50% DOD, from memory, but is trying to find me a cycle life curve from their vendor. Deka has a sales rep for my area but no call back from him yet.

    I concur on the advantages of AGMs vs flooded. I just wish the same level of development effort was going into Nickel Iron batteries; I think they are inherently better suited to our needs, but no real development there since the days of Edison, and no US manufacturer since 1974. Found one CA source for them- my battery bank would be 100 individual 1.2V cells (from China) and $6500. plus freight. Not very practical for my high voltage string.

    Best Wishes,
    Bruce M
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,

    I'm afraid that I don't have a specific source recommendation for you. However, you might try contacting MK's Battery Warehouse in Phoenix to see if they can help:

    Phoenix Warehouse
    1202 North 54th Avenue, Suite 107
    Phoenix, AZ 85043
    Phone: (602) 323-2944

    HTH,
    Jim / crewzer
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Thanks very much Jim!
    I'll check out MK tomorrow. My East Penn-Deka sales rep quoted me $156. ea for 10 delivered in Snowflake for the 8G31. They claim better cycle life for their Gel vs their AGMs. What do you think about Gel vs AGM? ( I noted you have the "A" for AGM series.)

    The Deka "Solar" gels claim a 50% DOD cycle life of 1000 cycles (77F), 2100 cycles at 25% DOD. That's in the same ballpark as the Concorde Sun Extenders, but at a big cost break.

    Bruce M



  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,

    The quoted price, including delivery, is comparable to my "nearby" battery warehouse (~$140 each plus shipping and tax), so It sounds good.

    I decided against gel batteries for several reasons:

    1) NAWS (this site's owner/operator) had a lot of gel battery returns from their customers. As a result, they stopped selling gel batteries. However, I don't know if they were bad batteries or uninformed users.
    2) Gel battery energy density is lower than that of AGM's. For example, the 8A4D is ~200 AH, but the 8G4D is ~183 Ah.
    3) Seems like there are more AGM manufacturers than there are gel battery makers... I wonder why?

    Regardless of whether you go with AGM's or gel's, make sure you set your charge controller for the correct absorb and float voltages, and temperature compensation is highly recommended.

    Ten 12 V batteries, eh? What's your planned battery bank configuration?

    HTH,
    Jim / crewzer
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Jim, I'm planning on a 120VDC system, 10 batteres in series. I'm building my own charger, with individual battery charge voltage /bypass load resistors like the ManzanitaPower EV system.

    Also doing my own inverter. (Small, just for refridgerator, and other very limited needs.)

    This is not a "for fun" hobby project, but a medical necessity. My MS and epilepsy are severely affected around switching power supplies, etc. I can't be near the typical off grid setup, even the top of the line systems. Also can't be near typical computers, flourescent lights, motors, etc. Growth of power demand in my area is forcing me to move- but the upside is I found an offgrid area where I function dramatically better in just hours.

    I'm a retired EE, looking for a good engineer or electrical tech to help (paid) with the bench test part of the project at least. Once I have to work with the oscilliscope, I'm a wreck, and pay for it dearly, sometimes for many weeks

    120VDC helps with a number of issues; particularly extending power at a distance, and reducing current draw which is a big asset when very high levels of passive filtering are needed. It makes incandescent lighting a snap, which is a sorry technology but best for my needs.

    Bruce M


    P.S.
    MK AGMS have this life cycle data: 500 cycles at 50% DOD, 1200 cycles at 25%, 77F.

    When I get the Gruber AGM data I'll post it here and delete the health crap.

  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,

    As a reasonable healthy 55 year-old, I cannot even begin to fathom your medical challenges. When possible, I’ll offer some remote technical assistance.

    To start with, there are a couple of companies that manufacture high quality DC-to-AC inverters that run from 125 VDC nominal. These include Analytic Systems and Exeltech. An “off-the-shelf” solution might be quicker, cheaper and less risky than a custom job. As you are likely already aware, the fridge will operate better from a true-sine-wave inverter, and the inverter must be able to handle the compressor’s start-up surge.

    See: http://www.analyticsystems.com/
    and: http://www.exeltech.com/ex_root/ex_products/ex_inverters/ex_xp/ex_xp_series.htm
    and: http://www.exeltech.com/ex_root/ex_products/ex_inverters/ex_xp/ex_xp_specs.htm

    If you’re interested, Northern Arizona Wind & Sun (NAWS, this site’s sponsor) can special order an “108 VDC” Exeltech MX inverter for you.

    See: http://store.solar-electric.com/
    and: http://store.solar-electric.com/exsiwain.html

    Note that your ten gel-batteries-in-series bank will operate at 120 VDC nominal, but the charging voltage at 77 F will be ~138 VDC. As you’re also probably aware, DC affects switches and circuit breakers differently that does AC. Nasty arcing problem… For example, readily available and cheap Square-D QO breakers are rated at 125 VAC (or higher), but for just 48 VDC.

    I haven’t checked on switches in a while, but breakers rated at up to 125 VDC and even 150 VDC are available from MidNite Solar and OutBack Power (actual certifications need to be verified). NAWS carries most (all?) MidNite and OutBack products.

    See: http://www.eastpenn-deka.com/assets/base/0919.pdf
    and: http://www.eastpenn-deka.com/assets/base/0139.pdf
    and: http://www.midnitesolar.com/
    and: http://www.midnitesolar.com/Price%20sheet%20Jan1%202007%20rev%20A.pdf
    and: http://www.outbackpower.com/index.html
    and: http://www.outbackpower.com/components.htm
    and: http://www.outbackpower.com/pdfs_general/FLEXware_Price_List.pdf

    Finally, another useful source for various DC odds and ends, services and information are these places:

    http://www.solarseller.com/
    http://www.backwoodssolar.com/
    http://www.gaiam.com/realgoods/default.htm
    http://www.thesolar.biz/
    http://www.homepower.com

    I hope all of this is at least of some small use to you.

    Regards,
    Jim / crewzer
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Thanks so much for the high voltage DC breaker info, Jim. That's a big help, I hadn't researched them yet.

    Interesting to see 120VDC inverters. I may contact Analytic to see if one of their designs might be an ferro resonant type that I could modify.

    The problem is that modern "good" designs use very fast MOSFET or IGBT switching, and are not concerned about EMI very much. Practical levels of filtering just don't work- I've tried.

    I will be adapting the old ferro resonant transformer type design, switching my 120VDC to a custom toroid transformer primary winding as a modified square wave, while using power bipolars to slow down the switching time, and hoping to avoid using a saturated core (power robber) for output regulation by doing pulse width modulation instead. Sort of a hybrid of old and new. I have part of this built using MOSFETs, but had trouble with using them as slow switchers; the gates glitch when driven by a high impedance (200K plus) source which gets a decent slow switch out of them. Semi linear operation of MOSFETs is possible but a real stinker, and is also very temperature sensitive, so for now I'm just switching the N-channel mosfets to NPN bipolars.

    Do you have any ideas about light switches for 120VDC? I know it's hell on the contacts of normal switches, but unless I can find a substitute for the more oftenly used switches, I'll just have to live with very short switch life.

    Thanks again for the thoughtful suggestions and marvelous related links, Jim!

    Best Wishes,
    Bruce M
  • BB.BB. Posts: 27,905Super Moderators, Administrators admin
    Re: Bargain AGMs

    Bruce,

    What is it that you are trying to minimize with your design?

    At first, it seemed that you may have been bothered by the noise of less than perfect sine waves causing noise (buzzing in sheet-metal, wires vibrating, and/or flickering by voltage modulation from loads). Or, possibly the flicker of lights by 60/120 Hz fundamental frequency, and going away from the 120 Hz flicker from tube type fluorescents (CFLs with electronic ballasts operate at something like 12-15kHz--don't they?). But you also talked about RF interference--which is usually of high enough frequency that it should be difficult for Bio-Organisms to detect (unless you are talking about pretty high power devices like microwave ovens and RF transmitters).

    I am a big believer in reducing "noise" at the source rather than trying band-aids down the road. But depending what you are trying to control/minimize, frequently, it is easier to reduce the effects by localized shielding and/or simply remote mounting to use the law of squares to simply diminish the effects on you and/or other "things".

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,

    Some good news: Here’s a link to some inexpensive DC switches: http://www.solarseller.com/dc_photoswitch__dc_timer__voltage_controlled_switch_dc_relay.htm#wall_switch___dc_rated

    Some perhaps not-so-good news: The batteries you’re considering may have lower “cycle rating” that otherwise suggested. Take a look at the note under the “Gel Cycle Life vs DOD” chart in the following document, and note the “8G31DT” comment.
    See: http://www.mkbattery.com/images/S31.pdf

    Some perhaps useful news: You may be able to use some efficient LED lights instead of funky ol’ incandescent “bubs”.
    See: http://www.superbrightleds.com/

    Finally, you lost me after the core saturation comment. That, of course, is why designers can get away with small transformers in HF switcher designs. However, like Bill above, I’d be interested in learning more about what environment you’re trying to contain/avoid.

    HTH,
    Jim / crewzer
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Bill, Thanks for your interest and thoughtful questions.

    I'm trying to minimize both magnetic fields (low and high frequency) and high frequency E fields. Low frequency magnetic fields are easiest to eliminate via distance, though modest reductions through shielding can be achieved (3-6db). High frequency is not so easy due to conducted radiation.

    I'm knowledgeable in EMC, something I studied much more in depth some 10 years ago after failing repeatedly to shield and filter via typical commercial practice a specialized computer setup using a rear projection screen (for distance to source) for myself. I knew I had to rethink shielding as a solution when I found that a Tempest keyboard powered by a battery bothered me badly.

    For a source which is problematic in it's high frequency emissions spectrum, I've found that even high levels of shielding (say 60dB or better) are not adequate. So I often use distance and fiber optic cables (to eliminate conducted radiation) when practical to do so, sometimes I'm forced to use both distance and shielding/filtering.

    The presently prevailing view that RF energy doesn't affect biology except for cellular heating is not one that I can presently support. My neurology is seriously abnormal now from MS and a previous bout with viral encephalitis. I suspect that this makes me more susceptable- as I didn't have this problem before I became ill, and happily worked with groups of engineers on my projects in labs chock full of unshielded computers, power supplies, displays, avionics and cables most of my working life.

    You don't appreciate how limited our medical knowledge still is until you have chronic illness(es) which are not treatable except by poorly effective medications which "control the symptoms" inadequately while giving you new illnesses.


    Bruce M
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Jim, You are a gem!
    Wow, I missed the fine print (0.6 times the chart value) on the Deka battery chart- that sucker is only a 600 cycle 50%DOD battery! Makes the Gruber look good, price wise assuming they finally come up with some real data that matches their talk.

    I did leave a message at the MK battery warehouse in Phx- but got no call back today.

    Thanks also for the Cooper brand 120volt DC switch. Now that I know there is such a beast, I should be able to track them down much easier, maybe even through my local electrical supplier.

    Re: Old time inverters- they used to step battery voltage up to the +-180V peak to peak needed for 120VAC by using a big 60 Hz transformer. Trace used to build these monsters at one time. Sometimes with a center tapped primary, with one pulse to the upper side for the positive half of the square wave, and after some delay, a pulse to the lower side of the winding for the negative. They also sometimes had an extra winding which was shorted during zero crossing time to clean up the waveform when driving inductive loads. The output was shaped to a sinewave via an extra secondary winding with a large capacitor across it, to make a 60Hz resonant filter.
    Output regulation was done by running the transformer somewhat oversaturated- so that output would stay constant despite changes in input battery voltage.

    In modern inverters, high voltage DC is created by a DC-DC switching supply from the battery, using high frequency square wave switching to reduce inductor and capacitor size. This can then be switched at high frequencies to build a filtered replica of a sine wave without using huge, expensive inductors and capactors. The high frequency radiation follows both the DC wiring and the output wiring and re-radiates about the entire wiring system.

    I want to control emissions at the source by going back to the old transformer, and slowing switching time to about 200 usec instead of a few nanoseconds. I've used this approach successfully using grossly oversized MOSFETs (ones which IR helped me pick for being able to handle short periods of linear operation) in a redesign of the EL SID 20 watt circ pump. No measureable change in flow or power consumption, but now it's very quiet. The stock units are a disaster, EMI wise.

    I hope that was a helpful explaination, forgive me if I just insulted you and/or made it more confusing besides.

    Best Wishes,
    Bruce

  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Jim, I did experiment with LED lighting. While the white ones light character is very wierd and somewhat creepy to me, mixed 1:2 with amber they appear like normal incandescent light to me.

    The manufacturers/marketers are lying through their teeth when making their "equivalency" comparisons. The present LED's just don't have enough light for area lighting. Look at their lumen output and compare that to around 800 lumens for a 60 watt incandescent bulb.

    Where they do shine is in small task lighting- here they can have no reflector, and the losses that come with one, so they start to look much better.

    I do hope that in the coming years they will keep improving in output and efficiency. That will give me a viable alternative to halogen/incandescents.
  • BB.BB. Posts: 27,905Super Moderators, Administrators admin
    Re: Bargain AGMs

    I too have worked on quite a few small and large systems to obtain Class A and B FCC, as well as the newer CE susceptibility requirements (been ten years since I last did this)...

    I am not quite sure why you are having issues with high frequency leakage of EMI... I guess I really need to know the frequencies you are having issues with... Conducted noise is either differential or common mode... below 30 MHz, conducted noise is almost never a problem (hard to get enough energy coupled to free space) and above 100 Mhz (or 300 MHz, don't remember now), cables again where not a major factor in emissions. And to kill conducted noise, it was pretty easy to do that with a couple wraps of lossy ferrite beads (if nobody wanted to pay for a minimum of about 20' of well shielded cable).

    Differential noise, while a problem of introducing noise into connected equipment, was never a free space problem as long as the wires where close together (parallel runs of line cord/ROMEX, etc.). Just getting a good EMI line filter was usually able to get almost any piece of equipment to pass differential noise.

    The bigger issues where almost always those gaps and seams in sheet metal acting like slot antennas (into the GHz range, if you had fast parts). Fixing those usually required both good design rules (circuit board layouts, strip-lines, and proper component selection and circuit design). If you still had problems, you could get any one system to pass with just a bunch of 3M copper tape (of course, you can't ship with that).

    While I don't believe that being exposed to EMI radiation at low levels is harmful, I would be the first to agree that minimizing the radiation is good thing.

    Low frequency magnetic field type radiation was always a very difficult problem to control... There, you almost always had to go with Mu Metal to even begin to dent those emissions.

    I am really wondering at what levels you are trying to obtain? When I was doing testing, I had to have my antenna's about 10 feet away (or closer) in the SF Bay Area to even see any emissions from my FCC Class A systems--basically, if I did not see any problem frequencies (down in the "mud"), I knew that I would probably pass my Class A requirements in open field tests (20-several hundred miles away, usually down in a valley somewhere). Class B requirements were, generally only 10db lower than Class A.

    Tempest (from what little I have read--not a requirement for my designs) was something like 120 db down or something(?). Finding a specific signal with tuned/direction antenna (for spying) is one thing, trying to reduce all signals down to that level for health reasons seems to be another issue.

    Just as example of how little power we are talking about--The amount of power required to fail a Class A/B test (with one frequency connected to an ideal directional antenna) was something like in the Pico Nano (I think)Watt range (IIRC)--in other words, if your device used as much power as a digital LCD wrist watch, or less, you did not have to do any FCC EMI testing.

    In the end, I would have to suspect that if you placed almost any good quality inverter/charger/whatever in a nice tight metal (Aluminum or Steel) box with shielded cable, emi common/differential mode filters, and screened (or perf'ed holes) ventilation, you would be hard pressed to measure anything radiating from the unit (plus it would do nicely with an of the CE compatibility tests--radiated/ESD/etc. susceptibility tests).

    You talk about 3-6 db of shielding for low frequency magnetic fields--without testing, I would probably agree (just guessing). But 3-6 db in shielding is almost non-existent as shielding--you get those variations just moving a cable or breaking down/setting up (otherwise identical) tests.

    I guess that using cordless phones, cellular phones, WiFi cards, garage door openers, virtually any heterodyne type (regenerative) receiver, brushed motors, any motor, remote controls, LED Flashlights with switch mode regulators, etc. would bother you. IIRC even GPS satellites transmissions (around 1.024 GHz) are something like at -120 to -150 dbm levels (really stretching here--I think those are the numbers).

    Bruce, I am not trying to second guess that you find yourself suseceptible to electromagnetic radiations, but if you are injured by virtually DC To Daylight RF energy in terms of frequencies, at micro or pico Nano Watt levels--that is a difficult problem in today's world (like those that are hyper allergic to many of the common man-made chemicals around today).

    -Bill

    PS Regarding the feel of white LEDs--yea, that is a problem for many folks... White LED's are really blue LED's with some green/red phosphors that add up to "white". But not all people see white exactly the same way--and in any case, that white is not based on a black body radiator (like the sun or filament lamps are). A good Halogen light is not too bad in efficiency--you just need to protect against the UV from that nice "hot wire" filament.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    I agree Bill, the situation is technically so fuzzy that it is frustrating to me. I'll try to quantify it a litle for you.

    I have tried to determine the specific frequencies via frequency generator (audio through 150MHz) and whip or coil emitters. I did find areas that were less bothersome, and some frequency ranges that were very painful and disturbing. In low frequencies magnetic fields were more problematic, at higher ones coil or whip didn't matter. My complex partial seizures are felt by me as both disturbing, like a nightmare and depressing/confusing, with accute head pain. With continued exposure to less bothersome pieces of electronics, however, I seem to sensitize to new frequencies. So my general strategy is to "cherry pick" gear that bothers me less, then shield it as much as possible.

    I am not able to safely drive or ride in an ignition car anymore, but after years of not being able to drive I modified a mechanically injected diesel (85 300D) to eliminate the alternator (solar panel on the roof with non pulsing charge regulator). It was a new lease on life. Later I did more, like degaussing the tires, drivechain, remove most electronics, etc. to increase my driving range somewhat. Most buildings and stores are painful, but I have enough latency that I can cope briefly if I get in and out fast enough. I am distressed, in pain and disturbed after 10 minutes in the small local IGA grocery, but it's the best one for me. Some sections of powerlines are particularly problematic- and usually wipe out the entire AM band as well. I have learned to cope with the seizure onset disturbance, and can feel when I am at my limit. My medication is only slightly effective in increasing my tolerance, depite many years of trying new medications.

    Digital solar powered calculators bother me only in close proximity. Someone using one across a table from me is OK, but if i use it for more than a minute I can add the same 4 numbers 3 times and come up with at least 2 different answers every time. (Very mild impairment.) A digital watch does not seem to bother me. Likewise with a great deal of trying I was able to find a digital camera that I can manage to turn on, take a picture or two and turn off without too much problem. I had an friend survey cameras via AM radio and magnetic field meter, then I bought the 6 that were the best, and then picked he one which bothered me the least. I don't use it alot, and it has stayed "tolerable" for short use.

    Power line fields do bother me- much more so when the source is dominantly a "twitchy-transient filled" neutral current through the earth, (which I suspect may have biological frequency component or some other frequency that is particulary bothersome). I would love to research this more, but haven't the health or funds to spend on it. In this case (very rural- only ground current from not nearby distribution lines) fields in the 10 microgaus (not milligaus) or more level are cumulatively (within a few days) aggravating to my epilesy and ms. Below 2 microgaus, I start steadily improving. For cleaner power line sources, levels 10x this are OK, and for short exposures (seconds) up to maybe 4 milligaus is OK.

    Cell towers are an increasing problem in the rural area where I live. In areas where the average signal strength is only 10dB higher than at my home (outside), say within a mile of an active tower, I am impaired badly within 15-20 minutes. I can drive through the area, but I'm now at the point where I just can't be in any of the nearby towns for long at all. I miss movies, and the few restaurants I used to be able to enjoy (that still had no flourescent lights or wiring problems).

    I also do have multiple chemical sensitivities, but find that relatively easy to cope with compared to my problems with EMFs. My home has no carpets or paint, mostly portland cement plaster, tile, and raw maple. I live in a very rural area with mostly 40 acre parcels, so neighbor's lawn care, clothes dryers, etc., is not a significant issue.

    I'm wiped out now from using my computer setup too much, despite my best efforts and years of work on it. I get pretty goofy from this much time on it so forgive my rambling and disorganization.

    Best Wishes,
    Bruce
  • System2System2 Posts: 6,290 admin
    Re: Bargain AGMs

    What about placing yourself or the gear inside of a faraday shield? You could do your whole house or just a room.

    Just a thought.

    Skip
  • BB.BB. Posts: 27,905Super Moderators, Administrators admin
    Re: Bargain AGMs

    To be honest, I was thinking the same thing... Normally, a simple screen room could be constructed of brass or copper screening from a hardware store--in your case, I would be thinking of an old shipping container (or even an old metal refrigerated truck/shipping container to make it a bit more livable).

    Wire cloth would not be thick enough to develop full skin effect depth needed to cancel the magnetic fields at the lower frequencies.

    You could line the inside of the container with ferrite plates to prevent reflections (if you have a computer or something inside)--but that would undoubtedly be too expensive unless you found a used chamber from the dot com bust.

    There are also places that sell Aluminum lined "bubble wrap"--but you would have to make sure that you get good electrical connections at the seams.

    http://www.insulation4less.com/

    I am sure that you have thought of the same thing too...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,

    Thanks for the additional explanation of your design. While I also thought about the Faraday cage approach, I have to admit that EM ain’t one of my strong suits. However, one of the great features of this forum is the skill range of the regular participants, and it’s heartening to see the additional support they’re offering to you.

    You’re of course correct about some of the LED hype. While I like white (high color temp) light, I find the common blue-ish tint of many “white” LEDs to be off-putting. However, white LEDs are getting better (i.e., Cadillac now uses them for their backup lights), and there are established useful applications for other colors.

    For example, virtually all of the path-, deck- and shed lights outside of my house are 12 V amber LED modules that I designed, built and installed. A single 40 W PV module, a cheap controller and a single Group 27 battery power most of the overnight perimeter light I need outside, and, except for when the controller is in its low-frequency PWM absorb mode, it’s all “quiet” DC. I may just use this approach for "night lights" inside my next house.

    Best wishes,
    Jim / crewzer
  • FrankFrank Posts: 54Solar Expert ✭✭
    Re: Bargain AGMs

    Good luck Bruce with your travails.

    I've been looking at AGM's for a small electric motorcycle I built and have decided on a Universal Battery UB12100 (group 31, 110 AH). It turns out that UB makes batteries for www.powerupco.com and they seem to sell them at a lower price. EV use is a bit different than your typical home power setup (higher draws for shorter times) but this battery has a 1 hour rating of 80 A! This is very good from what I've seen.

    Best,
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Good thoughts about shield rooms- and yes, I do already use it to live here.

    I have found that a home with a foil vapor barrier (behind my plaster on steel lathe walls) and aluminum windows/screens plus low E glass or UV film does provide 20 decibles of shielding from ambient RF (radio, microwave, at considerable distances here). For my new home I'm including a foil laminate under the insulated, pex'd slab and secured to the wall/ceiling foil, with provisions for better window shielding, as ambient microwave levels just keep going up, even in very rural areas.

    I have designed and built proper shield rooms, equipment enclosures with honeycomb vents and ITO glass (for my custom built rear projector), etc. Shielding does work, it's just hard to have the illusion of normalcy when you're surrounded by foil or mesh.

    I developed a new wall system that uses 1 mil foil laminated to drywall with sodium silicate, which is then finished with my own recipe clay putty and claypaint which uses a cellulose gum binder. I've used this in my new off grid shop which has temporary living quarters, and another new house for a someone near my present home for a person disabled with multiple chemical sensitivities. The foil works as a decent shield for the house wiring, were we use 12-3 wire (lazy twist) for magnetic field canceling.

    My new off grid homesite is located in a little valley so I get some natural microwave shielding. There's no phone lines for many miles. There's plenty of cell signal on the 35' tall hills on each side, so I have built a nultimode fiber optic audio link to a cell phone with voice dialing, and use a yagi antenna turned 90 degrees to house/shop site. A whip antenna was a bust even at 400 feet unless I was in the steel sided/roofed shop. I built this last winter and tested it here; it has yet to be set up on my off grid property. I used a Picaxe chip in the remote interface to manage power and do cell phone control via solenoids to operate buttons. On the home end I use a stethescope to an old ear piece and electret mic at a distance to avoid audio frequency magnetics, as a speaker phone was too much work. At the "phone" end I used only class A amplifier descrete transitors for extremely low noise. It took me a few months to build, as I had a few operational surprises and false starts.

    It's a challanging existance. I'm hoping my new location will give me enough improvement that I will have a fuller life.

    Thanks for your interest and helpful suggestions.

    Best Wishes,
    Bruce






  • nielniel Posts: 10,311Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    bruce,
    i thought i had it bad with my health problems, but you are going through it royally. the ability of getting rid of all radiation sources near and far is an unbelievably difficult endeavor. as a amateur radio operator i know some of the difficulties in controlling electro-magnetic radiations. there isn't any place on earth that is isolated from them as even space radiations, be it satellites or background from other stars are always present let alone from the sources closer to the earth. even my radio signals get bounced around within the ionosphere and can pop up anywhere and everywhere. there are millions of transmitter sources worldwide with huge amounts of power being utilized in the transmitting waves in total. in addition to beefing up the shielding, you may need to be underground as well. as huge of a task as you are trying to accomplish i fear this will be very limited in success. those in the medical field need to stepup to the plate and help you better. i know what you mean about those in the medical field though through my experiences with them. also my son is epileptic so large explanations of your difficulties there aren't necessary as they tend to fail everybody with this condition with the lack of meds available that work long term, let alone coming up with cures. you have ms on top of it all to boot. i wish you the best in your efforts and wish that the medical field would pursue things like they should with cures in mind and not money. with that i'll drop it as i don't want to get into a debate or rant on a subject that would be off the real subject matter here on the forum.
  • System2System2 Posts: 6,290 admin
    Re: Bargain AGMs

    LED's have made big time advances just in the last 6-8 months. If you are used to working with typical 5mm LED's, even superbrights, using them for room lighting is impossible.

    Cree and Seoul (and soon Lumileds will be coming out with new designs) are making LED's that are (in quantity) very acceptable for room lighting. They are used now in tactical flashlights brighter than their incandescent counterparts while consuming far less energy.

    Cost is a factor of course. Color rendition is not as big of a problem anymore, either. The new Cree die produces a very white (not at all blueish) with what seems to contain a wider spectrum than most other LED's.

    The 5W Lumileds typically produce a yellowish light that most flashlight users find TOO yellow, but in multiples would make a great room light in proper quantities.

    So, the proper LED's are available, just not in 'room light' configuration. I'm in the process of converting my camper/RV to complete LED lighting using multiple 5w Lumileds - the effect if far more 'incandescent' than you would imagine.

    I'd be happy to provide links to these newer devices if you are interested.

    There, another project for you... <g>

    John F
    LV, NV
  • BB.BB. Posts: 27,905Super Moderators, Administrators admin
    Re: Bargain AGMs

    Problem with going underground is Radon Gas--Darned if you do, darned if you don't:

    http://www.enviro-awareness.com/c.php?p=63

    Hopefully, regarding MS and other serious medical issues, there will be something found from some natural interactions that are out-there:

    Parasites may reduce relapse in MS patients: 17 January 2007

    http://www.newscientist.com/article/dn10964-parasites-may-reduce-relapse-in-ms-patients.html
    Parasitic worms may have their uses after all. The bugs could alter the course of autoimmune diseases like multiple sclerosis (MS), a new study suggests

    Previous studies have suggested that parasites can influence the progression of autoimmune diseases in animals. To test whether this was also the case in humans, Jorge Correale and Mauricio Farez at the Raûl Carrea Institute for Neurological Research in Buenos Aires, Argentina, spent four-and-a-half years following the disease progression of 24 people with MS. Half of the patients had recently shown symptoms of parasitic infection, while the remaining 12 were otherwise healthy controls.

    Every three months the patients were checked for disease activity and any worsening of symptoms, and during the final 18 months of the study their blood was checked for immune cell activity.

    Those infected with parasites had fewer relapses, and less overall deterioration of their condition than uninfected people with MS. There were just three relapses in the parasite group in total compared with 56 relapses in the uninfected group.

    “This is the first direct evidence that parasites might be relevant to protection from an autoimmune disease,” says Graham Rook, an immunologist at University College London, UK, who was not involved in the study.
    Hygiene hypothesis

    The findings mirror observations of a decreased incidence of allergies in Vietnamese children who are infected with parasites compared with uninfected children (see Intestinal worms may not be totally bad news). They also shed further light on the so-called “hygiene-hypothesis” of allergic disease, which proposes that allergies have become more common in recent decades because we are exposed to fewer infections as children.

    Bacterial and viral infections trigger a subset of immune cells called TH1 cells, while a different subset called TH2 cells mediate allergies. The assumption was that in the absence of micro-organisms, the balance tipped towards TH2 cells, meaning people experienced more allergies. However, autoimmune diseases have also risen steadily in developing countries in recent decades, and these are driven by TH1 cells.

    The answer to what is driving this increase in allergies and autoimmune disease may lie with a different subset of immune cells called regulatory T (Treg) cells, which regulate both TH1 and TH2 responses. Correale showed that these were elevated in patients with both parasitic infections and MS, but not in MS sufferers with no infection.
    Into overdrive

    One hypothesis that is gaining growing acceptance is that certain bacteria and parasites – which have lived alongside humans for millennia – have gradually developed ways of stimulating Treg cells to dampen down the immune system, enabling them to survive in the body for longer. With modern standards of hygiene these “old friends” are gone and Treg cells are consequently less active, meaning the TH1 and TH2 cells go into overdrive, triggering allergies and autoimmune diseases.

    Researchers have been developing drugs that interfere with Treg cell activity. It was one such drug for rheumatoid arthritis that triggered the catastrophic immune reaction in six human volunteers during a clinical trial at Northwick Park hospital, London, in March 2006 (see One drug trial, six men, disaster).

    Theoretically, parasites might provide an alternative mechanism for dampening down immune responses – other groups are already experimenting with parasite eggs as a means of treating inflammatory bowel disease.
    Novel therapies

    However, Correale cautions that parasites may also induce different regulatory mechanisms other than just "upregulating" Treg cells – and parasite infections are often disadvantageous to health. “A better knowledge of the immune response during autoimmunity and parasite infection will allow us to select the best strategy for treatment,” he says.

    Journal reference: Annals of Neurology (DOI: 10.1002/ana.21067)

    Now back to your regularly scheduled program already in progress...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    John, Thanks for the update on the new LEDs. I would appreciate any info you could provide. It will be a year before my new house is built (shop has living quarters and is almost finished now), so maybe by then LED's will save me from the power hungry incandescents and Halogens. If the forward voltages stay in the 4 volt range, something like a separate, modest sized 12 or 24volt PV/battery system for just the house lighting would be perfect.

    I've been only half following the LED progress as I'm hoping the LED powered "pocket projectors" such as those by Mitsubishi, Toshiba, will catch on and solve my projector power problem. My present hombuilt low EMF computer/TV projector uses a line voltage halogen- 600 watts! I did experiments on some of the earliest prototype DC metal halide lamps; the arc wasn't stable if fed clean DC! I'm hoping that the DLP flicker problems will not be too bothersome and that the video/DLP controller chips used won't be a disaster for me.

    Thanks for the kind words Neil. I know some aspects of my situation are not uncommon; about 80% of people with complex partial seizures get no relief from meds. I was refused for epilepsy surgery because of the MS and can't try the vegas nerve stimulator because of my EMF related problems.

    The big money is in pain, boner and hair pills. I don't see straight capitalism working so well as the foundation for public health. A commitment to fund long term basic research is what we need to get to the bottom of the chronic, autoimmune diseases; it would save far more in productive lives lost and the growing fortune wasted on "disease management".

    Does anyone know a source for OLD type, ferro resonant transformer type inverters?

    Bruce M
  • System2System2 Posts: 6,290 admin
    Re: Bargain AGMs

    Bruce,

    You might check into the Tripp Lite products. They are built like tanks and can be had for salvage sometimes. I used to have access to a place that salvaged most of Sprint's stuff from 6 states. You can't believe the stuff they get rid of. Sony Pro Tubes, laptops, UPS's (Most just have bad batts) audio gear (Love that stuff!)

    Good luck

    Skip
  • System2System2 Posts: 6,290 admin
    Re: Bargain AGMs

    Front / rear projector TV's - Laser will be taking over, and soon - many say by this time next year Plasma will be dead, and LCD dying. Here is a taste:

    http://www.audioholics.com/news/editorials/laserprojectorscellphones.php

    Advantages are many - no cooling fan, no optics, extremely small and very low power consumption.

    DLP color wheels, even at the very high rotational speeds used in the newer models, can be problematic for many people. I am diabetic, and can very closely monitor low blood sugar levels by my eyes' / brain reaction to my DLP front projector. I wouldn't think DLP would be a good choice for those prone to seizures, current LCOS would be better as no color wheel is used.

    Forward voltage for the very high output LEDs now being made seem to range between 3.7 - 3.9v. I'll round up some links to spec sheets and post soon...

    John F
    LV, NV
  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Thanks, John. I look forward to checking out those links. I'm also aware of some research that shows insulin need is affected EMFs. One company was selling keyboards that had a white noise generator hooked to a coil of wire around the keyboard interior case. It generated broad spectrum (audio) frequency magnetic fields and I guess there was some data to suggest it alleviated the effect of sitting near a computer for some diabetics. I think it was Catholic University of Washington DC, and EMX was the company(?).

    The EMX keyboard was the opposite of helpful for me. I do notice that if I can jack up my blood sugar temporarily, it raises my seizure threshold, and I use that for when I've got to go into stores and such. And for a while I found that excitotoxins like nutrasweet also helped to temporarily raise my seizure threshold but were a bust for regular use. All kinds of interesting interaction between the endocrine system and the brain. I wish medicine was 100 years down the road already.

    Skip, thanks for the Tripp Lite tip. I'll keep my eyes open for a bargain.

    Back to the issue at hand:
    Gruber Power Systems came back with data from their battery vendor:
    600 cycles at 50% DOD, 1500 cycles at 25%, 77F.
    This is nowhere near the Concorde Sun Extenders, but at the price ($96/100ah) may be a good value for my application.

    I haven't gotten the MK pricing yet.

    Bruce M
    PS I'm astounded by the thoughtful, knowledgeable help here. Thank you, gentlemen!


  • mike95490mike95490 Posts: 7,915Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    To solve your High Current DC switch problems, may I suggest a power rated FET ?

    They have very low forward drop, and a simple millamp switch can control them. They are a linear device, not digital.

    part IRF3706 is a couple of bucks, and quite sturdy, I use them all the time at work, and have not zapped one yet.
    http://www.irf.com/product-info/datasheets/data/irf3706.pdf

    Good luck

    Mike
    Powerfab top of pole PV mount | 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 ,

  • BruceMBruceM Posts: 23Registered Users
    Re: Bargain AGMs

    Hi Mike,
    I looked at the spec- the IRF3706 is a MOSFET, for switching applications. Maybe you were thinking of another part? The problems with slow MOSFET switching is that to get a decent looking RC type soft output you must use a very high resistance to drive the gate. The gate capacitance only kicks in as the MOSFET starts to switch on. If you add capacitance to the gate, it delays the overall on/off time but not the switching time. When you start switching higher voltages (120VDC in my case), using a very high impedence gate drive is a bust- it's too susceptable to glitching from nearby MOSFET's switching. IGBT's are slower inherently, but not slow enough for my needs. I've used them before but not experimented with them for slow (200usec) switching.

    Best Wishes,
    Bruce
  • crewzercrewzer Posts: 1,832Registered Users, Solar Expert ✭✭✭✭
    Re: Bargain AGMs

    Bruce,
    I haven't gotten the MK pricing yet.

    Too bad  :x  ... They snooze, they lose!
    Does anyone know a source for OLD type, ferro resonant transformer type inverters?

    Something like this? See: http://www.carebase.com/Dc-to-ac-inverters-transformer-isolation-sine-wave-voltage-regulation-24vdc-48vdc-to-110vac-115vac-120vac-200vac-220vac-230vac-240vac.htm

    Or this?: See http://www.philtek.com/products.html and http://www.philtek.com/pdf_files/piv_brochure.pdf

    HTH,
    Jim / crewzer
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