Bargain AGMs

2»

Comments

  • mike95490mike95490 Solar Expert Posts: 9,361 ✭✭✭✭✭
    Re: Bargain AGMs
    BruceM wrote:
    Hi Mike,
    I looked at the spec- the IRF3706 is a MOSFET, for switching applications. Maybe you were thinking of another part?

    We use them all the time for DC power control in the lab up to about 15A. I thought you were needing to switch 12VDC for lights. If you are switching 120VDC, I don't know about that high of voltage. In the lab, we just slam the Vcc onto the gate, and that enables the part. Higher voltages, you may have to protect the FET with resistors. For just switching on 12v halagon bulbs, I thought it would work fine.
    Just don't let the kids sit there all day, flipping the light off and on. That will cause some switching transients. Are you wanting to "soft start" and stop the lights ? FETS are good full on or full off, mid point, they are really lossy and overheat in a bad way.

    IKEA (WWW & mail order too) has lots of trendy 12v track and wire lighting options, and if you just buy the fixtures, and not the transformer package, you should be able to get some decent 12v directional lighting.
    http://www.ikea.com Then even have LED strips and fixtures too.
    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 Registered Users Posts: 23
    Re: Bargain AGMs

    Jim, Once again you amaze me. The Philtek inverters are 120VDC, and say they use PWM into a ferro resonant transformer to make a sine wave! Gee, I thought that was an original idea of mine!

    I'm going to contact them and pursue it. You sure hit the nail on the head. Thank you!

    Mike- a misunderstanding- the soft switch discussion was relative to a custom inverter design using 120VDC. I'm familiar with MOSFETs and have used them for both switching and linear designs. Thanks for the tip on IKEA.

    Best Wishes,
    Bruce

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

    Bruce,

    Glad to help... all I did was type "ferroresonant", "inverter" and "120 VDC" into Google!  8-)

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

    Jim, I talked to Philip Pong at Philtek...designer of their PIV series. The design is exactly as hoped- no high frequency switching, though they had recently upgraded it to IGBT switching transistors instead of Bipolars. Boo! I just emailed him and will let you know how it turns out.

    The list price of the 500VA unit is a whopping $2200, but oh, the pain it would save...

    I thought I'd googled the heck out of my situation, and just never got that link! Thank you, thank you!
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Bargain AGMs

    Great news! 8-)
  • JamesJames Solar Expert Posts: 248 ✭✭
    Re: Bargain AGMs

    Hi Bruce,
    I don't know if this will help you at all, but if you do an ebay search under "DC Breaker" you will find 3-4 sellers with good pricing on 250 amd 100 amp DC breakers. These are rated. only issue may be that most of them are cable lug style, which may or may not be a problem for your setup
  • System2System2 Posts: 6,290 admin
    Re: Bargain AGMs

    Bruce,

    Sounds like you are getting some great leads. I have been getting Hawker 6VF11 (100AH @ C8 12 volts, 105 #), or the 4VF11 (the 8 volt version) for $.40 per pound. If I want to trade them in on others, it just costs me a lunch and I can trade in for no charge for same weight. The 12 volt 100 AH cost me $42 ($700 new) and the 8 volt cost me $30 ($469 new). These have been in float service by the phone company and came fully charged. I just got a Trimetric, so I'll load test some to find out the capacity. I have 5 strings of these right now. There are also Lucent 4VR125E (115 AH @ c8, 125 @ c10, or 150 @ c20). These cost me $21.2 each and I can trade them in. These are 2 volt cells bussed together with copper buss bars which can easily be taken off leaving 2 - 2 volt cells that just come apart, (BUT are still sealed VRLA units). That way if one dies, I can have extras on hand really cheap, so just swap them out. I have not load tested these, but they came fully charged. I think both of these units were designed for a 12 year life.

    Good luck,

    Skip in Kansas City
  • BruceMBruceM Registered Users Posts: 23
    Re: Bargain AGMs

    Skip, those telephone cells sure sound like a sweet deal! I've heard of others getting very good service from that type of used cell.
    Bruce M
  • BruceMBruceM Registered Users Posts: 23
    Re: Bargain AGMs

    The silence is deafening from Philip at Philtek. I'm now thinking about a separate 12V setup for a ferrups or other ferro type inverter, to do my small AC loads; mostly a small chest freezer, 120 watts to run. Does anyone know some brand names besides Best/Powerline? Something surplus would be sweet.
  • mike95490mike95490 Solar Expert Posts: 9,361 ✭✭✭✭✭
    Re: Bargain AGMs

    Hmmm.... here's a thought. What about a old style motor/generator setup ? Where you have a DC motor flywheel coupled to an AC generator, like old WW1 field units. Nice clean sine waves. You use speed control for the DC motor (brushless would be sweet) to keep the output at 60.0HZ Park the motor/gen out in the power shed, run AC in thru steel conduit.
    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 ,

  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Bargain AGMs
    "... thinking about a separate 12V setup... to do my small AC loads; mostly a small chest freezer... "

    Bruce,

    How about a DC freezer? See http://www.sunfrost.com and http://www.sundanzer.com

    HTH,
    Jim / crewzer
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Bargain AGMs

    I believe the standard DC freezers still have a small dedicated inverter inside.

    How about a propane powered fridge/freezer?

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

    Bill,

    That sounds odd indeed... sounds like an unnecessary expense and complication... might be worth further investigation... :?

    Regards,
    Jim / crewzer
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Bargain AGMs

    The reason, I believe that they would use an inverter is because you don't want brushed motors and seals, or brushed motors inside the refrigerant circuit.

    Sundanzer uses this model--I believe that the motor is a three phase unit, with a inverter unit on the outside (inverter may be the wrong term--more like a "H" connected FETs, with a variable frequency controller, creating a rotating three phase field--just like 99% of the DC Fans cooling fans used in computers.

    http://www.sundanzer.com/PDF/Danfoss_Compressor_Specs.pdf

    So, in terms of Bruce's requirements for concerns about EMI fields--this may or may not be an issue for him (think of a large DC Cooling Fan for a computer--does that cause problems or not for Bruce). I have seen one DC fan with a timing/commutation failure that was very tough to catch--Had a DSU (basically a T3 Digital Modem for the Phone Company interface) that kept failing with high error rates (looked like injected noise). I found the problem by wrapping a small coil on the end of a 1 GHz scope and traced the source to a standard cooling Fan. The fan ran fine, but I did see what appeared to be slight browning (over-temp indication) on the paper label. So I do know that if there is a problem with the circuit (looked like two FETs were on at the same time for a few nano-seconds) can radiate/inject nasty high frequency spikes.

    We have had discussion here before where it seems that the dedicated Sun Frost / Sundanzer fridge/freezers seem to be too expensive to justify--and one is usually better off just using a new energy star listed appliance+inverter for almost the same power consumption.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Bargain AGMs
    ...more like a "H" connected FETs,...

    Got it!

    I agree the Sunfrost / Sundanzer fridges are usually too expensive to justify. I'm usually involved in those discussions on this board and over on the OutBack forum. In this case, I thought the units were "pure" DC, and that such an architecture would have been helpful to Bruce.

    Oh, well... thanks anyway.

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

    Thanks for the help, gents.
    Mike, I looked into motor-generators, but brushed DC motors are a broad spectrum RF generator, and no suitable brushless DC driven ones (which would have to be modified to slow switching times) could be found. I lost interest when I found out their effeciency would be horrible compared to a resonant transformer type inverter design.

    Jim, Bill, thanks for the ideas on refrigeration.

    I have looked at the Sundancer and other DC fridges (all use the same compressor and controller). I haven't measured one, but "good engineering practice" would be to use the smallest mosfets possible in the H bridge brushless motor controller as Bill suggests. This also implies the fastest switching times, EMI not being a consideration in the design. I could reverse engineer the design, then redesign the brushless motor controller. I was able to do this for the EL SID circ pump successfully, though this was a very simple design, comparatively. I think this is way too much work, starting from such an expensive (Sundancer) design. I also think most of the efficiency of the Sundancer is the 4" foam case. If I could check out a Sundancer with an AM radio and magnetic field meter I'd feel a lot more confident about using it as a temporary solution off a dedicated 24V source battery. It's such an expensive temporary solution it makes me think propane...

    Propane is still a consideration. I'd have to put it in an outbuilding, as I don't get along well with propane fumes because of my chemical sensitivities. I can use propane outside, and my house plans are for a separate enclosed patio type gas kitchen with propane, though I do plan to use a chemical hood type arrangement over the stove to reduce my exposures in cold weather. Otherwise, the room has cross ventilation from two outside walls and will be left open.

    Propane refrigerators/freezers seem impossible to find used, and are very expensive new. It would be a great temporary solution if I could find a used one. My long term plan is to remote the compressor of a chest freezer outside away from the house, and then bury a water tank 6 foot deep to use for ground source condensor cooling. Soils temps at 6 foot are 63 degrees here. This would allow me to have a more normal kitchen, with no noise and no EMFs. A local refrigeration guy is wiling to help with the remote compressor project which he says is no problem, technically.

    So that's where I'm headed but I need a temporary solution so I can live in my shop till the house is done and I have more time for such projects.

    If I coud find some help for the resonant transformer design, I think I could fix my existing inverter breadboard-prototype in just a few days work.

    Thanks again for your help, and good ideas!
    Bruce




  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Bargain AGMs

    Regarding a propane fridge, here is one place that sell Amish built units up to 18 cuft in volume... Price wise, not cheap--but may not be as expensive per cuft as the SunFrost units. But these big units consume a fair amount of gas (~0.35 gallons per day at 75F). And I agree, I would want any propane/gas appliances vented to the outside (this is after 20+ years growing up with gas range and pilot lights--finding out how much it smelled/stuffy when coming back for a visit.

    I don't really know anything about ferro resonate inverter/transformer designs--but they seem to be pretty wasteful of power since (as I understand) they run at least one part of the transformer core in saturation. But, I did run across one homebrew organization in Australia (google searching) that is experimenting with winding/building their own FR Inverters. You might contact them if it sounds interesting:

    http://www.arnsw.org.au/html/news_homebrew.htm (FR Inverter near bottom of page--may drop off in time).

    Have you tried blind and/or double blind testing of your EMF sensitivities? If you are doing the tests yourself--our minds are pretty involved in how we perceive (duh, obviously) the world and can mislead us towards false conclusions. Knowing specifics of your sensitivities can lead to novel solutions (frequencies--good/bad. Would a strong local DC field swamp small AC effects, using lossy ferrite plates around an EMI source better than simple wire/plate shielding, etc.).

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

    Hi Bill,
    Thanks for the lead on FR. The trick is to not run the transformer in saturation, but to use PWM to regulate the output voltage. I believe this is what Philtek is doing on their unit, I previously thought is was an original idea. So you need a fairly large capacitance on a separate secondary, and a feed back loop to the pulse timing. My present prototype circuit does not have the pulse width modifier built in, but I do have a circuit tested on spice that does (also 555 based timing). How it should be done is to use a PIC or similar microcontroller to do the pulse timing, with voltage feedback via A/D used to modify parameters set to the PWM registers. I don't know if I can handle the PIC assembly language to do this- it would be very time consuming to learn.

    Yes, I have been tested by a neurologist while hooked up to a QEEG machine (change noted but not as big as I was already significantly abnormal when near the QEEG computer), and also single blinded by a PhD medical researcher (could clearly distinguish 60Hz magnetic field vs EMX's white noice magnetics with 100% accuracy in less than 30 seconds) . Only a fool or someone outright delusional would spend so much time and energy solving a simple psychological problem, and I'm neither. I would wonder the same myself, no offence taken.

    Bruce M
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Bargain AGMs

    Bruce,

    I am glad no offense was taken--You know as an engineer you try to take all variables into account--and I have found through the years that humans are hugely variable. :-)

    I have a relative that is a very functional (runs own business) schizophrenic who believed, among other issues, that people were putting things into the food--well, family members were trying to hid medication (which did help the symptoms) in the food... The old joke, just because your paranoid does not mean people aren't out to get you.

    One question I would have is regarding your auditory sensitivity... I have read occasional accounts (over many years) about autistic children that seem to have specific frequencies where the child responds to even natural sources (like a storm sewer grate/lateral resonating at a very low frequency that the parent (don't remember exactly) could not hear (or could only hear standing right next to it) but their child became agitated over a block away. Auditory testing showed a extremely peaked sensitivity to sounds around the same frequency of the storm sewer.... I have also read about a few people that had success (reduction of autism symptoms) by testing auditory range and changing the patient's sensitivity to those specific bands (it was not stated--but I guess this was done by damaging the inner ear with intense noise at that frequency)... In some causes of autism, the theory was that the child could not develop normally because they never experienced enough silence to let them form thoughts.

    Round about way to my question to you... Is it possible that for EMI energy in, at least, the audio range is contributor to your medical issues? With most physical material, they will flex and could emit sound in response to purely electrical current/magnetic/voltage inputs--like, I think, you where using a EMX branded electromagnetic security door lock possibly giving you an audio cue. Do you have sensitivity to, for example, mechanical tuning forks (or for that matter, musical instruments--especially those with no fixed pitch steps, like a violin) to audio stimulations? Perhaps, in some cases, sound deadening of electrical appliances may help.

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

    Bill,
    The EMX test was with a "black box" with two rotary switches with about 12 settings each (for the blind part), with their circuity, placebo or 60Hz sinewave driving a heating pad. No audible sounds of any kind, not related to the EMX you're thinking of.

    Some degree of electrical sensitivity (ES) is common in people with serious MCS. (These also have diffuse brain damage seen in SPECT scans.) A few of the specialists (like Dr. William Rea and Cyril Smith, PhD EE) have published papers regarding the non-psychogenic characteristics of ES. I was not that impressed with the science, but at least it's something. My neurologist (retired now but former head of the VA neuro-psychiatry center in San Francisco) had seen and worked with enough cases over the years that he no longer assumed delusion. The growth of ES is now rather rapid, from the build out of the cellular system, and more widespread use of cell phones, I suspect.

    With AZ state rehab funding materials, I built (volunteer) a shielded computer setup for a disabled lady with ES who wanted to try and work from home via computer. She reacted badly to it and I started unplugging gear back at the remote computer end, with the incandescent backlight to her LCD display off, so she had no idea what was on. I got down to the remote cooling fan, with no gear on. She was still miserable. Fan off- she reported relief in 10 seconds. On- felt bad again in 10 seconds. I replaced the fan with a lower speed blower, suspended via spring and wrapped with insulation in the attic. She was then able to work with this setup for the last 10 years, including winning a internatinal "Resourceful Women" award. She had been unable to use conventional LCD or CRT displays with a remote workstation, but for years had only been able to use a non-back light monochrome Mac "Luggable", which when I measured it had the lowest EMF levels of anything I'd ever tested, by a couple orders of magnitude. She had no technical knowledge at all. This woman had grand mal type seizures from the sound of a vacuum cleaner or a microwave oven running.

    I've often run into people with ES who are determined that "EMFS" from remote fans and such are bothering them. So you're right on in that whatever neurogical pathway causes the problem can be equally well triggered by sound or chemicals or other stimuli. I'm well aware of this situation, and find that adapting a "something is getting to me" open minded approach with some good detective work is often fruitful. I worked at a research lab where half the staff were research psychologists; I do understand the design of proper research.

    Bruce M


  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Bargain AGMs

    Bruce,

    Sounds like you have the issues and possible solutions--as best as can be done with electrical equipment. I can't even begin to imagine how bad it would be for you and fellow suffers.

    I hope that there is not something in the genes or the (becoming more man made/influenced) environment that is causing more and more folks to become sensitive to our daily modern devices and living conditions... But I am far from hopeful. I do fear that this may become a Darwinian exercise where it is a race to the end between those hooked on oil/modern devices and those trying to exist on the margin (hunting-farming/Amish type lifestyle) against a background of limited resources and (IMHO) natural climate variability.

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

    I think the studies that show via PET scan grossly abnormal brain activity in children from just short use of a cell phone (brain taking I believe a few hours to recover) tells the tale. Our electrical technology is way ahead of our knowledge of biology.

    It may be that by specific modulation schemes, microwave transmissions may be made orders of magnitude less harmful. I do know that ES folks were a whole lot less affected by the old analog 800MHz gear than the new digitally modulated equipment.

    The same is true for power line magnetic fields; by adopting appropriate grounding strategy, ground currents could be eliminated, without complete redesign. In a few areas with Delta power systems, where the ground is separately derived on the customer (secondary) side of the transformer, there are virtually no ground currents, and homes have ambient levels below 2 microgaus away from appliance and the power panel.

    In Wye served areas (most western states) homes levels of 100 microgaus to 2000 microgaus are more common. A Wye system can be changed to a unigrounded wye with (mostly) just the removal of a bunch of ground straps and rod connections. This is as good as a Delta in terms of ground currents.

    Most electrical engineers don't realize that the power co. is using 100 year old grounding practice- every transformer in a Wye system has a "ground tie" jumped from the secondary center tap (neutral) to the primary neutral. So there is no transformer isolation for any load or distribution line, anywhere. You get just what any engineer would predict- ground loops on a regional scale.

    So in Western States and other areas with Wye power, the earth ends up carrying about 25% of the return current to the power plant. (This from a power engineering text- though power "engineers" don't know or believe this.) The earth has less inductance than the wires and now ends up carrying a lot more high fequency content, since the advent of switch mode power supplies. So you end up with elevated magnetic fields throughout most of the power service area, and some occasional strange readings in places where it follows creeks, mineralized aquifers, etc.

    I don't think Amish like lifestyles are needed, but in the case of microwaves and RF energy in general, we need some serious research, looking at endocrinology, neurology, immunology. We might need to freeze expansion until we know more. The proliferation of high speed power switching particularly concerns me; I suspect that some of the negative health aspects of "cell phone near the head" are not just microwave, but the high frequency magnetic fields ( 1MHz and rising ) from switching DC-DC converters in very close proximity to the brain.

    Bruce M
Sign In or Register to comment.