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Topics - BruceM

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Everything else / DIY single axis solar "tracker'"
« on: May 17, 2024, 07:49:42 PM »
Per Ade's request, here are some photos of my DIY single axis tracked arrays.

I have revised all my racks to (3) 2 inch, 0.10 thickness square tube rails for greater stiffness, having retired my original 800W rack and badly snail trailed 175W solar panels.  It was designed for seasonal tilt only with thinwall 1.5 inch rails and wasn't long enough for the 325 to 355 W surplus or used panels I can get locally for very cheap.

This is all part of my custom inverter upgrade, now with sufficient power to run my 1500W home cooler plus have enough power left over for all my other activities. The cooler works by chilling water for my in floor heat system, and that project was previously reported on here.

Under the solar panels you will see two aluminum boxes.  One of these is the Arduino Nano plus Accelerometer board for panel angle sensing, plus real time clock module and H-bridge board for driving the linear actuator.  The second box is unrelated to the tracker, and shorts out one of the 5 panels when there is excess voltage for the current load.  This pre-voltage regulator allows my simple custom linear PV current regulator to handle the new larger capacity input. The linear PV regulator uses 7 IGBT transistors, each with an op amp current sensing driver to evenly share the total current load.  My battery bank is nominal 125VDC, 10 100ah "marine" (lead calcium) batteries in series. 

The entire tracker system is powered by one very small 12V panel and a small AGM battery which is located 1.5 foot below grade in an 8 inch section of round galvanized duct with cap about 12 inches above grade.  The trackers are timed so that they all do their hourly movement staggered in time a couple minutes apart, keeping the max current demand to about 2 amps.  The real time clocks and tracker program of the Nano with specific data table for the individual array orientation are set via laptop and USB cable.  The manual motor drive cable can be used any time by just unplugging the 4 wire auto trailer plug at the Arduino tracker control box, and plugging in the manual cable.  Once the
Arduino is plugged in it checks current position versus table position for month and time of day, and motors the panel to the proper position.  The real time clock has a lithium cell to keep date and time when 12V power is removed.  As you can see in the photo of the tracker box internals, there is zero custom hardware, it is just wiring up of off the shelf components. There is no heat sink required for the H-bridge controller at the puny power levels (2A of 12V) required.  The Nano board provides the 12V to 5V linear regulation.  While the Nano is sleeping, power draw of the whole thing is < 5ma, if the Nano power indicator LEDs are clipped. 

The PV rack mechanicals are pretty simple and derived from older my seasonal tilt rack design.  I'm using 1/2 brass rods with steel split pins as the unlubed pivot points, with stainless steel washers to reduce pivot drag. Many here are very skilled in practical mechanical design  and will come up with there own solutions.  I am pleased with the results here.  It is very solid and does not bounce in the wind, and easily supports my weight and bouncing on the rack with very little movement.  I did all welding myself with my now 3 12V marine battery DC stick welder (with galvanized sheet strip resistor) and 3/32 6013 rods. It was a challenge but I did get the hang of it. MIG would be much better suited to the 0.10 inch wall square tube. 

At present to develop the data table needed for month, hour and position, I used a solar calculator service online to get the plots of sun azimuth and elevation for my location.  I built a scale model with digital inclinometer, and would set up the sun angle and azimuth pointing to the properly oriented scale solar rack, and then eyeball the best tilt angle of the array, reading the angle from the  inclinometer.  A very tedious process.  I then convert via table the angles to accelerometer units. 
A better solution would be to have a program which does this all for you given rack orientation and range of tilt, GPS coordinates and spits out the actual text data table to be inserted in the Arduino Nano program.  I have not done that as my programming skills are now quite diminished.

Having operated this for about a year, (the summer rack for a bit less) I am quite pleased with the cost, performance and reliability.  One design idea I have is to tilt up a version of the summer rack to say 45 degree inclination (I have a south facing hill handy) to do a "winter rack".  This would add to winter day performance but if the drive was changed to +- 90 degrees via gear motor and chain drive, it could also futher increase sunrise/sunset power all year.

I keep watching battery technology and may someday change to LFP or one of it's successors as prices continue to fall and performance continues to improve. 

Best Wishes,
Bruce M


Listeroid Engines / Vibration Sensor prevents Flywheel launch
« on: April 27, 2024, 05:23:48 PM »
My off grid Listeroid has served me well for 16+ years.  It gets less use now that I have expanded my PV system and designed an ultra low EMI inverter which does almost all the AC power generation now.
It still serves as air compressor when I need more air flow, often combined with the inverter powered air compressor.   

I implemented some serious idiot proofing (I have impairments related to MS and epilepsy.) when I installed it 400 feet over a small hill from my homesite. A site chosen for sound, before I found out about the lovely sound of the CS series which does not need such a distance or a hill.  I added remote starting and shut down, and monitoring of oil (high and low levels), temperature, rpm and vibration. It can still be run entirely manually.  I used the Picaxe 40X2 pin Basic running PIC chips to implement this, which predated the now prevalent Arduino. The control panel in my shop communicates to the Lister engine shed via a couple pairs of a 450 foot run of CAT5 cable, using a simple opto isolated 600 baud asynchronous serial current loop.

Wednesday of this week I was running the Listeroid for some Gast 1UP based yard trimming, and it shut itself down showing a vibration fault.  On inspection, I found the red vibration sensor indicator showing.  The flywheel tapered key was on the floor against the North wall, and the (unloaded) generator side flywheel moved outboard from the engine about 2 inches. The flywheel had rotated on the shaft about 1/4 inch at the key- and this had caused the imbalance before the flywheel walked outboard all the way off the shaft.

This happened after 16+ years of running, and that flywheel key had never been removed.  I had neglected to add a 2" split collar to block the key to this side...something I will be adding later today.

This is the second time that my idiot proofing has paid off.  Once before it caught a low oil situation.

How I missed this key loosening on my monthly service and manual start and why it did so after 20 years is a mystery.  But I'm glad I had been ambitious about monitoring of this remote but highly valued engine.  It could have been a very expensive and dangerous disaster if the flywheel came off the running engine and through the wall of my shed.   

For a vibration sensor I used a surplus industrial mechanical vibration sensor unit that uses a magnet and spring, and have it adjusted to JUST not trip during the normal start up vibration. Cheaper new sensors are available now but this one, bolted to the cylinder just below the head did the job nicely.

Idiot proofing saved this idiot.

Don't trust your flywheel keys.  Put on split collars!

Best Wishes,

Other Slow Speed Diesels / Still at work, original 6 hp Bamford
« on: May 14, 2023, 07:17:30 PM »
Ive been a fan of Bamfords since 38ac first showed one here many years ago.
I ran into this video that others might enjoy.

Everything else / DIY water chiller - reading suggestions?
« on: July 15, 2021, 08:34:35 PM »
This year's fires and record heat have forced my to re-consider adding a water chiller to my in floor heat system for some modest cooling.  Since the house is only 1100SF and superinsulated, and based on tests with my neighbor's home using well water, about 12,000 BTU would just do it, and that's within my daytime PV/inverter power of 1500W at 230VAC.  I only need to pull out about 4 degrees per day, my hot day heat gain which I normally can overcome with just opening windows at night.  But not when smoky or clouds hold in the heat at night.

I've read all about refrigeration systems and understand the principles, but lack hands on experience. 

Water chillers are grossly overpriced for their BTUs, using titanium clad heat exchanger assuming corrosive, oxygenated water.  My heating system is closed loop, so that's a non-issue and so I'd like to use a tube in a tube or stainless plate type exchanger between refrigerant and the in-floor, recirculated water.  This will require new tubing on the low pressure side.

I'd love to find a book or other resource so I can learn how to estimate the amount of refrigerant required after evacuating the assembled system. I would prefer to use a non-inverter mini split outside unit, or modified evaporator window AC unit  with 3/8 pipe run of about 6 feet to the plate heat exhanger. Issues I need to learn include  when to purge after brazing,  how to calculate refrigerant charge and lubricant, how to adjust the evaporator valve for optimal efficiency.

Any suggestions for good texts or websites?


I'm looking for the practical experimenter's guide to homebrew refrigeration, I suppose. 

Everything else / Lithium cell balancing
« on: July 04, 2021, 07:30:42 PM »
I've noticed that LiFePO4 cells direct from China have come down quite a bit.  So I've been researching how to best handle cell balancing for a 120VDC battery bank (39 cells in series operated from 119V to 132V. (3.4 to 3.05V)  I've got a few years to get ready for the switch.

I wondered if Starfire or anyone else might chime in on homebrew designs?  I am familiar with the various commercial  balancing products, but they generate a lot more EMI than I'd like.  The modest current, passive balancers are lowest EMI but still it is connecting a microcontroller with SPI interface to all the cells.

General Discussion / Batteries- Lead Calcium vs true deep cycle
« on: July 13, 2019, 04:56:21 PM »
My custom 120VDC battery charge management system was designed for 10- 12V AGM batteries in series, and has individual battery shunt regulators so that variations in batteries don't matter, and less equalization is needed.  I used cheap lead-calcium batteries (marine "deep cycle") initially for testing, and found that due to my very low average DOD, I was getting 4.5 years of service life. AGM batteries never came down in price so I've left well enough alone.  These Everstart (Johnson Controls) Marine batteries are stocked at the local Walmart.  They use so little water that I top them off annually, needing about a gallon of distilled water.  Low water use is one of the characteristics of lead-calcium.  They also have very low bulk taper charge characteristics similar to AGMs; as they become full, the charge current goes to well below 0.1 amps, typically below 0.050 amps.  This helps explain the lack of water use. 

I just added a T105 type (floor polisher battery - again "Everstart" by Johnson Controls though Walmart) 6V battery to my welder and am shocked at the difference in charge current.  The bulk charge current NEVER goes below about 2.2 amps, even if left on the charger, full, overnight.  I thought something must be wrong until I checked the Trojan data; they expect 2-3% of the C/20 to be the lower limit of charge current! 

I never fully technically appreciated the lead-calcium "Marine" batteries as I should have, since I was comparing them to AGMs and not wet lead true deep cycle batteries.  ( I use a 110AH AGM for my small 12V supply; I found 12 and 120V to be a very useful combination of home power). As long as you can keep your DOD below 20%, the lead-calcium seem to have good lifespan, good charge efficiency, very low water use.  They can also put out relatively high current, as I've found for the welder.   For my 120VDC system, currents are below 15A, usually well below that, which greatly improves effective capacity and efficiency.

It has been very educational to see how the T105 type 6V battery compares in a series application with the Marine (lead calcium) batteries.  While I have no doubt the T105 types will outlast them for the DC welder application, it gives me new appreciation for the Marine type batteries where DOD can be kept to modest levels for an expected service of 4-5 years.

Listeroid Engines / Propane Listeroid status- 1400 hrs
« on: June 17, 2019, 03:27:25 AM »
My neighbor with the propane converted DES CS clone just did an old change at 1400 hrs, last one was at 400 and it looked like it just came out of a new oil bottle.  At 1400 hrs today, he said it didn't look quite like new oil but it looked good.

The last 1000 hrs have been utterly problem free until my push rod kludge failed, and with the new welded extension to the push rod, he's back in action with full power again. So the keep to success for a propane CS is a CA110 carburetor, Garrett type regulator, and a hot spark module.  A special thank you to Gary at DES again for his awesome technical support on our conversion project.

I'm surprised there isn't a surge of interest in CS's for conversion.  ;)

Listeroid Engines / Propane CS clone power loss, welder fixed it.
« on: June 15, 2019, 11:17:21 PM »
My neighbor Jeff is the owner of the Propane modified CS from DES. He's been running it for the last 4 years with no troubles.  He mentioned he was having reduced power- couldn't carry both well and washer at the same time.  I suggested he check valve timing, as we had twiddled those to reduce exhaust/intake overlap to reduce propane smell in the engine room.  He did, and found that our extended push rod for the intake had failed. We had added 0.5 inches of aluminum spacer under the cylinder to reduce compression, so the longer exhaust rod worked fine for intake but former short exhaust needed a couple inches added. I had done weld bond kludge with some bits I had on hand; epoxied carbon fiber tube and added rounded end bit.  It had failed after 4.5 years, the carbon tube was now cracked as the ends pushed together, reducing the intake opening to only 4 mm from a normal 8mm.

I was thrilled to have a small welding project.  I had some rod of about the right diameter and welded on a new extension to the push rod. I used 7018 for the job, with some 6013 for finish filler.  It is very satisfying to have my new 24V battery welder put to good use, again. We installed it and reset the intake opening per the IO flywheel mark we put on (using 38AC's brilliant method), and now she's back to full power again.

General Discussion / Welding on clean DC
« on: May 25, 2019, 12:42:31 AM »
I bought a new group 29 "marine deep cycle" battery to give the clean DC, 24V welding thing a go. They are rated 385 cranking amps so a good match for 100+ amp welding current, and they are what I have in my 120V battery bank now.

I made a 600 uH choke from a gapped 1000watt laminated toroid core; 22 turns, 16 feet, of 6 strands of 12 awg. I gapped the core with a 10" abrasive chop saw blade in my table saw. I only lost 1/4" of blade on the job, but it took 4-500 gallon tanks of air to make the cut.  I filled the gap with steel filled epoxy. To save some $ on the trial, I used some heavy jumper cables for welding cables. 

The exciting news for me is that yes, I can do it. While regular welders have me running for the hills from EMI headache, this was doable for me.

Welding on 2-12V batteries does work, and as the article I found by a welding enthusiast stated, the choke makes it possible. When I bypass the choke, it's just not possible to maintain an arc and get the puddle going. Alas, I seem to be a bit lower voltage than I'd like- no such thing as long arcing with this setup!  7018 (3/32) rods were a bust, could not maintain an arc and liked to stick and melt the rod. 6013 (3/32) worked, best with positive on the electrode.  I'll have to set up some meters on volts and amps and get my neighbor to watch them while I do a practice bead.  I'm ordering some 1/8 rods- more current may have better arc length and stability.

I suspect the losses in the jumper cable are not helping, so I will pop for some fat and short welding cables.  I may also reduce the turns on the choke.  No need for that much inductance, but I goofed on calculations when shooting for 250-300uH.  Battery and all cables were cool immediately after a 6 inch test bead. 

I'm very rusty, my last stick welding was in 1974.  I think with some practice and some fine tuning of the setup, I can do my own welding again.


Generators / ST-3 is out
« on: January 22, 2019, 10:16:55 PM »
My ST-3 is out, won't operate on the harmonic winding system either, and flashing the FC dinn't change anything.  I did use the generator yesterday and it worked fine.  So far I'm baffled. The static (off) testing of brushes and slip rings looks good, field coil resistance is OK, harminic winding resisitance is OK, stator resistance winding is OK, my other various switches, fuses and relays OK.

Came in for late lunch, meds, and a study of the circuit diagram.  The bridge diode is a modern 800V unit so highly unlikely to have failed. I'll have to start using my handheld o'scope with a 15 foot extended probe lead and see what's gone wrong with the spinning harmonic signal while I stand outside.  It's cold, cloudy and windy.

General Discussion / snowed in, again
« on: January 13, 2019, 04:06:22 PM »
More cloudy and cold stretches this winter than we've had in 20+ years, and last night a forecast 0-3 inch now has turned into 8+ and still snowing this morning.  This just after the last snow finally melted.  I'll be on PV and solar hot water snow removal when/if it stops.  An alarming change after over a decade of milder, warmer winters (and hotter summers).   

Lucky for me a friend brought groceries 2 days ago. There's no county maintenance on our dirt roads here, it's DIY all the way.

Massive PV to the rescue.  With my additional 1500W, despite heavy overcast (though with snow on the ground assist) I've got plenty of power to charge.  By the time I finished shoveling snow, my main battery bank was up to bulk charge voltage. 

General Discussion / cold weather gear motor lube
« on: January 10, 2019, 07:13:30 PM »
I had a failure of the 5 rpm gear motor actuator which I use to control my projector focus.  Focus control is needed as the Qume Q5 focus is not temperature stable. it's a 24VDC rated little can type brushed motor I operate on 12V.  It stopped working when it got cold, even at 40F the motor would not start.  I use a modifed 2 channel IR receiver to control the gear drive, since I already have IR extender control of the projector.

I took it apart the failed gear motor and found the motor, brushes and commutator are clean, and the motor starts and runs freely at 12v in both directions.

So I'm thinking that the black grease which covers all the metal gears, and the worm drive which is on the motor shaft gets so stiff in the cold that the motor can't spin up.  Spin up is not aided by the two pole commutator. 

I'm thinking of cleaning out the grease and putting a bit of ATF on the gears.  I'm also going to boost the voltage.  I think there's some 19 or 21VDC for the projector I can use. This is not a high stress application and it only runs for maybe 30 seconds a day.  Any other ideas?

General Discussion / IDC connectors suck
« on: December 16, 2018, 11:45:10 PM »
I spent a few hours troubleshooting my remote fiber-cellphone hardware today. My memory is so poor it's a relearning project, though fortunately with pretty good documentation. The fiber-phone was a 2006 project, all hand soldered, no PCB, with a Picaxe M18 controller.  Ended up being one of the few Molex insulation displacement connectors I have left on that...on the 12v power to the solenoid that pushes the button to turn on the cell phone.

I never use Molex IDC connectors anymore, for good cause.  The contact to the wire is just not reliable over time. 

Not much fun working in the cell phone dog house when you're having a bout of Graves and your heart is going 100 BPM and your hands are shaking. 

Everything else / DIY Low EMF 5 step Sine Inverter
« on: July 29, 2018, 03:12:30 AM »
I thought I should play nice and quite stuffing this in Glort's PV -grid tie work.  While I did add 1500 watts of panels to my existing 875 for this project, I'm now down to the inverter work.

A little review:

I live off grid and have lived with my own 120VDC system and Listeroid for AC and compressed air for a long time.  In preparation for adding inverter power to my system, I upgraded my 120VDC PV charge regulator to handle up to 3000 marketing watts of PV.  It's linear, not pulsing, for very clean DC.

My 120VDC input inverter design is based on the venerable Trace SW series which does low frequency switching of transformers with secondaries in series to create a sine.  That general concept is about all I'm using.  I'm using very soft (slow) switching plus snubbers and minimal passive filtration to generate AC with no audible (via AM radio) EMI on the AC or DC supply.  I'm only using 2 transformers of equal output secondaries, and they are used to make a 5 step sine wave; zero plus two steps up and two steps down.  I originally did a 7 step sine but found 5 step better. The 5 step sine gets the THD down below my ST3 generator head, and eliminates the typical 20% motor heating loss of a MSW inverter.  I use 120VDC for my home and shop power, and have been using a Listeroid 6/1 for AC generation for well pumping and washing machine.

I have previously done quite a bit of testing of the prototype on motor starting at 120VAC output; it would start a 1.5HP tile saw like grid power, instant and effortless.  I ran into a bunch of trouble when I switched transformers for 230VAC output; ultimately I tracked it down to huge inrush surge current.  Until I worked up a software solution of soft starting the transformers, I could only test by starting the processor and H-bridges with 0 volts input, then switching on the 120VDC through two huge chokes and 30K uF of DC filter caps. This provided a slowly increasing voltage which kept inrush current minimal. The massive DC filter was needed for keeping AC off my clean 120VDC. With the filter in place, I now have 1 millivolt of AC ripple with 1000 watts of load.  Backfeeding 230VAC to my step down transformer outside the shop, I've run a couple loads of laundry in the washer (about 1100 watt load also) with no trouble and barely warm heatsink on the H-bridges.  I've also been testing with 500, 1000, and 1500 watts of heat lamps in the shop.

I got the prototype jury rigged on the floor of the battery bank shed and then found that due to my new short 120VDC supply wires to the 10K uF fiter output capacitor, the old Antek transformer inrush current problem came back and bit me.  I should have tested with small fuses, but I got cocky...with 4 mosfets, 3 ICs, and 2 transistors fried the result.  I got it repaired, changed the soft start to extend from 50 usec to 5 millisecond pulses, and now she starts and stops nicely on small fuses, again.

Tomorrow I'll test on my 1/2 HP Franklin submersible well pump. It pumps from a depth of 200 feet.  It normally runs at 1150 watts, with starting peak over 3400.  The issue to be tested will be surge load capability and compatibility with the operation of the Franklin QD solid state capacitor start relay.

Listeroid Engines / Icreasing rpm of 6/1 with SOM flywheels
« on: January 11, 2018, 02:35:02 AM »
I'm thinking of leaving my 6/1 on diesel for now instead of doing a propane conversion.  My new SOM wheels are 25  inch diameter so I must increase the ST-3 pulley size.  Since it worked out well for my neighbor's machine, I'm going single B belt.

At the same time, I'm considering a modest increase in RPM- say to 700 (ish) rpm.  This will benefit my air compressor which was being driven well below it's max rated speed. 

Are there any hidden surprises I should be thinking of?  My 6/1 has the iron piston.  Adjusting counterbalance weights on the new SOM wheels for a smooth run isn't be a big deal for me.

The B belt riding flat on the flywheel gives it an effectively large diameter compared to belt on the pulley vee shoulder.  So 1800 rpm at ST3 over the pulley ratio of 25.6"(SOM flywheel effective dia with B v-belt and no grooves)/10 (pulley size at ST3) gives me 1800/2.56 = 703 rpm engine speed.  A 10.25" pulley should give me 720 rpm. Either would be OK for my air compressor speed with existing 19" drive pulley.

Any helpful thoughts or gotchas I'm missing?

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