My experience

[farmerjohn]

Hello all!

Long time lurker - first time poster!

I have a powerline 6/1 that I run 24/7 from WVO.  It has approx 6000 hours on it and going pretty strong! - thought I would share my experience

I change the oil once a month and in between add a liter or so every sunday and check / adjust the valve clearance - other than that - I don't really do a darn thing..  it just keeps chugging away and I do not really think about it. I dump the waste motor oil into my WVO tank thats waiting to be filtered by centrifuge which I do once per month
The waste vegetable oil that I use is delivered to my farm once per month for free!  I then let it settle for a couple of months and then run it through the centrifuge.  I do it in 1000L batches at a time - once per month

I paid about $1200 Canadian dollars for the listeroid and about $400 for a 5KW chinese ST genset - pretty cheap if you ask me.  I have that coupled to my solar power system via a bridge rectifier and a capacitor bank that then gets fed into my charge controller 300 feet away in the house.  I cranked the voltage up on the AVR to 250V before going into the rectifier.  Under no load the charge controller sees about 360VDC.  I do not care much about frequency or voltage since the charger can work with upto 600V and will auto adjust for the best efficiency.  Under 3600W load the voltage dips down to about 275VDC.
I have a 10KWH capacity battery bank as well as a net metering contract with my utility company.  I keep the batteries topped up 100% and send the excess into the grid for credits.  The grid and batteries act as a capacitor when large loads come on that the solar + generator cannot support

Since a full rebuild kit is less than $400 - my plan is to run it into the ground and then rebuild it when it dies.  So far it has more than paid for itself, my electricity bills used to be ~$600 per month.  They are now $0 with net metering credits to spare! 

I run the engine with high compression since most of the time it does not see a full load.  At night my loads go down to under 1000 watts while during the day they can average 3,000 watts.  My solar system allows me to communicate with it via Modbus over TCP.  I wrote a small python script running on a raspberry pi that will constantly adjust the charge rate of the generator's charge controller in order to maximize my solar when its available.  With that in place - my fuel economy is fantastic - I average 0.75L per hour during a 24 period

I made several modifications to run with WVO
1) I advanced the injection timing to 25 deg BTDC
2) I Increased the injector pressure to the maximum
3) I preheat the oil with a copper coil wrapped around the exhaust pipe which the oil flows through before the pump

Basically I followed the findings in this paper I found: https://www.slideshare.net/XZ3/a0018-12759205

I also use the waste heat from the head and the exhaust to heat my house.  I put a stainless steel swimming pool heat exchanger on the exhaust and buried 300 feet of Logstor insulated pipe from my barn to the house.  The coolent starts in an old hot water tank, enters the cylinder head via a thermostat or goes though a bypass, then into the exhaust heat exchanger, then to the pipe to my forced air furnace where I have a heat exchanger that is the same size as my old filter, it then loops back to the hot water tank.  Last winter it cost me close to $6,000 on propane to heat my house.  This year it has only been approx $1500.  A major savings!  The lister is not able to fully heat my house in the coldest of days but it does a great job most of the time.  I keep the furnace fan running on low 24/7 in the winter.  My house is 2900 sq/ft

This project has been a great deal of fun and I love being "off the grid".  Thanks to all of you who have posted to this forum - I have learned an incredible amount from it and cannot wait to do the rebuild!

Let me know if you want more details about my system

John

[dieselspanner]

Hi John

Nice first post, thanks for all the information.

It's good to hear the whole story in one post, there's nothing like the 'big picture'!

Cheers Stef

[mikenash]

Very interesting, John.  How has the reliability been with that ST clone?  Cheers

[farmerjohn]

Very interesting, John.  How has the reliability been with that ST clone?  Cheers

So far it has been rock solid!  I do wonder about its longevity though..  with my rectifier setup the power factor is only 0.7 and it is rated for 0.8.  I'm wasting power to heat

I have an old online UPS system from work that at some point I plan to gut.  It has active power factor correction built in.  I can tap into the high voltage DC side and feed that into my charge controller..  or so I hope

Or I am thinking about ordering a couple of these:
https://www.digikey.ca/products/en?keywords=AIF04ZPFC - they can be tied together to act as one bigger suppply

Only issue is they are very expensive!  I've found clones on ebay from china for a fraction of the price..  not sure if its worth risking it

[BruceM]

Marvelous setup, John. 

Your suggested PFC DC supply is one way to improve your PF though the typical 15% loss at the power supply may make it an exercise in futility. Given your choice of the ST-5, and your 3000 watt load  I don't think the PF penalty more than 20%.

The simpler and more efficient approach is to add a BIG choke (inductor) after the bridge.  One of the custom toroidal transformer companies makes these to order and could help you specify it.  They will need your minimum and maximum load currents.  But since PF is less of a concern at low loads, this helps greatly since you can then design the for the smaller size of the large typical load.  You must have at least the critical value of inductance for that load to get high PF. The critical value is:  L (henries) = E (volts) / I (ma)  You may want to crank up your voltage even higher, depending on the lower voltage limit of your charge controller, because with a properly sized inductor, your DC voltage out is the same as the RMS AC voltage, instead of 1.4 times the AC voltage. 

I'd like to learn more about your heating a distant house with the exhaust heat of a Listeroid.  Especially with a 600 foot round trip in minimally insulated pipe.  What is the water temperature at the radiator in the air handler and what is the flow rate?  Many of us have considered this application but were daunted by the likely losses.  What is the soil temperature and/or your winter climate like?

[farmerjohn]

Bruce,

Thanks for the insight!  I've thought about a choke as well.  My generator is a "Wuxi Dingol DG164B26" and seems to be very well built with a SX460 AVR.  My capacitor bank consists of 2 X 10,000uf 400V capacitors in parallel.  Without them the charge controller gets all confused and only draws about 300 watts.  If this generator ever craps out I will upgrade to 3 phase to get cleaner power from the rectifier.  In the meantime - I have one of these to play with and take apart: http://www.apc.com/shop/us/en/products/APC-Smart-UPS-RT-3000VA-Rack-Tower-208V/P-SURTD3000RMXLT3U  It has a 400V DC rail inside - I'm thinking I can just tap into that and it will auto adjust close to unity

As for the heating - I use "Logstor Dual PEX-Flex" insulated pipe with a 1 inch inner diameter.  The heat loss is pretty minimal, only about half a degree.  I live close to Niagara falls in Canada.  I buried the pipe 4 feet below the surface.  That pipe was very expensive - around $5K Canadian dollars plus the cost to install it. I installed it myself by renting a mini backhoe - took me a couple of days. I have it filled with a mixture of propolene glycol and water.  It holds about 400L total.  I have a waste oil boiler waiting in the wings if the lister was not able to work.  Was a good gamble.  Although I may tie the two together at some point in the future to get off propane 100%. 

If I have the generator pumping out a full 3000+ watts for a sustained time, I will get approx 120-140 degrees F to my heat exchanger.  My exchanger is 15"x20" and fit directly in where my old furnace filter sat.  My furnace had one of those really thick box ones.  I still have room to fit 2 X 1" standard paper filters in front of it.  The registers will reach about 90-100F.  It takes a few hours to build to that.  I just checked it right now and the incoming water is only 80F and about 70F coming out of the floor registers. But its been running at very low load for the past 4-5 hours.  The temp in the house is 63F and I have not noticed the propane kick in all day.   Its about 37F outside right now

One thing to note - I keep my house at around 62F in the winter.  Pretty cold to some but we like it.  The lister is not able to keep up on colder nights.  I have 2 thermostats next to each other.  One will turn the furnace fan on / off on low speed and is set for 62F.  The other is set for 60F and it will turn on the propane heat on high.   With the lister in place, I burn far less propane.  If my house was half the size or better insulated - I feel that it would easily keep up.  The key is to run everything 24/7!

I have no idea what the flow rate is.  I have a 3 speed groundfos circulation pump - I have it set on the lowest speed.  All the tubing is 1 inch.
The soil temps I think are around 50-55F - not sure

Once the warm weather rolls around I will divert the heat to a radiator outside the barn close to the lister.

John

[Tom]

Hello John, A Listeroid also powers and heats our off-grid home in Northern California. One thing you might try is using an inexpensive 3 Ph motor for a generator. Since the charge controller is rather flexible about input voltage, these seem like they might be ideal. That was my plan to replace an ST5, but I was given a balancing transformer that solved about 98% on the issues I was dealing with.

We have a concrete floor with a hydronic loop and the generator shed is right next to the house.

[BruceM]

That was a heck of a trenching job, John, glad it's paying off.   I agree with both you and Tom, three phase is the best way to go if you want DC output.

[farmerjohn]

Hello John, A Listeroid also powers and heats our off-grid home in Northern California. One thing you might try is using an inexpensive 3 Ph motor for a generator. Since the charge controller is rather flexible about input voltage, these seem like they might be ideal. That was my plan to replace an ST5, but I was given a balancing transformer that solved about 98% on the issues I was dealing with.

We have a concrete floor with a hydronic loop and the generator shed is right next to the house.

Tom,  that is good to hear!

I thought about using a 3 phase motor as well.  I have a 575v 5HP 3 phase motor sitting in my barn - I am tempted to start playing around with it.  It came with a 100 gallon 2 stage air compressor that I bought.  I replaced it with a single phase 240v

Looking back - It would of been more economical to build a shed next to the house instead of laying that pipe - live and learn I guess

[Tom]

575 is an unusual voltage, can it be reconnected for 240 or 480v? That would allow the rectified DC to go straight into the charge controller, assuming it's a 600v model.

[BruceM]

Glort- No way you're going to PWM to a capacitor to make it a "variable capacitor" for a motor/alternator rig, I agree.  An Arduino switching in motor run capacitors via solid state relays based on voltage and current is quite a practical and low risk project, I think.  There is code out there for RMS voltage sampling, and you could sample a current coil as well.  But admittedly not a project for a beginner.  There are also RMS voltage converters on an IC which elminates the whole real time software sampling and calculation bit.  I tried one, only trouble for my application was it was slow and took about 100ms to get a good read.

[BruceM]

Digikey here in the US carries the RMS to DC converter IC I used.  It works well, just takes about 4-5 AC cycles to slowly change to the new value. So remember that when designing the software to change the capacitors- wait and go slow or you can create and oscillator.

https://www.digikey.com/product-detail/en/analog-devices-inc/AD737JNZ/AD737JNZ-ND/751029

The trick with switching in capacitors would be to have 3 caps, each twice the value of the last.  Then hook them up to the 3 least significant bits of say PortD and you can get 7 levels of capacitance on top of whatever your minimum always on cap is.

The typical Omron solid state switch takes 1 msec to turn on and up to 5 to turn off.  So don't be in a hurry and expect a bit of a bobble in capacitance vale until they settle.  I don't think that should be a problem for this application.

Some googling on Arduino and RMS voltage should show you some other more software intensive approaches to RMS voltage calculation. 

Best Wishes,
Bruce

[BruceM]

You can't really do PWM with most SSR's.  Look carefully at the spec sheet for on/off times.  Some allow slow (10KHz) PWM, most cannot at all.

A dump load as a solution for a generator regulator seems rather counter productive to fuel efficiency, but I don't have the big picture. 

[millman56]

Posting links is beyond me but if you google "Induction Motors As Generators"  a scan of that book by N. Smith comes up, although this book is about micro hydro schemes in which dumping electrical load is not an efficiency problem, the mark-space load controller described in the book could work on an engine driven IMAG so long as the ballast load was used for heating, as suggested by others.                                                                                                                                                                                                                                                                                                                   A financially humbling experience with my mk1  induction motor generator, was frying a £435.00 circuit board on a packing machine due to overvoltage, a salutory lesson  about having some basic instrumentation when tinkering with electricity.

Mark.

[BruceM]

I don't think an AVR is worth much for IMAG regulation.  They are designed to supply or not (in rapid succession) current for excitation.

Most of the AVR's don't regulate RMS voltage, they just regulate based on the averaged peak voltage.  This is accomplished with bridge rectifier, resistor voltage divider, small capacitor.  Sometimes a small transformer is used to provide and isolated AC voltage proportional to the output. (I prefer the transformer approach for immunity to line transients and safety.)  Non-RMS regulation becomes a problem only with a crappy PF load like a high current battery charger or some other monster switching supply that chops the top off the AC waveform. 

On the bargain instrumentation front:
I recently used an OWON dual channel, 25MHz bandwidth usb scope with built in usb isolator. It was $100 on Amazon.  It would be a good tool for someone not ready to invest in a good bench scope, and the build in isolator makes it safer to use around higher voltage AC. It worked pretty well but the software to make report/development notes screen images was shoddy.  (Saved images are fine to view on the computer.)  It is also a bit sensitive to EMI from nearby equipment such as switching supplies, which shows up as low level noise in your signal.  It was good enough that I kept it for backup rather than return it.

I then bought and do prefer the Picoscope, but they require an external usb isolator and are twice the price.  I have the 25MHz Dual Channel Picoscope with built in 16 bit logic analzyer ("MSO" feature) which is perfect for my low frequency design sine inverter project which has both digital and analog. The Picoscope software is a bit more complex to operate but wow, the features include the ability to do THD measurement (and spectrum analysis, RMS voltgae, etc.).

I do have a high bandwidth dual trace analog scope, but I very rarely use it.  With the Picoscope I can capture a big buffer full of data, then scroll through it looking for my problem- expanding and contracting the timescale to see details as needed. You quickly learn to use and depend on the features of digital storage scopes.