Micro 12VDC Generator with a Cox .049 Sure Start Diesel Engine

Maybe easier to hook it up to a brushless outrunner, especially for a test run of the theory.

Here's one using an outrunner.

RknRusty wrote:Welcome to CEF, Steven.
Is this intended to fit into a backpack? I don't have as much experience with diesel efficiency compared to glow fuel. Is it necessary to have a throttle to keep the rpm in the peak power band as the load changes? For instance adding and removing devices makes the generator harder or easier to turn. That Surestart, probably puts out 50 or so watts at full scream(.06hp, I'm just guessing). You think it will turn that generator hard enough to support the fans and electronics, as well as a 12v/25W supply plus a 5v USB port? A drained laptop battery is going to seem like a bottomless pit to it, but if you can supply enough fuel I'd be curious to see it work.
Rusty

EDIT: I see you wrote a bunch while I was posting. I'll go back and re-read, maybe you answered my questions.
Rusty

The generator is intended to fit in a backpack and be very light even as a prototype. Future developments may greatly reduce the project. One of the main space consuming parts is the 1L tank which can be replaced with a lower volume tank.

Diesel engines consume 30mL per 15 minutes when adjusted properly and without any other load than the air resistance generated by the air and an 8 inch dual blade propeller. However, The consumption may be decreased at lower RPM. Also, however, to increase reliability, burning rich mixture at low compression may be preferred by the user which would increase the consumption of fuel even at lower RPM.

On the prototype, the air valve ( the throttle ) is controlled by a guitar tuning machine, a standard fishing cord, a tiny fishing hook and a spring. The spring tries to pull the throttle ( air valve ) lever down while the guitar tuning machine can pull the lever up to any desired position between fully closed and fully open continuously. Of course, there are standard linkages and even props which can be used.

The DC generator ( dynamo ) can generate a given power at given load at given RPM.

In case the load is constant, the higher the RPM the higher the voltage and power generated by the generator. The higher the power the higher the load which the generator puts on whatever rotates the generator.

In case the RPM are constant, then the generator can provide a given voltage at zero load. With the increase of the load to the generator, the voltage will decrease and the load which the generator puts on whatever rotates the generator will increase.

When nothing is constant, then with a given load at given RPM the generator will generate a given voltage and power. When the load to the generator increase, the voltage and power of the generator will decrease and the load to the engine will increase and the engine RPM will decrease. The RPM of the engine can be increased manually. Thus, the voltage of the generator will increase as well as the power.

The prototype will not have any manual or automatic gear shifting nor any electronic system to maintain a given voltage by adjusting the controls of the engine. Such can be done in the future but can only be done in an appropriate environment.

The pulley system can be calculated to reflect the most usual cases.

One way to calculate the pulley gears is to start from the bottom up : The minimal engine RPM for stable work can be measured. The RPM of the generator necessary to display the minimal voltage at zero load can also be measured. Thus, the pulley system can be calculated to provide the minimal voltage at the minimal engine RPM. Load to the generator will bring a load to the engine which will bring a decrease in the RPM. The RPM will be increased manually to be able to provide the necessary RPM to the generator to generate the desired voltage for the load which will hopefully be possible otherwise the pulley ratio has to be changed. The problem for the bottom up approach is the pulley ratio is not calculated to reflect the most usual cases ( the nominal work of the system ).

The top down approach is very similar : The pulley system is calculated to provide the maximal RPM for the generator to generate the maximal possible voltage at zero load at the maximal RPM of the engine. Then, the engine RPM can be decreased to provide the desired voltage for a given load. The disadvantage of the top down approach is the same as the disadvantage of the bottom up approach.

Another way to calculate the pulley system is for the most general case, the nominal case. Then there is a range around to teak for different voltages and loads. The RPM to power function of the engine is best to be known or can be approximately measured. The RPM to voltage to load function of the generator is best to be known or can be approximately measured.

Here is an example : The engine can provide 50W at high RPM. The nominal voltage of the generator is desired to be 12V to cover most of the cases and 12VDC is used by many convertors which are plugged in cars. Thus, the pulley system can be calculated for the engine to provide the necessary RPM for the generator to generate 12V at zero load in such a way, so the engine works at low RPM but not at the lowest ( so the engine can provide other popular volatges at most popular loads, such as 5V, 10 to 15W ). When more load is added to the generator, the RPM of the engine must be increased ( but not to the highest and not very close because other popular voltages such as 15V, 16V and even 24V can also be provided at a variety of loads ), so the generator continues to maintain 12V for very large loads.

The characteristics of the engine as well as the generator are not known. The engine must be able to supply 24W even at low RPM because the maximal power of the engine is 50W. True, every engine can generate different power at different RPM at different load.

The power maximum of the generator is unknown but is supposed to be higher than 24W, probably less than 50W.

I am pretty much sure I would be able to get more than 24W, 12V and range the voltage between 5V and 24V with power output at the extremes 10W to 15W.

The blowers are mainly used to reduce the heat on electronics components and have a wide flow output which is not very powerful yet may be of assistance to the engine. These consume 0.72W at 12V each.

The computer chassis fan consumes 1.8W at 12V. The problem with the PC fans is they are very large : 12cm square but may be OK.

The output of the generator is adjustable manually by adjusting the air valve ( throttle ), the fuel needle valve and the compression. To adjust these to display a given voltage for a given load, an ampermeter and a voltmeter are provided at the output and therefore a wattmeter too as power is the product of voltage and current.

Attention must be paid the controls not to became too sensitive.

I think a 25W consuming laptop battery can be charged with this generator even with a battery charging control system designed to only charge at 12V and not less. Without such a restriction, the generator can start to charge the battery at lower voltages and then adjusted to be not more than 12V.

As the battery gets charged, the power consumption may decrease although the battery voltage increases because the current through the battery is supposed to decrease more.

Power monitoring and protection electronics may be done as a next stage of the project but are not necessary as a non regulated power output is sufficient for most or all applications.

USB ports are not a problem as most devices for these are designed in accordance with the USB spec which postulates the maximal power consumed from the USB port is 5V, 0.5A, 2.5W.

Also, the power output at lower RPM of the engine depends on the fuel too.

The DC generator which I use is RS555. This can be easily replaced by another one. I would like to use this for the prototype and, may be, for the rest because these are the most popular and available everywhere.

Admin wrote:Here's the link to StevenStanleyBayes' Document

I downloaded it and skimmed it, I'll need to fully read it later.


I had an idea similar to yours. Basically to build an .049 powered flashlight that could be also used to output 5vdc to power and charge USB devices such as a cellphone. I would use a car engine with a pull start for ease of starting and because of the clutch that disallows it from running backwards. A good 10+ years ago a stand that was selling gasoline generators out at the Minnesota State Fair had a Cox Babe Bee fitted with a big flywheel connected to a gearbox that was spinning a small ac alternator that could power a few flashlight bulbs and I think they even had a handheld TV hooked up to it. I regret never getting a picture of it.

I don't recall what the average horsepower of a standard Cox .049 engine is but you can't load these down too much before they kill. That would explain the gearbox on the one I seen at the State Fair, needed to increase the torque.

Without measuring, from what I have experienced Cox .049 SureStart Diesel has so much power at low RPM so when I put a hand on the way of the propeller, I got cut and started to bleed and the engine continued to run as nothing happened. Not the best way to measure the power outpu I would say.

I like your design. I am happy this works.

I have also had the idea to make a mini ( not micro ) generator which would use a standard, pull start grass trimmer engine. You can get a gas trimmer for $80 and get rid of the grass trimming stuff and put a generator to get a good power output.

Obviously, Cox engines are much more original and better. Also they are much tinier and lighter. Your generator may as well be lighter than a solar panel and works even at night.

Anyway, so far, from what I have been reading on the internet, you hold the first place for original idea to make a generator from RC engines.

I have been looking at pancake generators which are available from China and USA BUT at a huge price, even the ones from China.

The best generator I have seen for the project is a YAF 54 from China. However, the price of this is around $70 after postage. Obviously, I think, this does not make sense even for a prototype. A huge company, however, can purchase thousands of them for probably around $5 a piece, easily for $10.

WingingIt74 wrote:Maybe easier to hook it up to a brushless outrunner, especially for a test run of the theory.

Looks good but, probably, very expensive. So is YAF 54 alternator.

Here is a link to Steven's thesis:

https://www.dropbox.com/s/s9p8yamjp65mppd/Cox%20.049%20SureStart%20Diesel.doc?dl=0

WingingIt74 wrote:

Looks perfect. Happy to see this. Yet another contender for who has been the originator of the idea of RC engine generators! : )

WingingIt74 wrote:Here's one using an outrunner.

Happy to see. Looks like using and RC engine. Yet another contender for who has been the first. : )

The generator, however, is rather large, otherwise OK. I use dynamos and not alternators with brushes and not brushless because of the price.

The originality is here but the grass trimmer engines can be very tiny too. Yet the RC engines are much tinier and more original.

WingingIt74 wrote:

Also perfect but the exhaust ( back blow pipe ) and the generator are rather large. The exhaust can be gotten rid of but the generator will continue to occupy lots of room and be heavy.

StevenStanleyBayes wrote:

WingingIt74 wrote:

Also perfect but the exhaust ( back blow pipe ) and the generator are rather large. The exhaust can be gotten rid of but the generator will continue to occupy lots of room and be heavy.

Also, the engine looks rather large and may as well be a similar size to a grass trimmer engine. Still better than Honda.

WingingIt74 wrote:On Pg 71,
The engine that you are using will run both clockwise and counter clockwise.  Only the Tee Dee or the RR-1 will only run one direction.

True. Sow after the engine is 100% symmetrical inside. This is from what I can see from the outside. I now remember I wrote something on going one way only. This is because I was unable to see the crankshaft well and looked like a one way propeller. After I fully disassembled the engine I saw the crankcase is 100% symmetrical.

The spring and the nut, however, can start the engine one way only.

Will have to correct the document although I forgot where I wrote this. For now, will put this in a correction file to do in a while.

WingingIt74 wrote:If you don't mind me saying, after briefly reading your document, don't get stuck on the diesel power.  Get the project put together and operating, then switch to diesel.

This is an excellent advise which I fully agree with. I better get the things running and then try to experiment with fuels. For now, I can run the engine on standard fuel. Also, I will have a better stand when I put everything and thus, I will have two free hands to put alternative fuel while the engine is running.

Still, in case anyone knows anything of biodiesel such as the fuel components and percentages as well as the settings of the air valve ( throttle ), fuel needle valve and compression, I will be happy to collect this information for a future use.

Also, has anyone been able to start the engine on biodiesel or put biodiesel while the engine was running on standard for the engine fuel?

microflitedude wrote:Here is Steven's thesis:

https://www.dropbox.com/s/s9p8yamjp65mppd/Cox%20.049%20SureStart%20Diesel.doc?dl=0

 you Almost live close enough for me to visit ,, that is a lot to read man I will wait for Steve's reply !!!! Eric O yea THANKS !

WingingIt74 wrote:Also, you mention later about oils.  Castor oil is necessary in the operation of COX engines, to protect the moving parts, as it will leave a residue.  Similar to lead in older gas for the valve seats.

True Castor Oil creates a protective film which clings to metal. However, I am slightly concerned with the residue.

True, certain amount of residue would protect the metals. However, a great amount of bur caused by burning organic materials may even get the piston stuck in the cylinder.

This is why car engines are preferably de burred either by chemicals ( including cleaning oil at oil change ) or mechanically at engine rebuilt or reconditioning.

However, Castor Oil burns at huge temperature and hopefully would never burn in a Cox engine.

Some people on the Internet replace Castor Oil with high temperature synthetic oils but these are difficult to find and extremely expensive.

WingingIt74 wrote:

Happy to see. Another contender. : )

Take a look at those little Ohlsson & Rice Tiny Tiger generators. https://www.youtube.com/results?search_query=O%26R+tiny+tiger I believe they are the smallest gasoline generator ever put into production. I see them every so often at antique sales for $200+, always wanted one just to play with.


The second smallest would have to be the Power Pony, https://www.youtube.com/watch?v=smm4kP3zn1M

StevenStanleyBayes wrote:

WingingIt74 wrote:Maybe easier to hook it up to a brushless outrunner, especially for a test run of the theory.

Looks good but, probably, very expensive. So is YAF 54 alternator.

Take your pick, they are pretty cheap.
http://www.hobbyking.com/hobbyking/store/__517__59__Electric_Motors-Outrunners_by_size.html

StevenStanleyBayes wrote:

WingingIt74 wrote:Also, you mention later about oils.  Castor oil is necessary in the operation of COX engines, to protect the moving parts, as it will leave a residue.  Similar to lead in older gas for the valve seats.

True Castor Oil creates a protective film which clings to metal. However, I am slightly concerned with the residue.

True, certain amount of residue would protect the metals. However, a great amount of bur caused by burning organic materials may even get the piston stuck in the cylinder.

This is why car engines are preferably de burred either by chemicals ( including cleaning oil at oil change ) or mechanically at engine rebuilt or reconditioning.

However, Castor Oil burns at huge temperature and hopefully would never burn in a Cox engine.

Some people on the Internet replace Castor Oil with high temperature synthetic oils but these are difficult to find and extremely expensive.

Cox engines were designed to use castor oil. Synthetics are very hard on these little engines, they won't last long.... which brings up an interesting thought. What is the "Lifespan" of a Cox engine, especially the difference between constantly running or intermittent runs (normal operation).

[quote="Admin"]Take a look at those little Ohlsson & Rice Tiny Tiger generators. I believe they are the smallest gasoline generator ever put into production. I see them every so often at antique sales for $200+, always wanted one just to play with.


The second smallest would have to be the Power Pony

These are very nice. Ones built with RC engines are supposed to be tinier and lighter.

In case you would like to have one of these as on the videos or similar, you do not need to go to antique sales. All you need to do is to purchase a brand new grass trimmer for $80 and get rid of the grass trimming stuff. Then you have the engine and the tank. For some tiny electrical load, you may be able to use the magneto of the engine directly. However, better for you is to purchase a 72W DC generator ( dynamo with brushes ) for around $20 from eBay ( brand new Johnson ) or a YAF 54 alternator ( $33 from China and another $33 for mail ). YAF 54 is a brushless alternator which is quoted to give between 50 and 100W at 12V.

You can easily assemble these and drive them with a belt and pulleys. You will not have the automatic control system though, the one which will adjust the RPM as per the load. You can build this or you can just leave the output unregulated and put an ampermeter and a voltmeter each for around $4 from AliExpress and eBay. Thus, you can adjust the output manually. Obviously, you will have to readjust the output for loads which change with the use. Most of them do not or not significantly.

I call these generators mini generators and the ones with RC engines micro generators. You can even put a more powerful alternator or dynamo on the mini generators and with a help of a switching power supply, you can even get 120V or 220V ( in case you are in Europe, 240V for the UK ) AC 60Hz ( 50Hz for Europe ).

However, instead of building a switching power supply, you can use the generator to give you 12VDC at a give power and then use standard car voltage 12VDC to house voltage 120VAC, 60Hz ( in North America ) converters available at the auto shops for $20 and more. The price goes up with the power.

In Canada, a shop which will sell these convertors is Canadian Tire. In the US, this maybe Auto 1 Parts or something alike. Walmart USA can also sell them.

The convertors which are not very powerful ( a few tens of Watts ) will not take too much room. The size increase with the power.

The trick with mini generators is they are standard and use standard engines which everyone knows and knows how to start the ( pull start ) and how to run them and maintain them. This because everyone in North America has a lawn mower, grass trimmer, chain saw, a bike for children, a cart for children or anything else powered by these engines. I saw on TV one made a kitchen mixer with one of these engines. I am not sure how important a mixer is for outdoorers bu I saw the mixer running and mixing and cutting fruits and vegetables.

Thus you will have a standard generator and this may even be less big than the ones on YouTube because modern grass trimmer engines are tinier and lighter, usually, fully built by Aluminium or alloys.

I have been fascinated with these and was thinking whether to build one of these or with an RC engine and decided to go for the more original idea of an RC engine based generator but am still thinking to use a grass trimmer engine for the next project.

You can also use a motorbike or a moped alternator for these. These, however, are a bit more expensive.

I think you will be able to complete this project for around $200 or less.

WingingIt74 wrote:

StevenStanleyBayes wrote:

WingingIt74 wrote:Also, you mention later about oils.  Castor oil is necessary in the operation of COX engines, to protect the moving parts, as it will leave a residue.  Similar to lead in older gas for the valve seats.

True Castor Oil creates a protective film which clings to metal. However, I am slightly concerned with the residue.

True, certain amount of residue would protect the metals. However, a great amount of bur caused by burning organic materials may even get the piston stuck in the cylinder.

This is why car engines are preferably de burred either by chemicals ( including cleaning oil at oil change ) or mechanically at engine rebuilt or reconditioning.

However, Castor Oil burns at huge temperature and hopefully would never burn in a Cox engine.

Some people on the Internet replace Castor Oil with high temperature synthetic oils but these are difficult to find and extremely expensive.

Cox engines were designed to use castor oil.  Synthetics are very hard on these little engines, they won't last long.... which brings up an interesting thought.  What is the "Lifespan" of a  Cox engine, especially the difference between constantly running or intermittent runs (normal operation).

Although the Internet speculates a lot on Castor Oil versus Synthetic, I am inclined towards Castor Oil with a precaution not to overheat them.

The longevity of a Cox engine is not exactly known but I have been told the company have run tests with Cox engines running for days, 60 hours or more, without any problem at highest RPM possible.

Once the engine is broken in and the piston is reset, the longevity may be very high. I would assume months without problems or even years of continuous work. However, in order to achieve this with more certainty, one may wish to take precautions : in order to increase the reliability ( longevity included ) of any engine, good precautions are to run the engine as less hot as possible and to the lowest RPM possible and not to change RPM frequently. Thus, when you run your car with 50 miles per hour ( 80 km / h ) without any stop and any acceleration and deceleration on an even surface, you car engine may last for even 1000000km with only changing oil. However, putting load on the car ( heavy luggage ), racing the car with a lot of breaks and immediate acceleration from 0 to the max would wear the engine and the engine may not last even 200000km.

Thus, for Cox, a good idea is to run them with as rich mixture which burns at low temperature as possible and at as low RPM as possible and as low compression as possible with as much retarded ignition as possible but too retarded ignition would bang on top of the moving up piston and when the piston is vertical and would increase the possibility for the piston rod or crankshaft to bend or break.

Obviously, for most application, pure idle is impossible but whatever minimum is possible without running the engine with too much retarded ignition.

I think, one of the ways to do the settings for high reliability is to adjust the mixture to rich giving some slack, of course, and once the mixture is adjusted to be very rich, to adjust the compression screw to the highest RPM possible with this mixture and load yet one must never go to the highest compression. Usually, the increase of compression would lead to increase of the RPM and power to a given point and then more compression would decrease the RPM and power for this mixture and load. In case this does not happen and RPM and power continue to increase with the compression, one may wish to put even richer mixture.

I think, one way to find out whether the ignition is too retarded is to listen for a metallic noise coming from the engine. In case of such, either the compression has to be decreased or the mixture has to be made richer or the two thereof.

A simple way how I have " measured " the temperature versus richness of mixture dependence is I have stuck a finger to the cylinder and opened the air valve ( the throttle ) to make the mixture leaner. The temperature of the cylinder started to increase and keeping a finger there was not a good idea. Then I closed the air valve ( throttle ) to make the mixture richer and the temperature decreased and sticking a finger became comfortable.

People say the temperature is the biggest enemy to the engine as well as quick combustion as with low grade gasoline ( for standard engines ). This is why taxies which run high octane natural gas burning slowly and at low temperature last for a million of kilometers or more, much more than the same engine run on 87 octane fast combusting and at high temperature gasoline.

Also, regardless of the quick combustion the standard diesel have, because diesel has an autoignition of 210C as opposed to gasoline ( 283C or more, depending on the grade ), people say diesel engines run longer because the temperature is a more important factor than the slow combustion.