Gasoline Generators for 12Vdc Applications...

[Lee Mauser]

These are a few critters i have been playing with for a few years... they are great for charging batteries when the power is off or for running 12Vdc lighting in a cabin or other off grid operations...


https://www.youtube.com/watch?v=-q_Lg4j4mVA
the first one here is the smaller of the two generators... it uses a small 3HP Briggs & Stratton and a Delco DC generator from a old GM car... i use it for single battery systems and for light duty 12Vdc devices (lights, general battery charging, etc)... it is quiet enough at the 500RPM it runs at that at 100m you do not hear it... it also sips gas and will run for a day on a gallon...


https://www.youtube.com/watch?v=cTlZ-jH9R68
the second one is the largest of the two... it consist of a 12Vdc generator off a 1940s Brill Bus and a 8HP Briggs & Stratton... i use it to charge the battery backup on my house when the power is off for long periods... it also run at 400-500RPM and will charge the 10 large CAT batteries i have for my battery backup in a couple of hours... i can run it each day for a few hours to charge the batteries and not burn a half gallon of fuel... it is also very quiet and does not draw any attention, which is what you want for emergency situation so you are not announcing to every looter in the world that you have power and something to steal... they are both great for when you want power if you have to just fade back into the woodwork and let things blow over...

the best thing about them both is they are also EMP resistant due to the mechanical regulation system and lack of electronics...

[MrWolf]

Impressive. I am electrically challenged. Yea I know everyone says it is easy but nope. I can wire a house but applying it like you, nope.

[deltaenterprizes]

Nice! Where did you go get the generators? New I would think that they would be pretty expensive!

[Petrol & Powder]

If quiet battery charging is your goal, solar panels are about as quiet as you can get. Solar requires some capital outlay for panels, charge controllers and batteries. Even after you get beyond the initial equipment cost, solar has the limitations of nighttime and bad weather; so a generator powered by some type of engine has some real merit.

Those old DC generators (dynamos) were widely used before alternators became the automotive standard (early 1960's) and do have the advantage of making DC current without the need for a rectifier and they will make some useful power at low RPM's but their output is considerably less than an alternator. If you have a little power available (a battery that's not completely dead) to energize the field, an alternator will make far more power.

Those old Briggs & Stratton flat heads are a dime a dozen and readily available but I wouldn't call them efficient. An overhead valve engine of the same HP rating will use significantly less fuel over the same amount of run time, and they are generally quieter. A horizontal shaft Honda engine is the newer choice in that class. But those old Briggs & Stratton engines will get the job done and they are cheap.



As for worry about EMP...........that's just not on my mind but then I don't have an avatar displaying a guy wearing a gas mask ;-)

And Welcome to the forum.

[rancher1913]

he uses old tractor generators and alternaters, got loads of them around here.

[GregLaROCHE]

I once set up a car alternator with a brigs motor. It worked, but never charged as much air as fast, as I thought it would. I found out later, when installing a high output alternator on a boat engine to charge a battery bank, that I needed a regulator that was more efficient for charging. I got an electronic one that varied the charge from beginning to full charge. It worked really well.

[Petrol & Powder]

I agree that solar is not cheap but the point was solar IS quiet. I don't think solar should be your sole source of power for emergencies but it does have some advantages. (sunlight is a free "fuel", you don't have to deplete your fuel supply to run it, it is silent, there are no moving parts, etc.). Solar isn't THE solution but it can be part of the solution.

I cannot argue with free or nearly free generators. Using what you have available just makes sense.

As for batteries "loving pure DC"? I'm not following you there. An automotive alternator uses a rectifier bridge to convert the AC output to DC and an automotive generator uses brushes and a commutator to produce DC output. So they both produce DC voltage but the generator uses a mechanical means to change that AC current to a DC output.
For the amount of mechanical power that goes into an automotive generator or alternator verses the electrical output - The alternator wins by a huge margin. That is one of the reasons generators are no longer used in automotive applications.

The drawbacks of the alternator are: it does rely on diodes to convert the AC to DC. And it requires some electricity to make electricity (you need to energize the field). However these drawbacks are relatively minor. The brushes and slip rings used on an alternator are far less complicated than the brushes and commutator on a generator but I'll grant you that when a diode bridge dies, you're out of business if you don't have a replacement.


Flat head engines are far simpler than OHV engines and therefore less expensive to manufacture. However, the shape of the combustion chamber severely limits the efficiency of the engine. There is a STRONG reason the flathead design was replaced by the OHV configuration decades ago. The only reason it lived on in small engines was the reduced cost of making those cheap engines for lawn mowers, cement mixers, generators, etc.
The small increase in complexity of the valve train of an OHV engine verses a flathead is outweighed many times over by the increase in efficiency of that OHV design. The OHV design flows mixture and exhaust in and out of the engine better, the compression ratio can be higher, the amount of power made with the same displacement is higher and the mixture is burned FAR more completely.
The flat head ruled the small engine market for decades not because it was good but because it was CHEAP.

OK, none of that is criticism to using old automotive generators and old flat head engines. I spent many hours on a Ford 8N that had a flat head 4, a generator and a 6 volt positive ground system - IT WORKED FINE !

[Lee Mauser]

but what i was getting at is the alternator is not true DC... ill try to explain... the alternator produces 3 phase Alternating Current and runs that through the diode trio... they use 3 phase in an attempt to smooth out the ripple created by the nature of AC... the diodes are like a check valve as they limit the voltage to one direction... however, the diodes do have a slight reverse leakage which does let a little power flow in the wrong direction.... this amount is negligible in most cases... also due to the very nature of the AC wave form, the voltage will go to zero at the end of each cycle... this can be seen with LED headlights on cars with cheap regulators, they will flicker to an extent...

the generator however, while it does use a commutator as a mechanical means of producing DC, the voltage produced is unidirectional, there is no rise and fall of the voltage to cause ripple... and with the arrangement of the brushes, there is always a DC voltage present at the output... there is also usually no reverse leakage as with a rectified AC voltage....

[Petrol & Powder]

I don't think your batteries know the difference.

[GregLaROCHE]

Talking about batteries, regular automotive batteries aren’t near as good as a deep cycle batteries. I used to use 6 volt golf cart batteries from Sams Club. Two batteries connected in series to give 12 volts.

[Three44s]

An alternator is at its best for short quick charges. Hooking them to a long high current application shortens their life such as a bank of deep cycle bats when they are fairly low.

In an extended run maintaining a battery under a moderate load they excel even if there are surges needed to maintain a battery.

Three44s

[3006guns]

First of all, I LIKE the OP's generator setups. Since I'm an antique engine nut, anything that runs slow and steady appeals to me. Both his designs are more than enough to make power/lights for a small cabin or emergency situation. He is to be congratulated...........although I'd keep an eye on the engine temperatures at such slow speed....not enough air passing over the cylinder head? As for the generator/alternator argument......who cares? If the generator unit makes enough power to suit your needs and not burn out a priceless diode, it wins in my book.

A couple of observations............from someone who lived without commercial power for five years.

Photovoltaic panels should be your first choice, and hang the cost. They are passive, require no energy input (except installing them) and will work when you're out of fuel for your generator. Buy enough panels to recharge your batteries/considering load by a factor of 150% or greater.......it's generating capacity, not battery capacity that will give you performance. My first set up had 8 panels of 35 watts each (long time ago) and a MASSIVE battery bank. I found my energy use exceeded my charging capability...........energy storage meant very little. Fast recharging meant EVERYTHING.

Stick to D.C. voltages ONLY. Don't assume a D.C. to A.C. inverter will give you all the advantages of "city life". No matter what the manufacturer claims, inverters use gobs of amperage to boost and change the current to A.C. Use D.C. lights (LED's) and motors (permanent magnet) as much as possible. Remember, we only use A.C. because it can be run through a transformer and sent cross country. If you're generating locally, stick to D.C.

Use the highest practical D.C. voltage you can, either 24, 36 or 48 volts. Simple rule of thumb: The higher the voltage, the greater work you can do with less amperage (draw on batteries). Or to put it another way, it's more efficient.

Don't even think about lead acid batteries unless you have no other choice. The new battery technologies are far superior and tougher.......coming down in price too! I just got an ad from a battery recycler, offering NEW 36 volt vehicle batteries for around 500 bucks......a battery that will outlast you instead of needing replacement every 6-8 years. The old Edison nickel/iron cells from a century ago are still a better choice than lead acid, and the new lithium/iron/phosphate cells are phenomenal.

[Petrol & Powder]

3006guns - You're on the mark.

Inverters lose a lot of energy in the conversion process (that's why they have those heat sink housings with cooling fins -all of that heat they produce is LOST power). Your advice to stay with DC is good advice.
Same is true for using the highest DC voltage possible except that a lot of DC equipment is designed around 12 volts. This is getting a little better as manufacturers branch out from RV and boating applications and are fulfilling off grid needs a bit more.

Batteries have improved greatly, but very large lead acid batteries still hang on due to well established history. I think eventually lead acid batteries will be replaced in the industry but they're not going away anytime soon.

And solar is an excellent system once you get beyond the initial cost. It is quiet, uses free sunlight and they don't deplete your fuel that you need for other uses. Stretches of cloudy weather will force you to go to an alternate source but over the long run solar is a far better source than a generator.

[lightman]

Welcome to Cast Boolits! Thats an interesting example of using simple old stuff to perform a job.

[jaguarxk120]

Are we going back in time? Charging battery's, generating your own power!

Back in the 1930's many farms in the Midwest had windmill generators and battery houses. This was long before the U.S.
had the power grid.
Those farms were lit at night by DC power and all of the appliances were DC powered, usually 36 volts.

Remember power co's make it very easy to buy power. But the fact is you do not have to buy power from them.

If you can generate power cheaper - then have at it, and good luck.

[PNW_Steve]

There is an outfit selling machined aluminum mounts for common small gas engines and alternators. It makes assembling a 12v or 24v Genny easy.

[roadie]

In researching solar power a few years back, I came across a company called Aquion, they were working on a battery using, IIRC, salt water, a saline solution of some sort. It seemed by the specs that it would be an excellent battery, safer than lead acid and longer lived. I think one "flaw" was draw down was limited, and sustained could damage the battery.

I read later that the company went bankrupt, though an article I saw today said they sold out to China, unfortunate either way. For my power usage it wasn't economically feasible as it would take the rest of my life to pay for itself......then no doubt get junked when I croaked.

I still think a nice old Lister would be handy to have around though.

[Alstep]

3006, As another rusty iron nut, you'd appreciate my 1913 5 HP ball top Lister throttler belted up to an alternator. It's the easiest starting, smoothest running engine I have. When I get a chance, I'll have to go out to the barn and get a picture.

[Wayne Smith]

Solar seems wonderful, unless your house is a 10 on a scale of 100 for solar usefulness!

[Mal Paso]

I lived with a 5 hp Briggs and an alternator as primary power for over a year. Secondary was a Lister Petter LS1 generator but you could listen to the din only so long.

Solar is Cheap! When I started it was over $10 a watt. I've seen panels lately as low as 32 cents a watt. Lots of USA made panels now.

You want 36 or 72 cell panels for charging batteries (12 or 24 volt). The 60 cell panels are for grid tie and are harder to use with batteries.

[Mk42gunner]

I like the small engine powered generator concept for charging batteries. It has the advantage of being fixable at home. I well remember tearing apart and fixing both the generator and voltage regulator on my 57 F-100.

roadie I remember one of the guys in my class making a battery using a pill bottle as a container and a strip of metal wound to fit, he used a piece of shirt cardboard as the insulator. The electrolyte was a salt water solution.

No idea of the voltage but it did get a bulb to light up.

Robert

[Lloyd Smale]

12 volt at camp we run a 900 watt honda gen that is whisper quiet with a 12 volt battery charger and charge two deep cell batteries wired in parallel. We also use it to power the tv. charges the batterys every night when were watching tv. Tried solar but theres enough snow in deer season when we really need them and theres not many bright shiny days then. But im sure with the right set up it would have worked. Already had the generator and battery charger sitting in the garage I never used so I went that way. We also have 5k honda at camp for the 120 load. Like the water pump, power tools ect.

[38Special]

I love the good old Chevy Delco Alt, belt drive with a Honda 5.5 or 6hp engine. Chinese knock offs work great.

All you need is a Napa alt- an external regulator alt, the old type (not) the newer internal.

A big Ohmite Rheostat like this, and an auto amp meter:
https://www.google.com/search?q=Ohmite+Rheostats+50+watt+12+ohm+750V+Std+ Shaft&source=lnms&tbm=isch&sa=X&ved=2ahUKEwivkoDQ0OvoAhUjHzQIHcOCDa0Q_AUoAnoECAsQB A&biw=1234&bih=663

Easily put out 40-60 amps of efficient DC and fully adjustable,.

[Lloyd Smale]

as long as 400 to 750 watts is all you need. At 60 amps you only have 720 watts. Fine for a few lightbulbs but that's about it. 900 watt honda or other brand generator does that with about 2 hp and much better fuel economy and already comes with a invertor to give you both 12 vt and 120vt. You can buy a small gen like that for around 300 bucks. Time you buy a 5 hp motor and alternator and regulator and pay the extra fuel bill on it your loosing money. Heck I even had one of those cheap 2 stroke harbor freight 800 watt generators that cost less then a 100 bucks. Held like a gallon of fuel and would run all day on that gallon. probably not durable enough for the long haul but you could buy 3 of them for what a decent 5 horse motor costs. before we went to the 900 watt honda at camp for light loads to save gas money we had a menards 1700 watt unit I bought for 300 bucks on black Friday. It was used for 10 years at camp. Started in the morning and shut off at bed time for about all of oct and nov and it still runs as good as it ever did. Cant afford that? Sell a gun. or use your 1200 dollar welfare check to buy one :kidding:

[MaryB]

LED lights use far less than 620 watts! My 600 lumen office light is 24 volt(my solar setup is 24 volt) and they draw less than an amp!

[38Special]

My Favorite mfg gens are the Harbor Freight 3500 watt Inverter gens. I run 3 of them back feeding the house. They are not 220VAC but I run one on each leg. Super quiet, super efficient and just sip fuel.

[Meatpuppet]

https://www.affordabledcgenerators.com/

Ive got 2 of them and they work great for what they are designed for.

[Lloyd Smale]

im sure they do mary but someone building a generator out of a motor they have laying around and an old chev alternator probably doesn't have led lights or anything 24v.
LED lights use far less than 620 watts! My 600 lumen office light is 24 volt(my solar setup is 24 volt) and they draw less than an amp!

[Alstep]

Here's my 1913 5HP ball top Lister belted up to an alternator. It's really just for kicks, but is useful just the same.

260782

[38Special]

Ha..! nice. I had actually
(4) Chinese Lister Kit motors and wound up selling them. They became to valuable cause you can't import them any more and I made a killing on them.

[Alstep]

Ha..! nice. I had actually
(4) Chinese Lister Kit motors and wound up selling them. They became to valuable cause you can't import them any more and I made a killing on them.


Didn't know they made them in China. For a while a number of years ago, somebody was importing Lister Diesels from India. They didn't meet EPA standards so the Gov't shut them down. They were nice running engines. My 1913 original was made in England.

[15meter]

Kind of impressive that the OP was banned with 2 posts, not only did he step on somebodies toes, he must have jumped up and down on said toes with hob-nailed boots.

What would have made that even cooler was if he had used a starter/generator from an old Briggs and Stratton from the 60's. My dad's first rider lawnmower had one. AC Delco if I remember correctly. It was the size of a standard automotive starter. Probably weighed as much as the aluminum gas engine.

260809

Wouldn't even have to pull start the gas engine.

[38Special]

Didn't know they made them in China. For a while a number of years ago, somebody was importing Lister Diesels from India. They didn't meet EPA standards so the Gov't shut them down. They were nice running engines. My 1913 original was made in England.

You're correct. I meant to say India, not china.