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Homebrewed Electricity => Other => Topic started by: Stainless on November 15, 2017, 11:20:49 AM

Title: Spitballing a car engine/multi-alternator large-ish generator
Post by: Stainless on November 15, 2017, 11:20:49 AM

Most of us have seen the YouTube videos in which some enterprising soul attaches an alternator to a lawnmower engine or something similar, adds an inverter, and winds up with a decent (and loud) little 120 VAC generator. If you're like me, you have the remnants of one of those contraptions laying around in the garage.

While sipping scotch the other evening, I got to wondering if this could be viable on a larger scale. Say, a VW mechanical diesel engine with two or three alternators and a large (say, 2 kw continuous) inverter. 2 kw is the largest reputable 12 VDC feed voltage inverter that I could quickly find.

As a cocktail napkin sketch, let's assume that the inverter could pull up to 200 A at full load. If a person could feed more than 200 A back into the battery with alternators, would it work with any reliability? For the sake of argument, let's also assume that cooling the alternators and inverter isn't an issue.

I guess the biggest question for me is how a typical lead acid car battery would cope with that kind of continuous charge current and draw over a span of several hours (or days). Car audio guys have been piling on multiple alternators for decades, but they also tend to have numerous batteries in a bank. With maintenance and cost in mind, I'm wondering if one battery would do.

The upside that I can see here is that one wouldn't have to tightly control the engine RPMs as with a real 120 VAC generator attached to the engine. The VW 1.6 NA diesel probably produces 20 HP at 1000 RPMs, which might even be enough to spin the alternators, thus also saving money on fuel.

Anyone with any thoughts?
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: mab on November 15, 2017, 02:21:38 PM
1st thought is 2kw isn't much load for the size of engine and diesels don't like being underworked.

2nd though is about the 200A; are you thinking of running 200a continuous from the battery then starting the gender to charge at 200a until charged and so on? If so your battery is going to get too hot fairly quickly. I suspect that even at higher volts (see next paragraph) you'd be better off just leaving the engine running to supply the power

3rd thought is go 24v - a lot of trucks are 24v so an alternator should be easy to come by, 1/2 the amps, better efficiency and bigger inverters available. 48v would be even better, but unless you're electronics savvy to mod an alt I'm not sure where you will find an alternator.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: Mary B on November 15, 2017, 03:28:07 PM
Why not pick up a generator head and skip the alternators, battery, and inverter? probably be cheaper in the long run.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: SparWeb on November 15, 2017, 11:34:48 PM
Hi Stainless,
I'm afraid I'll have to echo the skepticism of the others.  It will be very inefficient. 
A 1.6L engine with a 1.5 HP load is basically running at idle and converting a lot of fuel into a small amount of electricity.
The same alternator could be run with a single piston 100cc motor for a lot less fuel. Of course, they build those already and they're pretty common.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: electrondady1 on November 19, 2017, 07:53:11 AM
i hate the smell of diesel but a four cylinder  engine can do a lot more than just make  electricity. once up to temp it could heat your home. run hydraulic  systems. you can experiment with water injection. hydrogen injection . build a water jacket on the exhaust system to heat your home .   pump a bit of air into the exhaust system to reignite the exhaust gas and create a secondary burn chamber for hot water or steam. with a decent muffler and shroud you would barely hear it . not like some little Briggs and Stratton waking up the neighborhood.

Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: XeonPony on November 19, 2017, 09:26:38 AM
At the logging camp we drove engineers nuts by saying we had a near 100% efficient gen set lol, but we left out the part of all the heat recovery we rigged up!

a thermal static bypas valve for the coolant system was used, it routed the water through old iron radiator blocks in the trailers, if no heat was needed and temps got high it would dump the excess through the radiator.

Exhaust was run through a 45gallon drum with cooper pipe and filled with sand to make a thermal storage / water preheater for the shower house, it used on demand water heaters so that preheating made world of difference!

So the gen when running heated the trailers and shower water and provided the power
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: george65 on November 19, 2017, 05:07:01 PM

Anyone with any thoughts?

Few things.......

Highly doubt the engine would be doing 20 Hp at 1000 rpm.  It's a lot lower than you think. I have seen engines being Dynoed and at Idle  even high power engines, petrol and diesel might be doing 6-12 Hp.  Other thing is, if you are going to be just driving some alts, gear the things right up with BIG pulleys.

This will accomplish 2 things:
First, it will increase the load which is a good thing. 2nd, it will spin the alt in a more efficient range.  1000 Rpm is idle and the output from the alt will be less than half capacity. Large output alts are no so much designed for their max output but rather to get the amps at Idle up where a lot of smaller alts would be at the upper end of their curve.

The thing about diesels working hard is largely outdated internet Myth.  If one looks at industrial engines, they are tuned to the job they are purposed for. These days it's electronic but it can also be done on mechanical engines just by winding the fuel down.
Industrial engines are purposefully de tuned for economy and moreso, Longevity.
The DIY'ers are all talking about working the engines hard, The industrial users are putting in oversize engines so they are NOT working hard and they get the longest life possible.

If you are using car alts as standard, the alternators are efficient enough but the charging control is poor.  If you can get an alt like a Lecce Nevile and an EXTERNAL controller ( few different ones available and are not expensive) you can pretty much set the alt to whatever output you want. 12, 24, 36 or 48V. Just dial it up.
You will also get multi stage charging and efficiency as good as anything else at a much cheaper price.

Using the alts with the OEM built in charging, I calculate about a 60% inefficiency. IE, 1Kw of power out takes about 1.6Kw of motive power. Most of my 6 Hp Diesels from the lister to the China Diesels and Lombardini will be working hard with 2x 80A, 12V alts.  I don't think they would drive 3 alts to full power without being overloaded and smoking badly which is not what you want.

I am looking at setting up my 5 Cyl 3.0L OM 617 Merc engine to a large 240V Generator and running some smaller 12/24V alts off the thing as well.  Even a 20Kw 3 phase 240V alt will still be under loading this engine which is fine as I can just wind back the fuel screw so there is no excess fueling at all. As I will be running Veg oil, I will also be running water injection. I have been doing this a LONG time now and as usual, the internet fears and myths don't  come near reality.
I would not run a diesel on any fuel without water injection. It solves so many problems and keeps diesel running at top performance  as well as adding a fraction of power..... which on my Veg fueled truck is always fun no matter how well it's dialed up. Add 50% Methanol......Wheeee!

As far as keeping the alts cool,  Pffft! Another internet myth conjured up by those with a lot of imagination but no experience.
Running a car alt in a stationary application, IE, not in an engine bay that can easily excede 100oC, the things are cruising and never breaking a sweat. Sure, they will get hot but the fact the cooling air is probably at least 80oc cooler makes a huge difference.
Like the difference between running a semi trailer up a mountain in the dessert and in the snow. Still going to be working and getting warm but totally different environments and effects on the machinery.

If you are supplying the same power from the alts as the inverter is pulling, the load on the battery is nil.
I have done this with 6Ah battery's driving 2Kw inverter and had no problems. IF the loaded voltage coming from the alts is at a decent voltage for the battery, it won't be loaded.  If it pulls down hard, then the battery will "float" at that loaded voltage.  IF one is pulling less than the alts output, the alts should level their voltage out at the proper battery float voltage.
 I used 2x 80A Mitsubishi enclosed alternators which I have used extensively.  I have found them to be virtually indestructible.  I have run them direct to the inverter for many hours with NO battery's at all which folklore says will kill them.  I have done the same with Bosch Alts and also had no problems.
Because I get the alts for nothing, I have TRIED to break them and so far failed.  They are not anywhere near as fragile as people always seem to make out.

I have an interest in engine generated power and a lot of the feeling is use the heat and take the power as a bonus.
If you are using bought fuel, this can be important. If you are using Veg / alternative fuel, Maybe not so much.
Exhaust is supposed to be a significant amount of heat but many feel recovery from exhaust is not worth the time and effort.  Myself, I think there is not much to making a tube in tube type HE, even if it were to direct the exhaust through an old gas water heater with the burner removed for pre heating.

 Again, depends on what efficiency you are motivated to recover.

Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: Stainless on December 09, 2017, 11:37:09 AM

Sorry for the delay in my response. I'm juggling three clients in my "real" job, so things have been bananas.

Thanks for all the feedback. Yes, I'm well aware that this idea doesn't present any kind paradigmatic efficiency, but it would be dead-nuts cheap and fun to monkey with. I shore do love me some junkyard tech, and I always like the idea of building stuff that I can repair without waiting for proprietary parts to arrive on a slow boat from wherever.

From what I've seen in my travels, accurate governing seems to be among the significant nuisances and costs involved in DIY IC AC generators, and I thought this method might help in that area. Also, I figure that the reduced engine RPM would help in another notorious area -- noise. Although, I admit that this whole contraption would introduce a new headache and cost, the big inverter. Realistically, I think it's got to be a 24 or 36 V system to be worth the effort. 2 kw from a car engine isn't anything very impressive, but anything beyond that gets us into pretty expensive inverters for the scope of something like this. Eh, maybe two or three 12 VDC 2 kw inverters? Who knows? I'll sip some more scotch and mull it over.

george65, I'm glad to see that someone else has thought this through as well. You're probably quite right about my estimation of engine idle power being optimistic. I also agree with you about the myth of underworked diesels. Even OTR and heavy industry engines are underworked more often than one would guess, and they live exceptionally long lives with any decent maintenance. Your thoughts about alternator heating are interesting... especially in modern current-hungry vehicles with engine bays that are too packed to allow much airflow.

electrondady1, that's true. This apparatus could do more than just generate electricity, and those are good ideas that are also worth spitballing.

I am attempting to put myself in a position to afford a small rural acreage in the next year or two, and that will mean strange experiments like this one and several others. So, maybe it becomes more than spitballing one of these days.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: mab on December 09, 2017, 01:14:58 PM
hi Stainless,

If you just want to do it for the hell of it that's fine :)

I might suggest you could go for 48v inverter as they're better for high power and perhaps easier to come by than 36v.

After my previous post it did occur to me that rather than trying to mod an alt for ?>24v you could just run separate 12v alts, each on charging one 12v battery in your 24/36/48v chain - the only difficulty there being that most 12v alts come with the -ve terminal grounded internally, so you'd have to mod them to isolated outputs to prevent them shorting out.

I have to say I'm surprised to learn that the issue of under-running diesels is a myth as my 1968 david brown tractor suffers from this myth! - at least, if i don't work it hard it starts burning oil, and when I do work it a bit the problem clears up; but I do accept that some modern engines may well not suffer this way (a chap I know who makes gen-sets uses Yanmar 3cyl for small sets and iveco/ford engines for larger as he's found those engines don't suffer from this problem when underrun). If someone can tell me how to fix my tractor I'd be very interested - i don't have a lot of heavy work for it to do ATM, and I periodically have to find some hard work for it when the white smoke appears.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: george65 on December 10, 2017, 05:58:20 AM

 Assuming your problem is not physical/ mechanical/ wear issue and all is in good nick, I can tell you how to fix it based on well over 10 years hands on practical daily experience of my own and others that have followed My advise.
It's cheap, simple and damn effective.

Water injection.

I have run it on my veg fueled diesels for years and wouldn't run one without it on any fuel.
If you are interested I can give more detail but the first thing is NOT to get carried away with the hype and BS.  Firstly, it does not have to be injected as a high ipressure, micro mist vapour by a $500 pump and expensive injectors.  My systems have NO nozzle at all. Used to use plastic micro watering nozzles but worked out that was overkill. Now My " Injectors" are nothing more than a bit of flattened copper tube. Not flattened to get a spray, flattened to regulate water flow.

Secondly, forget paranoia about hydrolocking the engine.  I had a mate that mistook my instructions to put 200Ml / min of water into his 3L NA engine and put 2 LITRES a minute in the thing.  It coughed, it steamed and there was water running out the tail pipe but it did not lock up or suffer any damage. wasn't even water in the oil which amazed me!  You can work out the displacement by RPM but suffice to say you need a LOT of water to hydro and engine and believe me, you'll well no its getting too much Waay before you lock it or even get the chance as the engine will stall way before that happens.

3rdly, it will NOT save you fuel. If done right, you may use a little more.  It may give you a slight increase in power but I doubt you'd notice that on a tractor with the low gearing they have anyway.

Finally, the water does not have to be on 100 % of the time The engine runs.  If you were going to run the tractor all day and put say a 2L water tank on the thing which you used up in the first hour, no biggie. Fill it again for tomorrow and the water will still do it's job and clean the engine and have it run fine.  The problems the water fixes which are usually carbon related in the rings, combustion chamber and ports don't happen instantly. All you need to do is keep them from building to critical level and you'll be fine. The Key to WI for MAINTENCE as against performance is regular doseage UNDER LOAD.
That's not working it's guts out, that's normal operation as against idle.

You can pretty much ignore most of what you read on any WI commercial site.  Don't need fine mist and high pumps, don't need staging, or basicaly anything bar to get a regulated trickle of water in the engine.
My base suggestion is 200Ml Min for a 3L engine. If I want to have fun, I inject my 4.2 L engine with about 5L Min of methanol and water at 50%.
That give it a boost that is VERY noticeable and a lot of fun to drive.

All you would need is a pump, a tank and a metering method. 
Good pumps are the diaphragm / Caravan type water pumps. Come in a bunch of sizes, usually around 4L / Min and vary pressure from 20 to 110 PSI. Don't matter what you get, they are all overkill.
Trick on a tractor will be switching.  Being a "68 it's for sure non turbo.  Turbo is easy, pressure switch to cut in under low boost and that's it.  NA cars can be easy too. Put a switch under the loud pedal so when you floor it occasionally it activates the WI.
For a tractor, I'd me looking at something more like a microswitch on the throttle  which kicks in at PTO revs or where ever the throttle/ revs are normally set.

Start with 200Ml min at 30% engine speed or above and just have it entering the inlet manifold somewhere.  For cleaning purposes, it is my well tested opinion that actually having droplets is best. If you understand or want to look up what true cavitation is, this is why. The droplets in the Combustion chamber will violently and instantly phase change from water to vapour and thats very helpful in removing deposits. It will erode carbon but proven not to be powerful enough to erode any metal being aluminium or steel as in an engine.

DO NOT expect to put this on and instantly see a difference. Not unless you want to add alcohol which  seems to make the cleaning effect much quicker.
First car I had this on as my old W123 Merc. I did -think- I felt some improvement after just a day of usual running around but I knew the effect was ongoing for about 3 months. I ( and my kids) could feel the ever so slight increases in performance which took 3 months to level out.
By then the thing was different. Starting was SO much easier. Thing pulled my trailer up the same hill with the same load 10 KMH faster and along the highway with the water, where before I could only do 90 and the thing would over heat, I could now sit on 110 and the thing was cool as a cucumber.

I have put WI on cars  and felt a very rapid change, I think it all depends on what the problem actually is ( stuck rings, clogged ports etc) as to how quick and how long the final result takes. I will gaurantee you though, on an engine that isn't in need of a rebuild or have mechanical problems, You WILL see an improvement. Starting in the cold will be the first. In this case the lack of smoke or other performance degradation will be the icing on the cake.
You ill also notice if the tractor gets hot doing heavy work or in summer there will be a temperature reduction. This is due to the water pulling latent heat out of the air charge and the phase change.

I have WI on my stationary engines, The lister, The China Verticals and the Italian Ruggerini. They are real easy, drip into the intake. Solenoid controlled. Engine stops water stops but thats overkill because where I have it going in it would just run out again if the engine stopped and it was still flowing.
Just a drip every few seconds is enough to keep these engines ticking along  perfect.  again, key is regular delivery not fine mists or shoving down the most you can get in.

I have done WI setups for as little as $20 using a washer pump  from a car and a normal switch. Tank was a plastic 4L water bottle.  You could start with This if you are sceptical and go from there.

Something that may also prove the value of WI to you is to just pour ( if you can) the water into the intake. Have the motor doing about 50% revs and just pour the water slowly in. As the engine slows, back off on the water and let it clear and go again a little slower.  Even if you put 2L of water down the engine when its clagged and burning oil, I'll bet it will be better after the water treatment if not totally fixed. That takes time to clear the same as it took time to happen in the first place.
Clearly that's gummed rings and Water is about the only thing I know that will fix that short of a tear down.

A regular dose of water and you'll be able to idle the thing all day and never have a problem.

Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: mab on December 10, 2017, 07:04:27 AM
Thanks george, (and apologies to OP for hi-jacking your post).

I'll certainly give it a go - it's good to hear it can be tried without spending , I was thinking I may be able to gravity feed by strapping a container on the top, although regulating the flow with such low head may be imprescise - just got to be sure I feed it in where it can't pool and get sucked in all at once - and if it improves cold starting that would be great.
Title: Re: Spitballing a car engine/multi-alternator large-ish generator
Post by: george65 on December 10, 2017, 10:15:11 PM
I recommend having the tank BELOW the injection point so if for any reason the water does not shut off when the engine does, you don't fill it with water. 
Also have the tank vented.
Twice I DID fill a cylinder with water when the car sat in the sun, the tank got hot, pressurised and forced water out into the engine.
To clear it, all I did was keep bumping the engine on the starter every couple of minutes. Eventually the water ran past the rings and once I got the thing to exhaust stroke the water went out.  No real dramas and no damage, just took about 10 min to clear it out.  A mate did the same to his and being at home, we just took out the Glow plugs ( which luckily he was going to change anyway and had a set waiting) spun the thing over, watched at the impressive streams shoot out with force we would not have credited, put the GP's back in and all was good.

I also find pumps are easier for metering. I have been playing with a little PWM board for varying pump speed and I like the possibilities it offers.
It can be turned down for when cruising along the highway to save water and particularly water/ meth mix and then dialled up again when Climbing hills or traffic Light grand Prix.  For your application, you could use it just to regulate the speed of the pump to get the delivery you want.
If you do constant work like ploughing or slashing, you could just have a switch to turn the water on and off. If the motor is not working hard enough for the amount of water and you have forgot to turn it off as you disengage the pto or whatever, you'll feel it stumble and miss a little and that will remind you to flick it off.

The PWM boards would work well with windscreen washer motors. Don't underestimate those little things! They can deliver far more water than what you will need and tend to have very long lives.  I'd also suggest a GOOD size tank, especially at the start.
On my 4wd, Going up the hills on the highway to see my dad, I can easily go through MORE than 25L in 200 KM. I don't know how much more, I only have a 25L tank and it's always empty by the time I get that far and pull in for a burger and fill it back up.  It's usualy got a bit left time I get there a further 130 Km along but the back half is a lot flatter and you are on the throttle a lot less than the front 9.

This is the sort of board I'm refering to:

This is the Diaphragm pump: