Micro CoGen.

I was able to purchase parts for our Kubota EA-300 a couple of years ago,  but the life of me can not find the link...    I think if you locate an industrial engine supplier (not a tractor supplier), you could purchase parts locally, I know several years ago I was able to find them at a supply house in Portland.

If you ever want to pimp out your DC generator, check out:  http://smartdcgenerator.blogspot.com/,  we crosses the 1,000 hour mark sometime last year and so enjoy the variable speed nature - lets me FULLY recharge the batteries every once and a while, without having to listen to the noise..   Going to do a re-fresh of the controller design this fall as well.

A while ago (Yeaks, several years ago) while working on my DC generator controller the question came up:  What was the reason for so many High-Drive type alternators, esp given that from an electronics stand-point is is so much simpler to design around low-drive  (being able to use NPN trans or N-Channel FETs).  Today I think I might have come up with a reason:  Flyback

With high-drive config the flyback snubber directs the current into GND.  While with a low-drive deployment, that energy is routed into the + side of the battery - creating more line noise.

Seem plausible?

Quote from: hwew on November 18, 2016, 06:42:15 PM

I think the Ford 300 six was one of the best gas engines ever put in a Ford pickup. I miss my 1993 F150  short bed 4.9 liter 5 speed 4x4.

I would have to agree  - to the topic of this post, the last vehicles I owned was a '89 F150 with the 300 I-6 engine, and the T18 4-speed manual.  Didn't get great millage (around 18mpg), was not fast (65 and you knew it), would pull a TON (actually, 8500lbs per ford spec).  Always started.  Biggest issue I had was the fuel hose rotting out when they added all the alcohol.

Last I knew, had around 370,000 miles on it.   Reliable, and yes very simple to maintain. 

Quote from: veggie on October 05, 2016, 03:15:37 PM

Yep, that is the Mechman/Transpro External alternator available here...

http://www.mechman.com/accessories/external-adjustable-voltage-regulator/

I contacted them but a few weeks back and found that they do not make a 36 volt or48 volt model.

veggie

FWIW, the Transpo 911 regulator is the 'truck' regulator I have used for years after tossing out the fancy Blue Marine Unit, and before my project.  I still carry it for a backup.  Has been a reliable unit, but I do not remember then being so costly.  IIRC, I paid around $50 for it....

Quote from: mobile_bob on October 06, 2016, 12:06:34 AM
your alternator looks like a pretty well designed unit
it looks a lot like the bosch high efficiency unit.

anyway, something to consider

the prevalent losses in these alternators are
1.. stator resistance, so fewer turns result in lower losses
2. rectifier losses, these losses are the same whether you are rectifying 12, 24 or 48vdc
3. windage and friction losses, they are all about the same, however speed has affect
4. iron/core losses, due to hysteresis,  these losses speed has affect as frequency goes up. this is why i like alternators
with short stator cores, and thinner laminations.

just some random thoughts
bob g

Hey Bob, thanks for the nice summary.  The alternator is a Denso 'Hair-pin' alternator, part #421000-7001    The larger 138.5mm stator version.

-al-

Hey guys, thanks.   I need to think a little, one reason for changing out the pulley to a dual V-Belt is it would match the other large alternator install on the main engine - and the spare alternator I carry with its pulley already mounted.

I also found some insight onto RPM/output here: blog.dcpowerinc.com/2013/11/01/the-truth-behind-denso-hairpin-high-output-alternators/
Looks like my alternator is an example of their 'Large Frame 270A' model.

It looks like keeping the 1:1 ratio will work, unless efficiency creeps up into the 80% range for this 12v application.  ( I run the small Kubota engine from 1600 - 2800 RPMs depending on the required charging load).

Quote from: mobile_bob on September 30, 2016, 10:16:21 AM
if i had to guess the field current and voltage at 36vdc and 20amps output, i would guess somewhere
in the 10vdc range at around 2.5-3.5 amps for the leece veggie has to work with, that being if the alternator is spinning
at around 5k rpm... lower rpm and the field requirement goes up, higher and it will go down.

sorry Thomas, i forgot  your project!  geesh this getting older and busier sure takes its toll.

there you go Veggie a ready made solution, and if you can't or don't feel up to soldering, i bet you can find
someone locally to do it for you for very low cost.

a little practice, the right iron and solder, and it isn't that bad.

bob g

Its Ok - I am somewhat thin skinned, but tend to get over it quickly.

Hey, just to restate it:  I have a few people who are interested in fully assembled (less plastic case) version of this.  This winter I will be looking into making up 10-20x of them - will have  a better idea once I hand solder the PCB I just received yesterday and proof the latest revs.   But if folks are indeed interested, would be a good time to get a fully assembled copy.

-al-

A nice shiny new HAIR-PIN alternator!

This is a 220A larger stator (138.5mm) Desno unit.  Speced as an option for some of Dodge light and mid-duty trucks, was able to pick up this one on Ebay for under $180.

I am very interested to see how this unit's efficiency compares to slow-turing the large frame Leeve Neville 4800 series alternator I have been using for this past year.  I do know from one of the folks who is running my alternator regulators these Hairpin alts cut in at a very low field drive.










Couple of questions though.   Does anyone know if these alternators have the same charismatic improvement in efficiency at lower RPMs as more traditional designs?   Wondering if I should look to set this up for a 1:1 ratio,  or would it be better to do an RPM speed up.  (Try as I can, I have NOT be able to find any RPM/output curves for these alternators - let alone any RPM/efficiency plots).

2nd question:  It comes with a nice Ribbed belt pulley.   I am under the impression ribbed belts require a spring belt tensioner, but I also have seen some installs w/o it.  In fact, that same person I mentioned above purchased a ribbed belt refit kit, seems the belt was a special version designed to not need a spring tensioner idler pulley.   Does anyone have any insight on this as well.  Or I might just change the pulley and keep the current dual V-Belt setup I have.  Thoughts / ideas???

Guys, overkill or not,  I am hurt that not one remembered an Arduino Alternator Regulator has already been developed.   Over 3 years ago by yours truly.   
http://arduinoalternatorregulator.blogspot.com/

Gee,  spend a few summers living the life on their boat and folks just forget you.   (BTW, have 1,000hrs on the Arduino based fully automated DC generator as well).

With a BOM cost around $50 I have sent out over 100x blank PCBs - lately to a lot of LiFeP04 folks as they like the ability to properly regulator (not just back off) the alternator temperate.  This winter am doing an updated version - might even do short professional assembled run,  would hope the cost could be under $100 all said and done.

Oh, and to configure it for '32v'  battery,  all one needs to do is send the ASCII command via a USB cable to configure the 'voltage multiplier' to 2.667  - works like a dream.  (36v?, send 3.0)

Quote from: veggie on May 23, 2015, 07:58:07 AM
Thomasonw,

Great post.
Thanks for documenting that data.
I was always under the impression that my Leese alternator was 50% efficient at it's "worst case", but looking at your graph I see that they can drift towards 40% at the higher speeds. I have my belt drive set to run the Leese at 2000 rpm when the engine is loaded so I assume I am running approx. in the 50% effy area.

Which raises a question for all...

We use a rule of thumb that 2HP can generate approx. 1kw of electrical power.
But that is when we are applying an AC generator which may have an efficiency of 90% or more.

What rule of thumb should we use for HP required to produce 1kw of DC Alternator power?
Should it be more like 4 engine HP to 1KW of DC power ?

veggie

For 12v, the 'Rule-of-thumb' has been 1HP for each 100A produced when using a 12v alternator.  Or approx 1HP for 1.4KW? 

As Mobile_bob is pointed out, things change a bit when using a '12v' alternator to produce 24v.  Top end efficiency goes up, but one looses all output at lower RPMs (his comment about 48v needing 6500rpms).  There are several research papers out there from the 2000's looking at increasing efficiency of alternators, specifically targeting 42/48v deployments in anticipation of the Auto industry making a change.   Many of them use this basis of in effect a '12v' alternator to gain the efficiency at the higher end (ala, what Bob was seeing), while applying some other technology to boost up the output at idle RPMs w/o having the rewind the alternator and hence loosing  top end gain.

Lots happening here, bottom line I think is:  Our DC generators are a rather different set of needs vs. an auto - specifically with the RPMs required / allowed.  And as such one can easily think that there are hidden gems for us to dig out    Perhaps this one datapoint, and the work of Bob is a start..

Quote from: mobile_bob on May 29, 2015, 07:48:45 AM
<SNIP>

failing that, i have resigned myself to running twin 555 series connected to get the 48vdc nominal charging ability.

<SNIP>

bob g

Bob,  are you actually running a 2-alt in series setup?

-al-

Ya, too bad - esp after they made such a point about the Yamaha engine being used!  And USB to boot!  (Err, wait honey, need to charge the phone!)   

Hey, FWIW:  I was able to use our Honda brand 2000i generator to run an old 1/2HP craftsman table saw.  Did need to disable to smart speed mode, but it worked Ok spinning things up and would power through even thick purple heart wood.  No idea the real 'watts' being asked from it.

-al-

OK, going to take another run at this - aside from the ST approach, which might be a bit costly and heavy for some applications, looking for suggestions on 'alternators' to use for 42/48v DC generators.

A quick note:  In addition to the work Bob did looking at the 555 alternator in 24v applicaitons, here is a rather interesting paper which in part gives some insight into the advantages of using a '12v' alternator in higher voltage systems:  www.researchgate.net/profile/Nesimi_Ertugrul/publication/237464668_EXTRACTING_MORE_POWER_FROM_THE_LUNDELL_CAR_ALTERNATOR/links/0c960532a1b4458951000000.pdf

In short:  we get better efficiency but need to spin it faster (higher cut-in RPMs, just as Bob noted).  The attached paper is looking at one way to overcome this higher cut-in w/o doing the traditional approach of rewinding (which lowers peak efficiency) by the application of a boost switching power supply.  None of which is needed for a DC generator; we can just take advantage of the stock '12v' alternator - spin it fast and get an efficient 48v charging source.

But which alternator to target? 

• Which ones do not have 'avalanche' diode packs - clipping things around 29v?
• Is there an easy way to determine?
• use the 555?
• How about a more modern alternator?   

Suggestions / thoughts? 
Has anyone actually made a 42/48v DC charger using a '12v alternator'?

-al-

Ya, I am happy with the gain in output, cutting the amount of run-time during 'bulk' by 19%.  When combined with the already existing ~5%-7% reduction in bulk run-time due to maintaining a consistent load on the engine at all points of bulk operation (actively managing amps/watts vs. a fixed amp output), this controller / alternator regulator should be reducing overall run-time by upwards to 25% vs. when I was using the more commonly available 'smart' regulator.

It would be interesting to connect up a graduated fuel supply and verify actual engine HP output (vs using the spec sheet values), but I do not have that equipment available - plus it is kind of a PITA plumbing things in.   I used EGT as a control point because I already had the EGT probe installed.  The controller allows me to actively regulator EGT to a target value, so it is simple for me to fix that one variable when comparing configuration changes: engine loading.

And it occurred to me there might be even more good news:  With the active throttle management, slowing down engine speed as load is reduced, we have found we will often let the DC generator complete a full acceptance phase more often then not.  Just so happens as the engine speed slows the system is pushed more into the point of alternator operation with even higher efficiency!

Hello.   Has been some time that I had anything to post, but though this might of interest.  One of the longer term goals of my DC Controller project (http://www.microcogen.info/index.php?topic=2941.0) was to look at how different configuration options might impact overall efficiency.   By using the EGT as a control point proxy (consistent engine loading / output at the same RPMs) I 1st am looking at the difference between a mid-frame alternator spinning  around 6,000 RPMs vs. a very large frame one spinning at 2,600.

As shown in this graphs, Alternators are typically more efficient at lower RPMS: 





Last winter I swapped out the existing 130A alternator (Leece Neville 2700 series)  using a 2.5:1 drive ratio for a larger frame 200A alternator (4800 series) and a 1:1 drive ratio.  Here are the results (remember this is a 12v 'system'):

As a baseline using the 130A alternator I recorded the following:
       Alt:           135A using 2.5:1 drive ratio
       RPM:        2,550
       EGT:         943f
       Output:    1,610W

Swapping out the larger Alternator, changing the drive ratio and then increasing loading until EGT was back up in the 940f range; indicating the engine loading / HP being produced is the same as when driving the 130A alternator.   I now get:

       Alt:            200A using 1:1 drive ratio
       RPM:         2,580
       EGT:          944f
       Output:     1,920W


A 19% increase in DC generator output from the same engine loading.  More details here:

http://mvvikingstar.blogspot.com/2015/05/improving-dc-generator-efficiency.html

--or--

http://tinyurl.com/ktqjq5h


Perhaps next winter I will try to dig up a  Desno "Hairpin" Alternator from a junk yard and see what that gives me.  But for now, am very happy with the increased overall system efficiency this change represents.

-al-