(pdf) high output/efficiency alternator white paper

[mobile_bob]

hey now, don't get carried away there, i am a mere mortal diy'er like the rest of the membership.

(although professor bob has an odd ring to it, don't you think?) 

i am not at all familiar with the unit you have in your diagram, or how it would be best used to accomplish
what you are after.

having gotten my dr. to up my meds i think i am going to be up to doing some testing this weekend (sunday)

i am also pretty sure i have everything i need to do the test that you need, for higher voltage generation/transmisson
then a 3phase transformer step down, rectification and charging a 12volt battery.

this is really not something i plan to use myself, but i have no problem setting up and giving it s whirl to see if it works
out to be something you might find useful.

bob g

[mobile_bob]

well i picked out a nice matched trio of 1kva transformers, the secondaries are heavily wound with what appears
to be ~3/32" x 1/4" copper, and probably about a 5:1 ratio

i attached a junction to the primaries and connected them as delta, and used a 3 wire 10guage piece of nice stranded rubber covered cord.

the secondaries are connect in Y configuration, because the alternator i am going to drive it with puts out about 60volt under load
and a 5:1 step down would get me to 12, but i opted to go for the 1.73 step up afforded by Y connections for the first test.
that should allow me to get solidly into the 14 volt range after rectification with very low excitation current, after the initial test i might
reconnect the secondaries as delta just to see how it works out.

for a rectifier bridge i cheated and used an oem set from an old leece neville i had laying around, i will have to put a fan over them if i try
to pull max amps for any length of time.

i have to attach a 12 volt battery for it to work against and a dummy load, amp shunt and attach the other end of the 3 phase cord to the stator
external taps on the test alternator. and of course the controller to provide excitation and monitor the sense line to the battery.

the test should prove the concept in that the alternator will be excited with a 12vdc source, and managed by the controller, via the sense wire to the battery

the alternator will provide ~60 volts AC 3phase, which i will take off and transfer a few feet with my 10/3 cord

the transformer will do the step down to a voltage low enough so that it can be rectified and provide for charging at around
14.4vdc

i will be running two tests, one with the alternator in stock setup, and do a bsfc at a fixed load of X amps at 14.4vdc
and then run a second test with the alternator running with the remote transformer/rectifier setup, a the same X amps at 14.4 vdc

from that i should be able to tell if/or there is an increase, decrease or parity in charging efficiency of the system from that of the stock oem
alternator.

i would expect some losses, but there might not be as much as i would expect, and there is some supporting text that would tell me
that the system will return a higher efficiency over the stock oem alternator, even though there are transformers involved.

sunday is the next opportunity to run the test, and i am looking forward to getting some decent testing and solid data for discussion here.

btw, this topic has morphed well away from the original intent of the white paper section of our forum
next opportunity i get i will split out this new direction and setup another topic under "testing" or somesuch, and after we get some solid
results and a workable system we can then writeup another white paper to cover this method.

gotta think how best to deal with all that later, for now i just want to get my head around a full battery of tests and setting up a protocol
to get as accurate data as possible.

more to come

bob g

[mobile_bob]

decided to move the experimental portion of this discussion over to a more appropriate board

http://www.microcogen.info/index.php?topic=687.msg8141#new

bob g

[elnav]

Bob  I just found your paper on alternators. Excellent  read BTW.    Interestingly I arrived at  choosing the same 160 amp Prestolite alternator by a totally different route using completely different criteria. In my marine design work I deal in a very small niche market of boat owners who cruise long distance , some of them literally around the world.
While I worked for Xantrex as a a marine applications / sales engineer I met  a number of interesting people  including the staff from Balmar.  Since you used a Balmar regulator  I assume you also know pf their other product offerings.
My  clientele  wants  a totally reliable charging  system and if they do need repairs,  want to be able to find competent service people any place in the world. They also would want  readily available parts  and not have to have them sent air mail from back home.
Given the electrical demand  found on a typical  modern yacht  a 24V system is preferred over a 12V system.  As you clearly stated  in the paper concerning I squared R losses, the higher voltage  at same wattage means less current. The cost difference between wiring with  2/0 instead of 4/0 is very compelling. 
I always specify Balmar  regulators because of the Amp Manager and specify the regulator be limited to around 95% - 90% or less of full output since this also serves  as a added protection feature. 
Many of my systems  require the use of twin 160 amp alternators driven b y the same engine pulleys.   Average loading  would require close to 200 amps @ 24V  and peak demands hit 400 amps.
My clients  do not like to listen to a diesel genset rumbling away  overnight so they want silent power from inverters  but  when cruising in the tropics  they still want  air conditioning  overnight. 
Because you cannot store AC power  this requirement leads to needing batteries  for storage of DC; and  24V is the most common system voltage. 
Yes I know 48V makes more sense but in the marine world a lot of regulation mandated safety equipment navigation gear etc. is only made for 12V, 24V DC, or  230V AC ( european) so the vessel system becomes 24V DC  and either 120V or 230V AC. 
To provide  AC power I rely on Victron  equipment which is a European  company with  manufacturing in India not China so the quality is better  than chinese built equipment.
Design wise the Victron outperforms  products like Outback  in some key  areas. For examble  their chargers can handle  either 50Hz or 60HZ and the latest  models of their Skylla charger  handle any voltage from 90V to around 265V AC over a wide range of  frequency and it will even handle  several hundreds volts DC.  This one feature alone makes it an  almost  perfect  candidate for  running from near unregulated AC generators. Their sine wave output inverters run at about 95% efficiency. The  inverters  can be  synched  in parallel to deliver  15 - 20 kW of regulated stable  AC power provided the DC source  is capable of such high currents.
Dr. Jim Clarkes 'Hyperion' yacht  had  around 45 kW of 3 phase inverter power for silent night running.  BTW  the Victron can also be configured for 3 phase power.


Now that the old Prestolite VLF series 300 A @ 24V alternators are discontinued  the next  best choice is the 160A  Prestolite model.  Balmar deliberately designed their MC612 or MC624  regulators  to handle 10A of field current  so it is possible to govern two alternators  from one single  unit.  It makes for a more stable  output than  when driving two separately  regulated  alternators feeding the same battery.  So a pair of these 160 Amp alternators paired up and derated to 150 amp output still provided 300 amps of output current.
Unfortunately  my photos of  such installations are too large to post on this forum. 
Elnav

[mobile_bob]

i have been following victron for some time now, particularly their work in testing various classes and manufactures
of gensets in the classes we work with.  it is nice to have a goal post to work toward and they have provided that
with their published test results.

for me, i started my quest for learning based on my belief that it might make more sense to charge batteries and then
use the power through inverters using a genset, that was about 12 years ago now.

in the beginning there really wasn't much published about this principle for offgrid use, and quite frankly the whole sector
has been slow to adopt the strategy, so

i spent all my time researching two major sectors to adopt the technologies and develop my philosophy, those being
both "NASA" and "Marine" and of course pawing through tons of paper from sandia labs

it didn't take long to find overwhelming support for the strategy from both sources, mainly in my opinion because they
are both the ultimate in off grid, you can't plug into a grid in space, nor can you out in the middle of the pacific.

the limited run time at peak load, charging a good set of batteries and powering a good inverter has far more "pro's" than
"con's" in my opinion, efficiency, increased lifespan, improved heat quality, lower emissions to name a few of the positives,
first cost and complexity might be said to be the "con's"

as far as i am concerned offgrid folks could learn a lot from the marine side of things

as for balmar and the mc612 being fuse limited to 10amps, yes they can control 2 heavy alternators in tandem, and the fuse can be
removed and replaced with a 15amp as per balmar engineering (but i might not want to do that myself)
otherwise the unit has so many useful features it is hard to imagine building an engine drive dc charger that isn't controlled with a balmar
or comparable controller. that amp manager is of huge benefit for trigeneration where a refer compressor is also driven by a smaller engine
and one is faced with trying to share the available power between the two driven components

the only thing i don't care for with the balmar is its being potted and non repairable should something go awry, they are fairly expensive
and it leaves a huge pit in ones stomach to see the smoke come out of one and know they are not repairable.

bob g