alternator choices, pm vs electro field...

[mobile_bob]

being a curious old fart i thought i might ask
based on the various folks exploring alternative generator designs

to those that use the hydrogen appliance pm alternators, the windblue pm alternators
and other modified small frame automotive alternators.
why would you want to use one of these units? what were you hopeing to gain by using one?
how has it worked out for you?  how does it compare in fuel consumption efficiency to other alternators you have used?

i am trying to get my head around all the hype surrounding these modified delco alternators with the magnet rotors
personally i can see no benefit to using one, and i can see a couple of issues surrounding their use that are negative.
i don't buy into their claims of longevity of 115k hours, and wild ass claims of output amperage, and most especially i take
exception to their claims that their pm units save huge amounts of power needed by standard alternators for excitation
their claims of 50% going to excitation is over the top.

so lets hear about it, or lets hear about other options

bob g

[Doug]

Well I could see 50% of power going to the field if the RPMs are low and the load is low.

You probably put bigger pullies on alternators years ago Bob to increase the performance right?
Slowing them down has some negative effects. For the sake of hype and smoke I guess youcould find a situation where an alternator is putting out little power and using a significant amount of what it generates just to sustain the field.

[mobile_bob]

your probably right there Doug, but usually we don't worry much about excitation losses with engine
driven alternators because it doesn't amount to much generally.

its just that i see a lot of folks getting all wound up about field power losses as if it was several hundred watts
so they automatically go with magnets to replace the field coil and find that the tradeoff doesn't work as expected.

its hard to justify the cost and trouble of replaceing the field with magnets when a good alternator can produce
4kwatts using 45 watts of excitation power.

you put out the money for magnets, machine the rotor to fit them and in the end have higher eddy and hysterysis losses
than what you had with the wound field rotor,, often times more losses than the 45 watts you were trying to save, also

you lose control of regulation, at least off the shelf simple control of both volts and amps if you are battery charging.

you can however control amps and volts with a sophisticated controlled rectifier, but that ain't cheap or easy, and certainly not
an off the shelf item.

i just see so much wrong with hydrogen appliances claims, and those of windblue as well.

you probably know better than i, but when was the last time you saw a sealed ball brg and a rear needle brg like used in
the delco alternators being rated to 115k hours?

apparently folks can claim just about anything, and sell it, and never get called to task?

nice gig i guess if you can get it, and can look yourself in the mirror in the morning

bob g

[Doug]

Yip.....

http://www.youtube.com/watch?v=9Txqmgr1k0Y

Hard to tell sometimes Bob, I guess thats why I am skeptical of everything....

[jzeeff]

I notice that even efficient long haul truck alternators (eg. Bosch) don't use permanent magnets.  From what I can tell, they run a lot of hours and will use anything that pays for itself in fuel savings.

I've wondered why one can't create a hybrid - use PMs for some base level strength and then add more with excitation.

 

[mobile_bob]

we're going to see more and more of the hybrid alternators as the 42 volt standard comes in with the automotive industry
pm's with field coils to buck/boost with, and also there will be more water cooled stators as well.

i am considering a water cooled stator on the current version of the prototype alternator i am working on, not sure how the payoff
will be until i run some tests, the gains have to be more than what it takes to pump the coolant or you just break even and why do it?

i don't see the advantage to the development of a pm alternator unless you got the resources to do the R&D and get it right, otherwise
you lose in the tradeoff's and end up with a more expensive unit that may not be as efficient as what you could have used.

bob g

[apogee_man]

Multipower looks very intriguing for our application!

Catalog page #'s 5 & 14

(3.8 meg download. I copied the text below for those on slow connections)

http://www.prestolite.com/literature/mixed/PP-1184-US_Quick_Reference_Guide-lo-res.pdf

New MultiPower™ Technology

The MultiPower™ system allows for the installation of up to four (4) alternators on a single vehicle,
for a possible total of up to 1,080 amps.

The unique feature of the system is the ability of the alternators to communicate through a simple wire
connected to a transmit/receive terminal on the integrated regulators. No external control or processing
unit is required, greatly simplifying installation and increasing dependability.

This constant, real-time communication by the regulators allows the MultiPower™ system to share
the load of the vehicle dynamically and effectively. This alternator unit can be installed in a single
application where future expandability may be required, or in any configuration of up to 4 units on a
single vehicle. Multiples of a single part number can be used in applications with requirements
ranging all the way up to 1080 amps. This single unit capability means you only need to stock one
alternator model.

The load sharing capability is integrated into the regulator that is installed on the alternator. No external
CPU or CU is required, only a connecting wire between the alternators. The technology used utilizes
proven components with long established reliability records.

Multiple alternators provide back-up power in the event of a partial system failure, allowing for
significant “Continue in Use” and “Limp Home” functionality. Very high amperage capabilities allow
for large amounts of available power at engine idle. There is no need to operate alternators at high
speed to obtain the desired output, extending the life of the units. These units are also high
temperature rated at 110°C for installation on new EPA emission compliant engines.

The system will initially be confined to the 270 amp 4000 series alternators, with possible expansion
to additional lines in the future.
6 © 2009 Prestolite Electric, Inc. www.prestolite.com