seems to be interest again with charging 48volt banks
i have a question i would like to pose to those so interested
"how many amps would you like to have available to charge with?"
it would appear that 40-45amps is about what most folks have capability of,
would a unit that can do 75-85amps be of interest?
the reason i am asking, i have something like 50 or 60 leece neville alternators that i can setup for 48volt charging
(capable of anything up to 62volts or more if needed, although all testing will be done at 57.6volts dc)
its going to be a while before i can get to building these up, i am about half way through the unpacking, sorting, building and loading
all my crap on shelves in the new shop. it is a long process that i want done right so i don't have to do it again later.
bob g
I have interest in the units. I could possibly use more than one.
if you build it, they will come.....
Yes, I'd be interested. But they wouldn't have a charge controller, right? My 6/1 wouldn't do more than 40 amps right now w/ thermosiphon, but it would be nice to have greater capability.
I'd be interested in as many amps as could be gotten out of a flogged, wound out, 6/1 roid.
Depending on price, I need something to charge a 825ah NiFe bank I'm installing next week. Planning on solar (in the winter - ha) or the 6/1 driving the 240v ST head, into the XW6048 .98 PF charger. But another source is not a bad thing to have.
I think I could probably use one funds permitting....
I'd be interested in a 24v (28)....in case you have one for sale...
I would be interested in one also. I won't be running a lister but I do have an arrowboard engine with deep sump. Got lots of biodiesel to feed it.
Sounds easier than transforming down and rectifying my st-5 output? Interest depends on price as usual :-)
Bob,
Please give us a price and a time frame. If you can provide in 24 (27) volts, I too would be interested.
veggie
I would be interested as well. Out of curiosity which Leece Neville alternator is this based on?
Simon.
Do you still have these units available? I may need a few if the price is right.
Hey Bob,
I'd love one, or even just a stator rewound. I can deal with diodes, controller etc. I just emailed ya this AM from the Fieldlines forum becuase I had lost my login here.
Jonathan
for all of you interested in running a 48 volt alternator at 48 volt native, Balmar now makes an MC6-48 regulator, and it even has Li-ion charge capabilities. It's the same regulator as the MC6-24, with some software tweeks, it's a true 48v remote sense. 3 stage regulator.
Lloyd
who is selling the balmar mc48?
bob g
Quote from: mobile_bob on October 11, 2012, 11:07:28 PM
who is selling the balmar mc48?
bob g
balamr,
If ya need a part # let me know, I just had em build me 2 X's MC32v regs based on the same, they can do 24,32,36, & 48 native from the same reg/w software changes.
Lloyd
Quote from: Lloyd on October 12, 2012, 01:48:05 AM
balamr,
If ya need a part # let me know, I just had em build me 2 X's MC32v regs based on the same, they can do 24,32,36, & 48 native from the same reg/w software changes.
Lloyd
Regs I got.... so where are the 'efficient' high amp rectifiers? In 2 months keyboarding, I unearthed only
one that I could actually buy, and it's only a 50 amp. Just yesterday, I put in an order for two GMM3x120-0075X2-SMD modules the vendor advertised as "in stock". Not 2 hours later, I received the following;
"Im sorry, but we don't have this parts available at stock or with any short lead time now, seems like it's a rare thing at our market. please feel free to contact me on any questions. Maybe you need something else to quote?"
not sure why the interest in a high efficiency rectifier?
at 48volts nominal, the voltage drop comprises about 1/4 the loss of a 12 volt nominal system, as it relates to the diodes.
its very unlikely that you will find a high efficiency rectifier that will reduce this to half of that, or 1/8th that of a 12volt system.
you rapidly reach the point of diminished returns.
i think you will find your choice of alternator will have a much larger impact on the overall efficiency of the system, just as your choice of prime mover.
another consideration is cost and reliability
a high efficiency rectifier is likely to be priced substantially higher than the replacement diodes i listed earlier, and i would also be concerned with reliability.
diodes can and will fail,
i would be very concerned with the "load dump" capability of any rectifier i planned on using.
just a thought?
what are you goals?
bob g
Quote from: mobile_bob on October 12, 2012, 09:34:54 AM
not sure why the interest in a high efficiency rectifier?
(http://i47.tinypic.com/m7q7i1.jpg)
how about a little more data
what alternator does the chart relate to?
what operating voltage nominal and at load?
also not the increase in efficiency between the first column and the second
column..
the third column really does not illustrate the change in rectifier alone, it also takes
into account the replacement of the field with neo magnets and the reduction of stator resistance, both of which are the factors responsible for the increase in efficiency.
so naturally i want to see more info so i can get my head wrapped around this one.
also in the first column the rectifier loss is about 100 watts more than the mosfet
rectifier of the second column. shaving that 100watts off the rectifier by going to a mosfet while useful is probably going to be a costly cut in losses.
what i mean is this, that 100watts comprises 1/4 of the efficiency effect at 48volts as it would at 12 volts
for instance a 12 volt @100amp alternator with a 100 watt diode loss would work out to be 12 x 100=1200watts -100 watts = 1100 watts or 1100/1200= 91.6% or an effective loss 8.4% attributed to the diodes
on the other hand 48volt@100 amps with the same 100watt diode loss would work out to be 48 x 100 = 4800watts - 100 watts = 4700watts or 4700/4800= 97.9% or an effective loss of just 2.1%
of course the number shift a bit due to actual charging voltages, but you get the idea.
don't get me wrong i am all about finding even fractions of a percent in efficiency gains, so long as the price is not prohibitive and there are no reliability issues.
so in recap
what alternator is the chart related to?
what voltage are they working at? and at load?
thanks
bob g
it would appear the alternator in question is a 12volt nominal unit
probably tested at about 14.6-14.8vdc at load
bob g
I would think that switching to Schotky diodes for a 12V alternator could reduce the loss by at least half. Less robust, but so is synchronous rectification. So even at 12V what you are looking at is largely marketing hype.
As mobile_bob point out the losses shown are for 12V, and are bogus for 48V. But the losses do point out the inherent inefficiency of low voltage systems. In most power electronics designs, you rarely see synchronous rectification used except for 6 volts and below, because with schotky diodes, it just isn't worth the complexity until you get that low.
The integrated rectifier/charge regulator Brentcraft found seems a good choice, since there is no reliability penalty for the low side Mosfets; they are both regulating and providing "half synchronous" rectification by eliminating the low side diodes. But at 40 amps it alas isn't rated high enough current for many 48V charging apps.
Of course, I say why stop at 48V, Edison had it right at 120VDC as a good compromise for safety and being able to run power about without using tons of copper. At 120VDC, your diode loss should be significantly less than 1/10th, as diode bridge voltage drop is reduced at the lower currents.
Bentcrafter
that chart has been haunting me, somewhere in the back of my mind
i couldn't get past the idea that i had seen it somewhere before.
been laid up with the flu for 4 days now, and it finally popped back into my head
i have seen this chart somewhere before, but can't remember where!
bob g