Help puting together a automated 48 volt charging system

[rosscat3]

Hi guys, I'm not new to the forum but it's been a long time since I've posted anything. I've been reading a lot on the forum about automotive alternator's and have read most all of the posts on white pages from mobile Bob. What I'm trying to do is put together an automated charging system so I can go on vacation. I'm sure a lot of you realize that we can maintain work on our own systems but other people find it very challenging and intimidating. This in itself makes it very hard to go anywhere for any extended period of time. My system is two trace 4048s, two Trojans 24 V 600 amp hour forklift batteries which I'm not sure if it's 1200 amp hours or 600 amp hours when combined to make 48 volts. Right now I use a 10 KW generator powered by a little four cylinder Kubota motor that intern goes through my trace inverters to charge my batteries.I've gotten an automotive alternator, it's a Leece Neville# A0012258 AC. It is a 28 V alternator that is exterior regulated and exterior rectified.I also have a Lister Petter TS2 that I was thinking I'm making my prime mover. I'm not saying that I have to use a this motor or alternator if it's a good one to use I will. I think I can make the Trace inverters do most all of the automation unless there is a better way.What I would like to do is put together a good dependable system that doesn't have to be babysit.If I have to go buy every piece to make this work I will.Any help from you guys would be greatly appreciated

[Tom Reed]

I have not found a more straight forward to charge 48vdc than what you're doing now. The Trace inverters will auto-start and shut down your engine/generator. This should give you completely unattended operation, with the exception of watering the batteries.

[mike90045]

.... two Trojans 24 V 600 amp hour forklift batteries which I'm not sure if it's 1200 amp hours or 600 amp hours when combined to make 48 volts. .... 

the 2 batteries in series gives you a 48V, 600ah battery.

[rosscat3]

Thanks Tom I agree about the Trace inverter being a easy way to automate charging although the efficiency of the generator makes me think there has to be a better way. The white papers says charging with an automotive alternator efficiency is approaching 80% with the cost of fuel that's a major concern.Like my self after 10 years off the grid my equipment is getting tired and needs to be replaced. 

[DanG]

...Automotive alternator efficiency is approaching 80%...

Just for future readers... If true, in the best case,  that would be 50 to 80% of output harvested from the 12% to 16% efficiency internal combustion engine providing input, then less 20-40 watts field exciting power required at full output, then line and battery chemistry losses...

My vote is for solar photovoltaic maintainer panels and an excellent smart charge minder!

[rosscat3]

Thanks Dan, I live in the pacific NW coastal area near the rain forest I do have solar panels they turned out to be a bad investment for my area I also have a 10' arel flux wind generator that takes some of the slack. However I do live next to a river and that's where I am trying to get off the fuel all together but for now the generator supply's most of the power

[mobile_bob]

DanG

i would like to address your concerns

"Just for future readers... If true, in the best case,  that would be 50 to 80% of output harvested from the 12% to 16% efficiency internal combustion engine providing input, then less 20-40 watts field exciting power required at full output, then line and battery chemistry losses..."

lets take a look at this one concern at a time.

" that would be 50 to 80% of output"
in testing the 110-555jho modified with higher voltage rectifier/diodes will reach 80% efficiency at 28.8vdcand i see no reason it would be much different at 57.6vdc

"harvested from the 12% to 16% efficiency internal combustion engine" 

i assume you are using a gas engine?
a changfa S195 comes in at 32% efficiency in testing as measure by BSFC (btu's input vs btu's output)

"then less 20-40 watts field exciting power required at full output"
not less, the field excitation is included in the 80% efficiency of the alternator at rated output.

"then line and battery chemistry losses"
you will have those losses no matter what you charge with, beit from the mains, solar, wind, hydro or engine driven generator, they will all be the same save for losses due to transmission over longer distances common to many hydro, wind, and solar installations.

the bottom line is this

an st head is about 78-80% efficient, if you use that to power an inverter charger scheme which is likely about 92% efficient, then you have
an effective efficiency of 78-80% x 92% = ~72-74% overall efficiency in power generation.

if Ross does what he would like, and does it right, he can exceed that level of efficiency by 6-8 percentage points, which equates to ~10% increase in efficiency.  if you are burning fuel that is significant.  also from a reliability standpoint, i would rather replace an alternator than have my inverter charger out for repairs.

there is also another factor that will increase efficiency as well, that is reduction in fuel consumption of such a system, as the batteries top off their ability to absorb massive amounts of power is diminished, this means we can reduce engine rpm with this system, something we cannot do driving an st head that must remain at 1800rpm.  an additional 5% in fuel consumption reduction has been shown to be within possibility.

Ross, i have a few idea's for you, but am short of time. i will think about your needs and look up the alternator you have, maybe we can help to get something worked out for you.


bob g

[Tom Reed]

Ah so efficiency is what you're after. Well the automotive alternator is one way to do it, BUT 48vdc is tough to do with no alternators rated at that output and no commercial charge controllers either. My approach, which sadly I haven't done yet, is to drive a 3ph induction motor through a rectifier and put that in to a Midnight charge controller. I do have a 100 amp rectifier sitting on the shelf ready to go. I now need to get a 7.5 hp induction motor and charge controller. Another advantage is this config would give me some redundancy in charge controllers in case my MX60 fails.

Good luck with your project and keep us informed on your progress.

[BruceM]

Ouch, generator as the prime battery charger is tough on the fuel bill. For efficiency where I had to charge via generator I'd be thinking about AGM batteries for much better charge rate and efficiency, leading to reduced run time and better fuel economy. But perhaps you're using the AC power too during the charging times, and are already getting good "bang for your buck" on the generator run time.

I hope you can get something going on the water power front.

PV works so well here at 5600 feet in AZ that I have scrapped my plans for wind power. 

[mobile_bob]

there are 48volt alternators out there, you just have to keep an eye out for them.

leece neville made at least two such units.

having said that, there is no reason that a 110-555jho can't do the job, even though it is designed to
be a 12volt unit, spin it to 6500rpm and do like illustrated in the white paper and you will get your 57.6volts needed
to charge a 48volt bank.

limiting to ~75-80amps will give you ~4500 watts, and the efficiency will be better than the st with an inverter charger.

the only thing you will have to do is have the avalanche diodes replaced with standard silicon diodes with a PIV rating of 200volts
which is commonly available from any rebuilder.

an engine used to maintain or do battery charging is inherently expensive, however as part of a cogeneration system, why not?
as long as you have use for the heat generated the overall efficiency can be quite good.

as part of a cogeneration system, it could be argued that the use of batteries and an inverter, being charged from the cogen system can compete very favorably with many other alternatives.  power the cogen with natural gas around here and i can produce electricity as a byproduct competitively with the electric company, with nat gas being priced as low as it is now.  (factoring in all the line charges, taxes, and other add on charges plus the base rate of 12 cents per kw/hr).

the use of AGM would certainly help in overall efficiency, however even the lowly flooded lead acid battery can take a pretty serious charge rate up to the point of gassing (~80% SOC), and in large banks is useful if for now other reason than to keep the electrolyte mixed up.  in any event it is going to be hard with a small engine driven alternator to deliver sufficient amps for a pair of forklift batteries that would damage them in most cases.  a good controller would protect them in any event.

bob g

[rosscat3]

Thanks guys for chiming in. Any and all help is greatly appreciated I didn't have parts of the code generation system that has not yet been put together I have a thermal siphon system for the generator motor, and all my exhaust runs through the tank that holds the water intern the water heats my shop. I have pex lines ran to the house with the intention of running water through a radiator to use my old HVAC system. I have good intentions but I haven't been able to finish the project as of yet time  never seems to be on my side.I read somewhere a post by Bob G running two 110 –555 JHO with the balmar MC 612 controller with a single prime mover. I have the 15 horsepower Lister Petter motor that already has a four grooved pulley already mounted maybe I'm getting too complicated and that's why I'm trying to enlist your help simple with less moving parts is usually always better.what I have now works fine actually I use the 12 wire generator to power my three-phase equipment. What I intend to do is leave this generator only to use it when I need to use three-phase or backup for my Main battery charger that I'm trying to put together now. Tom May have hit right on the head about using the trace inverter for my automation. I guess up to now I have enjoyed messing with my equipment. Now I have the funds to change things and I would really like to do it right I have enjoyed reading all your posts and have the utmost respect for you guys

Thanks Don C

[Lloyd]

Of Note.

Balmar Now has A M632 volt charge regulator. I have installed 2 in the last 3 weeks.

It's the the same as the M612/614, and the M624.

I spoke with Balmar  Tech Rep. and he said they tweaked the 24 volt boards and, some software changes, wa..la M632 Volt 4 stage regulator. He also said they can do a tweak to make a 48 Volt regulator. They don't list the 32 or 48 volt in their catalog or online, but if you call Rick he will give you a part number to order through your local Balmar Dealer.

I have Rick working on a tweak to the 24 volt Digital Duo-Charge, he thinks he can tweak it just like the regulator...

WoooooHoo.

Lloyd

[Tom Reed]

Thanks for that info Lloyd, that opens up a lot of possibilities. Do you know if there is any extra cost for this tweak?

[Lloyd]

Hi Tom,

Same price for the M612/24/32 so I'm guessing, but the M648 should also be the same price.

Lloyd

Thanks for that info Lloyd, that opens up a lot of possibilities. Do you know if there is any extra cost for this tweak?

[mobile_bob]

i would spec it for a 12volt rotor!

if they do that, we got a winner for 48vdc systems!

bob g