STC Mod for 48 volt charging

[rosscat3]

  I decided to move this progress from general discussion to an appropriate subject. This all started when my inverter/charger went out I had a spare inverter and was left with no way to charge batteries . My battery bank is from a large 48 volt forklift and I always suspected that my trace 60 amp charger just was not enough charger to deal with a 800ah@6hr rate battery.
   So this is my progress to date and I will document the results as I proceed  What I started with is a STC 7.5 KW generator head which is a three phase design. My goal is to take apart the STC separate all six coils on the stator that should give 60 volts per coil .This procedure has been laid out in another post by bschwartz in the topic 48V charging via ST generator and solar charge controller (no ST mod).The STC is similar to the ST except for the stator windings have six coils oh the STC and four coils on the ST The stator windings have got to be pressed out of the case to see the jumper wires that are between the case and the coils.Well that is where I am at right now I will take more pics this morning that show where the jumpers are located on the stator.

     Don C

[bschwartz]

Now yer just showin off cuz yer pictures are nicer than mine 

Thanks for posting.  Your head looks 'cleaner' on the inside than mine.  My wires were a pain to locate and pull apart. 

[rosscat3]

If it wasn't for your posts and pics I probably wouldn't even tried this you took the first step.Have got yours up and running? How do you like it?Any numbers Yet?

[bschwartz]

Sorry, as is typical, I got sidetracked with many other projects.  All the connections are out and tested on the ST-5.  They are currently connected normally for 120/240.  I just got in my GVFX3648 and FX-60.  4 days ago, I got my first 840 watts of solar panels up on the roof, so now even with the engine down (like it currently is) I can still feed a little back into the grid.
Mbyrner is currently running his ST into a charge controller/inverter setup.
The current issue is current draw.  We are trying to figure out a way to limit the draw the system puts on the ST/engine combo.

To sum things up.
ST mod was a success.
4 pairs of wires at 60v worked great.
I will be putting each pair through a bridge rectifier, then filtering with a large choke of some kind.
Once I get the engine back together, I'll have to figure the current draw issue.
I'd think for bulk charging, I'd be close though.

Sorry I don't have more data for you.

[injin man]

Just out of curiousity why not get one of these rather than dismembering your
head? This of course is only one variation that I found that could be powered by
the ST type heads. I also have a 240v to 48v to 120v UPS that might work as well.
I do realize we are a bunch of experimenters but the older I get the less inclined I am
to work on stuff.

http://cgi.ebay.com/NEW-FORK-LIFT-TRUCK-Battery-Charger-48-V-Volt-AC-110-/220697711606?pt=LH_DefaultDomain_0&hash=item33629bd3f6

[bschwartz]

Just out of curiousity why not get one of these rather than dismembering your
head? This of course is only one variation that I found that could be powered by
the ST type heads. I also have a 240v to 48v to 120v UPS that might work as well.
I do realize we are a bunch of experimenters but the older I get the less inclined I am
to work on stuff.

http://cgi.ebay.com/NEW-FORK-LIFT-TRUCK-Battery-Charger-48-V-Volt-AC-110-/220697711606?pt=LH_DefaultDomain_0&hash=item33629bd3f6

429 reasons why one would want to rework a currently owned ST head vs buying one of  those chargers.......

[injin man]

Okay, start with the most basic reasons, I'm new. Besides the cost.

[bschwartz]

Sorry you didn't get the humor that was $429 was the number of reasons.
Cost.
In many cases, one can purchase a solution to a problem.  Here we tend to try to solve our problems with what we have at hand.
We aint so old that we mind working on stuff. 

[Crofter]

It didnt state what the output Kw is. If you were doing it as a serious battery bank charger you would be getting another layer of efficiency loss too.

[injin man]

I have an Achitectural Metal Fabrication business and I understand making things,
some brackets for rails can be bought for less money than making them but I tend
to make them to keep the labor in the shop. I probably wouldn't take apart my ST15
and try to change it on that level though, it would make more sense to find a reasonably
priced industrial charger that's designed to charge a battery that big properly and be done with
it from my perspective. Your way is appropriate for your needs and that's really all that
matters, I figured there might be some underlying problem running the charger from the ST
head.

The Charger I picked seemed like decent unit and I was just throwing the concept out before
I dive in the deep end of the pool. Just like inverters I would expect some power loss from this
arrangement.

I did get the 429 humor, it did take a second.

[mbryner]

Hey, I like the forklift battery charger idea.   Only problem I see with it:  it says "current limiting" but not how much.   What's it's max charge amperage?   Probably a lot more than a 6/1 would handle?

With as much time and energy I have into building this 48 volt charging supply I could have easily bought that forklift charger, but hey, it's been a lot of fun and I can fix mine when it breaks.

[injin man]

Marcus, you were what brought my thinking around to this idea.
The Bigger the Battery the more power it takes, since I'm setting
up my system initially with a 3 cyl Deutz an ST15 head I figure I've
got surplus power anyway and losses wouldn't be that bad. Here
in Houston I've got access to numerous industrial battery sources
some friendly some not, and used 36/48 volt chargers are everywhere,
and the 48v system makes the most sense.

[mbryner]

Hi Injin Man,

Yes, definitely 48 V system is the way to go.   

Since it looks like to you have a prime mover with much more HP than a 6/1 Listeroid, then you could use one of those 48 V 100 Amp forklift chargers.   There don't seem to be many options inbetween the 48 V 15-25 amp chargers and the ~100 amp chargers (at least on e-bay and the limited google searching I've done).   Something around 50 amps would be perfect for a 6/1.

Sorry, I didn't realize you had a 3-phase STC on some of those earlier posts.  With your three phase head you could rectify each phase and have "relatively" smooth DC if you did a homebuilt charger into a solar charge controller.   And I trust the solar charge controller for charging a large battery bank better than the forklift chargers.   They are built to run a complete charge.   The MPPT solar charge controllers are made to handle varying charge w/ cloud cover, rain, bright sun, etc.   I may be able to charge for a few hours then turn off the engine to go to bed.   Those forklift chargers want to complete the charge cycle before being disconnected, correct?   And they don't give any feedback except for a single LED light: charged or not.   Hmmm.  Writing while thinking.   I'm still going to try to perfect what I started.

Marcus

[injin man]

Marcus

You are correct, the chargers typically run for 8 hours, it's a 24 hour cycle. Run for 8,
charge for 8 and cool down for 8.

The folks I'm going to buy my batteries from should be able to tell me about what the
chargers are capable of and what the current draw is for a smaller charger.

The head I have is an ST15, it's really big! it takes a serious engine to run it full out.
I could run it with the Ford 4000 tractor I have but it's not real practical at the moment.

Ben

[rosscat3]

Well here are more pics. I had to work last week so I didn't get more done.The wires are brought out now to separate the coils .Is it best to have opposite coils paralleled together?