Author Topic: Operahouse, reuse of old stuff  (Read 3667 times)

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gww

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Operahouse, reuse of old stuff
« on: January 24, 2015, 09:27:11 AM »
From your post on the thread paraleling mutiple inverters.

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I love inverters and keep a stock of defunct ones around for projects.  Many have damaged H bridges.  I just tear that section out and run 140V DC to run CFL lamps with electronic ballast.  I also run VCR and DVD decks on 140V DC.  A lot of line powered electronics will run just fine on 140V DC.  Others will go up in smoke.  One old HF inverter has multiple inverters that produce about 32V each that they just add up.  That seems very useful but I haven't found a use for it yet.

Have you any ideals for dummies of how to use some of this stuff to end up with something that would put about 40 dc amps to a 48 volt battery using a 5000 watt generator.

I have a couple 350 plug and play computer grid tie inverters and maby a few computer power supplies. 

Something I could run unregulated and turn on and off with a ssr from a charge controller aux. 

I am doing my best to not buy more stuff but still get done what I wan't but don't really need.
Thanks
gww

OperaHouse

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Re: Operahouse, reuse of old stuff
« Reply #1 on: January 25, 2015, 02:45:39 PM »
I don't think even Ricky Jay could make that appear.

I have been thinking about that ever since you first mentioned it.  48V just falls into a crack. I have a nice rack mount telco 48V supply.  I ca barely pick it up, but it is only 17A.  Got a nice 100A electro machining DC supply.  Ever see a three phase variac? About twelve UPS would give you enough transformers.  A 5KW 480V to 120V transformer would be a good start for something standard.  I used to pick these up for $20 at auctions. Pretty common if you are in an industrial area. Then use a buck boost to lower the generator output voltage a little.

gww

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Re: Operahouse, reuse of old stuff
« Reply #2 on: January 25, 2015, 03:07:33 PM »
op
But then the boost/buck would be a big item.  I kind of knew the answer but thanks.  Oz had tried to explaine a retifie the generator out put and then cap it to control the amp output.  I read you threads and you guys are always above my head so I should leave well enough alone anyway but I just keep asking.
Thanks
gww

joestue

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Re: Operahouse, reuse of old stuff
« Reply #3 on: January 25, 2015, 03:10:28 PM »
Have you any ideals for dummies of how to use some of this stuff to end up with something that would put about 40 dc amps to a 48 volt battery using a 5000 watt generator.
gww

Find the midpoint of the coils and cut both of them, this will get you 60vac. Parallel or rectify all four coils separately. reduce generator speed to regulate amps.
Install two DPDT switches to return the generator back to 120/240 operation.
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gww

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Re: Operahouse, reuse of old stuff
« Reply #4 on: January 25, 2015, 04:21:30 PM »
Joe
I have never had it far enough apart to see how hard it is to find the mid point.  I need to find a junk one to practice on.

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reduce generator speed to regulate amps.

wouldn't the battery take all the generator would give and just kill the motor.  So if I have it correct, the generator will only put out its max, and speed up to the highest it can, but it wouldn't overload it?

It states on the generator that too big of loads could damage it.  If not this seems a pretty decent solution depending on the ability to find the mid points of the coils.  Am I correct that it would take 4 single phase retifiers with a dc output of about 84 volts.  Too bad I can't get the output to 60 dc volts, I could run it unregulated. 

So I may look at this, are we sure the reducing the idol speed will control the amp output regaurdless of what the battery would take?
Thank you
gww

gww

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Re: Operahouse, reuse of old stuff
« Reply #5 on: January 25, 2015, 05:06:53 PM »
I also have one other question.  How would I handle the starting and stoping of the charging?  I know dc arks badly and I know the generator is supposed to be run for 5 min before puting a load to it.

Is this question clear?
Thanks
gww

gww

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Re: Operahouse, reuse of old stuff
« Reply #6 on: January 25, 2015, 06:23:48 PM »
I feel like an idiot asking the last question, of course, use a dc breaker like I have used on every part of my system.  Never arked yet when switching one.

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So I may look at this, are we sure the reducing the idol speed will control the amp output regaurdless of what the battery would take?

I do want to know this before I tear into anything.
Thanks
gww

joestue

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Re: Operahouse, reuse of old stuff
« Reply #7 on: January 25, 2015, 09:12:46 PM »
The brushless generators will not be a candidate for what I described.

So yes 60vac makes 84 volts. -2 volts for the diodes.

To be honest I'm not sure what is going to happen if you run a regular brushed generator at significantly lower rpms. the maximum voltage will follow the same volts per hz curve, but the slope of the voltage/amps curve will be different.

So my 5KW generator drops about 40 volts at full current, 260vac no load and 220v full load.
If you set the generator governor to deliver a few amps into the battery at 56 volts dc, you would be looking at full load amps being pushed into a 48 volt battery assuming your 5k generator is about the same as mine.
I think this is perfectly reasonable. 

the lower rpms may be more or less efficient for the engine, and you can't expect to get 5KW running the generator at 75% rpm.. also keep in mind the fan will pull less air through the system so it may run hotter.. however the lower rpms mean less iron loss in the stator too.. so, i guess i should try this myself as an experiment.
i've been meaning to rewire it for 60vac.. as that would be plenty for arc welding.
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gww

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Re: Operahouse, reuse of old stuff
« Reply #8 on: January 25, 2015, 09:39:47 PM »
Joestue
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To be honest I'm not sure what is going to happen if you run a regular brushed generator at significantly lower rpms. the maximum voltage will follow the same volts per hz curve, but the slope of the voltage/amps curve will be different.

I'll be honest, I don't know if my generator is brushed or brushless.  It is a devilbiss, so I guess I will have to look it up again.  My intuition is brushless but not cause I know anything. 

I do know that I hooke a welder to mine and had to turn the welder to 175 amps to weld and the generater blew the 20 amp push button a couple times.  It barly did the weld job but did do it.  I am thinking that it will just cause the thing to try and put out more amps then it can.

I am in no real hurry so if you ever do do yours I would like to know the outcome.  I just hooked it up to the outback and got the outback inverter to accept it well enough to pass through the power to the loads but not well enough for the inverters charger to work.  It is the g series inverter and honda inverter generators are about the only ones that keep tight enough tollerances for the inverter.  Strait battery charging would work fine but I don't want to spend money on a 48 volt charger.
Thanks
gww

WindriderNM

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Re: Operahouse, reuse of old stuff
« Reply #9 on: March 26, 2015, 09:21:58 PM »
You may be able to use your welder. Maybe with a voltage doubler.
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