How to connect a generator with a battery(12v) or with a lamp?

5 Posts
Mar 8, 2010 10:35 am
How to connect a generator with a battery(12v) or with a lamp?

I need some help with my schoolproject which is to build a windmill.
The windmill is all clear and the last thing is to connect the generator to the battery.

I know that I need some sort of chargecontroller, but I wonder if I can connect it without the chargecontroller and charge the battery? And if we say that I want to run a simply lamp instead of charge the battery, what do I need then if I don't have a chargecontroller?

My generator is an Ametek 60VDC. The output voltage is around 0-30 volt depending on how much wind it is outside.

 

 
220 Posts
Mar 8, 2010 04:37 pm
Re: How to connect a generator with a battery(12v) or with a lamp?



hi robin,


"I know that I need some sort of chargecontroller, but I wonder if I can connect it without the chargecontroller and charge the battery?"

you can run it without a controller while being supervised but i would NOT run it for very long unattended.

here is a diy controller that rivals or surpasses the high priced wiz-bang commercial units. (IMHO)

http://ghurd.info/

note: in this configuration the battery controls the wind turbine and the controller controls the battery.

i got the crayons out and put together a few scribbles to how we can run things (for demo) before we install a permanent controller.

standard configuration with stud diode. (these can get pricey and be hard to find at times)
http://www.surplussales.com/semiconductors/Diodes-3.html




optional configuration with easy to find bridge. (radio shack part #276-1185)
http://www.radioshack.com/family/index.jsp?categoryId=2032269



we included a demo light here (small tail light bulb would work)..we want to NOT stall the machine out here by going too big...

things will get complicated if we try to run a light without the generator being loaded by a battery.

we want to size the blocking diode BIG..something like 20 amps and 50 volts minimum. with a heat sinking mount.

cheers, dave
 
462 Posts
Mar 9, 2010 11:23 am
Re: How to connect a generator with a battery(12v) or with a lamp?

Robin, you say 60 V DC, what is it's maximum rating in Watts? V x I = Watts. If you know that, then calculate the maximum I in amps. Then use V = I x R, to find maximum R.
 Then, some type of cheap voltage regulator and/or variable resistor may be of some use.  If you start out at a high resistance it should handle the current and then you could hook it up directly to a DC light source. Then vary the resistance and the bulb should get brighter or dimmer if the windmill is rotating steadily.
  If you add motor to spin the windmill at a certain speed, for demonstration purposes, you can then have it operating at 12-14 V to charge a battery.
  Since this sounds like a classroom experiment, safety first. As David mentioned not running the windmill long at high speeds unless properly connected to a circuit or controls that can handle the output, but spinning the windmill slow shouldn't pose much danger and if there is a voltage and or current meter installed you should be able to show how wind speed can change these values and how controllers regulate these changing values. 
 
 
5 Posts
Mar 10, 2010 01:44 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

Thank you very much for helping me understand! I appreciate it very much. I will strongly recommend this site to all of my friends that work with this kind of electronics.

I also found this kind of chargecontroller, http://www.fieldlines.com/story/2004/9/20/0406/27488
what do you think about that? Which one of the two chargecontrollers would you recommend? The one on http://ghurd.info/ or the one Ive found?



 
220 Posts
Mar 11, 2010 03:05 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

never had the chance to work with a "miller" controller (the fieldlines link) not sure what ever happened with tom- he used to write for a few magazines and be active in the HAM chatter on the net..he may have become overwhelmed with requests for advice on his controller design and gave up?

put together and used several of glen's (Ghurd) controllers with happy results.

glen designed the circuit and pcb and sells the things out of his basement for twelve dollars a pop! with every sale he includes $1000 worth of free tech support to his customers Smiley..kinda like here at altE. Wink

for a ready made controller, our hosts have some available.
http://www.altestore.com/store/Charge-Controllers/Dump-Loads-Dump-Load-Controllers/Diversion-Dump-Load-Controllers/Xantrex-C35-35A-1224V-PWM-Charge-Controller/p2069/
or
http://www.altestore.com/store/Charge-Controllers/Dump-Loads-Dump-Load-Controllers/Diversion-Dump-Load-Controllers/Morningstar-Tristar-45-45A-Chg-Ctlr-Without-Display/p806/

note: all of these controllers will need a "dump" (usually power resistors) for an ametek 60, a resistor bank rated at about 0.7 ohms and 200+ watts would do it. the whole idea with a controller/dump load is to fill the battery up and get rid of any extra that would result in overcharge. kind of like bailing out a boat..all the while keeping our wind turbine loaded and under our control.

best of luck with your project and kindly keep us posted with your progress.

cheers, dave

ps. with a good sized battery bank and a watchfull eye we can run a small wind turbine full time without any controller at all. just the blocking diode.

edit: changed 0.07 ohms to 0.7ohms YIKES big difference.
« Last Edit: Mar 11, 2010 03:25 pm by david ames »
 
5 Posts
Apr 11, 2010 11:32 am
Re: How to connect a generator with a battery(12v) or with a lamp?

Hi again!

Recently Ive finished my windmill,chargecontroller and the dump.

Here is a pic on the windmill for those of you that want to se the result:
http://i42.tinypic.com/29mup09.jpg

And here is one on the chargecontroller and the dump:
http://i40.tinypic.com/264rfaw.jpg

And a video that shows it running:
http://tinypic.com/player.php?v=femdde&s=5


But over to my problem now. When I checked the output volatage when the windspeed was high outside, it showed around 9-10 volts. I cant understand why it not generate more volts? Can it depend on how how good the quality is on the cable between the generator and the battery? Cause my cable is a usual speeker cabel, not that wery thick. What could it be else?

** The chargecontroller and the dump works perfect!



// Robin
 
220 Posts
Apr 11, 2010 03:19 pm
Re: How to connect a generator with a battery(12v) or with a lamp?


 SWEET!!! Smiley Smiley Smiley

 super duper job all around..love the tiered approach to keeping our dump load wiring safe (i'm gonna steal that idea for the next build) i see glen has you set up with three banks of four 10 ohm 25 watt power resistors in parallel each bank running off it's own n-channel mosfet. (you did remember the flyback diodes?) you will be good with almost any small wind turbine with that. (total dump rating at 14 volts of 235 watts).

 as you have found out the ametek 60 is not one of the better choices as far as the ametek line goes.

http://www.tlgwindpower.com/ametek.htm

 sounds like we are real close, only need about 30% more rpm to reach "cut in" the wire size is not a factor (yet)..we won't start to drop voltage in the line until we are "loaded" (producing power).

 couple things to try...seeing that these ametek motors all have the same shaft size might consider trading that one in for a better performer? if we stay with that one we have to make it spin faster..

 from your photos it appears you have made your prop about four foot diameter? we can get the blade speed (tsr) up quite a bit with a few mods. hard to describe but here is a sketch.(click to enlarge)



 i would take that blade diameter down to 42" try it and if needed take it down some more to 36"

 again, excellent job there!

kind regards, dave
 
351 Posts
Apr 12, 2010 12:45 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

Your cable might be a problem now, it will definitely be one later.

You said that you checked the output voltage when the wind was "high". What is your best guess of the windspeed.

Where did you take your output voltage measurement?  At the generator
terminals or over near the battery/controller ?

Were the controller and battery online, or were you measuring open circuit voltage ?
What is the wire gauge of your speaker cables and how many feet of it are used from the generator to the battery/controller.
« Last Edit: Apr 12, 2010 12:48 pm by ken hall »
 
220 Posts
Apr 12, 2010 02:26 pm
Re: How to connect a generator with a battery(12v) or with a lamp?


 ah yes, never occurred to me that the darn thing could actually be trying to run into a waayy flat battery, (assumed voc) and also that wire size thing...gonna have to up the size either way so now is as good a time as any.

 hope to hear about those voltage questions ken brought up.

always good to have extra eyes on these posts.

cheers, dave
 
5 Posts
Apr 12, 2010 05:25 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

Hmm if I would guess, around 6-8 m/s.
The measurement was taking at the end of the cable, and the controller and dump was online then.

My speakercabels is 2mm in diameter. And the length in meter is maybe 5. That would be around 16 feet. But some of it is convoluted.

// Robin
 
351 Posts
Apr 13, 2010 02:56 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

If your speaker cables are a full 2 mm, that would make them about #12AWG.  So you should have been good for at least 5 amps or so. Probably not the problem, right now. 

I have been trying to find the specs on the Ametek 60, but have not found them.  Do you know what the rated rpm is ??

From the comments that I have seen, The rpm is most likely the problem, even in winds of  6-8m/s (15-18mph). 

If the rpm problem is as big as I suspect, I would NOT try cutting down the blade length.  The marginal rpm gain will not help. 

You may be in the position where you have two choices.
1)Get a different motor to use as a generator.
2)Increase your blade length for greater torque, and then use a step up gearing to spin the generator faster than the blade rpm.

Ken

 
5 Posts
Apr 13, 2010 04:22 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

OK. Thanks for the help Smiley
I found an Ametek 50VDC now. So I think I'll go for that. And that was the better one of the 50VDC.
Hope that will work!


Robin
 
351 Posts
Apr 13, 2010 04:42 pm
Re: How to connect a generator with a battery(12v) or with a lamp?

Great !
Please post your results with it.  We like to hear how things work out.
Best of luck,
Ken
 
220 Posts
May 11, 2010 02:02 am
Re: How to connect a generator with a battery(12v) or with a lamp?


 we gotta' be close to getting an update on the new generator?

 figuring three weeks from the midwest u.s. to clear customs and swedish port authority and a week to change over.

 any news? Smiley
 

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