best way to convert harris 24v hydro to 12v output

[billw]

I acquired a 24v Harris high output wheel and desire it to produce 12v to keep my 12v Outback inverter happy. What is the best way (most efficient) to do this? I currently use a 12v Harris wheel which produces 12 amps. Am thinking that the high output alternator will outperform the older Delco alternator. Thanks for any assistance. Bill

[tecker]

Make up a 24 volt bank from 6 volt batteries and let the outback snack on 18 .The voltage won't rise on the upper 6 of the 24 volt string with the comtroller going to shunt at full charge . This is a good spot for used or scap batteries One car battery and a couple of galf cart battereis or the like even if you have shorted cels this they'll work here if they don't boil dry .  Check the Outback to see if it can handle 18 but that's pretty much the lowwer range on a 12 volt solar setup so you should be good .The other way is to cut into the alternator and bring out the star node and setup a neutral to the three phase that easy enough but you may want to opt for another rectifier set up that make good use of the star neutral .

[tecker]

I doubt if the alternator is wired delta but if it is thst calls for a Jerry rigged delta .

[Jerry]

Yep there you go. If its wired star now just "Jerry Rig" it.

                       TAS JK Jerry

[shaniac]

Hello, I am sorry, I am not quite understanding your post. You are suggesting he have the hydro output into a 24V bank, that has one bad 6V battery so it cant output more than 18V? Then presuming his Charge Controller can handle that 18V have it feed his regular 12V system from that bank?

- Thanks

Shaniac.

[tecker]

Ok setup a 24 volt bank with at least 2 6 volt bats in there . The outback's controller can make use of the 18 volts of the 24 volt string . Batteries even if they are bad will hold the output of a 24 volt genset at 24 to 29 volts . With the outback in full charge the batteries connected will give up all  the amperage needed , even if they have internal problems thet you would find in a battery with a pqrtially shorted cell .

[Madscientist267]

Talk about jerry rigging... eek... Guys, that sounds a little, um... out there?

If I'm getting this right, there's a 6V (good, bad, indifferent) in the equation that the inverter never sees?

The surplus juice dissipating into the 'donor' battery as it just goes into runaway, dumping it as heat?

Never done such a thing in practice... not gonna knock it over definitively either, but it sounds like just plain old bad practice... ?

Steve

[Jerry]

OK here is how I would make the 24 volt alternator work at 12 volts. 2 things I'm asuming.

1. the Harris wheel is a GM alternator?
   
2. this 24 volt GM alt is wired star. Most are but not all.
   
   

To "Jerry Rig" this alt for 12 volts.

Disasemble the alt. Remove the stator. Find the star point. Seperate the star point wires. Remove the factory GM rectifier.

Wire each seperate phase to its own and seperate fullwave bridge rectifier. Perelell all the DC outputs of the rectifires.

Now its "Jerry Rigged" for lower voltage and higher current.

                            JK TAS Jerry

[billw]

Jerry,

Thanks for the "Jerry Rig" input. I am not sure if the alt is GM. The housing top says "Harris" and I don't see any other manufacturing info as yet on the case. I think your solution is the most appropriate for my application and I will dig deeper into the alternator until I find the star point and continue from there. I enjoyed your photo page. It looks like you have a 110v motor belted to your wind unit to bench test the output? This might work for me to test the reconfiguration that you kindly offered. I also plan to contact Harris for advice since this can't be the first time this has been done. Thanks again Bill

[Madscientist267]

LOL play on words misconstrued - hahahah

The rewiring of the alt I get - its the battery as a sacrificial load that I have question about...

Steve

[hydrosun]

If this is the larger alternator on a harris unit it is a 70 amp motorcraft alternator. Your 24 volt stator is only 24 volts at the head it was designed for. What head was it used for? What is your head? If the designed head is much more than your setup it should work as is. If you don't know what head it was designed for you could just  install it to see if it puts out more or less than your present delco alternator.  If more you are done. If less go to your local junkyard and get a regular motorcraft alternator out of a 1970s car and swap stators. Or call up Don Harris and tell him the size and number of windings on your unit. He'll tell you if you need to change and get a new stator to you for about $80.

You'll get more out of the larger alternator if you are pushing the upper limit of your present delco. If you upgrade to the permanent magnet unit from Harris you'll be sure to get 30% or more than at present. I replaced both of my units and got about 60% more from one unit that probably wasn't as well matched as it could have been. The permanent magnet one is so much more efficient I can run on less water and start running it earlier in the  fall when the stream just starts to flow. That alone was worth the money to upgrade instead of having no power from solar.

Chris