Hi All,
I just recently found the board. Surprising since I have been researching all our hydro troubles online for months. Couldn't find what I need in old postings, though.
We moved into a rental powered by an old harris. Owners really weren't informed on the setup as the previous renters of ten years had put it in. After months of no output due to problems with the alternator and time delays with it's rebuild, we have been getting some output, but far below what I expected to see.
Site and System:
40 ft head--16.5 psi dynamic
approx 420' penstock, 4" PVC
Harris four nozzle (1/2 inch nozzles) 120gpm potential I believe, flow accomidates
Delco style alt, shop guy said it had a 24V stator.
285' 2/0 aluminum triplex, creek to batts*
trace C40 with 450W @ 12V diversion
12V battery array
*recently replaced old #8 copper thhn. New 2/0 is actually 315' at present as it has not been trimmed and installed permanently yet.
Obviously 8 awg was way to small, but there were some clues that seemed to show that the alternator was underproducing. We got 6.5 amps at the house with the #8, and now we get 7.5. After seeing that, I pulled a battery from my truck, and lugged it down the hill with a 1 ohm resister in order to remove the transmission line from the equation. Hooking the alternator to the battery with jumper cables and connecting the resister to the battery I saw 10 amps. Head and flow should give me 250 watts assuming 30% alt efficiency, right? Did I not present a big enough load perhaps?
I also drug the wire back up the hill and compared the charge from an automotive charger connected directly to the batteries, and to the transmission line, at the 2, 10, and 50 Amp settings.
Batt connection gave: 5.5, 9.5, and 21 amps, respectively
Trans lines gave: 3.8, 6.2, and 13 amps
This also seems to point to the alternator producing in the neighborhood of 10-11 amps.
At this point, I feel pretty certain we need a new alternator to see any noticable improvement. However, I'd like to save a bundle and not buy a Harris PM upgrade. So, now, all the questions:
How do I find expected turbine RPM?
How much will turbine damage effect efficiency (bent out on the inside corners of some buckets--bent somewhat to position)?
If X amps at 24 volts was applied with our C40, the charge would only be X amps at battery voltage, NOT 2X, correct?
If the input voltage is higher that batts, I know the batteries regulate it down to their voltage, but does that mean transmission voltage is also lowered? I.E. would we gain reduce voltage drop from an alt producing a higher voltage without an MPPT or other stepdown method?
Look forward to meeting some of you, and hopefully figuring this out.
Any other suggestions to boost effieciency would be welcome also.
Justin