another load question

[greenkarson]

part 1

Got a chance to go up north and work some more on my cabin turbine.  Got it installed in the creek and cable ran to my battery box. with no load it was putting out 41v dc just to try it I connected it to a 12v trouble light. with no batteries just connected  + and - wires out of rectifier to the + and - from 50watt 12v trouble light. Voltage dropped down to 2.5v dc. light was just a small glow.

just wondering will i get the same voltage drop when i connect turbine to my 24 volt battery bank or will 40v dc with no load be lots to charge my batteries?

part 2

my turbine is wired for 24v so i was going to put in a 24volt battery bank. but can i not put a 12 volt charge controller on my input and go with a 12v battery bank to get more watt hours out of my batteries every thing is going to be going through a inverter anyways

thanks

[wdyasq]

Start with Ohm's law... V X A = W

Part one - you have 41VDC. You then connected to a load and got 2.5V. Volts times Amps ... oops lacking that A figure.....

Part 2 ... see part one ....

On a note that may help you , the batteries will 'clamp' the input to the battery voltage. The Amps will remain Amps. Going back to that pesky Ohm guy and his laws, if one has 1A going into 12V it is 1A X 12V = 12W (Number A).If one has  1A going into 24V it will be 1A X 24V = 24W (Number B). Now for the hard part, which is larger, A or B?

Ron

[TheCasualTraveler]

Oh! OH! Pick me! I know the answer, pick me!

The answer is, uh, number B

[greenkarson]

it produces 3 to 4.2 amps depending on water speed if my calcs are right it should be producing a little above 3amps. so lets see if i have this figgered out right when i connnect my turbine to my 24v battery back i will be producing roughly 72+watts 3amp x 24vdc=72watts. so the result of 2.5vdc with the light bulb has no relevance to its charging abilty.  so do i have it right?

[Flux]

When you connect to a 24v battery it will drop to a nominal 24v.

A water turbine should run at half no load speed so dropping from 40v to 24v is is in the right order as long as your alternator is efficient. If it is not very efficient you will be running too fast for the turbine.

If it runs too fast at 24v you will match the turbine better at 12v but it is very unlikely that you will gain any significant current if the alternator is that inefficient. Unless you can get over double the current at 12v then you will get more power at 24v.

The only way to really do better at 12v would be to use a mppt controller but that is just not cost effective for such a tiny supply.

Flux

[Rabrsniver]

Hi,

I saw your post and thought I would direct you to someone who has helped me many times in the past.

He is very knowledgeable about hydro, (actually all forms of alternative energy) and has assisted people all over the world. He does not access this site often, so its best to contact him at:

nando37-at-tx-dot-rr-dot-com (Correct the anti-spam)

Good luck with your project.

[ghurd]

Until you know the amps it will put into a 12 and 24V battery, you don't know much about the system.

Testing with a bulb causes too much confusion to sort out.

"but can i not put a 12 volt charge controller on my input" has me a bit concerned.

It will need a windmill controller.

G-

[scoraigwind]

wdyasq wrote

"Start with Ohm's law... V X A = W"

It is true that volts x amps gives watts (for DC systems) but that's not Ohm's law.

Ohm's law is the one about resistance : amps x ohms = volts.  resistance = volts/amps

Best bet for the hydro turbine is to run it connected to a battery at teh correct voltage.  The light bulb has probably stalled it right down to a very low speed.  I wonder why people use bulbs and resistors to test machines that are designed for charging a battery.

As Flux points out the turbine will work best at about half of its runaway speed, so 24 volts is not far off the mark.   However when you allow for losses, 12 volts may be closer.  I suggest you try both.  And also make any adjustments that the manufacturer suggests for tuning the turbine once connected.

have fun