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Way remote power source help please!

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Posted by gomango on September 26, 2008, 1:42 am
 
Im facing a problem this winter trying to keep the batteries up.  I
have a small stream down the hill from the house that seems to be the
logical source for power.  Last year We purchased gas and ran a small
generator into the ground trying to maintain batteries.  This year
with financial grips a bit tighter, Im thinking that the generator is
out.

Here is my issue.   I have an old scrapped out 1000i generator and had
a shaft made to run a couple pillow block bearings and a pulley as the
power input.  Now the plan is to build a water wheel and spin the
shaft at whatever RPM is required to create 120V output to transmit
the power up the hill.  Im a bit shaky on all the math thats required
for all this so I thought I would drop you all a line and get some
advice.

Some factors to consider.....
Overall goal: 5-10 amp charge @ 12 volts 24 hours per day.
Generator would be roughly 500' from the batteries.
generator is capable of 1000W at 120 Volts after the inverter.

The plan was to run a small solid state charger at the batteries to
simply maintain the batteries.  We dont use that much power.

Soooo the big question.... how many amps are required to run a small
10 amp charger????  I need this to calculate the wire run.  Im
clueless about how to figure out the amprage requirements.



Posted by Cydrome Leader on September 26, 2008, 5:44 am
 

measure it. Having somebody on the internet guess and then you running out
to buy 1000 feet of wire is asking for failure.

Posted by Vaughn Simon on September 26, 2008, 12:29 pm
 

Your 10-amp 12-volt charger will need a bit more than 120 watts, which implies a
bit more than one amp at 120 volts.  Unless you are planning on making a 500
foot ditch, you should price aluminum "duplex" aerial cable (commonly used for
street lighting).  Attach it to poles with the simple hangers (AKA "baskets")
that are made specifically for that job.  As cable goes, this stuff is not
terribly expensive but you will not find it in a retail store.

Don't bother with the cable you have been successful in generating power.

Vaughn



Posted by Cydrome Leader on September 26, 2008, 3:24 pm
 
Figure a charger can output 14.4 volts @ 10amps.

now add in the incredible series regulation losses plus the awful power
factor of the type of transfomer you'd find in a the battery charger.

You're looking at over 1 amp and well over 120 watts.

I'm pretty sure my 4 amp float charger from Xentek? (something like that)
is fused at 2 or even 3 amps on the AC side


Posted by Vaughn Simon on September 26, 2008, 3:42 pm
 

   But at that voltage the typical charger will no longer be outputting anything
near 10 amps.  The charge will have tapered.


   Big assumption here.  You you know more about the OP's charger than the rest
of us?  Heck, the typical cheap charger has no regulation at all.

  I said it would be something more that one amp.  I was thinking 80% charger
efficiency which would give you something like 1.2 amps @ 120 volts.  You are
welcome to make your own assumptions and do your own calculations , but without
more information your result will be no better than mine.

   Appliances are always fused for more than their typical current draw, or we
would be changing fuses after every surge.  Have you ever measured the current
draw of your charger?

Vaughn



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