Full!

[SparWeb]

Lots of wind this past couple of days, and I woke up this morning to find the charge controller in float mode!  Well I didn't think I'd see this so soon but the resistors are nice and toasty warm.

Judging by the voltage drop, there's about 10 amps running through the bank of resistors (5V/0.5ohm=10A).  The surface temperature of the resistor is 34 Centigrade (about 90F).  I also measured the pulse frequency of the C40's PWM at about 170 Hz.

Lots of interesting observations, but obviously the system works.  I'm just thrilled!

Steve

[DamonHD]

Lovely, that would warm my heart as much as my hands!

Rgds

Damon

[Jon Miller]

Cool!

Get using that power is I can think of!

[TomW]

Spar;

Excellent. These are the stories I live for. One "I did this" story helps to offset 50 "help me with the math" posts.

Great to see the batteries floated out, hey.

Glad to see your system coming together. Quite satisfying in my experience.

Cheers.

TomW

[wooferhound]

I ran a telephone wire from my Dump Controller to inside the House, so I would have an LED indicator that the batteries are full and dumping. When that happens I am happy to use the power however I wish without fear of using the battery.

it's a Happy Light

[ghurd]

Warm resistors = Warm feeling.  :-)

G-

[SparWeb]

Hi Tom,

I love math.  

Bring it on!

But then, even my wife calls me a nerd.  

To my face.

:-)

[dbcollen]

It is very nice to have batteries in float, congrats.

Am I the only one who noticed resistors mounted on plywood?

I find it scary to have anything flamable near dumploads, that seems to me to be inviting disaster.

Dustin

[richhagen]

At the current temperature there is probably not much risk, but I don't like the idea much either.  I mounted my dump loads on a sheet metal frame with an air gap from the wall.  Wood becomes dryer and more flammable with continued exposure to higher temperatures.  On occasion I do stupid things, or miscalculate how much heat or current, or whatever.  Failsafe and Foolproof are necessary goals for me.  I would likely add a piece of sheet metal between the wood and the resistors when I found the time, if possible leaving a small air gap between the wood and the sheet metal.

It is great to hear that Steven up and running though.  Rich  

[ghurd]

Thank You!

Every time I tell someone I don't want anything too hot to leave my hand on, they call me worry-wart.

Stand offs would be easy enough.  Stand offs on heat sinks on stand offs?

It is dumping, right?  Why not a fan circuit?  Super simple enough.  Cheap.

G-

[Flux]

If those resistors are running at the full 300W I would also question the plywood.

If possible try to keep them below the 300W, if you have to run them at full rating then you will probably find the connecting cables start to get a bit toasted and brittle after a while. Try not to keep one above the other, the cumulative effect on the top one will aggravate the wire problem.

Usually with wind power everything seems fine for weeks then  a storm comes and things get so much hotter than ever before when they are dumping the continuous rating.

Flux

[windstuffnow]

  Nice job Steve!  I would agree about putting a sheet of aluminum on some stand offs behind the resistors, when mine are dumping 500+ watts they glow pretty bright...

.

[SparWeb]

To allay everyone's fears, there's basically no way for the resistors to burn anything.  This is why:

The resistors are on 2" stand-offs, so there is a 1" space between the resistor and the wall,

The resistors are rated at 300 watts each, the bank 1200W,

The bank is shedding 150 watts, through 4 resistors, hence 75 Watts each,

The outside temperature (yesterday) was zero Celsius,

At 75 W their temperature was about 35 Celsius,

so the math goes:

(35deg-0deg)/75W = 1/2 degree C per watt.

The resistor would reach a dangerous temperature only if it was shedding over 200 watts.  That would be 800W in the whole bank.  I'm pretty proud of my windmill, but I'm sure it will never do that.

Putting a sheet of metal wouldn't be a problem, though.  Just time consuming, and not a "winter" project.

Currently it's blowing like mad, 20knots gusting 30, 20 below (Celsius), and I'm taking turns on "foal-watch".  My wife's little mare is due to give birth tonight.  We're more worried about the foal than the windmill tonight.

Good night

Thanks for the encouragement and support!

[s4w2099]

I would put some Al foil in the back (home depot have some for 10 bucks per roll). Mine are dumping about 80 watts and they get pretty hot. One is never too safe.

Take care

[BigBreaker]

Wood is a pretty good thermal insulator and can accumulate heat in a way that the surrounding air will not.  Think about the radiant heat you feel on your face in front of a fireplace.  Just the radiant barrier effect of the foil would be quite helpful in preventing a build up.

[kitestrings]

SparW,

Congrat's.  It's nice when things work.  Seem's painfilly simple...at times.  Good luck, -kitestrings