Simple Dump Load

[ghurd]

Seems sort of obvious, although I do not recall anyone mentioning it before.

Headlights eventually burn out.  Not good.  Kind of a pain.

Everyone has access to bad motors, with bad bearings or maybe a bent shaft.  Maybe that conversion that didn't go quite as planned.

Computer supply type fans, or muffin fans, can be had at a reasonable cost in most common DC voltages. The ones with ball bearings last almost forever.

Remove the ends and rotor assembly from the motor.  Add some heat duct for a chimney effect, because it can't hurt.  Place the muffin fan so the air blows up the center of the motor, maybe leaving some space between the motor and fan to encourage some extra turbulence.

Figure out how the coils should be connected for the dump needs.

Connect the factory windings and fan to the dump controller.

Add a freewheel diode or bridge reverse connected to keep a voltage spike from killing the controller.

Possibly a second fan at the top, drawing the air up, in case the lower fan fails.

I am not sure how to determine the maximum amps that can be dumped given the HP, KW or winding wire gauge.  I think double the nameplate amperage would be OK?  Depending on how the coils were connected.

Not that I foresee needing much dump load in my future.  LOL!

Anyone see any problems or improvements?

G-

[ghurd]

Any idea why the uploaded jpg is 192 x 378 px, but it is displayed 638 x 1257 px?

G-

[The Crazy Noob]

It's because of the "with=80%" tag that is automatically added to the a-tag (html). Its point is to get all the images on one screen withouth scrollbar at the bottom.

About the fans: what will you use them for? To cool the stator in your generator? To cool the batteries (they don't like high temps)? To cool your house?

[kitno455]

what browser are you using? firefox automatically messes with image sizes when displayed.

[ghurd]

But the image got BIGGER!

Fan to cool the stator and coils.

[ghurd]

Both Firefox and IE.  Sometimes they display differently, but not this time.

[dinges]

Ghurd,

Yes, headlights can burn out. Heaters can burn out too.

In a way, you are using the stator of a motor as a resistive dumpload. It can burn out too...

If you really don't want a burned out dumpload to cause a problem, may I kindly suggest Co/Amanda's dumpload controller? (or was that one below the belt )

I agree, you could put a few amps through your motor stator. (at least the current nameplate rating, perhaps a bit more because of forced cooling; BTW, forced cooling can fail too...)

I was a bit reluctant about using lamps too, but with a good dumploadcontroller (i.e. like Commanda's) I have no more fears.

BTW, you could try to parallel two lamps. That way when one burns out, there's still one left.

Also, lamps tend to last VERY long if they are operated below their nominal voltage. I.e., a 13.8V/55W headlight at 10V or so should last almost endlessly. Add another one in parallel for safety, if you like.

You see, I try my best to outsmart mr. Murphy. But he's much cleverer than I. No such thing as 'foolproof'.

Peter.

[dinges]

Hmmm...

As I reread my own post, it looks like I'm picking on it. It could be an idea, but it can fail too, was all I was trying to say. Why not fix those failed bearings or rewind the stator for energy generation? Perhaps even build a new rotor, if it cogs (coggs?) very bad.

When the fan fails, the dissipative capacity of your motor/stator would get a lot less than with forced ventilation.

I prefer to see these motors used to GENERATE, not DISSIPATE. LOL.

Still think I like lamps better though (smaller; visible indication; cheaper; easier)

12V seems ideal for 12V systems; 24V lamps (from trucks) ideal for 24V AND 12V (24V lamps will never burn out on 12V).

[ghurd]

Ouch!  Below the belt!  Particularly the 'good dumploadcontroller' part.

Remember... "Small Systems".

Heaters burn out, yes.  But my parents have a 1/4 or 1/2 HP vent fan running 24/7. The 1st one lasted about 10 years before the bearings quit (never oiled, not once).  The wiring was fine, but new bearings cost more than a new motor at the time.  The next one is still running after 20 years (oiled it about 3 times- it is due for more).

"forced cooling can fail". Hence the chimney and 2nd fan, but I'm not very concerned about it.  I have a 110VAC muffin fan that can surplus with bad (sloppy) bearings, so it did not get used for what I intended it for.  It has been running all summer for about 10 years, and seems no worse than when I got it.  It's marked "Xerox January 12 1972" on the blade hub.

I had considered lamps being run at a lower voltage, given the (my) problems of voltage drop, etc, of which you are aware.

However, I would like to keep the dump load at about 130~150% of the maximum generation capabilities to avoid excessive cycling.

And sockets for 15mm tail light bulbs seem expensive (or a pain to get at the junkyard).

"using the stator of a motor as a resistive dumpload"  Yes, but I figure there could be considerable induction with some motors.  

Not sure how much heat can be dumped in a motor. I figured it was related to 'dissipated watts'.

Like a 1/2 HP, 0.373KW motor should be able to dump that much, and more, if the coils were connected properly.

For those familiar with my controller, for about $3 I could add another stage, be it sloppy in the voltage adjustment, set at a lower voltage to control the fans.  The fan(s) would come on sooner and stay on later than the motor coils, cooling the coils after primary dump cycles.  I doubt it is worth it if the chimney works as I figured.

G-

[ghurd]

I tried re-winding. Gonna leave that to Zubbly.  Except for another box fan, I hope.

I have many motors... too big to use (for me), 3600RPM 3-phase, etc. Can get 100 more just like those.

DumpLOAD or DumpSTER.

Seems cheaper / easier / better than nichrome etc.

G-

[powerbuoy]

I believe using the stator only for dumping will be a bad idea. It'll generate heat pretty fast. I remember some motor rewinding shop powering up the stators without rotor to heat up and dry the varnish after working on the windings. It did not take long for it to warm up ...

Powerbuoy

[commanda]

Not sure how much heat can be dumped in a motor. I figured it was related to 'dissipated watts'.

Input electrical power minus shaft output power equals dissipated watts. It's all a matter of efficiency. If you study the nameplate on your motor you can probably figure it out. Just because a motor is rated at 1/2 HP output doesn't mean it can dissipate that much.

As you explained, if you have the motors available for zero dollars, and they are otherwise unusable by you, it's a better choice than throwing them in the dumpster. From someone who's just starting to play with nichrome wire, I'd say it was a pretty good idea.

Amanda

[Opera House]

Although nichrome is a nice high temp wire, I think a common steel wire like that used to tie rebar is a good choice.  It is cheap and can use more of it for greater surface area at lower temperature.  With low temperature, the chance of failure is about zero.  

Lamps are nice, but have almost a 10 to 1 increase in resistance from cold to hot.  That can almost make them look like a dead short when they are switched in. This could cause some strange problems.  This can be reduced if you put two lamps in series and operate them at no more than half voltage or if you use a proportional dump load.

[Flux]

If you remove the rotor from a motor it will heat quickly unless you run it at much reduced volts, the magnetising current will go sky high, it heats quickly because you are dumping a lot of power.

I see no reason why scrap motors shouldn't be used as resistors to dump power. They are poor resistors in terms of power that can be dumped for a given size but if you have the space then does it matter.

If you do use any form of motor or transformer as a dump be careful to include the freewheeling diode that Ghurd mentioned, controllers normally expect a resistive load. There may be strange effects with some pwm circuits.

If you have lots of scrap copper cable you can burry that in the ground and make a soil heater for your plants.

Flux

[The Crazy Noob]

I forgot to mention: it's 80% of the total width of your browser-window. Not 80% of the width of the original file. That's why it got bigger (if you resize your browser window so that it becomes more narrow, the image should also be resized)

[ghurd]

That sounds right. Except for when pic's are twice as wide as my screen.

G-

[coldspot]

ghurd-

flux-

"copper cable you can burry that in the ground"

Thats something I need to research.

"Dump to ground"

How safe or wise is that???

(My FlexCharge NC25A-12 has a 25Amp charge divert circuit)

They say it is perfect for motor type divert loads.

[commanda]

If you have lots of scrap copper cable you can bury that in the ground and make a soil heater for your plants.

Soil = moisture.

Moisture + DC current = electrolysis.

Please don't do this under your vegie patch; I believe copper poisoning is not good for you.

Amanda

[fungus]

Soil = moisture.

Moisture + DC current = electrolysis.

Please don't do this under your vegie patch; I believe copper poisoning is not good for you.

Of course it would be insulated copper magnet wire or cable and also the wire has less resistance than the ground.

[ghurd]

Hardly an expert...

I figure a straight to 'ground', as in buried, would be vary current and resistance to much to use.  The only common use I can think of is fencers, and they have a high internal Zohms while supplying a low current at a high voltage.  Keeps it from killing cows and people as often.

But I don't believe thats what they mean by dump to ground.

Even if the book said 'perfect', I would still add some big high volt freewheel diodes.

Because it will be repetitive surges.  Overkill works. Usually. Not always.

I can get anything to release its smoke.

G-

[coldspot]

ghurd-

"Hardly an expert",   lol

"big high volt freewheel diodes",   ?

The fence idea I like but girlfriend wouldn't I'm afraid.

"I can get anything to release its smoke"

LOL, That I love.

Thanks

Have a great Day/Night !!!!