Solar powered ball mill

[OldMarine]

I haven't seen anything recent on this subject so I thought I'd start afresh. Getting the power back on at my brother's place is proving to be harder than I thought it'd be so I'm thinking of using a little solar

setup I have from HF in the interim.

I have three of the 45 watt kits with controller, inverter and 2 deep cycle golf cart batteries. My question is whether this would operate the hobfir mill for the necessary 4-6 hours?

The motor is rated at 1.4 amps which I think figured out to around 160 watts. I'm not sure of the batteries ratings. Any input appreciated

[FloridaCracker]

The mill is going to be 120V AC and batteries are going to be 12V DC. Even with an inverter I can't imagine two of the smaller batteries being able to power the mill for that long but it could. I'm not sure how long the batteries will last with much use either. Those rock tumblers are usually over loaded a bit already with the use of lead media and can sometimes need a little push to get going. That is just my seat of the pants feeling so maybe someone more knowledgeable about the subject will chime in.

 

I also don't think the Random topic forum gets all that much traffic compared to the other forums. You might get more views in a forum more specific to the topic or the beginner section. Just a thought.

[Mumbles]

I can move it if you'd like. It's really up to you. It could probably fit into the tools, pyrotechnics, or even electronics sections. We can always give it a couple of days, and move it if this thread isn't getting much traffic.

 

For what it's worth Hobfir, which is short for hobby fireworks, mills are actually pretty well built. This would be what he's talking about: http://www.ebay.com/itm/15lb-Capacity-Rock-Tumbler-Heavy-Duty-Complete-with-Instructions-/351475351550?hash=item51d5903ffe:g:mpIAAOSwBLlVQmtJ They're based off of the Sponnenburgh design. On the surface, I can see how they somewhat resemble the much cheaper ones from Harbor Freight at the like, but the similarities end there. They're not perfect, but they're still quality machines.

 

I'm not going to be of much if any use as to the electrical portions though. I'm not well versed in the implications of inverting the signal into AC, or how swapping in a DC motor might work. Most of the DC motors I've worked with had brushes and sparked. I know this does not include all options though.

[Col]

As it`ll be running an inductive load, the inverter will need to a pure sine wave type with enough capacity to handle the inrush current. Another option is a micro generator (typically 700w) which could probably do at least 6 hours on a gallon of juice.

[carbonhalo]

I've been running a small solar mill for few years, but mine uses a DC motor straight off the panels and only runs when the sun shines.

The motor needs an extended shaft to keep it away from the barrel to reduce any sparking hazard. Mine runs in an old hayshed to keep it ventilated, so no powder can build up from dust from measuring,weighing etc. which takes place elsewhere.

I was originally using a printer paper feed motor, but the drive band perished and replacements haven't lasted. The tiny motor needed a fairly high step up to spin the 4" x 12" barrel I made, which only made 400g batches of powder, so it span a little slowly, needing much more time to mill effectively.

It ran comfortably on a 10w panel with more than 2kg of media.

The new system I'm building uses an old drill motor and gearing, has a shaft 8 feet long and needs a 50W panel to feed it.

[OldMarine]

The motor on my mill has no problem starting under a full load. I haven't checked the amp draw on startup but I will.

I have a 1000 watt true sine wave inverter.

Still, I may just knuckle down and put in some new power poles to the barn and wait on the BP milling. I'll be putting 1kw of panels on the roof next spring and I'll tie into that then.

I think this thread can die now since it served it's purpose.

Thanks y'all.

[MrB]

I have a 1000 watt true sine wave inverter..

Might want to check the efficiency on that inverter if your running only like 15% capacity. But i to would suggest a (brushless) DC motor.

 

Threads never die... They are just abandoned, and wait for someone else to... Take pity on them.

B!

[OldMarine]

I think I'll wait awhile before mangling my mill. I haven't even got it good and dirty yet.

I use my solar setup to power a small fan in my shop and two in my dog's house in summer. Those don't run but 25 watts dc apiece.

I've got generators I can use if I just get so impatient I can't wait until I've reconnected the barn to mill some powder.

I have to keep reminding myself that patience is a virtue and not a curse on fun.

[mikeee]

A solar powered system is very versatile, you can always add another solar panel to increase the energy

being produced and stored in the batteries, this will allow a quicker recovery for the battery charge level.

Or you can always add another battery which extends the run time and volume of electrical energy to store.

Or you can use a larger wattage inverter to increase the size of the load to power, but will draw your storage

down quicker. If you have the time in between charging cycles of the battery to run your equipment load, you

can get by with a smaller wattage system. The other variable is the quality of the battery you are using to store

your electrical power in. Older battery technology tend to discharge quickly with age compared to some of the

newer deep cycle batteries used for these applications. The high quality batteries are expensive compared to

a standard car battery, so you have trade offs with every aspect of a solar system, but they are very versatile.

Edited November 26, 2015 by mikeee

[Arthur]

12v at 100AH should give you 1200watt hours take half of that to preserve battery life so 600watt hours

 

Motor rating 1.4a at 120v = 168watts

 

600/168 = 3.57 hours run time.

 

Add a bit for input from the solar cells in good sunlight you should have little problem running the mill from sunlight for long enough.

Lose a bit for inefficiencies and my guesswork -it's worth trying but not guaranteed. But there is no issue with running three hours on day and three hours the next.

[OldMarine]

Well, my brothers and I gave it a try with a media only barrel. The batteries were at 13.8 volts at start. I used a 400 watt true sine inverter from my work truck rather than the 1000 watt I run the fans at home with. After 4 hours operation the batteries (sunny day) were at 12.2 volts. Ideally I'd only run this a few times a month max. I'm giving it a shot.

Worst case scenario it kills my free golf cart batteries.

 

 

I can't see a few hundred grams making a difference in efficiency but I have been and will continue to be mistaken.

Edited November 27, 2015 by OldMarine

[FloridaCracker]

Just so you know, running a mill that isn't properly charged will put significant wear on your media as there is nothing to cushion the impacts and create a thin layer that greatly reduces media on media contact. I'm sure it's fine I just wouldn't make a habit of it.

 

Any reason you can't use a 100' heavy duty 12ga extension cord to run it out by itself in the yard? That's what many people do and it gives the advantage of being able to remotely start and stop it so you don't have to approach it while running. I assume there is power close by since you are going to run it to the barn from somewhere. Just a thought.

[OldMarine]

My brother's barn is 150 yards from the house. A storm trashed the power line and poles. I've got to rerun them and I'll have power.

[FloridaCracker]

Ok, but why not run an extension cord from the house? A 100' is plenty of distance.

[Col]

100 ft. 16/3 Extension Cord from home depot would get you up and running for $17

[OldMarine]

The terrain doesn't allow for any level ground in between the house and barn. It's all a wooded hill until you get up to the barn. My old fat ass ain't traipsing up the hill toting a barrel full of BP and shot! One good stumble and no more OldMarine :/

[Arthur]

I like the solar option. Add the solar to the batteries and you should be up an running for as long as the batch takes.

[FloridaCracker]

BP isn't that sensitive. If you're using proven techniques such as lead media, a PVC jar, and a grounded circuit then the odds of an accident are likely less than you getting struck by lightning while being attacked by a shark. Ok, maybe not less but you get the idea.

 

I have a little cart that contains my ball mill, loaded jar, and extension cord and I roll it out away from everything. When it's done I roll it to where I process the BP which is also away from everything but under a tree in the shade with a picnic table set up to work on.

 

But you know your situation. It's just a suggestion if you want to get up and running without fooling with an unknown setup that could get hot, have grounding issues, or batteries or an inverter and maybe some sort of controller(?) that could possibly fail and throw sparks. Now I don't really think the odds of that happening are even low and not trying to scare you, just pointing out I don't know about that kind of setup and what it's capable of. It would be nice to be able to shut it down from a distance like with an extension cord. Also, ball mills full of BP have been blown up on purpose with an e-match and it's not the grenade you would first think it would be. The blast is around the media and not behind it so it doesn't go very far. Something like 90% of media was within ten feet.

[OldMarine]

I've read Lloyd's report on the ball mill explosion test. I'm not too worried about an accident but my inner OCD Marine likes an orderly system with contingency plans.

I actually enjoy the planning almost as much as the execution.

Meanwhile I've got my little HF mill in a sandbag "bunker" at my house to get me by until I get my preferred setup going.

[OldMarine]

I found a good use for my solar setup! I had a 100'roll of 5" corrugated drain pipe sprawling across the ground behind the barn. As I was gathering it up I noticed how hot it was compared to the air temp. Lightbulb lit up!

I robbed a 12 volt cooling fan from an old tube amp housing and mounted it onto one end of the pipe. The other end I shoved under the wall of my HF portable garage. Within minutes the inside temp was 30° warmer than out. No recirc so no ignition hazard. It would only work well on sunny days but it's free!

 

The outside temp during my test was only in the upper 40's so I don't know how well it'll do during lower temps. Still, that temperature difference was impressive.

Edited December 17, 2015 by OldMarine

[MrB]

Check out "solar air heater". People build these things out of any material that can be made, or already is, black. Beercans seam to be a somewhat popular choice, but take a fair bit more "work" then using for example straight black PVC tubing. Black window-screening (the kind for keeping the bugs out) is another popular choice.

As you said, they work as long as there is sunshine, and they make an impressive amount of hot air even when it's cold outside.

Your corrugated pipe might have a harder time when the chill sets in, since it's exposed to the elements, but then, it's a fair bit cheaper, and not so elaborate as building an insulated box with a window, and put the black pipes in there...

 

Also, if made "just right" these can be made passive, hung on the wall(s) of your drying shed, facing the sun. Put the intake, and output in the shed, and you'll slowly pump the heat up in there as the sun heats the recirculating air. Not really a need you have, since you power the fan(s) with solar-panels anyway, but i thought i should put it out there. The lower airflow through the unit does make it less efficient, but on the other hand it's not a cost to keep it running. And it tends to be easier to make sure the intake is screened to keep bugs, dust and other things of nature out of it...

 

Anyway, yes, solar power, comes in a lot of flavors, and is quite good.

B!

[Col]

pvc pipe will soften and outgas nasty fumes at high temps Corrugated steel sheeting sprayed with high temperature black BBQ paint is a quick and easy way to get a lot of collector area.

[mikeee]

Surface area with a clear glass panel is what you are looking for to maximize thermal gain.

A perforated sheet of aluminum painted black and mounted inside a wood or aluminum

frame with a glass panel mounted on the front is a very efficient design for a solar collector.

An air inlet and air outlet circulates air through the collector panel. There are high efficiency

paints that are used that absorb the sun light and increases the efficiency of the panel. A series

of these panels connected together increases the output temperature at the exiting end of the set

of panels. Tempered glass panels are what you want to use, two panes with an air gap in between

the two panes also increases the efficiency. If you look on CraigsList you can find greenhouse glass

panels or cubical glass panels are also tempered glass that can be used. Find the glass panels and

build the frames to fit the glass panels you can find. A small squirrel cage fan pushing air through the

system will quickly harvest the heated air and push it into the room needing heat. We built thousands

of these type panels in the 80's and most of these systems are still operational today.

[OldMarine]

I was going with freebies. My little HF garage/tent won't hold in heat once the temps get too low and my arthritic old body won't either.

Once I get the barn put back together I'm definitely going to use some solar heat. I've got a system I removed during a remodel job with a 20 sq ft collector with pump etc.. I'll get an 80 gallon storage tank and an Apollo style heat exchanger and Voila! Almost free heat. I could go with hydronic radiant wall panels and eliminate the fan and the waste of constantly heating incoming air (no recirc allowed) Using cement board laminated over the piping is said to work well with foil faced foam board on the outer face. I've got Pex enough to do a couple of homes. I hate routing cement board for my loops but my son needs to learn it sometime.hehe

[MrB]

pvc pipe will soften and outgas nasty fumes at high temps

 

I wouldn't want to use it for house heating, but for the drying shed, it should be sufficient. That is unless the airflow is so low that the tubes actually deform from overheating.

I know the commercial units a friend sells uses plastic (Most likely not regular PVC) tubes behind a 2 layer vacuum isolated glass front. The sales-pitch includes "lightweight design, easy to handle & install" But i cant for the life of me remeber what brand it is, and they aren't listed on their web-page. Perhaps since what they really trade in is wood fired heating.

Anyway, i didn't intend to start a whole debate on solar-air heaters. It's a great bit of tech, and utilizing the drainage pipe is a good way to minimize labor.

B!