"Turn on when sufficient power available" (& back off) ...

[markm]

What would be required in order to power up gear - such as, say, USB block eruptors - as and when sufficient power becomes available, and shut down as power fades?

I am thinking that it could be nice to use solar panels for power but save on batteries by being able to use all the power when it is available.

I don't really have the option of hooking up to the power grid because doing so woudl require re-wiring a whole building, which would involve ripping out all the plaster inside so electrician can put wiring in the walls, then putting up gyprock drywall in place of the old antique plaster.

A bunch of gear is supposedly going to be too expensive to run one of these months because of the cost of electricity on the grid, solar using battiers gets pricey too because the batteries cost quite a bit, but I am thinking the old gear could be used to soak up excess power on bright days when the sun is pouring in more electricity than one has enough batteries to store.

Is there some kind of common rack of relays or chips or something one can get that turns things on in sequence as more and more power needs to be used, and back off as less and less power comes in?

-MarkM-

[Photon939]

I've thought about this for the possibility of completely off-grid bitcoin mining myself.

My original idea was to have a small bank of supercapacitors. Once the sun rises, the panels would begin charging the capacitors. Once the voltage rises above the minimum required for the microcontroller it would boot up and begin testing if there is enough power available to begin mining. The supercapacitors would also provide a small amount of backup power in case birds or whatever fly over your solar panel for a few seconds.

Mosfet based power switching would be more efficient than relays since they do not require any significant amount of power to remain switched on vs a relay coil which wastes power in the electromagnet. I would set it up so the microcontroller has a few switched mosfet outputs, some for the actual load (say a raspberry pi and some block erupter USBs) and a dummy load (power resistor or semiconductor shunted regulator that draws approximately the same amount of power as each load stage)

The microcontroller would then switch on the dummy load for a period of time and watch the voltage of the supercapacitor bank. If the voltage sags below the operating threshold it would switch off and try again in a minute or so. Once there is enough sun to keep the capacitors above the operating voltage it would then switch on the actual loads and monitor the capacitor voltage in case of clouds, etc. You could add as many stages as you have outputs for the microcontroller assuming sufficient solar panel size

[markm]

So definitely it would be something custom then?

No off the rack power-switching boards with little screw-turned thingies you turn to set how much more power you want to be remaining after prior outlet is turned on before turning on next outlet kind of thing?

Hmm maybe some kind of thermal thing, stick it on one eruptor's heatsink, when it gets warm enough it turns on next eruptor, when that gets warm enough it turns on the next, etc?

Or hell with it if its so damn complicated maybe just turn on whole shebang when day/night porch-lights go off and back off when they go on... if those things can be tuned for how light or dark you want the day to be before they go on / off that might be all you'd really need?

-MarkM-

[Photon939]

If you want to go the easier route, check out ebay. Ebay is full of cheap grid-tie power inverters that are capable of backfeeding power into your house's electrical circuits with a standard outlet plug. You plug it into the wall and connect it to your solar panel. When power is available it will backfeed into the house. Then you would just plug your little miner into an outlet as normal.

Note: I don't know how well they work or how legal they are to use, but a little 400W unit or something is unlikely to cause any issues outside of it maybe blowing up if a component fails

Assuming they actually work decently and you always have some load in your house consuming power equal to or greater than the power output of the solar panel, then you will offset your electric bill with the power generated by the solar panel.

You need a special agreement with the power company and a new electrical meter to have one that "spins backwards" and lets you sell money back into the main power grid.

[balanghai]

Hey Mate we're on the same page. Currently preparing a solar farm and wind turbines (diy version) to curb electricity costs and fire up my GPU miners again.

Batteries are expensive, solar panels aren't. So just measure your entire rig with a kill-a-watt meter and then you can figure out how much wattage you need and +20% allowance. You can use it for 12 hours during the day and probably 2-3 hours at night.

[markm]

If you want to go the easier route, check out ebay. Ebay is full of cheap grid-tie power inverters that are capable of backfeeding power into your house's electrical circuits with a standard outlet plug. You plug it into the wall and connect it to your solar panel. When power is available it will backfeed into the house. Then you would just plug your little miner into an outlet as normal.

Note: I don't know how well they work or how legal they are to use, but a little 400W unit or something is unlikely to cause any issues outside of it maybe blowing up if a component fails

Assuming they actually work decently and you always have some load in your house consuming power equal to or greater than the power output of the solar panel, then you will offset your electric bill with the power generated by the solar panel.

You need a special agreement with the power company and a new electrical meter to have one that "spins backwards" and lets you sell money back into the main power grid.

I guess you didn't read the first post.

To get grid hookup for the house requires electrician signing off on the house's wiring.

Electrician wants the entire house gutted of all its nice antique plaster interior walls so he can put wiring behind the walls, then put up modern drywall crap as no one hardly anymore except maybe some specialist craftsmen even has the skills to do real plaster anymore.

It'd eat up easily $50,000 probably more just to get the house hooked up to the grid.

But, supposedly, off the grid solar power does not have all that crap about having to have a livable house etc, you can do it anywhere, a camp, a camper, a cabin, I know someone who lives in what amounts to a tent and has solar power.

So the whole point was, there is no grid, and batteries cost a lot, so maybe it'd be better to soak up excess power on sunny days using old inefficient mining gear like block eruptors or whatever than to buy enough batteries to store power to keep gear running 24/7.

Sure I am trying to talk landlord in town into letting me put solar panels on his roof and hook them into the grid.

But meanwhile I am still looking for ways to make use of my existing house out in the countryside that would cost way more than the house originally did to get its grid hooked up again.

-MarkM-

[markm]

Hey Mate we're on the same page. Currently preparing a solar farm and wind turbines (diy version) to curb electricity costs and fire up my GPU miners again.

Batteries are expensive, solar panels aren't. So just measure your entire rig with a kill-a-watt meter and then you can figure out how much wattage you need and +20% allowance. You can use it for 12 hours during the day and probably 2-3 hours at night.

Yeah exactly, but what I am asking about in this thread, is how it will automatically turn on and off in accordance with how much power the sun and/or wind actually happens to be putting out at any given moment.

Like maybe even one by one block eruptors coming online as the sun is seen directly, one by one going offline as a cloud passes the sun etc.

Or maybe have some small amount of battery to allow time for clean shutdown so its not on off on off too rapidly.

Maybe USB hubs that activate one plug at a time as enough power becomes available, instead of dividing the power in parallel across all plugs, stuff like that. So if there is only enough power for one eruptor it powers just one, instead of all of them failing to work due to only having a fraction of enough power each.

-MarkM-

[balanghai]

Very Easy. Use UPS. when the inverter marks fail (drained battery) UPS takes over, you hear the beep, plug it back to the grid.

[markm]

Very Easy. Use UPS. when the inverter marks fail (drained battery) UPS takes over, you hear the beep, plug it back to the grid.

So we need an audio-triggered switch of some kind to listen for the beep?

-MarkM-

[balanghai]

Audio triggered switch is a very bad idea, it beeps from time to time so it would switch on and off. To automate it, it would be easy to use timer switches. 12 hours on the solar and 12 hours on the grid.

Have you seen some timer switches on your local electronics store?

[markm]

Yeah for really rough guess stuff a timer switch would work.

But if it only turned on enough stuff to eat the power an overcast, no-wind day provides, it would miss out on all the power it could be getting when a sunny, windy day happens along.

In other words it doesn't adapt to the actual conditions prevailing at the time.

Even just some kinfd of porch light switcher, if it could be tuned for how much light/dark to switch at,, would probably be better than that, as you could have banks of miners each one triggerd by brighter light than the previous one so on dull days only some would come on, whereas on bright days all would come on.

Not sure though if porch light switches have enough adjustment range to make them not come on on middling-bright days, only on the very brightest days.

Oh and of course their logic would need reversing, maybe double pole double throw switch or something, so they go on in day off at night instead of vice-versa.

-MarkM-

[balanghai]

You can get digital controllers if you have extra bucks to spend. You can start researching from this item:

http://www.alibaba.com/product-gs/805984391/Saip_group_12_24V_solar_grid.html

[Photon939]

If you want to go the easier route, check out ebay. Ebay is full of cheap grid-tie power inverters that are capable of backfeeding power into your house's electrical circuits with a standard outlet plug. You plug it into the wall and connect it to your solar panel. When power is available it will backfeed into the house. Then you would just plug your little miner into an outlet as normal.

Note: I don't know how well they work or how legal they are to use, but a little 400W unit or something is unlikely to cause any issues outside of it maybe blowing up if a component fails

Assuming they actually work decently and you always have some load in your house consuming power equal to or greater than the power output of the solar panel, then you will offset your electric bill with the power generated by the solar panel.

You need a special agreement with the power company and a new electrical meter to have one that "spins backwards" and lets you sell money back into the main power grid.

I guess you didn't read the first post.

To get grid hookup for the house requires electrician signing off on the house's wiring.

ELectrician wants the entire house gutted of all its nice antique plaster internior walls so he can put wiring behind the walls, then put up modern drywall crap as no one hardly anymore except maybe some specialist craftsmen even has the skills to do real plaster anymore.

It'd eat up easily $50,000 probably more just to get the house hooked up to the grid.

But, supposedly, off the grid solar power does not have all that crap about having to have a livable house etc, you can do it anywhere, a camp, a camper, a cabin, I knw someone who lives in what amounts to a tent and has solar power.

So the whole point was, there is no grid, and batteries cost a lot, so maybe it'd be better to soak up excess power on sunny days using old inefficient mining gear like block eruptors or whatever than to buy enough batteries to store power to keep gear running 24/7.

Sure I am trying to talk landlord in town into letting me put solar panels on his roof and hook them into the grid.

But meanwhile I am still looking for ways to make use of my existing house out in the countryside that would cost way more than the house originally did to get its grid hooked up again.

-MarkM-

It's a much better option although you've made it clear that it's not an option due to the age of the wiring and cost to bring it to code.



As far as doing the sequencing forget about using a UPS, you would end up replacing the lead-acid batteries frequently and it seems you want to avoid batteries completely at this point.


As far as off-the-shelf components go, I am not aware of anything that would do what you are requesting. Adjustable voltage switching relays are available, but without any kind of "smarts" and control logic behind them, they would end up oscillating and repeatedly switching loads on and off during periods where there is more power available than what is being used but not enough to support an additional load.

You will need a temporary source of power though, and ultracapacitors will be prohibitively expensive if you are planning a decent size system. A lead-acid battery would be a good candidate here as it would really only be handling temporary brownouts (small passing cloud, etc) and would not be deeply discharged.

Without it even blocking the panels for half a second would kill your mining setup and frequent power cuts will quickly corrupt the OS on your mining controller.


Back to the sequencing logic - if you want to take a bit of time to learn basic microcontroller function you could implement it easily with an Arduino and something like this http://dx.com/p/8-channel-5v-relay-module-board-for-arduino-red-156424

Combined with a raspberry pi running CGminer (bfgminer doesn't seem to support hot-plugging currently) you could wire the relay board to switch the +5v rail to the usb ports on a modified USB hub.

The arduino can read the system voltages by using a voltage divider with the arduino's analog to digital converter pins

Current sensing and power reporting can also be done with items like this http://dx.com/p/20a-range-acs712-current-sensor-module-for-arduino-148656

[markm]

I am thinking probably have enough battery to power the master computer that runs cgminer or whatever, that could go on at early dawn and off in late evening or something on a timer, maybe it could be a laptop or something similar to a raspberry pi but without the pi's inability to properly handle some (such as 3.0) types of USB hubs. Also some battery power to cover a few minutes of cloud or birds etc.

Then have all the hubs, or even each USB miner, be what go on and off based on power available.

I will look up the various references people have given, thanks.

Lead acid in winter might have problems here in Canada if outside, or actually maybe even inside since the mining operation itself would be the only heat in the place...

Is cold going to be a big problem for pretty much all kinds of batteries?

I have coded in machine code and assembler as well as pretty much all generations of languages since, so a bit of coding should not be a big problem.

Though maybe a nice idea would be to make units as a product people can easily plug cheap solar panels into, and have someone actually put support for them into cgminer etc software...?

-MarkM-

[balanghai]

I am thinking probably have enough battery to power the master computer that runs cgminer or whatever, that could go on at early dawn and off in late evening or something on a timer, maybe it could be a laptop or something similar to a raspberry pi but without the pi's inability to properly handle some (such as 3.0) types of USB hubs. Also some battery power to cover a few minutes of cloud or birds etc.

Then have all the hubs, or even each USB miner, be what go on and off based on power available.

I will look up the various references people have given, thanks.

Lead aicd in winter might have problems here in Canada if outside, or actually maybe even inside since the mining operation itself would be the only heat in the place...

-MarkM-

Oh I see, it would be hard to do a setup like that. And remember it's dangerous to keep the batteries in enclosed areas because hydrogen (from battery's electrolysis) is highly flammable and can cause a disaster. Make sure to put your batteries in a well ventilated area.

Try to look up the link I posted above. As it is a grid <---> solar/wind controller.

[eroxors]

Pretty sure UPS software + usb/rs232 can do what you want... shutdown a system when the battery reaches a certain level and turn computer back on when it reaches a certain level. You might look at some of the higher-end APC models.

[markm]

Well cars don't start in winter a lot of the time, people use block heaters if car isn't going to in a garage.

Indoors well insulated seems to conflict with well ventilated, so I am thinking marine batteries or whatever, ones that don't have to be ventilated? Lithium ion even maybe? Expensive but that is why I am trying to figure out how to minimise the need for them.

It would be really cool to be able to make actual products, "solar/wind miners" that have pretty much everything they need except the actual solar panels or wind turbines, I imagine there could be a market for such things. Or even leave out the actual miners and make units that have USB and ethernet connectors for people to plug in end-of-life ASICminer and Avalon gear to, with 12 volt power plugs modular or somesuch.

-MarkM-

[markm]

Car batteries also are not deep cycle though, supposedly one wants deep cycle types of batteries for this.

Still, I guess in a pinch a bunch of old car battiers would be used outdoors if they would be kept pretty much charged all the time, thanks.

-MarkM-

[Photon939]

Car batteries also are not deep cycle though, supposedly one wants deep cycle types of batteries for this.

Still, I guess in a pinch a bunch of old car battiers would be used outdoors if they would be kept pretty much charged all the time, thanks.

-MarkM-

The idea would to be not discharging the batteries at all under ideal conditions, only using it as an intermediate buffer during short dips in solar output.

Alternatively, if the mining computer had a backup supply (easy for something low power like a raspi) then you could eliminate storing any power for the miners (and hope that CGminer deals with frequent usb comm errors gracefully)

[markm]

I noticed with hubs that if there isn't enough power some or eventually all of the USB sticks stop working, without ill effects seemingly.

Also I recall reading about bitfury's chip that he designed it specifically to be able to gracefulyl degrade in hashing power as it gets less electricity. So maybe his chips would be the best for this type of application.

If hubs would shut off individual plugs when they don't have enough power that would be great, but I think what is tending to happen instead is all the sticks get iffy when there is not enough power coming into the hubs. Having lots of hubs would likely end up with all of them not getting enough power so nothing working. So even just switching entire hubs in and out would be an improvement over that.

Maybe I will have to get a solar panel and a car battery and experiment a bit.

Though the arduino idea seems decent too at first glance.

Its possible I won't need to deploy until early spring or late winter, depending on difficulty increases. (Grid power here is $0.14 to $0.15 CAD.)

-MarkM-