Need help to work off grid and use a rock crusher

**SunEagle** · 07-27-2015, 09:38 AM

Originally posted by adamcatfish86

so i am looking for the best way and cost effective way to mine in the sun with out power why not use solar i think it can work i am 28 years old and i want to try my luck at owning a mine and crush rocks so i found a rock crusher that will work its a 1hp motor and this is all specs i can find
so my question is i want to run this about 5hr to 8hrs aday if possible with out having to build something huge i will be in the mountains with direct sun light all day in Az so what can you guys come up with ? to help me out would not mind trying to build it so any help would rock thanks

Name 1 HP Agricultural Farm Duty Motor
SKU 68288
Brand Smith + Jones
Amperage (amps) 13.1
Horsepower (hp) 1
Maximum speed (rpm) 1800 RPM
Quantity 1
Rigid base (y/n) Yes
Service factor 1.15
Shaft rotation direction CCW
Shipping Weight 34.10 lb.

Unfortunately and surprising even a small 1 hp motor running 8 hrs a day will require a battery system to provide at least 6kWh a day.

That means about a 500Ah 48volt battery system, a 3kw-4kw solar array, an 80Amp MPPT charge controller and a 3000watt generator to keep that battery system happy if you do not get enough sun to recharge the batteries.

That will end up costing you about $30k or you can just get that 3000watt inverter style generator and spend a lot less using fuel.

**lkruper** · 07-27-2015, 10:24 AM

Originally posted by SunEagle

Unfortunately and surprising even a small 1 hp motor running 8 hrs a day will require a battery system to provide at least 6kWh a day.

That means about a 500Ah 48volt battery system, a 3kw-4kw solar array, an 80Amp MPPT charge controller and a 3000watt generator to keep that battery system happy if you do not get enough sun to recharge the batteries.

That will end up costing you about $30k or you can just get that 3000watt inverter style generator and spend a lot less using fuel.

I am still trying to understand the use of solar panels without batteries. I know motors need the battery to buffer and handle surges, but just for kicks, since the OP mentions being in sun all day, is there any scenario where he could get buy with a small battery for buffering and just break up rocks, say, between 10AM and 2PM when panels get the maximum power?

Sorry for the run-on sentence!

**SunEagle** · 07-27-2015, 12:26 PM

Originally posted by lkruper

I am still trying to understand the use of solar panels without batteries. I know motors need the battery to buffer and handle surges, but just for kicks, since the OP mentions being in sun all day, is there any scenario where he could get buy with a small battery for buffering and just break up rocks, say, between 10AM and 2PM when panels get the maximum power?

Sorry for the run-on sentence!

If that motor was DC and could run at different speeds based on the input voltage he might be able to run directly from the solar panels.

Even though the OP did not mention what voltage the motor is I can pretty much guess it is 120v AC so he will need an inverter to go from the DC panel voltage to the AC motor voltage.

There might be a number of times he could run the motor directly from the panels through the inverter but even small sunlight changes would affect the input to the inverter and it would stop working. Using a small battery would help buffer the DC voltage to the inverter but if it is too small can easily be drained by the motor before the sun could get it back to some consistent SOC level.

IMO it would be a gamble to run the motor without having enough battery capacity all day as well as to cover for a couple of days without sunshine. Or the OP could just shut down the operation until the sun cam back.

It comes down to how much is it worth to be able to run the rock crushing process every day of the week or maybe one or two. If the OP could live with only a couple days a week then a small battery might be ok.

**Naptown** · 07-27-2015, 12:35 PM

Here is the issue with small battery and large array.
What happens when the battery is hit with a c5 charge current.
Could get ugly

**lkruper** · 07-27-2015, 12:39 PM

Originally posted by Naptown

Here is the issue with small battery and large array.
What happens when the battery is hit with a c5 charge current.
Could get ugly

Small AGM like Concorde which is ok with c5 charge?

**SunEagle** · 07-27-2015, 12:43 PM

Originally posted by lkruper

Small AGM like Concorde which is ok with c5 charge?

An AGM could handle the high current charge and but now you are paying twice as much per Ah for one of those compared to an FLA type.

Again what comes down to the cost justification for equipment to run the crusher whenever the OP wants for a reasonable profit or just enough to make a living wage.

**lkruper** · 07-27-2015, 12:50 PM

Originally posted by SunEagle

An AGM could handle the high current charge and but now you are paying twice as much per Ah for one of those compared to an FLA type.

Again what comes down to the cost justification for equipment to run the crusher whenever the OP wants for a reasonable profit or just enough to make a living wage.

True, but that depends on how small of a battery could be used for buffering. In the big scheme of things, a single 100AH AGM battery (or 50AH, how small can it be?) is not too much of an investment for a business and the alternative when looking at 500AH bank of FLA batteries would have to be an entire bank of batteries as well as replacement every few years.

**solarix** · 07-27-2015, 01:13 PM

Can a 1hp motor do much rock crushing?
The company near me that does rock crushing uses a 45,000hp motor! - and yes, a utility representative comes out in person to pick up the monthly electric payment...
They looked into solar and had a 1mW sterling engine type system all permitted before the supplier ran into technical problems.

**DanKegel** · 07-27-2015, 02:42 PM

I wonder if/when ultracapacitors will start making sense for small offgrid systems.
They seem to be useful for cranking enginrs, e.g. http://www.kemet.com/Large%20Cell%20Supercapacitors

**SunEagle** · 07-27-2015, 02:46 PM

Originally posted by lkruper

True, but that depends on how small of a battery could be used for buffering. In the big scheme of things, a single 100AH AGM battery (or 50AH, how small can it be?) is not too much of an investment for a business and the alternative when looking at 500AH bank of FLA batteries would have to be an entire bank of batteries as well as replacement every few years.

I really can't answer the question "how small a battery will work"?

That answer has to come from the OP and how much of a lose is it to have to stop the operation should the battery fail to produce.

In all practicality you can work it out on paper and still be wrong. Until the motor is tested under "working" conditions you really won't know if a small battery will start the motor let alone keep it running for hours.

If the system fails to work does the OP lose more money than what could have been spent on a bigger battery system?

**SunEagle** · 07-27-2015, 02:55 PM

Originally posted by DanKegel

I wonder if/when ultracapacitors will start making sense for small offgrid systems.
They seem to be useful for cranking enginrs, e.g. http://www.kemet.com/Large%20Cell%20Supercapacitors

More than likely developing better DC load technology and matching it to an off-grid power system would be easier then developing a special "device" to run every type of AC motor.

Too many variables in motor starting and load profiles to know if a XXX watt pv / battery, starter system "Kit" will run a specific hp AC load every time and under all conditions.

Caps have been used in thousands of ways to "kick start" an electric load. From starting engines, running fans to lighting up fluorescent lamps. Now all that "cap" usage has gone by the way side replaced with better technology.

**bcroe** · 07-27-2015, 03:57 PM

Originally posted by adamcatfish86

so i am looking for the best way and cost effective way to mine in the sun with out power why not use solar i think it can work i am 28 years old and i want to try my luck at owning a mine and crush rocks so i found a rock crusher that will work its a 1hp motor and this is all specs i can find
so my question is i want to run this about 5hr to 8hrs aday if possible with out having to build something huge i will be in the mountains with direct sun light all day in Az so what can you guys come up with ? to help me out would not mind trying to build it so any help would rock thanks

Can you live with only running under good sun?
My opinion is try to build something without batteries or inverters. Test that crusher
with that AC motor and a generator; see if its up to the job.

If the answer is yes, find a 1hp DC motor and build up a PV panel array of suitable
voltage & power to run it. A multiple orientation array like this one provides 20 hp
for much of the day under strong sun; you could scale it down to about 1/10th
for 2 hp DC, at least 1 hp at the shaft. Bruce Roe

Attached Files

**Mike90250** · 07-27-2015, 04:06 PM

Originally posted by DanKegel

I wonder if/when ultracapacitors will start making sense for small offgrid systems.
They seem to be useful for cranking enginrs, e.g. http://www.kemet.com/Large%20Cell%20Supercapacitors

Capacitors rate power from 0V to working volts. So a 1F cap rated at 20V, used on a 12V (12-16V battery range) now at 12V, only has a bit more than half farad to work with. And if you figure your inverter shuts off at 10V, you are not touching any energy stored in the cap below 10V (there is half your Farad, stuck and useless). So Caps sound OK but in reality, they can only supply a small amount of surge.
A large cap is factory installed in my inverter, to help control DC ripple on the battery bank, but it's no replacement for batteries.

**lkruper** · 07-27-2015, 04:08 PM

Originally posted by SunEagle

I really can't answer the question "how small a battery will work"?

That answer has to come from the OP and how much of a lose is it to have to stop the operation should the battery fail to produce.

In all practicality you can work it out on paper and still be wrong. Until the motor is tested under "working" conditions you really won't know if a small battery will start the motor let alone keep it running for hours.

If the system fails to work does the OP lose more money than what could have been spent on a bigger battery system?

It would be cool if we could figure it out, but perhaps an experiment is the only way. My understanding is limited, but I was assuming that the only role of the battery was to handle the start up surges and perhaps momentary voltage drops from clouds, etc. However since the OP specified when the sun was shining, we can eliminate the clouds. If a motor runs at 500 watts but surges to 1500 watts for 1 second at startup, then the amps drawn from the battery would not require a large AH reservoir. At least that is my idealistic way of viewing it.

Need help to work off grid and use a rock crusher

Need help to work off grid and use a rock crusher

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