Power usage of various devices

[AZRedhawk44]

How many watts do these tools use?

-Vibratory case tumbler
-Battery charger for cordless drill
-Scroll saw
-Drill press
-Table saw
-Table router
-spindle sander, belt sander, disc sander, etc.

Getting ready to build a solar electric system for my workshop.  I don't have a table saw, router or spindle sander yet, but I'd like to know the power needs of those devices for my pure sine AC inverter.

Running all of the above simultaneously is not a goal.  Only 1 high-amp-draw tool at a time.

But, the lights + case tumblers (2) + battery charger + table saw might be a goal.

You jobsite guys with portable table saws... how large is your gas generator?

[Nick1911]

Just some food for thought:

A/C motors often draw 3 times the running current during the locked-rotor startup phase.
Most appliances list current draw on their nameplate.
For more precise estimates of what your equipment uses, get a "Kill-A-Watt" meter.  They cost about $25 and will list exact draw.
The most common portable generator seems to be the 5000 watt model.  Not sure if this is true of construction sites, though.

[AZRedhawk44]

Understood.  I had heard twice the initial amp draw for motors and compressors, like fridges and such.

Getting a watt meter won't do me any good because I don't have a table saw right now, which I suspect is going to be the highest draw out of all appliances I intend to put on this inverter.

Would a table saw use the same class of motor as a compound miter saw?  I have a good compound miter saw that I could stick on a watt meter.

[cassandra and sara's daddy]

yes  many table saws use same motor as chop saw. i use a 5000 watt generator and 2 big tools starting at same time you can hear/feel difference in how they start/run vs off line current

[Jim147]

I'm sure you know but just to make sure Volts X Amps = Watts.

I can hook the volt/watt meter up to most of the things on your list tomorrow night if it would help.

Have you looked into any of the DC lighting? I haven't just wondering how good it is getting.

jim

[InfidelSerf]

I've been wanting a watt meter for sometime.. if I get a chance to pick one up this weekend I'll plug it into my table saw (base ryobi model) and see what it pulls.

[AZRedhawk44]

I'd appreciate that, jim.

Oh, I forgot:  A shop-vac, too.  A lot of times I'll hook up the shop vac tube to the output end of my compound miter saw, palm sander and other stuff equipped with a dust output.

[Sawdust]

Understood.  I had heard twice the initial amp draw for motors and compressors, like fridges and such.

Getting a watt meter won't do me any good because I don't have a table saw right now, which I suspect is going to be the highest draw out of all appliances I intend to put on this inverter.

Would a table saw use the same class of motor as a compound miter saw?  I have a good compound miter saw that I could stick on a watt meter.

Table saw will be the biggest draw, but it obviously depends on what type of table saw - basic, cabinet, hybrid?

For example, my cabinet saw has a 3 hp motor - much more of a draw than any of my chop saws.

Sawdust

[lee n. field]

How many watts do these tools use?

Get yourself one of these.

[CNYCacher]

Just multiply the amp draw times the voltage to get wattage.

So, a table saw with a  10-amp motor you can figure on drawing somewhere north of a kilowatt when you're really chewing through the wood.

[AmbulanceDriver]

AZ, depending on the design of the motor, startup current can be as high as 10 times the rated current.  A lot of it depends on the mass attached to the motor.  For example, a compressor with a heavy startup, from the flywheel, piston(s), etc, plus the compressive load as the pistons travel.  So you could be looking at a draw of up to 100 amps on a "rated" 10-amp draw tool.  Now, this is a very short period, but if your equipment isn't rated for that 100 amp surge, you could really fry some stuff. 

Now, the full story is that the breakers in your panel are rated for say, 15 or 20 amps.  However, that's not an instant trip rating, rather a continuous draw rating (i.e., they're designed to trip after a fixed amount of time at their rated current).  For an "instant" trip, you need about 10 times the rated current.  In other words, a 15 amp breaker isn't gonna trip during a short load at 16 amps.  Rather, it's gonna instantly trip at about 130-150 amps.  But if you run it at 16 amps for 5-10 minutes, it'll trip.  However, I don't know how well that would bode for your proposed solar system.

[roo_ster]

Most vacuums are in the neighborhood of 10+ Amps.

[Hawkmoon]

Table saw will probably be the worst offender, but a good router may not be far behind. Similar motor horsepower, but a bit easier to start because a router tip has a LOT less inertia to overcome than a 10" circular blade.

About 20 to 25 years ago I was living in a rented house that was originally built in about 1947. The electric service to the place was a 60-amp service. I had a Sears 10" 2-HP (I think) table saw set up in one of the bedrooms, as a shop. If I just flipped the switch, the lights would dim WAY down, and it took the blade a seemingly long while to start moving. I got in the habit of flipping the blade with my pusher stick to start it spinning before I turned on the power. That made the startup quite a bit less painful.

The standard fuses were 15 amps, and the saw wouldn't run on those. I had to use a 20-amp fuse in the circuit for the "shop" and, even with that, trying to start the saw without a push had about a 50/50 chance of blowing the fuse rather than starting the saw. That was the real reason for starting the blade manually before flipping the switch.

So figure you'll need around 25 to 30 amps for the table saw.

[KD5NRH]

Figure around 7A per HP at 120V normal run draw.  As mentioned, startup ranges from a little more to a lot more.  Always plan for more than you need in case you find out you need more.  Dump loads are much easier to come up with than extra capacity.

[Balog]

Could you put heavy duty capacitors in line after the inverter to buffer the high startup draw?

[Nick1911]

Could you put heavy duty capacitors in line after the inverter to buffer the high startup draw?

Interesting question.

I think it would only work for a DC application.

For A/C, you might be able to use an inductor in parallel.  Maybe one of our resident EE's can say definitively.

[Balog]

Maybe he could wire the DC from the solar directly into the motor, skip the inverter.

[Gewehr98]

No.

1.  He'd need a DC motor or three.

2. He'd need a solar array so large to feed the amperage requirements that he'd have to take out a second mortgage.

3. Cloudy days would suck.

4. He couldn't do anything at night time.

5. DC power of high amperage and low voltage requires really thick wires.  Think vehicle battery cables.  

6. DC power doesn't travel long distances well compared to AC.  Depending on how far away the array is to the motor, there's gonna be voltage drop.

AZRH44 is trying to do something similar to what I've done here at Casa de' G98.  I have solar panels mounted on a pole in the back yard, but they only deliver about 5A at 24v on a really sunny day.  They are more of a trickle charger, going through a solar charge controller into my stack of leftover telephone company batteries, and those in turn feed a 24v/2000W ProSine inverter.   The inverter can deliver 83 Amps to the front panel 115 VAC outlet, but that puts a really big load on both the inverter and battery stack.  

If I have time later on, I will try to plug our Sears Craftsman shop vac and my big right-angle-gear-driven SkilSaw into the inverter at the same time and read the inverter's digital display to see what they draw.  Otherwise, I'll plug my handy dandy Kill-A-Watt meter (See photo above in this thread) into said power tools and just record what they draw from the normal household wiring.

[KD5NRH]

1.  He'd need a DC motor or three.

Depending on RPM and HP requirements, that may or may not be too hard to do.  Handheld tools (drills, circular saws, etc) would have to be found and special-ordered, (though some may already have universal motors - not sure if there's a significant efficiency difference with these between AC and DC supply) but stationary stuff like a tablesaw, shaper, lathe, drill press or jointer generally use fairly adaptable motor mounts, especially when they're belt driven.

2. He'd need a solar array so large to feed the amperage requirements that he'd have to take out a second mortgage.

Assuming he's not going to be using the tools constantly, a large battery bank can reduce that a lot.

3. Cloudy days would suck.

4. He couldn't do anything at night time.

Again, depends on the battery bank and usage.

5. DC power of high amperage and low voltage requires really thick wires.  Think vehicle battery cables.

No way around that, though going with a 24 or 48V system reduces the current requirement.  IMO, going way oversize on cables is worthwhile anyway.

6. DC power doesn't travel long distances well compared to AC.  Depending on how far away the array is to the motor, there's gonna be voltage drop.

Ideally, the array would need to be near or on the shop.  The main advantage of using the DC directly would be eliminating the need for a rather large inverter.  The bonus is eliminating the inefficiency of the inverter as well.

[AZRedhawk44]

AZRH44 is trying to do something similar to what I've done here at Casa de' G98.  I have solar panels mounted on a pole in the back yard, but they only deliver about 5A at 24v on a really sunny day.  They are more of a trickle charger, going through a solar charge controller into my stack of leftover telephone company batteries, and those in turn feed a 24v/2000W ProSine inverter.   The inverter can deliver 83 Amps to the front panel 115 VAC outlet, but that puts a really big load on both the inverter and battery stack. 

Perzactly.

The one in the shop is going to be the prototype, and then I will build out two more: one for the west side of my house, and one for the east side.  3 separate inverters, 3 separate charge controllers, 3 separate solar arrays, 3 separate battery banks.  Each probably between 3000 and 5000 watts max AC output.

G98 may only get 5A @24v sometimes from his array, but here in AZ with maybe $5000 total spent on solar panels I can get over 20 amps (maybe even 30) for close to 10 hours in the summer and 6 or 7 hours in the winter, then reduced charge for another 5+ hours the rest of the day.

That can trim my electric bill in half for the summer (normally ~$300-$350) and bring it to the $40-$50 range for the winter ($100-$130).  That's $1500+ savings a year, and cap'n'trade is only likely to hurt that much more with greenie taxes.

I'm going to start with the shop because it is the most infrequent use electrical system in my house:  I can skimp on panels to charge the battery since it will have 2-3 days between uses to trickle-charge and the inverter can be turned off when not being used to further save battery charge, and the biggest expense is a quality, high wattage AC pure sine inverter.

My yard is also pretty dark on that corner:  pitch black, really.  I have flood lights I can turn on that are WAY too bright, or it can be pitch black.  I'd like some DC lighting installed with light sensors that turn them on/off automatically with sunset/sunrise.  Nothing terribly bright, just enough to shake off the shadows.

It gives me a "sandbox" to test ideas with, that I can then apply to my house.

[KD5NRH]

the biggest expense is a quality, high wattage AC pure sine inverter.

What do you have in the shop that cares about the waveform?  If you have to have AC there, that's the place to go with the dirtiest inverter, since it won't be very clean when you're running powertools anyway.

[AZRedhawk44]

What do you have in the shop that cares about the waveform?  If you have to have AC there, that's the place to go with the dirtiest inverter, since it won't be very clean when you're running powertools anyway.

Battery charger for the cordless drill.

[CNYCacher]

Battery charger for the cordless drill.

Are you joking?

[Headless Thompson Gunner]

Certain AC to DC converters, wall warts, can do interesting things when the AC waveform turns funky.

[Jim147]

I'm down in my garage now. I have equipment strung out through a few out buildings so I'll take my meter when I run to the woodshop and get you a few more readings.

Drill Press: Small bench unit. I can't read the HP on the motor but I'll guess about 1/3.

Line voltage: 121 same for all of this group
Start: 2.5 Amps
Free run: 1.6 Amps
Load: 2.6
Stuck bit: 5 Amps

17 watt shop light: .25 Amp

Bench grinder: 1/2 horse with a wire wheel and stone
Start: 3.3
Free: .8
Load: 2.9

Tumbler: Rated .83 amp
Start: .5
Run .3

I should have more later.

jim