Small Garage Setup for Table Saw

[immanence]

Hi all, new here. I'm looking to build a small setup for my garage. The table saw will be the biggest draw. At 1.75 hp it should pull 4000w on startup and ~1800 watts when running. Would a 6500w inverter like this work for this case: https://sungoldpower.com/collection...erter-parallel-wifi-monitor?sscid=51k6_twv6v&

I'd hook this up to a 5kwh battery, and probably a couple of 200w solar panels to charge the battery. I don't expect the panels to generate the power to run the table saw, but since I use it infrequently, the battery should be fully charged every time I go to use it.

Thanks for any thoughts!

 

[rmaddy]

If the only thing you use is the table saw at 1800W (more like 2100W from the batteries due to inverter inefficiencies) then for every hour you use the table saw your solar panels will need at least 6 or 7 hours of solid sun to recharge the batteries. That could be a couple of days depending on weather and time of year. Your 5kWh battery can run your saw for just over 2 hours if it's LiFePO₄. If it's lead based then about an hour.

I would think a 3000W inverter would meet your needs. Many 3000W inverters can handle a 6000W surge for a second. But I've never tried to use a table saw with an inverter so I can't be sure an inverter's surge wattage is sufficient for such use.

 

[MichaelK]

This is NOT going to be a small system. My rule of thumb is to double the amount of watts of panels for the biggest single load you want to run. If that is a 1800W saw, then 3600W of panels. This is my rule, which others may chose to dispute, but I am able to run everything I want to run, without hiccups.

 

[immanence]

If the only thing you use is the table saw at 1800W (more like 2100W from the batteries due to inverter inefficiencies) then for every hour you use the table saw your solar panels will need at least 6 or 7 hours of solid sun to recharge the batteries. That could be a couple of days depending on weather and time of year. Your 5kWh battery can run your saw for just over 2 hours if it's LiFePO₄. If it's lead based then about an hour.

I would think a 3000W inverter would meet your needs. Many 3000W inverters can handle a 6000W surge for a second. But I've never tried to use a table saw with an inverter so I can't be sure an inverter's surge wattage is sufficient for such use.

Ah, thanks. I didn't realize watt ratings were for continuous usage, I was reading them as the absolute ceiling. Though in this case I will have dust collection going as well, which is around 800w. Surge questions aside, is it good to have some overhead on total watt usage? Also, moving down to a 3000w inverter would mainly mean cost savings, correct?

 

[immanence]

This is NOT going to be a small system. My rule of thumb is to double the amount of watts of panels for the biggest single load you want to run. If that is a 1800W saw, then 3600W of panels. This is my rule, which others may chose to dispute, but I am able to run everything I want to run, without hiccups.

I don't intend to run the system of panels. The batteries should be the main source of power. Do you follow that rule of thumb just for the sake of having available power?

If my system failed and I really needed to cut, I could run extensions, so I do have that as a back up.

 

[rmaddy]

Surge questions aside, is it good to have some overhead on total watt usage?

Generally yes. If you buy a high quality (more expensive) inverter you could probably run it at full rated continuous output all day without issue. But midrange and lower end inverters (cheaper) should rarely be run near full rated continuous output.

With a 1800W saw and 800W dust collector, both with very large startup surges (motors are brutal), you will probably want a higher wattage inverter to be safe. I can't be sure what the best cutoff would be but I would have to think you'd need at least a 4000W inverter.

Do make sure you will have at least a 24V battery. 48V would probably be even better given the high loads. You also need to be sure your batteries can handle the discharge current. A 2600W inverter load on a 24V system would pull roughly 130A from the batteries. That is more than many batteries can handle for more than a couple of seconds. At 48V it would be half of that. You don't want to consider a 12V setup for such loads.

Also, moving down to a 3000w inverter would mainly mean cost savings, correct?

Typically inverters get more expensive as the wattage goes up. Also, larger inverters tend to have larger idle power consumption. Simply being turned on and not powering any loads can result in 50W-100W in some cases. Whatever inverter you get you are going to want to turn it off when not needed or it could drain the battery in a few days just by being turned on, depending on your final battery capacity and final inverter choice.

 

[immanence]

Generally yes. If you buy a high quality (more expensive) inverter you could probably run it at full rated continuous output all day without issue. But midrange and lower end inverters (cheaper) should rarely be run near full rated continuous output.

With a 1800W saw and 800W dust collector, both with very large startup surges (motors are brutal), you will probably want a higher wattage inverter to be safe. I can't be sure what the best cutoff would be but I would have to think you'd need at least a 4000W inverter.

Do make sure you will have at least a 24V battery. 48V would probably be even better given the high loads. You also need to be sure your batteries can handle the discharge current. A 2600W inverter load on a 24V system would pull roughly 130A from the batteries. That is more than many batteries can handle for more than a couple of seconds. At 48V it would be half of that. You don't want to consider a 12V setup for such loads.


Typically inverters get more expensive as the wattage goes up. Also, larger inverters tend to have larger idle power consumption. Simply being turned on and not powering any loads can result in 50W-100W in some cases. Whatever inverter you get you are going to want to turn it off when not needed or it could drain the battery in a few days just by being turned on, depending on your final battery capacity and final inverter choice.

Awesome, this info is much appreciated thank you.

I don't know if posting links to equipment is allowed here, but I was looking at a 6500w inverter and the battery is a 48v LiFEPO.

The usage hours you provided are useful too. It seems like this would be much more affordable to me than running power to the garage, and provide more than enough power for what I'd need it for. There really won't be any time I'd be running the table saw more than two hours, and if my batteries were really out of juice, I could run an extension cord in a pinch.

 

[rmaddy]

I don't know if posting links to equipment is allowed here

Perfectly fine as long as they are not affiliate links.

I was looking at a 6500w inverter and the battery is a 48v LiFEPO.

6500W on a 48V LiFePO₄ battery would require close to 160A of discharge current from the battery if you were to actually have a 6500W load. Most such batteries have a max continuous discharge current of 100A (or even less - check the specs). You would need two batteries in parallel to make full use of such an inverter. But you can get away with one battery if you limit the use to about 4000W. That doesn't include brief surges. An appropriate battery fuse/breaker could be used to ensure you don't push the battery too hard.

 

[immanence]

Perfectly fine as long as they are not affiliate links.


6500W on a 48V LiFePO₄ battery would require close to 160A of discharge current from the battery if you were to actually have a 6500W load. Most such batteries have a max continuous discharge current of 100A (or even less - check the specs). You would need two batteries in parallel to make full use of such an inverter. But you can get away with one battery if you limit the use to about 4000W. That doesn't include brief surges. An appropriate battery fuse/breaker could be used to ensure you don't push the battery too hard.

Ah, okay, yeah it is 100A. So I'd need two to get that full wattage, but that would boost my price quite a bit and would be overkill on storage. Though... maybe not such a bad thing. I could just start with one though and see how it works out and upgrade if I need it later though couldn't I?

Here is what I'm looking at:

Inverter: https://sungoldpower.com/collection...v-solar-charge-inverter-parallel-wifi-monitor

Battery: https://www.currentconnected.com/product/sk48v100/?ref=wp

 

[rmaddy]

With your proposed 2600W load (saw and dust collector) you won't get near the 100A limit of the battery. The biggest limit will be the surge. The SOK 48V battery can handle a 200A draw for up to 3 seconds before the BMS will shutdown the battery. That's about a 8000W surge from the inverter. Assuming you turn on the dust collector first, you'll be at 800W. Then you turn on the saw and get a 4000W surge on top of the 800W load. Now you are briefly at 4800W. Then it should settle down to 2600W with both running. If all of those numbers are accurate (and the surge really lasts less than 3 seconds), one of those batteries with that inverter should handle those loads. If all goes well you can later add a second battery (and more solar) as needed.

Be sure you use good wire between the battery and the inverter. You do not want any voltage drop in the system given the loads and surges you will have. I would suggest at least 2/0AWG wire.

Disclaimer - I don't have direct experience using such high surge items. The numbers seem right to me but I could be completely wrong on what it actually takes to startup a dust collector and table saw in a setup like this. I'd suggest getting a second opinion before spending several thousand dollars.

 

[immanence]

With your proposed 2600W load (saw and dust collector) you won't get near the 100A limit of the battery. The biggest limit will be the surge. The SOK 48V battery can handle a 200A draw for up to 3 seconds before the BMS will shutdown the battery. That's about a 8000W surge from the inverter. Assuming you turn on the dust collector first, you'll be at 800W. Then you turn on the saw and get a 4000W surge on top of the 800W load. Now you are briefly at 4800W. Then it should settle down to 2600W with both running. If all of those numbers are accurate (and the surge really lasts less than 3 seconds), one of those batteries with that inverter should handle those loads. If all goes well you can later add a second battery (and more solar) as needed.

Be sure you use good wire between the battery and the inverter. You do not want any voltage drop in the system given the loads and surges you will have. I would suggest at least 2/0AWG wire.

Disclaimer - I don't have direct experience using such high surge items. The numbers seem right to me but I could be completely wrong on what it actually takes to startup a dust collector and table saw in a setup like this. I'd suggest getting a second opinion before spending several thousand dollars.

Sounds good, thank you.

If the surge was an issue, the most likely solution would be another battery and to run them in parallel so that I could make full use of that 6500w capacity on the inverter?

 

[rmaddy]

If the surge was an issue, the most likely solution would be another battery and to run them in parallel so that I could make full use of that 6500w capacity on the inverter?

Two of those batteries in parallel can handle 200A continuous discharge which is about 8000W at the inverter. They could handle double that for under 3 seconds. So yes, it certainly seems that if you have trouble running your stuff on one battery due to the surge, two should handle it just fine. It's not likely that your dust collector and table saw will ever hit 8000W during their startup surges.

 

[Supervstech]

Table saw motors have incredibly high surge draw.
I assume the saw is on 240V?
If 120V, MAN that is a strong load...
Figure 5TIMES running watts for startup surge. And if you cut dry hardwood... every time the wood bogs down, you get another surge nearly as high...
9000W isn't unheard of.
Keep that in mind. 120V is really hard to start a saw... I would wire the motor for 240 if it isn't already. A decent 4000W LF steel core transformer is a far better option for starting a 1.75Hp table saw up.
It will have larger standby watt waste, but it'll handle the startup with ease. They handle 12000W surge for 20Seconds... but feed them with strong battery and strong cabling.

 

[immanence]

Table saw motors have incredibly high surge draw.
I assume the saw is on 240V?
If 120V, MAN that is a strong load...
Figure 5TIMES running watts for startup surge. And if you cut dry hardwood... every time the wood bogs down, you get another surge nearly as high...
9000W isn't unheard of.
Keep that in mind. 120V is really hard to start a saw... I would wire the motor for 240 if it isn't already. A decent 4000W LF steel core transformer is a far better option for starting a 1.75Hp table saw up.
It will have larger standby watt waste, but it'll handle the startup with ease. They handle 12000W surge for 20Seconds... but feed them with strong battery and strong cabling.

It is 120V - here's the saw: https://deltamachinery.com/products/table-saws/36-725t2/

The surge power on that inverter is rated at 15000w. Though it seems like to hit that I'd still need two batteries.

 

[rbm1721]

I run a 800w dust collector and a 1.75hp tablesaw on a 12v 400ah lifepo4 battery bank and a 3500w PSW high frequency inverter. I have to let the dust collector spool up before I start the tablesaw. I can't start the saw first. I cut plywood's, soft wood and hardwood lumber(4/4, 8/4, and sometimes thicker) daily. I rarely have the inverter balk at me for drawing too much. This has been working for me for the last year. I run a 2000w PSW inverter simultaneously on the same battery bank. When the saw is running the 2000w inverter is usually providing around 400w for lighting, fans, and various chargers for tools and electronics. As a side note, my cables from the battery bank to the 3500w inverter are 4/0.

 

[Solarcabin Channel]

You may have answered this but how long do you run the table saw for on an average day?

 

[rbm1721]

Anywhere from a cut at a time to a couple hours at a time. If I am cutting for a couple hours there is about equal time of no load and cutting. Usually the long runs are sheet goods. I have ripped 8/4 ash pretty much full time for an hour with no problem. I think I hit overload protection on the inverter twice when I was ripping the ash.