Generator strategies.

3dworld · January 2015

I'm off grid and work from home. I do a lot of 3D printing. To keep up with orders part of the time we have printers going around the clock and I have done some prints that have lasted around 80 hours. We have 5 3D printers that pull up to 1.2KW each. We try to schedule our prints to where we do most of the printing during the early morning to day.

We have 2 mini split HVAC units, a well, 2 chest freezers, 2 large workstations, and are home most of the time. I have seen spikes on the inverters as large as 11KW and have seen loads of 9KW for long periods of time.

Curently our setup is...
2- 8048 radian inverter
2- 804 amp hour forklift batteries
1- 2800 watt medium head hydro
4- MX60 2,500 watts each
6 KW Cummins diesel genset

We use the genset with our 2 old VFX3684 chargers. We found the genset runs best with the chargers set at 43 amps each.

I'm ready to get a second genset as a backup to the 6KW, a larger unit that will cover all my loads that will connect to my 8048's, and or a DC unit.

I would like some other peoples thoughts as to what type and size of genset I should go with.

mike95490 · January 2015

Re: Generator strategies.

You answered your own question

spikes on the inverters as large as 11KW .... 9KW for long periods

Your genset has to have a 5 min peak surge of 11Kw and cont 9Kw rating.
Look for a 4 pole alternator, and 1800 RPM liquid cooled diesel.

And I'd beware of the 8Kw inverter loaded to 9Kw, you should program a alarm and cut back
loads. 9Kw is over 180A @ 52V That's pretty heavy stuff.

3dworld · January 2015

Re: Generator strategies.

I might not of posted very clearly, but I have dual 8k inverters. It handles the load fine.

I'm defiantly going liquid cooled next time. The genset I’m using now is left over from my old system from before I moved in my 3D printers.

Blackcherry04 · January 2015

Re: Generator strategies.

Once you go above 8-10 KW your looking at the name brand Manufacturers and the Assemblers. It's hard to know what is best. Most of the manufacturers do not build the generator end, but do have a good governor and control system. The Assemblers buy the engines and Generator ends and the control systems and put them together. It's really hard to know what way you come out best. The output is controlled by the AVR ( automatic voltage regular ) and those come with all kinds of different qualities of output, 2 % are less is normal.

Service is another issue, with a name brand you usually have a service network and a parts source. When you talk about parts it's a 20 year thing.

Look before you leap.

Vic · January 2015

Re: Generator strategies.

3d..,

Well it sounds as if you are serious about your power system, and your business.

So, it appears that you can afford a quality genset. Personally, would look to a name brand unit. As Blackcherry mentioned, the "integrators" buy pieces of the system from outside suppliers, and frequently change suppliers. This could create some service headaches later, and perhaps some reliability issues with loosely controlled quality, and so on.

Am very happy with the largest genset here, the Kubota. It is their SQ series, and this particular unit was all made in Japan. By now, some parts might well come from other parts of Asia, but still these larger companies care about their reputation, so should spec and control quality well. This SQ-3250 is a very solid, quiet, fuel-stingy genset.

FWIW, Vic

3dworld · January 2015

Re: Generator strategies.

Yes Vic I have sunk some money into my power system, my printers, and don't mind sinking more money in as long as it is the right move. Designing, prototyping, making new test tooling, making life size replica parts for testing, and the list goes on. We turn down work weekly.

Yes I would go with name brand and quality. Truthfully CAT would be great because I’m 40 minutes form a huge dealer and repair shop.

This is what my installer is thinking long term for me...
A 20KW genset and wire it through the inverters. Use the inverters chargers to get the genset to around 75 to 85% to prevent wet stacking.
A 5KW DC APU. He would have me use this the most.

oil pan 4 · February 2015

Re: Generator strategies.

If you want a reliable DC apu the first thing that comes to mind is an engine driven welding machine with an adjustable constant voltage setting.

And since all costs are passed down to the consumer is your off grid 3D printing going to be able to compete with other 3D printing shops that use cheap power grid electricity?
It sounds like you are expending a ton of capital to get where the guys who have a standard service drop are all ready at.

I am starting to get the impression that you would be better served if you were connected to the power grid, not having to turn jobs away weekly because so much of your capital is tied up in power generation and because your production seems limited by that same power production.

Iceni John · February 2015

Re: Generator strategies.

3dworld wrote: »

Yes I would go with name brand and quality. Truthfully CAT would be great because I’m 40 minutes form a huge dealer and repair shop.

Maybe something with a Perkins engine? Caterpillar now owns Perkins, and Perkins have always had a good reputation for small to medium diesels. Some folk on the bus conversion forums I read have Perkins-powered generators in their buses, and they seem pleased with those engines.

John

3dworld · February 2015

Re: Generator strategies.

I'm about 2 miles from the closest lines. The one farmer says no way for the easement and the other wants $200,000. It turns out to be way to rich for my blood.

I had a store front for 3 years that I co leased in town. I was part owners in the other company and was bought out. I was unable to find a new place to lease in town. The power in town always had power issues and that dose not play nice with 3D printers even with UPS's that lasted 10 minutes. We had issues finding trustworthy people to hire to train with the 3D printers so one of us was at the shop just about 24/7.

We have been doing a lot of looking for some property that has power, but have not found anything where we can keep the life style we want to live. If we did find something we would move most of our power system and use it as a huge UPS to get over the power issues.

oil pan 4 · February 2015

Re: Generator strategies.

That stinks, sorry you have jerk neighbors.
I 100% agree having a robust UPS is a great idea with 3D printers.
What you need for a UPS sounds like it would be so expensive you might as well build your own and save a few tens of thousands of dollars.

mike95490 · February 2015

Re: Generator strategies.

There is a Prius as a Backup thread somewhere around here - the traction battery powers a high voltage inverter from a large UPS

http://forum.solar-electric.com/showthread.php?12962-Using-a-Prius-as-a-generator

softdown · February 2015

Re: Generator strategies.

Safe to say that the Prius to generator transformation took skills and knowledge that most of us do not have. Good luck finding a repair guy after you say this "Hey mate, I turned my Prius into a generator. She is acting up a bit these days. Can you fix her up for me?"

mike95490 wrote: »

There is a Prius as a Backup thread somewhere around here - the traction battery powers a high voltage inverter from a large UPS

http://forum.solar-electric.com/showthread.php?12962-Using-a-Prius-as-a-generator

inetdog · February 2015

Re: Generator strategies.

softdown wrote: »

"Hey mate, I turned my Prius into a generator. She is acting up a bit these days. Can you fix her up for me?"

"Sure, just drive it down to my shop....."

westbranch · February 2015

Re: Generator strategies.

Has anyone thought about using a Prius' big battery to do a BULK charge on another battery bank and then letting the solar do the rest?

I had this arrangement suggested as a way to blend a 10kW FLOW battery with off grid solar... by the makers of a FLOW battery.

mmag · February 2015

Re: Generator strategies.

i am curious why you would use a DC GENERATOR when you have such large AC loads? kubota or multiquip 1800 rpm diesel generators should give you thousands of hours of low maintenance service, cat generators are probably good, a prius might be a cool way to run a house but buying a high quality commercial genset would be a wiser investment for a business

Vic · February 2015

Re: Generator strategies.

From past reading on earlier Prius' did show that the available Capacity of its battery was about 1200 Watt Hours. This may well have increased, but this is not a stunning amount of C, IMO. Vic

techntrek · February 2015

Re: Generator strategies.

Modification of the Prius is fairly easy, it is mostly manual labor digging in to access the power taps for the traction battery. The only difference between mine and most others is it has a hidden pigtail in the trunk. If a modified Prius "acts up", take it to your local mechanic.

Yes, the traction battery isn't huge, enough to get you through a few hours with the engine off with a minimal load.

No, I wouldn't use one for what the OP wants, but the larger versions of the UPS I use would easily handle the load of the OP's printers. You can extend the battery size fairly easily, I added 16 flooded lead acid batts (22 kw) to mine, did that for years before I hooked up the Prius. I was doing the same thing, just manually.

3dworld · February 2015

Re: Generator strategies.

I do not need an UPS at this time. If I move into a building that is powered from the grid I would need an UPS. My outback inverters and battery could be made into a very nice UPS with the stuff I already own.

I think using a car to charge my batteries is not very good when it comes to efficiency / cost / output.

mmag wrote: »

i am curious why you would use a DC GENERATOR when you have such large AC loads? kubota or multiquip 1800 rpm diesel generators should give you thousands of hours of low maintenance service, cat generators are probably good, a prius might be a cool way to run a house but buying a high quality commercial genset would be a wiser investment for a business

I have not done the math my self. But the way the outback inverters are set up a DC generator could be more efficient depending on the load and settings.

If I have a 15 KW generator and my max load is 11 KW then I would set the pass through to 10 KW and the charger for 5 KW. If it calls for the generator is called for at low batteries (needing to be charged), I only have 3 KW of load, 5 KW of charging, I could run into wet stacking issues, and would not be running in the efficient range of the generator.

If I got a DC generator it could be set to bulk charge and turn off at the end of the bulk charge. The generator would run all most 100% of the time in the efficiency range. The loads on the battery would only matter to how long it took the batteries to charge.

If I would of gone with a XW or a Sunny Island system I could of used the generator support settings to keep an AC generator running in it's efficiency range. The last time I checked Outback dose not do this.
I know someone that has a large off grid 3 phase Sunny Island system and know a decent amount of the issues that go with there systems.
I had thought about going with XW, but I'm unsure about the quality after Snider took over.

animatt · February 2015

Re: Generator strategies.

Is your hydro 24x7 x365?
2800 seams like a nice size.
Any chance you could expand. if you had resources another 2800 would seam to start carring a fair amount of base load.

Also with your hydro being I assume 24x7x365 I would not buy a bigger generator than peak. If you could get another hydro generator you may even scale diesel generator down a bit. Say 8kw. If one hydro goes down you still have one taking 2.8kw base. also I would imagine with 2 hydro suddenly lose of both would be uncommon.

Some thoughts. more hydro if available seems like it would be very useful as you can plan on its power without having to add batteries.

3dworld · February 2015

Re: Generator strategies.

No I’m not able to expand the hydro. For years I was off grid without PV because of the hydro.

The hydro almost caries 3 of my printers and we try to keep at least 2 of them running 24/7.

animatt wrote: »

Also with your hydro being I assume 24x7x365 I would not buy a bigger generator than peak. If you could get another hydro generator you may even scale diesel generator down a bit. Say 8kw. If one hydro goes down you still have one taking 2.8kw base.

Dose outback have generator support setting that I don't know about?
What would you set the charge rate on the Outback chargers?

animatt · February 2015

Re: Generator strategies.

I think a quality prime mover 8kw would probably were I would aim for. That plus hydro plus little battery help could taken peaks a good bit higher than your 11kw. And if you have less load like 7kw load and 2800 hydro you can have atleast 4200 on generator.

Depending where you are located you may want an even smaller generator. This way you run hydro full load, generator full load and draw say 1.5kw from batteries or even more from Batts. run a deficit at night then next day solar actually can work on recharging. Solar plus hydro is enough to cover peak. This way cycle batteries at night to allow greater solar collection.

I would imagine that is how the 6kw generator was working.
But have to balance fuel efficiency, with maybe future expansion, and other factors. Just get a high quality motor driving something like a 10kw Gen head. This way when it runs 16 hours at say 6kw it does well and does not over heat.

Matthew
Gen support I am not sure about. I know xantrex/conext can in certain situations. not that this info helps you.

edit/ -- when I say depending where you are located it is more accurate to say depending solar conditions and you can depend on solar to recharge you every day ---
the more I think about it a 6kw generator seems like a good fit. But only you can tell from your experience if 6kw was enough. Just need quality parts definately generator side larger than 6kw but engine size around 6kw. i am not sure super larger generator would be super beneficial /edit

westbranch · February 2015

Re: Generator strategies.

Some Outback models do Gen support, other may but do not say they do, others just don't... which one(s) do you have?

PS, please add a sig line via your 'My Profile' under 'Settings', so we can refer to it...tks

mmag · February 2015

Re: Generator strategies.

Sounds like you have a nice system and are thinking of all your options, its my opinion you should not have wet stacking issues with loading a 15kw to a 8kw load, that is roughly half of its rating, and some of the new tier 4 diesel generators have a electronic governor that probably reduces wet stacking, i think its better to not load a generator to its full output all the time if you want to get a good life span, but you do need to check fuel consumption charts to make sure it makes sense. it would be interesting to see the dc generator specs to see the fuel consumption comparison.

Alaska Man · February 2015

Re: Generator strategies.

I'd like to now how one makes a living printing 3D? Color me intrigued.

3dworld · February 2015

Re: Generator strategies.

There are a couple of companies that all they do is 3d printing. You send in you file with the information on how you want it printed. They check the file to make sure it's printable, some times the wall thickness is to thin, or it will need supports added. They let you know of any needed changes and an guesstimate of the cost (this is hard to do). Once OK it gets put into the queened list to print.

They charge by the amount of time it takes to fix your files and then by how long it takes to print. They charge extra to clean the part with a low power pressure washed and to assemble the parts.

I have been to a place that has 200 “Cube”'s set up. They run 5 days a week 24 hours a day. They have 30 employees. About half way through each college semester they start working 6 days a week to keep caught up with college projects.

I do a lot of prototype work for industrial machines and design new processes. A lot of times with new processes they want to see that it will work before they will pay for new tooling to be made. It's much cheaper than machining parts for testing. There are some parts that we make that are made to snap if there is a machine crash.

Alaska Man · February 2015

Re: Generator strategies.

3dworld wrote: »

There are a couple of companies that all they do is 3d printing. You send in you file with the information on how you want it printed. They check the file to make sure it's printable, some times the wall thickness is to thin, or it will need supports added. They let you know of any needed changes and an guesstimate of the cost (this is hard to do). Once OK it gets put into the queened list to print.

They charge by the amount of time it takes to fix your files and then by how long it takes to print. They charge extra to clean the part with a low power pressure washed and to assemble the parts.

I have been to a place that has 200 “Cube”'s set up. They run 5 days a week 24 hours a day. They have 30 employees. About half way through each college semester they start working 6 days a week to keep caught up with college projects.

I do a lot of prototype work for industrial machines and design new processes. A lot of times with new processes they want to see that it will work before they will pay for new tooling to be made. It's much cheaper than machining parts for testing. There are some parts that we make that are made to snap if there is a machine crash.

Fascinating, I just bought two books on the subject.

Thanks

Generator strategies.

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