Plausibility of using GE WWII Searchlight DC Generator for Home AC Backup

I'm just as dangerous as you.

Why not. You'll need an inverter.

Most houses have a 100 AMP service from the grid.

Do you know how much power your house consumes.

These are probably noisy and overkill, but they're paid for, I guess.

Wow nice piece of machinery to have laying around....I take it this is diesel...? The first problem I see is you have to convert the DC voltage to AC, and probably 2 separate phases, and probably sinewave....Do you have an inverter 15k? 100vdc to 220vac

If not that would be probably over $1k us....if you can find one

8kW is plenty enough to run most houses. Getting it from 100 volts DC to AC is going to be the biggest problem. There are plenty of inverters that use 12, 24 or 48 volts as these are common battery bank voltages. I've not seen any that take 100 volts as a DC input.

Did you talk to the folks at Detroit Illuminating Service? Is there a way to lower the output voltage? If it's possible, then you may be able to use an off the shelf inverter.

You will probably want to find out what the output is like. Being the output of a generator, it's probably very noisy. I don't think an arc lamp demands clean power. You will probably need to filter the output as the noise may be too much for an inverter that is expecting input from a battery.

It's almost surely likely to be cheaper to buy an 8kW generator. Cheaper models can be found for around $1200. Honda, Generac and the better models will be more.

Do you have the arc lamp to go with it? I'm told pilots hated being lit by these, as it caused serious spots in the vision with even a glance and with the pupils wide open would cause temporary blindness.

I would forget about the DC generator and use an AC transformer welding machine, if your house can handle the load of approx. 240v/40-50 amps. The DC generator will require several very big and expensive inverter to convert the DC to AC. This will end up being a very expensive investment. 15,000 watts is a very big inverter.

For the lights an AC transformer type welder puts out about 40-80 volts at whatever amperage it is capable of. My 150 amp welder puts out 70-80 volts for a total wattage of 12,000 watts AC/DC. A slightly larger unit at 200 amps would probably be what you want. Several companies make a 225 amp AC models which is about the cheapest you can get. A more expensive variable unit would be better for your use. Unless the big pot is varying the output of the DC generator it might be useable with the welder. A cheaper and better set-up would to make a simple electronic current control on the transformer or controls. You may be able to reduce costs by buying a used but good condition welding machine.

If you don't plan this project efficiently, utilize personnel who know much more than you do or have to make development changes this could become a "money bucket with a very large hole in it". Develop it on paper first, have it checked out by several knowledgeable people, price out the bill of materials, make changes to lower the cost and finally put it together.

Good Luck, Old Salt

I would suggest that the thing you need is to find an experienced electronics engineer or PSU company who can build you a custom inverter.

100v DC at 100A is unusual but not that unusual. In the kind of power supplies you find in large industrial PC's - switch mode, high quality, and rated 1 kW to over maybe 1.5 or 2 kW of power handling. In their first stage these usually filter the mains then convert it to DC - with voltages of 80 - 100 or 200v not uncommon, along with very high amperages. The rest of the PSU then converts this DC to high frequency chopped AC which is then converted to the other voltages needed.

But like I said, for something like this you definitely need an expert, and with those high amperages this is definitely a case where a little knowledge can be 'very' dangerous..

Oops just wrote that while half asleep... 100v at 100A is 10 KW not 1KW. Sorry. That's why you should always double check your calculations. 10 or 15 KW is a different story even to 1 KW.

Definitely buy a professionally made device, a couple of thousand dollars now could save you a lot more later. Apart from anything else a professionally made device should have a guarantee and an insurance contract to cover potential liability.

If you don't have a properly built inverter 10KW could blow your house wiring, any connected electrical stuff, and probably the generator itself. Plus high danger of fire and or electric shock, when it goes wrong electrical stuff with that much power inside it tends to explode.

You should be able to find a grid tie inverter that will handle the 100v DC input and be able to output your mains voltage. You may have to settle for something around 5kW to keep the price down and also to meet the 100v start voltage limit.

Most larger inverters will have higher start and minimum input voltages than what you have available.

The anti islanding characteristics of the inverter can be overcome by providing a smaller mains voltage input either from a smaller inverter or from another small alternator, either of which would have to be pure sinewave output to enable phase synchronization.

You will need to take great care that there is NO possibility of the backup feeding to the grid during a power outage as this can be very detrimental to the health of linesmen attempting to restore the service.

As has been stated by others, you may be financially better off to purchase a purpose built outfit and possibly sell what you have to offset the cost.

TO EVERYONE!

This is what I expected and y'all are giving good thoughts from where I stand, and I have been here longest.

This is aspect A and I'll update a couple concerns, and the cautions are great. I too had been thinking that with these very large arrays, a professional unit would be there, or close enough to tweak, let's see. I'll report back.

Part B is a remote chance that someone may be interested in funding an Aereoponic indoor grow, for the "groups" fresh veges out of season. I'm a horticulturist, and with all the $ pumped into the information availability from the legal pot states...

Could the light be a economical source for grow light. Converting to propane is optimal in any case, but with the automated directional movement, combined with the machine on wheels, it could traverse the area back and forth...

Any obvious WTFs? ha-ha Steve (MiscExpert)

Remember the early car radios? They had the vibrator to produce 60HZ. Why not a scaled-up version (about the size of a 55gal drum with an octal base).

No really, I used these Waukesha units on the flight line, never had a problem.

Based upon other OP answers which are quite good taken as a lot, my recommendation: save the carbon-arc lighting sets and DC generator as a unit. You could consider (depending on if your location is remote or suburban) charging up battery banks that are set up in a 100 V input series/parallel array for charging, then switched to a 24 or perhaps 48 VDC output mode for supply to off the shelf inverter. You would obviously follow all recommendation of the OEM for the batteries, but seal lead-acid battery banks are not hard to come by, and charging controller might have to be custom-made for your application (not sure on this one). This would give you ample back-up power, allow you to select when to run the DC generator for charging (probably during day time when load might be low, but also neighbors are less touchy about noise).

Re-reading your posts I had a few more thoughts...rather than converting to propane, you might consider SVO(straight vegetable oil) or biodiesel(U of Az. has info on building your system from a water heater). I have also used HHO on diesels with some success and am currently working on a 100L/Min electrolyzer. Filtering free SVO from deep fryers works out at about 25 cents/gal. Making biodiesel w/methanol-lye works out to $1.15gal, buying 50lbs lye, and 55gal methanol. I've been using in a Case tractor and my '95 Ford F250 w/7.3 for over 4 years with no problems. I'm guessing those DC gen sets are 2-2.5 KW output (80 amps @ 14-18volts arc)

Since I live in the City, the back-up generator gives me the excuse to have it - but I feel the usefulness of keeping it as close to original important for obvious reasons.

I have natural gas here and converting it to that is a no brainer, and if done carefully, I believe can be switched back to gasoline. It's important to note these machines are high torque, 1800 RPM and VERY quiet, designed that way for warfare.

I need to look at the generator itself and see if I could cut the V in half, if so I now have off the shelf grid inverters...

Secondly however, I keep thinking outside the box - say converting most things - lighting, refrigeration, etc to 12 volts DC, and using it more;

Or how about in early manufacturing where we had a shaft driven system throughout the plant that always ran with a huge flywheel - only augmenting when needed. Adapt that to this somehow.

Is it totally ridiculous to store or retain energy by something as simple as gear driven bi-directional unit where I take an extremely heavy - let's say - work table - and have it elevated by cables, thus becoming like winding a watch - the purpose being to lengthen the cycle time between running this unit or have we thought of de compressing the engine and have the thing always running, just kicking in and out adding or taking energy. This sounds primitive, but I have solved some problems in the past by just allowing myself to think the "unthinkable".

Thank each and every one of you, I didn't expect so much help - I will try and post detailed information about the system as I acquire it.

Aloha, Steve

I guess that these are gasoline 1800rpm engines...I think I read diesel into the mix from the other posts....this genset is basically a constant current supply running an arc, and the arc length sets the voltage( the 100volts is the open circuit voltage) and the pot sets the field current so the genset delivers your 80 amp 'sweet spot'....if you measure the voltage when the arc is established, I believe it will be much lower. You could probably replace the pot with a regulator circuit that would make the set produce a lower voltage at variable current and by switching to pot or regulator circuit have a dual use unit. As it is, it would probably make a nice bead with 3/32 arc rod.

Let's, for the record, say gasoline. I own 2. and I think you are on the right trail.

I need to have y"all be able to look at the actual schematics and pictures. I will do this, ASAP.

Steve

You've got to keep in mind that the power you are dealing with is 5 to 10 KW on each unit. The safety rule with this kind of power is that it 'wants' to kill you, and low voltages (100v) and high amperages can make it particularly dangerous because you get serious heating issues.

Absolutely everything has to be up to spec - the wires must handle 150 to 200 amps, same with any switches, switch blocks, connectors, etc. This will give at least a 2x redundancy, especially important if your planning to run them for extended periods. Also adequate safety fuses*, and everything laid out carefully and properly, absolutely no bodging, and everything also needs adequate cooling.

*For a generator the fuse mustn't just go open circuit but should dump into a dummy load and must trigger an immediate mechanical shutdown. I imagine your arc lights are already be fitted with this kind of system - but it might need upgrading and its the kind of thing you really do need an expert for. Spend a couple of extra thousand now and save tens of thousands later.

BTE gasoline engines should run on natural gas just fine though you may need a special carburettor. I remember hearing that some of the old cold war air raid sirens used V8 gasoline engines powered that way.

Back on the farm, we used to use normal 6 cylinder or V8 GM engines (short block on the V8, I think, and they ran all the time on natural gas. Here at work, we have two really old Nordberg engines that start on fuel oil (No.2 Diesel?) and switch over to natural gas after warm-up. The irrigation pump motors lasted long enough to make several trips to the moon equivalent by hours operated.

Consider building yourself a bio-gas generator (maybe) as an alternate fuel source. Be prepared for several issues, not the least of which could be permitting that in an urban setting, but when the SHTF (and it will), you might be really glad you have that. Or just get all the stuff in place, then only start using it when SHTF.

By the way, I hear that zombie hunting goes really well with WWII search lights.

Your sharp. It does have a dummy load in the original design.

Miscexpert: You could really try this one, as there is no hazard other than possibly drowning!

1) large horizontal (or vertical tank above ground or even at ground level filled with whatever kind of water you have.

2) vertical shart large enough to go down and work a horizontal shaft, and for passage of the material for a bladder tank at the bottom in the horizontal shaft.

3) of course you have to shore up the vertical and horizontal shafts in whatever method is suitable and permissable and safe.

4) bladder tank is designed for 105% capacity of the top tank.

5) install pump/hydroelectric generator down at or near the top of the horizontal shaft. Pumped storage for a domestic situation, with water storage for WTSHF.

As to your earlier comments about storing some (or most) of the energy to reduce cycling, there are several interesting ideas:

(1) Drive a high-efficiency (DC) motor to spin a paddle impeller in a thermal oil (check the web for those fluids). Alternatively, use resistive heating directly from your generator. Pass the heated oil over gravel or metal ball filled tanks to store heat (pick a high enough temperature to be useful later). Tanks can be above or below ground in vaults. Use a heat engine (as in compression/expansion of gas or even supercritical CO2) to recover the heat and convert to electric power on demand. You could even use the heat to generate steam in a closed cycle system and drive either a piston steam engine (maybe not the highest efficiency) or a small turbine (costly).

(2) Use hydrolysis at lowest possible overvoltage to make hydrogen and oxygen (use PEM type cell and good electrodes for best results, and be selective in the water used). Efficiency might not be as high, but longer term fuel storage is possible, just be aware of hazards of compressing hydrogen, so maybe not the smartest thing to do in town.

(3) Use a system from www.isentropic.co.uk (patented energy storage for renewables). This system uses adiabatic compressors to store heat (not so much compressed air) in a gravel filled pressure vessel as a hot band spreads downward into the gravel bed during charging, re-expands the air over a smaller compressor to recover some of the energy of compression, discharges really cold air to ambient pressure. When cycle is reversed, heat is recovered from the hot zone, and drives the larger (upper) compressor, and shaft power is converts to electric power on the electric motor/generator. This is not an endorsement, just a snapshot of what is out there.

(4) Simply use compressed air storage, but you will lose a considerable quantity of energy unless you find a suitable thermal storage medium that the compressed air can be passed back through on the way to the expander.

(5) Your idea of lifting weights might also be of use, especially if there is any change in elevation on your property, or property you can have immediate access to and can supply/take power to and from. This is done using hoppers, cement balls (can be coated with plastic or rubber to deaden some noise), a conveyer system (as in coal mining), and companies exist out there that would be happy to assist you, search them on the web. Other weight lifting idea is the use of a vertical shaft similar to a water well (advantage is drill depth here). As you said, power winds it up, and generation winds it down, should not be that hard to ratio the speed with modern planetary gear boxes.

Good luck, but most of all plan ahead for (1) safety, (2) safety, and (3) respect for the local codes regarding any necessary permits (could save you a lot of heartburn).