Clearly when the locomotive is running and hooked to the train, that is your source for a 32V DC power system. However, if the locomotive is cold or unavailable, or the power system is not on a train, how can one provide power, either to a standalone train or to off-train 32V DC power systems.

I have been looking for some options to operate between 20-100 light bulbs and some other low power loads in a 32V DC system (all would be parallel connected). I calculate that for 100 60 Watt (600 watts) 32VDC bulbs i will require 185 Amps of capacity. The budget for the project is low, preferably what can be found spare or purchased cheap

Here are the options I have considered:

-32V DC Power Supply

All of these I have found are intended for electronics use. They are regulated far more than needed for light bulbs and other power-tolerant devices. They have very low amperage rating in the neighborhood of 1-3 amps. They are fairly expensive for the amount of power they generate.

-Motor-Generator Set

Use a fractional HP 120VAC or 240VAC motor belt driven to a 32VDC generator intended for marine use or older diesel use. New replacement generators are a few to several hundred dollars and I am dubious they have the amperage output needed. Vintage generators are and seemingly just as expensive with lower reliability and the same load issues. Possibly if I can come up with a vintage 32V appliance motor this might work.

-Series Deep Cycle Batteries

Three 12V batteries in series would provide 36V. A bit high but likely usable. Cost of batteries would be significant and would have availability issues if they were not fully charged or had to run for significant periods. Questionable load capacity. Questionable lifespan.

-Battery chargers in series

Three 12V battery chargers in series would provide 36V as well. Load capacity and availability would be better than batteries but could cause damage to chargers and is certainly not what they were intended for. Could be a safety issue. Cost would be lower.

-Abandon 32VDC for 12VDC using RV bulbs

A lot easier to accomplish but not historically accurate.

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I would like to solicit input for ideas, thoughts and experiences on how a project like this could be be accomplished.

How about a little quiet Honda portable off the shelf 110 VAC generator, a step down transformer and rectifier?

dave

First I would suggest getting clear on exactly what you need. In every rail application I have seen, 32VDC really means 16 lead-acid cells of battery. These are 32 VDC on paper, and 37-38 VDC coming off the generator/battery charger. If you actually want 32V batteries, they are easily obtained via 8V (4-cell) golf cart batteries.

Next get clear on amperage. 100 x 60 watt bulbs = 6000 watts of power. That's a lot. You can't get that from 120VAC. You'd need to go 240VAC @30 amps (when you figure charger/transformer losses). 3-phase power, either 208 or 480, would handle this easily. 480 3-phase has its precedent in Amtrak head-end power, will this coach ever share facilities with HEP coaches?

So, for dirt cheap, I'd find a used industrial-grade forklift battery charger. At WRM we inherited several which use 480VAC 3-phase, and have digital controllers. I would expect that most such chargers die by their digital controls going kaput and being too old to get parts for, leaving behind a perfectly serviceable transformer and rectifier array.

Do not lower the voltage to 12V. That will increase the amperage in proportion, overloading the old wiring inside the car. Raising voltage to 36V (nominal; 42V float) will probably not hurt anything. It will of course greatly shorten the life of 32V bulbs.

One last detail is missing here, ebtrr. How many hours a day is this 32-volt system going to operate, and how many days is it going to operate in a year?

If the duty-cycle (number of hours on, compared to the number of hours off) is pretty low, a smallish 120VAC charger can keep the batteries charged. The current drawn during operation is way too much for the charger to supply, but that's what the batteries are for. Once the load is shut off, the charger has a chance to play "catch-up", if the off-time is long enough.

My two cents' worth.

Are the 20-100 bulbs all in one car? If not, how many cars are we talking about? The reason I ask is that I was wondering how the lights were originally powered. I expect that they originally used an axle-mounted generator on each car to charge a bank of batteries in that car, but maybe someone more familiar with such systems can comment on this.

I am being vague because this is not a project yet, it is information gathering in order to propose a project, so I do not want to get too specific.

Let me clarify some, this is not for a rail car, although it could be used for that. The primary goal is to re-electrify railroad structures that historically operated on a 32VDC system, originally using a steam powered generator. Part of the system has been cut over to 120VAC, parts have been disused. The goal is to demonstrate a working 32V system to better illustrate the working conditions and environment and increase historical authenticity.

The project would start with disused, and possibly distant areas. Initially it would be a small number of bulbs but would hopefully grow and _could_ be as many as a hundred eventually. There will be separate circuits - all bulbs will not be on the same circuit. Other loads could be on the system as well such as horns, bells and other signaling devices. It would utilize the original knob and tube wiring. Not all bulbs will necessarily be 60 watt, some could be 40, 25 or even 15 Watt.

Difficult to estimate the duty cycle. It would not be all day every day, but it could be all day (8 hours) a couple days a week, max 40 days a year. Likely less. It would not be the day to day electrical system. The AC system would handle that.

120V AC and 3-Phase AC (voltage unknown) are available

McHugh Bros. New Hope & Ivyland built a battery charger that could be adjusted for almost any size battery. Of course, it had meters, timer, fuses, circuit breakers, cords, clamps, etc., and screws to fasten it to a wall. Later, it acquired cabinet, cooling fan, and wheels. The big parts started out with an isolation transformer with terminals for 240 volts or 120 volts Alternating Current in to 120 volts Alternating Current out. Next was a variable transformer with a big adjusting knob to change its output anywhere between about 1 Volt and full input. Last were a bunch of large diodes on giant heat sinks and condensers (capacitors) the size of coffee cans, to rectify to Direct Current. The parts were bought form some large industrial electrical parts supply company, a grown up version of Radio Shack or other hobby electronics store. The output circuit breaker was 60 Amperes, and it could be tripped, even at full voltage output. We used it for 6 Volt old truck batteries, banks of 112 Volt Copper Range RR. Baldwin Locomotive batteries, and lots in between, including 32 Volt coach batteries. I imagine that 32 of your 60 Watt, 32 Volt bulbs would be near the tripping point of the circuit breaker.
32 Volts Direct Current was common in the rural coal regions, where you had to make your own electricity. Can you just run a generator off the existing drive belt system used for the machine shop tools? Dare you just use a transformer to make 32 volts Alternating Current, if you are sure that none of the old sensitive electrical fans and machinery will be on line? Actually, some of them may use Universal motors that run on both Alternating Current and Direct Current, just like an old Lionel train.

While the idea of creating a new 32 VDC power supply is historically meritorious, the fact that part of the system has been retrofit to 110 successfully leads me to the conclusion that the quality of the wiring is capable of operating on the higher voltage - providing the same luminescent power at lower amperages would have been provided by more amps at lower volts originally. If the goal is illumination, might be the most practical alternative, and indistinguishable from the original with the correct lamps installed.

You could and should meggar the circuits to assure their quality no matter what current you run through them.

I still recommend the small off the shelf portable idea - to run more buildings, multiply sets. You will find portable generators very handy for a variety of uses, so no waste of resources involved.

Have you checked into wind power?

dave

The goal is not illumination nor practicality. The goal is to demonstrate an obsolete technology, just as we do with vintage diesels, steam locomotives, traction engines, line shafts, leather belts, speeder cars, hand forging and the many other systems we preserve. Historic merit is the intent.

For practicality 110VAC would have to be retained and used for real-time work, but the historical infrastructure can be returned (in part or in whole) to it intended use and design and used as an educational tool.

The information I need is how to provide power to such a system. Restoration of the historic generator would be years away if it is even practical. Line shaft driving a generator is not possible for many years either, and using a 110VAC motor to a 32V generator would be more serviceable anyway.

The suggestion of the electric forklift charger has a lot of merit, though probably further down the road. I would almost certainly start the system off with deep cycle batteries in series and charge them individually.

If demonstration is the mission, then your real option is to recreate the original steam plant. It is the heart of the system - and without it the 32 volts could come from, as shown in this thread, any variety of sources. Hardly meaningful interpretation. you can't see a volt - so there's nothing to experience any differently than turning on the lights at home for your vistors.

On the other hand, I'm very pleased to learn you guys are getting far enough along to actually have the resources to even consider this kind of thing - must be very different than the EBT I visited a long time ago.

dave

Knowing how historical and combustible the buildings are that your talking about I think you should have an new and safe 110v service installed and use the old reproduction light bulbs to simulate the old technology.

The old wiring would be a lot safer at 32 volts than at 120 volts, but I'd still check it closely. I once had to work with some post-and-tube wiring done circa 1918, and the then-70-year-old insulation was VERY fragile. It's a wonder I was able to wire-nut some lamp-cord to it.

ebtrr, for the sake of argument, let's assume fifty each 40-watt light-bulbs as a start, and set aside anything else like motors and whatnot.

Total power = 50 bulbs x 40 watts per bulb = 2000 watts.

Power = volts x amperes
or
amperes = power / volts

So, amperes = 2000 watts / 32 volts = 62 amperes, more or less.

Assuming 8 hours of use per day.....

Ampere-hours drawn from the battery = current x time
Amp-hours = 62 amperes x 8 hours = 500 ampere-hours.

If memory serves, locomotive batteries are 32 volts, with an ampere-hour rating of 420 A-h, so two of them connected in parallel (for a total amp-hour capacity of 840 A-h) would have PLENTY of charge capacity for this hypothetical lighting system. You may want to put a total of four in parallel, not so much from a capacity standpoint (it would be overkill) but instead from the standpoint of not wanting to run an individual battery down very far, as they're meant for starting service and would not last very long if they were discharged too far.

As far as charging such a beast of a battery is concerned...... well, lessee......

500 ampere-hours out of the battery would mean about 600 ampere-hours would have to go back in (due to inefficiencies in the charging process), and that charge spread out over 16 hours of off-time works out to an average current of about 38 amperes. (38 amperes x 16 hours = 600 or so ampere-hours.) That current would be delivered at about 37 volts, so the input power would be about 1400 watts. (37 volts x 38 amperes = 1400 watts or so.) That kind of power delivered to the battery would require about 1600-1700 watts delivered to the charger (to make up for its inefficiencies), which in turn implies that the charger would draw about 15 amperes at 120 VAC. It's actually a bit worse than that, thanks to the screwy volt-ampere ratings required for any transformer that feeds a rectifier, so plan on a current draw of 20 amperes at 120 VAC, maybe more. You're right at the edge of maybe having to go to a 240 VAC circuit.

A 36-volt forklift-battery charger could be made to work in this service. It may be necessary to fabricate a low-value, high-wattage resistor to restrain the current flow out of the charger-- otherwise, the charger might kill itself trying to charge a 32-volt battery, in an attempt to provide gobs of current to bring the battery up to 42 volts when the highest a 32-volt battery can go is about 39 or 40 volts.

(Such a resistor could be fashioned out of 12-gauge "Romex". Simply use all three wires-- black, white, and the ground wire-- in parallel for a safe current-carrying capacity of about 50 amperes. Dropping five volts or so at 50 amperes implies a resistance of 0.1 ohm, which corresponds to about 200 feet of Romex. It may be cheaper just to get a regular 0.1 ohm, 500-watt resistor, but the Romex wouldn't get as hot to handle. *chuckle*)

If you're starting off with a much smaller system (maybe 25 bulbs at 40 watts each, for a total power draw of 1000 watts) you can make do with two loco batteries, and a small, portable 36-volt forklift-battery charger designed to run on a 120 VAC circuit, and appropriate voltage-dropping resistor.

More ravings as I think of them. Certainly they're worth two cents.....

You see, there's a reason I directed my friend, the walking encyclopedia and calculator of vintage electricity/electronics, to this discussion............. <:-)

Anyone who recommends using old wire with deteriorated insulation and no ground in a historic building regardless of what voltage your running through it is NUTS! I have been through the shops at EBT and have seen the fragile condition they are in. Importunely the buildings are a tinder box just waiting to go up. Although the Friends are doing a great job on preservation there comes a point in preservation where you have to make the decision to make some change for the better good and preservation of the facility. The normal tourist who will tour the building really does not care what voltage is running through a light bulb, it is the atmosphere and historic fabric of the facility that is important. And to be honest your better off having a few repro bulbs for display and then using modern safe flood lights for general lighting.

In point of fact, there's a major resurgence in running houses on DC. That's because solar, wind and micro-hydro are cheaper than ever, and that makes several things possible, including "eco"/green sustainable solar homes, and off-grid living in remote locations. Most of those systems are DC wherever possible, using special lighting and appliances.

The only snag you'd run into is that most setups use voltages other than 32V. But they may be able to adapt, if your commitment is 32V.



Most of what I hear about knob-n-tube wiring is "look how fragile and dilapidated it is". Hold on - why is it still in service? Rip it out! if you're not going to maintain it. Otherwise, maintain it properly. That's what they would have done in the old days. No old-timer would have allowed deteriorated wiring to continue in service, they would have replaced it with new wire. Because they *understood* the hazards of bad wiring, the building was precious to them... and they couldn't afford a fire. New vintage-style wire can be obtained.

Oh and I must disagree about 32V being safer than 120V. Yes, lower voltage makes it somewhat less likely to arc/jump across bad insulation. If the current remained the same, that would be that. But as you say, power = voltage x current, and nearly 1/4 the voltage means nearly 4x the current. Quadrupling current flow on deteriorated wire is going to make the narrowest part of the wire heat up, set the insulation on fire, and goodbye building.