Since this was mentioned in the diesel storage topic, I was hoping to expand on it. For a while I have been trying to get in contact with the right people (electrical engineers/designers) in the solar charger industry, to find out if it is safe to run chargers in series (negative terminal of one charger on same bar/connector as the positive terminal of the next charger) to get the right charging voltage, ie: (5) 12vdc + (1) 6vdc solar trickle chargers to get 66-72vdc charging power (12-13/6-7 vdc max per charger). So far no one has been able to get me a straight answer.

So what are the experiences of the group in tying even regular trickle charges in series to maintain 24, 36 or 64 vdc battery sets? I can see no problem with doing it since all each charger will see is the voltage it is set for, but I am not an electrical engineer, so I cannot be positive.

I am sure others that have multiple locomotives and support equipment know how hard it is to get all the equipment close enough to power to keep the batteries topped off over the year, especially during the winter months, let alone the cost of the power since more is wasted by the transformer than what goes into the battery. I am kinda hoping that solar, though the equipment cost is higher would pay for itself over a short time period, especially since the output and quality of the cells are constantly improving.

Thanks,

Rich C

Rich, I'm in the military and we use a solar powered trickle chargers on vehicle we store in "war ready" condition. We mount the panel on the top and then the vehicles are cocooned. Do a google search and many companies now sell them.

http://store.sundancesolar.com/trchforcatrr.html

Without knowing the schematic of the chargers in question, that is a hard question to answer.

If the charger is LINEAR (as opposed to a switching) supply, you can indeed put your chargers in series.

It is far more a crapshoot on a switching power supply, especially if they are different makes from different manufacturers. Switching supplies operate at different frequencies, and their feedback loops which maintain their voltage & current outputs can interfere with other and offer some pretty unstable results.

Matt

I know this is not the Solar solution that you mention, but it is a 64V charger that runs off 110VAC. I had one of these at the Smokys, and one at the Whitewater Valley. It has a 25 amp charge, but the QPAE model will also off gas and float so you don't cook the water level down if you have to leave it for a while. They have gone up in price a bit, but what hasn't?

You can run one of these off a small generator, or a few good HD 12ga extension cords, as the 110VAC full load is only about 13-14 amps.

If you are going to charge a dead set of batteries, you should plan to charge for a day or so. That is really better for the batteries anyways.

Hope this helps!

Ryan

Contributed by a loco technician/electrician friend of mine, ex-Conrail and both professionally and hobby-wise electrician-geek:

"You CAN daisy-chain chargers together, but they really should be linear, really should be from the same manufacturer, not be switchers, and they all should have the same current rating. A definite answer is hard to give without a schematic, as one poster noted.

One thing to bear in mind-- if anyone on that board is good with electricity and electronics, it wouldn't be all that hard to whomp up a trickle-charger. A brute-simple one would use an isolation transformer (120 VAC in, 120 VAC out) of mebbe 150 watts capacity, run the current through a rectifier, put a bit of filtering on the output of the rectifier to get maybe 140 or so volts DC that can be throtted back by a resistor-bank to the 37 VDC a 32-volt loco battery wants when floating.

Or, as isolation transformers can get expensive, get a transformer that puts out 40 VAC or so. The lower voltage output means you'll need less resistance to drop the voltage, and you can use a lighter-weight one, as you're still looking for only a amp or so of output current.

To explain a bit:

1) The isolation transformer is NECESSARY from a safety standpoint. NEVER hook up a rectifier to the AC mains directly. EVER.

2) If memory serves, a loco battery is 32 volts and 420 ampere-hours. Take that ampere-hour rating and divide it by 500 or 1000 hours and you get anywhere from 0.84 to 0.42 ampere, which is about what the battery will draw when floating. So put enough resistance in series with the battery to throttle the current into the battery back to about one-half to one ampere, and the voltage on the battery should stay steady at about 37 volts. (That's 2.3 volts per cell, times 16 cells. Any higher than 2.3 volts or so, per cell, and the battery will start to gas. Once you get to 2.4 volts per cell, the battery will DEFINITELY gas when fully charged. 2.5 volts per cell will boil the battery dry in no time.)

My two cents' worth, and then some."

Relayed in Baltimore by Alexander D. Mitchell IV (while drinking some of the world's finest beers in one of the nation's finest beer bars)

Battery chargers aren't that simple, at least not if you want them to work unattended. If you're actively watching over the charge, then anything goes... but you need to know what you're doing if you're going to turn your back on it.

Voltage regulation is more than a resistor, just as air regulation is more than an orifice.

You need a charger that puts out float voltage as appropriate for your battery. This can be as simple as look at cheap float chargers for car batteries, and design something with proportionate voltage outputs for your pack.

When I had to maintenance charge locomotive batteries, I just put a 12V boost charger across 6 cells at a time. Inter-cell bars were exposed, so this wasn't hard. It was a pain, but got the job done.

If in doubt, ask the electric-vehicle hobbyists, they know a lot about charging battery packs of arbitrary size.

Getting and installing the 110 vac to 64, 32, 24 or 12 vdc chargers is not a problem, it is the site that is the current problem. We are still in the process of building our trackage, and thus only have a small amount of track is close enough to power to run the chargers. Our 4 most operable locomotives have full chargers, 2 of which have the desulfication pulse mode, I forget the brand, but once the batteries are up to full power, we throttle the chargers back to 1-1.5 amps for the winter, and make sure we check the sg, voltage and water levels at least once a month. If the voltage starts to drop but the SG and levels are close we will bump the charger up for a week or two before bringing it back down to 1-1.5 amps.

With the concern about snow blocking the solar cell, if the cell is facing south (for us) and is tilted more then 45 degrees from horizontal this is not a problem unless the accumulation is high enough to mound over the cell, since as soon as the sun comes out it will melt any snow that has adhered to the cell , especially once the black silicon panel starts to get exposed. Yes, over the winter the time you have to gather the solar energy goes down, but once the snow is on the ground, the little time we have in the sun is worth more because the sunlight get reflected back up and multiplies the power that can be generated over the same duration (within the limits of the charging circuit).

afboone, thanks for the link, I will check it out when I get a chance. If you are allowed to, what are the voltages in these BR machines, and who did and/or currently makes the solar chargers for the military?

Thanks,
Rich Cizik
MoW Foreman
Blacksmith Shop Co-head
Ct Eastern RR Museum
Willimantic, Ct 06226
http://www.cteastrrmuseum.org

Rick, Jeff or anyone,

Can you check and tell me the brands and models of the AC to DC chargers you are using? Especially any 64volt units you are using?

I've been using 32v Pro-Mariners at Travel Town for many years near now, but recently, I've had several fail, and Pro-Mariner has discontinued their 32v line.

SENS http://www.sens-usa.com

and La Marche make 32v chargers, but they are quite expensive, but I haven't found a 64volt unit that didn't seem to cost as much as the locomotive.

Also, how do others mount and wire the chargers? In the cab, in the engine compartment, or off the locomotive?

Also, is anyone else using a Single Point Watering system on their batteries?

Greg

For emergency generators for broadcast stations where instant quick start is vital I got the most reliable operation from pulse-type battery chargers. In the trickle mode they put out an extremely short pulse of about ten amps every twenty or thirty seconds. They keep the battery fully charged. They do not sulfate the battery or create bubbles to evaporate electrolyte. With a thin float of oil on top of the electrolyte the battery never needs water added. I don't know how the oil float would work on a battery in locomotive service.

These chargers are not cheap. The last one I bought cost about $220 years ago for a 24 volt starting battery. You can buy them through firms like Onan that sell emergency generators.

fk

Rich,
They use standard off the shelf companies. They use them on our standard trucks, heavy trucks/equipment, and the tracked vehicles. I would, of course, buy one and see how it works. I know here in Jersey that anyone who uses solar power, Hybrids, etc---Go Green stuff----you get a tax rebate for it.

Steve.

OK, I'm going to ask a question, that I doubt anyone will have a real answer to other than "it's the way the railroads have always done it". :-)

Why did the railroads standardize on 32 and 64 Volt DC systems (multiple of 8 volt batteries) vise 12 or 24 volt (or some other multiple of 6 volt)? Other than old fishing boats (and the marine world has pretty well migrated away from 32volt) I've never seen it used anywhere.

Even if you need more current than 24 volt will supply, it seems by now the railroads would have move to 48 or 120volt DC.

Greg

And don't even get me started on why railroad valves are open when the handle is perpendicular to the pipe, which is backward to any other industry. :-)

Some of the comments took me back to my days in electric utility telecommunications: 48 volts DC is standard for telecom equipment because the phone companies standardized on 48 many, many years ago for their central office batteries. It's considered low enough to not require insulation to prevent contact by workers, yet high enough for economic considerations (higher voltage=less copper). 130 volts DC is standard for electric substation control circuits. A typical "sub" has a bank of 60 storage cells which are normally charged by the "station light and power" circuit. Should the station "go dark", the battery provides power to operate station equipment until power is restored.
32 volts DC was commonly used in passenger car electric systems back in the pre-Head End Power era, usually charged by an axle-powered generator. This was OK for cars in main-line passenger service, but isn't practical for short tourist or museum railway operations. I was told that some passenger cars used 110 volts DC battery systems, as did steamships in the old days. Some early Alco diesel locos also used 110 VDC for their auxilliary power, including interurban-style air compressors powered by 110 volt motors. Why the diesel manufacturers didn't stay with/adopt 110 volt battery systems may be a mystery for the ages, or it may be that it was cheaper to standardize on a battery with fewer cells.
An interesting contrast is the two ex-USAF GE center-cab diesels at Orange Empire: the four-motor unit has a 70 volt electric system, and the one with two motors and side-rods is 24 volts. I think this represents the boundary between "real railroad" and "industrial switcher" design. One day we found the battery on side-rod unit too weak to start the Cummins diesels, so one of the members brought over his car and I spotted my pickup next to the engine. He connected our vehicles in series and hooked up heavy-duty jumper cables to the diesel battery and "fired that ---- up!" Since both of our "road units" had Sears batteries, I thought of sending a photo to the Die-Hard people.
Regarding single-point filling systems: We have a motor home with one on our "house battery". They're not that expensive, although finding one that would work on locomotive batteries might be a challenge. It certainly makes life easier and might encourage more regular adding of water.

Well as I suspected, the bottom line answer to my question of why 32v/64v was the same as the reason it has taken so long to update brakes, etc. That's they way they started doing things, and the need to keep thinks compatible has prevented a lot of improvements.

Just so other's don't forget, if anyone actually has an off the shelff 64 volt charger, I'd sure appreciate a make and model number.

Greg

http://www.electricvehiclesusa.com/prod ... -25sac.htm
one new charger. Ed

Sorry, I just realized I didn't include the link that I intended to in my last post. Perhaps it was all that turkey and stuffing. . .

http://www.quickcharge.com/portable%20chargers.htm

This is the link for the chargers I was refering to. There are many voltages, 64V being one of them. These are handheld with 110VAC supply.

Ryan