Many years ago, I recall reading an article in Trains about a couple of battery-oil-electric locomotives owned by (I believe) the DL&W. If my faulty memory has served in the time since, the locomotives used batteries to move short distances away from the catenary that normally supplied power. Once back under wires, they operated as normal electrics, while the oil (diesel) engine recharged the batteries. Two questions:
Did I remember this right? Was this, in fact, a real locomotive that operated this way or have I hopelessly confused things over the years? If so, then…
Why add an internal combustion engine to recharge the batteries? Why not just draw power from the overhead?
I’ve looked for the article off and on many times but I always get too distracted by other articles I haven’t re-read in a while.
Sounds right. The internal combustion engine charged the batterys because the trolley was I think 11,000 volts A/C . There was not technology that would rectify and reduce the voltage down far enough to gaurentee that no damage could be dome to the batterys . Also , no way to regulate it . They just didn’t have the goodies we have .
The Illinois terminal had oil/electric/battery engines also . Since the IT was a 600 volt DC trolley line there wasn’t a big issue using trolley voltage to charge batterys, after all they were 600 volt batterys.
North Shore line had a battery / electric locomotive for servicing industrys where a live overhead wire would be a safety issue.
Lackawanna catenary was 3000VDC, I think. Too high for battery recharge.
The “triple-threat” locomotives, I think, were NYC, where there was 600VDC third rail. Alco built the first one and GE a few more.
The operating theory was this:
On the road, they relied on 3rd rail.
In the yard, they used the diesel engine-gen output augmented by batteries for extra power. The idle time between hard shoves and pulls in the yard allowed the engine-gen set to get the batteries recharged.
Interesting. Still, I had thought that the additional electrical equipment to draw electricity from the transformer or motor-generator would have been less bulky or complicated than adding an internal combustion engine to the carbody.
I believe the title of the article was “The Ohms and the M’s” and it appeared early to mid-70’s.
The DL&W units were tri-power and the catenary was energized at 3,000V DC (changed about a decade ago to 25kV, 60 Hz - though with IGBT’s capable of running from 3.3KV it might have been better to keep the 3 KV).
RI & NYC had dual-powers at La Salle Street Station which were similar to the tri-powers but without the pick-up gear for third rail or overhead. Some of NYC’s tri-powers (and some R2 straight electrics) were later transferred to Detroit for that terminal operation.
The problem is that it used to be difficult to reduce the DC voltages to different levels. That is one reason AC power won out for the “Grid”. If we used DC power in houses, we would need local generating stations in every neighborhood. If you used high DC voltages, it would be unsafe; if you used low voltages, the resistive loss (which is a function of the number of amps being send down the line) would be outrageous. A/C is easily reduced using Transformers. Untill (relatively) recently, the best way to change high voltage DC to mid or low voltage DC was using a motor-generator set (Large, bulky, inefficient).
SOlid state technology has made the switching power supply ecomomical today. In fact, parts of the Western Power Grid use DC to transfer power for large distances. (Hey, it surprised me too!)