Quote:
Originally Posted by Bob_Sinclair
Hi,
Lead acid and NiCad are very much still an active and used battery, my understanding from researching online is that most electric trains use them for initial power/ stand
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Hi Bob.
Really? What are your sources? I suspect you may have been looking at heritage traction.
I don't quite understand what you mean by "initial power, standby power". Presumably you're referring to the standard 'Auxilliary system' of 120 volts dc that all diesel and electric traction units in the UK have? A generator for diesels/ or converter for electrics supplies this voltage and the batteries are connected in parallel. If the converter stops (usually because traction current is interrupted), the batteries continue to supply 120v for a limited period. But this does not feed the traction motors!
In the majority of cases, batteries are not usually used for traction on mainline units, and are only the
sole form of power in an emergency (to supply low level stuff like emergency saloon lighting, head/tail lights, and cab radios).
There are some prototype units that use batts for traction, and the new Heath-Robinson 'hybrid' units can travel a short distance on batteries, but most electric trains need to be connected continuously to either turd rail 750v DC or 25kv ac overhead traction current to function. Air is the lifeblood of every train, and air compressors are usually supplied from traction current, NOT batteries. So normal trains don't sit on 'batteries only' as they will lose their air, and the brakes will eventually fail to work.
AFAIAA all modern traction has used (at least) NiMH batteries for quite some time. From my experience, certainly the Bombardier & Siemens units, and the ubiquitous class 66 locos do.
HTH, BW