Train Batteries

[Lucan]

On another forum (not primarily train related) someone claimed the London Underground was dangerous because the trains carried lithium batteries (with their reputation for bursting into flames for no particualr reason). When I worked for LU the train batteries for emergency lighting and control were all lead-acid batteries, and I'd like to refute that guy. Is it true that the batteries are all still lead-acid?

 

[John Webb]

Sounds to me like confusion between the train's batteries and one or two recent incidents where lithium batteries on electric scooters being carried by passengers have ignited.

 

[Dstock7080]

Pre-1986 Stocks had lead-acid batteries.
1986 1992 1995 1996 have nickel-cadmium batteries.
2009 and S Stock have sealed maintenance free lead-acid.

 

[Lucan]

Thanks for the info.

 

[Nym]

"Maintenance Free" lead acid on S Stock and 2009TS that LUL are doing their best to not replace at their scheduled end of life replacement time.

 

[edwin_m]

I believe the new Piccadilly stock is designed to run a short distance on battery power to get it to the next station in the event of power failure. Will these use lithium batteries?

These batteries tend to go into thermal runaway only if defective or damaged. Hopefully on a train they'd be much more protected than on a portable device or even a car, though they might be bigger and therefore more dangerous if they do go into runaway.