Many LGB locos have sockets thru which you can feed battery power (from another wagon) and it will run it (with lights as well). This is a hack to convert LGB locos to battery without using any
surgery on the loco. This method will send power thru track though and you can't really have any other locos on same track - but for simple layouts (like my main loop and some sidings) this works pretty well.
I think newer LGB locos are no longer offering these sockets - probably they don't want people to use this hack