The Train Control Systems KA4 Keep-Alive® is a compact stay-alive capacitor pack that feeds backup power to your DCC decoder whenever the wheels lose contact with the rails. No more stalling on dirty track, dead frogs, or insulated turnouts — the KA4 keeps a locomotive running with its lights and sound on for roughly 6 to 20 seconds during a power interruption (depending on the locomotive and motor).
It includes Blue and Black-with-White-stripe lead wires to solder to your decoder's keep-alive pads (V+ and ground), so it works with TCS and most other-brand decoders that accept an external keep-alive.
Browse more decoder add-ons in our DCC Accessories collection, shop the full Train Control Systems lineup, or pair it with a new sound decoder from our DCC Decoders collection.
What does a Keep-Alive actually do?
It stores an electrical charge and feeds it to your decoder when track power drops out, so the locomotive keeps moving and its lights and sound stay on across dirty track, frogs, and gaps.
How do I connect the KA4?
Solder the Blue wire to your decoder's keep-alive positive (V+) pad and the Black/White wire to the ground pad. It works with TCS decoders and most other brands that offer keep-alive connections — check your decoder's manual for the correct pads.
How long will it keep my loco running?
Expect roughly 6 to 20 seconds with headlights on for a typical HO locomotive, depending on motor efficiency and current draw.
