Using two independent powerbases to feed the same analogue Scalextric track is not recommended. Here’s why and what you should do instead:
Voltage and phase mismatch
Even if both powerbases are nominally “12 V DC”, in practice each unit’s internal voltage regulator will sit at slightly different output voltages (e.g. 11.8 V vs. 12.2 V). Whenever two separate supplies of different voltages are tied together, current will flow from the higher‐voltage unit into the lower‐voltage one, potentially causing:
Overheating or damage to one or both powerbases
Uneven power delivery to your cars (one lane “pulls” more than the other)
Risk of track short-circuits when cars bridge the join
Controller-base isolation
Each Powerbase is designed to be the one master regulator for its loop of track and controllers. Tying two together bypasses the manufacturer’s safety and overload cut-out circuitry, so a stall or short on one section could take out both supplies.
What to do instead
Use a single Powerbase and, if you need more current or additional feed points, wire multiple track feeders back to that same base. Scalextric themselves sell “track feed” cables that allow you to inject power at several spots around a larger layout, but all back into the one controller box.
If you’ve run out of controller sockets, consider the Scalextric Powerbase Pro (which expands the number of controller ports) or an after-market booster/module designed specifically for Scalextric analogue.
For serious multi-lane or club-style layouts, many racers move to a digital system, where a single digital powerbase can support dozens of lanes and has built-in bus wiring to feed power uniformly.
Quick recommendation
Never connect two analogue powerbases in parallel on the same track—always feed every section of track back to one regulated supply. If you need more power or more controller inputs, use the manufacturer-approved expansion modules or track-feed cables. This keeps your cars running smoothly and protects your equipment.