Unlike the twin 6-volt arrangement of some contemporaries, the TD and TF use a single 12-volt battery within a positive earth electrical system. On a positive earth car the battery's positive terminal is connected to the chassis, the reverse of modern convention, which dictates how the cables are arranged. This polarity must be understood before ordering, because the cable functions are tied to it.
Battery Cables
Four cables make up the system, and their polarity is specific. The battery-to-chassis cable and the engine-to-chassis cable are the positive (earth) cables, while the battery-to-starter-switch and starter-switch-to-starter-motor cables are the negative supply cables. Each is catalogued individually, allowing a complete set to be renewed. Insulating caps are available to protect terminals.
On a car converted to negative earth, the terminal connections are reversed, so the car's current polarity should be confirmed when ordering.
Mounting and Securing Hardware
The battery sits in a wooden battery tray, secured by a stay clamp tensioned by J-bolts. A J-bolt and nut set is offered, along with individual J-bolts, nuts and plain washers, so the original securing arrangement can be faithfully reproduced. Reliable starting and bright lighting depend on sound, clean connections, corroded or loose cable ends are among the most common causes of intermittent starting and dim lights on these cars.
Master and Isolator Switches
Several battery switching options are catalogued. A standard battery master switch and an FIA-type master switch are both available, sharing a common key, useful for competition use or long-term security. A 'Discarnect' battery isolator mounts directly to the battery posts and cuts power at the turn of a knob, with a by-pass fuse to keep a clock or similar live.
Charging and Conditioning
For maintenance and storage, booster cables, 6/12-volt and 12-volt-only chargers, and the automatic Accumate battery conditioner are offered. The Accumate's three-stage programme charges and then maintains a battery during long periods of non-use without overcharging, suiting cars that are laid up over winter. As with all electrical work, correct polarity must be observed when connecting any charger to a positive earth car.
Ordering Considerations
Confirm the car's polarity, original positive earth or a negative earth conversion, before ordering cables, as the connections differ. Specify which cables are required, and note the wooden tray and stay hardware if the original mounting is being renewed.