The MGB GT V8 uses a 12-volt battery mounted in the boot area, with a battery box and securing strap holding it in place. Battery capacity should be appropriate to the V8's higher cranking demands compared with the four-cylinder MGB, the V8 engine requires substantially more cranking current than the smaller four-cylinder unit, particularly in cold weather. Modern batteries in appropriate specifications fit the original mounting and provide reliable cranking and electrical supply.
V8-Specific Battery Components
The battery uses a V8-unique terminal post, part number BHA5241, that differs from the standard MGB battery terminal arrangement. This V8 specification is correct from factory and should be retained or matched in restoration work. Positive cables run from the battery to the starter motor and are V8-specific items: BHH1256 for chrome-bumper cars, BHH1257 for rubber-bumper cars. The two cable specifications differ in routing details and length.
Battery Cables
The positive cable carries the heavy starter cranking current from the battery to the starter motor or to the starter solenoid, depending on installation. The earth (negative) cable connects the battery negative terminal to the bodyshell or chassis at a designated earthing point. Both cables are critical for reliable cranking, corroded or undersized cables cause slow cranking and starting difficulty.
Battery Box and Strap
The battery box provides a secure mounting for the battery in the boot area, with the strap holding it in place. Battery box corrosion is common where battery acid has dripped over years of use; replacement boxes are available. The strap should hold the battery firmly without crushing the case.
Earthing
Reliable earthing is critical for a 12-volt electrical system. The main battery earth strap connects the battery negative to the bodyshell; auxiliary earthing straps may connect the engine to the chassis to provide a low-resistance return path for starter current. Corrosion at any earthing point causes electrical issues throughout the car and should be addressed during routine service.
MGOC Spares
MGOC Spares supplies V8 battery components, V8-specific positive cables, terminal posts, battery boxes, straps and earthing components for the MGB GT V8.