The battery on a classic MG lives in a metal compartment exposed to the contents of the battery itself, the sulphuric-acid electrolyte that powers the battery's chemistry but that will rapidly corrode any unprotected metal it contacts. A small acid spill from an overfilled battery, a slow weep from a cracked case, or the accumulated acid mist from a vented battery over many years all produce the characteristic corrosion damage visible inside the battery compartment of any classic that has been on the road for several decades. Battery bins protect the bodywork from this damage.
The Function of a Battery Bin
A battery bin is a containment box that the battery sits inside, typically moulded plastic or pressed and welded steel, with the box itself being acid-resistant (in the case of plastic) or fully painted in acid-resistant finish (in the case of steel) so that any acid escaping from the battery is contained inside the bin rather than reaching the surrounding bodywork. The bin includes a drain hole at one corner of the base, allowing any accumulated acid to be drained away into a safe location (typically through a hose routed to a drip point underneath the car) rather than collecting inside the bin where it would slowly degrade even the bin's own internal finish. The combination of the contained bin and the controlled drain produces a battery installation that protects the bodywork indefinitely.
Application Coverage
Battery bins are stocked in the dimensions and shapes appropriate to the various battery-compartment specifications across the classic-MG range. The MGB has its battery in the boot (or in twin compartments on early cars with the two-battery arrangement), and the bin sizes are matched to those compartments. The Midget battery is in the engine bay on most applications, requiring different bin dimensions. The MGA and MGC each have their own specific compartments.
For owners renovating cars where the battery compartment has already suffered acid damage, the bin both prevents further damage and conceals the cosmetic issues in the original metalwork, a tidy bin installation looks dramatically better than exposed acid-stained metalwork.
Installation Notes
Battery bin installation involves placing the bin into the existing battery compartment (which should be cleaned, inspected for damage, and treated for any rust before the bin is fitted), routing the drain hose from the bin's drain hole to an appropriate exit point underneath the car, and then fitting the battery into the bin in the normal way. The battery hold-down clamp (which was the original arrangement for securing the battery in the compartment) typically fits over the bin and the battery together, securing both assemblies in position. The wiring connections to the battery are made in the normal way once the battery is in position inside the bin. The result is a tidy, protected battery installation that will not damage the surrounding bodywork across many years of service. The technical team is available to advise on the right bin specification for a specific car and battery configuration.