Let me explain: A typical buggy with fans, lights and fuel pumps, ecu's at tops could pull down 80 amps. The ground cable going to the chassis only needs to be big enough to handle this 80 amp load. But the starter can pull 200-300 amps, it needs the large cable. This means you must run a large ground strap from the battery negative post to the engine or transaxle case to support this kind of current demand.

Many buggy builders connect a battery ground cable to the chassis only and rely on the engine/tranny making a ground to the chassis. This is a bad idea, real bad.  If the assy loses ground connection due to powder coat insulation, or bolts coming loose, you can damage other items like an ecu or throttle cable because they are the only grounds left during high current demands (like starting the engine). An additional smaller ground cable should also be installed from the battery to the chassis for the rest of the car as a precaution to bad engine and/or trans ground connections over time.

We had a car in here at Outfront that suffered from a random shutdown of the ecu for a few seconds. It had been an ongoing problem for the customer. Guess what.... there was only a large cable going to the newly powder coated chassis, nothing direct from the battery to engine/trans. We installed a large ground from the battery to the tranny--problem solved. This will also aid in better cranking of the engine.