Now here's a question for the clever-clogs technical contributors. Assuming the BRM starts on the button every time (she does), and the starter motor is operating for, let's be generous and say 5 seconds, how long do I have to drive before the alternator has pumped back enough juice to refill the battery? Assuming it was full to start with. Idle curiosity.
Rule of thumb is 10-15 km of motorway driving. But this is pure speculation as many factors contributing to this (like state of car battery, state of starter solenoid, etc)
More ground rules needed...5 sec cranking of a warm engine, or one at -30 (self starting min temp? below that we allow external supply and up to 30 seconds for a diesel to lift off! I've no idea on the size of the BRM's starter 2hp, circa 1500 W x 5 sec? 7000W...Similarly no idea how capable the alternator actually is, but its probably up to a 14V output at well below 2000rpm, so is strongly charging anywhere above idle (you dont want it charging hard at idle for fear of dragging idle speed down causing stalls.) Volts x Amps = Watts, 13v x 75Amp = 950W for Something wrong with my maths! But I'd also say a couple of minutes of drive time is all it takes if the battery and the continuity is sound. .
