How much current needs a 2006 2.5i Z4 to start the engine?

[Zillo]

Time ago a battery isolator/disconnect switch was installed in my 2006 2.5i Z4 and I think that since then (although I might be wrong about the timing) sometimes the car fails to start the engine on the first try. I realized that the followng might not be the reason but recently I have found out by coincidence that these devices support different current capacity among them which is usually a different amount for continuous current and a higher one for spikes, so I have thought that maybe this is what is sometimes preventing the car to properly start the engine.

A few examples from Amazon of the different current capacity among these devices:

- max. current 250 A
- 100/300A
- 500A surge rating, 125A continuous power
- 500A Shock Resistance/125A Continuous Power
- 300A continuously and 1000A immediately
- 275 A (continuous) / 455 A (intermittent) / 1250 A (current)

Does anyone know how much current needs a 2006 2.5i Z4 to start the engine? (I am referring to a normal engine start and not one with a jump starter).

[garz747]

250 amps for a few seconds should light the engine.