Quote:
Originally Posted by omodos
Wpoll cheers...amazing how i can tips advice from all vorners of the globe.....the 392 amps i got was a negative figure cos i had damn amp clamp on wrong end of battery cable.l when testing....so need to do test again i guess....right the bad ground seen it on many posys here n there that bad ground can cuase odd gremlins...moreso on x3s where a groundin strap perishes....you have any clue where they are om the X?
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Sorry,
omodos, I wasn't meaning that the polarity was relevant (it isn't) - I meant that if you measure 392 amps (or -392 amps) then the circuit must be very good.
A bad earth would limit the current to the starter motor, acting as a series resistor and dropping the voltage across the starter motor.
The fact you see a current as high as 392 amps indicates that the circuit from the battery to the starter motor and back to the battery is very good. Ohms law tells me that if your battery is 12 volts (nominal) then the entire circuit resistance (including all cables, earth straps, starter motor and starter motor solenoid) must has a total resistance of 0.03 Ohms - very low indeed.
If 392 amps though the starter motor isn't turning it as fast as it should be, the fault will be in the starter motor (most likely a seized armature or bearings).
