Changing polarity

[Chris Edgar]

On Saturday I watched a car being "flashed" to change to negative earth.
I was amazed at how simple it was.

One question which occurred to me later after I had left was...
"Why does the starter motor not run the other way round after the change"?

Chris

[bmcecosse]

Because both the armature and the field windings still see the SAME polarity as each other - therefore - by Fleming's Left Hand Rule - the motor runs same way as before. Same with wiper motor and heater motor - although some claim to have seen a heater running backwards.....

[Chris Edgar]

Ah, an example of a vector cross product!

Do you know, I had forgotten all that... it is well over 40 years ago.

Thanks,
Chris

[mike.perry]

I hope you did not miss the bit where the battery terminals were swapped