Thomas Shay wrote: > Something is strange. The ammeter and E-meter > should agree within a few percent. If it were > my Sparrow I'd find the problem and repair it. > There's something wrong with the shunt, the meter > or the wiring connections.
I agree. The controller's input capacitors would filter out most of the ripple, and no normal meter would be bothered by the ripple, anyway. Most likely, it is a $1.98 meter, and just plain inaccurate. Try holding a magnet near the meter with no current flowing in the meter. If it is a D'Arsenval movement, it won't move. If it *does* move due to an external magnetic field, then it is a cheap moving-magnet type meter. They have very poor accuracy, and are strongly affected by external fields (such as high current EV wiring :-) Reference: A moving-magnet meter movement has a magnet on the pointer. A fixed coil of wire surrounds this magnet. Current flowing in the coil generates a magnetic field, which moves the pointer. A D'Arsenval meter movement has a large permanent magnet with a round hole in it, exactly like the field of a permanent magnet motor. The moving rotor of this "motor" has the coils and pointer. A pair of springs carry current to the coil, and also provide the spring force to keep it at 0 when there is no current. Since there is no iron in the rotor, an external magnetic field won't affect it. -- Lee A. Hart Ring the bells that still can ring 814 8th Ave. N. Forget your perfect offering Sartell, MN 56377 USA There is a crack in everything leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
