At 06:20 PM 7/25/2002, Jim Arnott wrote: >I guess that I'm a bit fuzzy on this... > >Does not: > >The 12v through the idiot LED energize the field of the alt? >Wiring is stone simple... two large terminals direct to battery +, one >small terminal to LED. If the current from the LED has to go through an >open relay to get to the alt, how would the field ever get power? > >Jim Circuit goes from +12 at instr panel, through an LED/resistor combination *in parallel with another resistor* to supply more current than can safely flow through the LED. From there it goes to Alternator D+ terminal, in parallel with fridge relay coil, battery relay coil, whatever else people have hung on there to be driven by the Alt D+ signal. Any such relay coils are current sinks and will cause the light to light (at least dimly) even though the wire is disconnected from its main load, the D+ terminal. However the current through the circuit will not be enough to activate the relay(s). In normal operation, once the alternator starts charging the D+ terminal becomes an output instead of an input, and supplies +12 at a reasonable current capacity (??an amp or two??) to the circuit. Since the LED is now seeing +12v on both ends, it stops lighting up; but since the relays now have enough current available to drive them they activate and connect the fridge, aux battery, whatever. Make sense? d
>David Beierl wrote: >>At 10:56 PM 7/24/2002, Dennis Haynes wrote: >> >>>If you have a camper, the refrigerator relay will also turn the light on >>>with the alternator disconnected. The alternator has to actually be >>>charging for the relay to energize the refrigerator. >>> >>>Dennis > -- David Beierl - Providence, RI http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage" '85 GL "Poor Relation" |
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