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Re: QTC: Starter issues
>On Jul 9, 12:42pm, Gary G. Erickson wrote:
>> I took a Bosch 30A relay (the variety that Audi already used
>> 12 of in the design of the car) and wired into the starting circut
>> as you described. I know that there is considerably more juice
>> there than 30A, but unless you're in the habit of cranking you're
>> car for minutes at a time you should be just fine. (Once as a
>> test I disconnected the coil and cranked the car for 45 seconds
>> and checked the relay . . . didn't even feel warm!)
>I'm jumping in here not having read the original description
>of the wiring, but I want to add a general statement here.
>A relay which is rated at 30 amps means that the relays *contacts*
>can switch 30 amps. Has nothing to do with the coil, and one
>wouldn't expect the coil to feel particularly warm just because the
>relay is switching more than its rated current.
Just wanted to get something clarified.
In the relay configuration described above, the full load current of the
starter is not going through the 30 Amp relay, this would fry it very
quickly. The current going through it is to pull in the solenoid which is
actually another relay. Main starter current is switched in the solenoid.
If I remember the measurements correctly, the solenoid only takes a couple
of amps to pull it in. The relay is not so much to increase current capacity
as to eliminate burnt contacts in the ignition switch caused by switching
the coil in the solenoid.
BTW relays can get quite warm when they are used at their full load ratings.
and other toys that always need new tires.