[DML] Re: Headlight switch savers

["David Teitelbaum" <jtrealty@xxxxxxxxxxxxx>]

While it is true that relays have a very high reliablity and low failure rate you MUST add the qualifacation that they have to be used within their rated capacity. Using a relay right up to the top of it's rating will shorten it's life compared to using a relay made at a higher rating. You must accurately calculate the load the relay will have to control to know how to size the relay. That includes knowing the type of load. An inductive load will require a higher rated relay than a resistive load to last the same amount of time. The difference in price is very small so it is always safer to oversize (within reason) to have a longer, more reliable life. Look at what happens with the door lock module for an example of underrated relays verses the load. They quickly fail and the contacts weld together causing the door lock solenoids to melt and the battery to die while you are locked in the car and can't open the doors!
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, "John Hervey" <john@...> wrote:
>
> I haven't followed all the comments about the headlight switch saver but on
> this comment I would say that most US built relays have a duty cycle of
> 100,000 thousand cycles. I don't think relay's are going to wear out as
> people think they would.
> John Hervey
> 
> 
> -----Original Message-----
> From: dmcnews@xxxxxxxxxxxxxxx [mailto:dmcnews@xxxxxxxxxxxxxxx] On Behalf Of
> Marc Levy
> Sent: Tuesday, June 02, 2009 7:40 PM
> To: dmcnews@xxxxxxxxxxxxxxx
> Subject: Re: [DML] Re: Headlight switch savers
> 
> 
> With all the talk of relays wearing out instead of the switch itself due to
> the amount of current draw, I am surprised none of the vendors sell a dual
> relay kit.
> 
> The left side and the right side of the car are electrically isolated by
> fuse #2 and #8.  It would be incredibly easy to install 2 relays in line
> with those fuses such that a separate relay controls each side of the car.
> This would also relocate the relays to the "relay compartment" instead of
> hidden behind the center console.
> 
> 
> 
> 
>       
> 
> 
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