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2020 Speed Triple RS, 2006 BMW R1200S
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2020 Speed Triple RS. I want to add a couple of electrical extras, heated grips and a chain oiler. Plan is to install a 30A automotive relay to supply +12V from the battery, energise the coil from the number plate light, as I have done a few times before. The relay has no diode to protect the driver transistor (if any) from the reverse voltage spike generated by the coil as it is de-energised. I know the number plate light can't be turned off apart from when the bike power is turned off, that's why I am using that circuit, but when that happens I expect it would cause a spike. My issue is that since I installed a tail tidy, the number plate light is LED, and it's on the same circuit as the LED tail light. Unless these LED lights are protected from reverse polarity by some internal full wave rectifier, are they vulnerable to damage by this relay?

In the service manual diagram (11-15 Speed Triple R/S) the cooling fan, fuel pump and engine management relays don't show diodes to protect the drivers in the ECU, but it seems unlikely to me that they are not there, incorporated into the relays, or perhaps in the ECU itself.
Just in case, I'll connect a diode across the coil of my new relay.
IanB
 

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It is always a good plan to include a back-EMF diode across any additional relays added to any machine with electronic systems. Many relays these days have a BEMF diode (or in some cases a quenching resistor) built in, however if the relay you are using does not, for the sake of a few cents, I would certainly put one in. A cheap and cheerful recitifier diode like a 1N4001 or 1N4002 is perfect for this application.
 
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