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<blockquote data-quote="Lasherž" data-source="post: 8704892" data-attributes="member: 679555">Awesome, glad you figured it out. I suppose in hindsight that makes sense, so those voltage spikes were actually very high, much higher than the alternator. A lot of circuits put reverse diodes due to coils reversing when they&#039;re deactivated, sorry I didn&#039;t think of that. Kudos for seeing it through to a solution and posting it, relay switching causing reverse voltage spikes is probably going to come up on these forums again.It&#039;s a pretty well known thing in all DC electronics, but many commercial relays come with the diode built in or the part utilizing a relay has it as part of the circuit. It&#039;s the inverse of how caps discharge nearly unlimited current when the voltage drops, coils discharge nearly infinite voltage in reverse direction when the current drops. It&#039;s fried many sensitive chips in many breadboard designs so it&#039;s good the car electronics are pretty robust against discharges.</blockquote>

[QUOTE="Lasherž, post: 8704892, member: 679555"] Awesome, glad you figured it out. I suppose in hindsight that makes sense, so those voltage spikes were actually very high, much higher than the alternator. A lot of circuits put reverse diodes due to coils reversing when they're deactivated, sorry I didn't think of that. Kudos for seeing it through to a solution and posting it, relay switching causing reverse voltage spikes is probably going to come up on these forums again. It's a pretty well known thing in all DC electronics, but many commercial relays come with the diode built in or the part utilizing a relay has it as part of the circuit. It's the inverse of how caps discharge nearly unlimited current when the voltage drops, coils discharge nearly infinite voltage in reverse direction when the current drops. It's fried many sensitive chips in many breadboard designs so it's good the car electronics are pretty robust against discharges. [/QUOTE]

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