Switching Automotive Relay Coil with Ekrano GX Relay | Flyback Risks

Anyone running an Ekrano GX relay output to switch an automotive relay coil — specifically curious whether the built-in relay needs external flyback protection or if Victron's already sorted that internally?

Context: wiring up my garden office 12V system and I want the Ekrano to trigger a standard automotive relay (coil resistance around 16 ohms) that then controls a larger load. The relay itself is a fairly bog-standard Bosch unit, no built-in suppression diode as far as I can tell from the datasheet.

My concern is the inductive spike when the coil de-energises — that classic flyback voltage that can, in theory, fry relay contacts or upstream circuitry over time. On something as pricey as an Ekrano I'd rather not find out the hard way.

A few specific questions:

• Does the Ekrano GX relay output have any internal flyback suppression, or is it a bare contact?
• Would a simple 1N4007 diode across the automotive relay coil (cathode to +12V) be sufficient protection here, or is there a better approach for a 16-ohm coil?
• Anyone actually measured the spike off a similar coil without suppression to know how bad we're talking?

Running Victron kit throughout (MultiPlus, SmartShunt, the Ekrano obviously), so keen to keep everything playing nicely together rather than introducing gremlins via a £3 relay I should have just suppressed properly from day one.

Always add a flyback diode — Victron's internal relay is just a mechanical contact, it doesn't care about your coil spike but your Ekrano's wiring loom absolutely will. 🔧

@NickBennett @WayneTaylor is absolutely right to recommend protection, though the nuance matters here.

The Ekrano GX relay is indeed a dry mechanical contact — it switches the coil circuit but sees no spike itself. The danger is to whatever else shares that circuit. If your coil's flyback pulse can reach any sensitive electronics (GX comms lines, 12V aux rail), you want a 1N4007 across the coil terminals, cathode to positive. Cheap insurance.

Worth noting: some automotive relays (Bosch-type ISO 280) already have an integrated suppression diode — check your datasheet before doubling up, as a second diode in the wrong orientation will short your supply.

On my narrowboat I use suppressed relays throughout purely out of habit. Takes 30 seconds and costs pennies. No reason not to.

@NickBennett Worth clarifying the actual risk pathway here — the flyback spike from the automotive relay coil won't damage the Ekrano's mechanical contact itself (contacts don't care about voltage transients), but it will stress whatever's sharing that circuit. If you're running long cable runs between the Ekrano and your automotive relay, you've also got induced transient risk back along the control wiring.

My setup uses a 1N4007 wired directly across the automotive relay coil terminals — cathode to positive, anode to negative. Cost pence from RS Components, eliminates the spike at source. If you need faster switching response, a TVS diode is worth considering instead, but for a static coil application the 1N4007 is perfectly adequate and what I'd reach for first.

Done this exact setup in my van conversion — chucked a 1N4007 across the automotive relay coil, cathode to the positive side. Pennies from eBay and takes five minutes.

One thing nobody's mentioned: polarity matters when you wire that diode. Get it backwards and you'll short the supply the moment the relay energises. Ask me how I know 😅

Also worth checking your coil's voltage rating matches what's actually switching it — I had a 12V automotive relay behaving oddly because voltage at the Ekrano's relay output was slightly different under load than I expected. Measured it with a multimeter before assuming anything.

@DevonDweller curious what nuance you were getting at — seemed like your post got cut off?