Bad relay or ground on LED light bar?

[ShadowHunter1991]

Hi All, recently installed an LED lightbar. Attached is a photo of where the relay and ground cable sits. It's the metal shield around the engine bay as the cars ground is too far away. I've been told grounding here is better than beg terminal on battery as it messes the Volvos BMS settings. Anyway, lightbar works fine, but I've noticed when I get out the car now I get a small static/electric shock which I'm sure wasn't happening before. I checked Ohm reading on ground for both the new ground point - blue circle - and the cars main ground and they both measured 1.5-1.7 on the multimeter. So I'm guessing bad relay? It's brand new so no idea why. Any advice greatly appreciated as I do t want electrical issues on top of all the mechanical ones! Thanks 👍


I was going to extend the ground with a negative battery cable and bolt to cars ground, but as they measure the same doubt it'll solve the shock problem..

[GreenV8S]

Nothing about this is contributing to electric shocks, which will be coming from the tyres - either the vehicle's or the trailer's.

There should be negligible resistance and voltage difference between any ground point and battery ground.

[Polly Grigora]

Have you possibly started wearing different clothing recently?

[E-bmw]

Just beware that it looks like your black wire is being crimped by the bonnet (I assume) as it is already damaged.

1.5 ohms (I assume you were set to) is a bit high but shouldn't be a major issue, I would expect more like 0.3 - 0.5 ohms for something like that.

The rest will be coincidence.

[TwinKam]

...but you really should be providing that wiring with secondary protection, eg running it inside a conduit/spi-wrap/loom tape.