Zener diode / relay question

[VroomVroom]

Hi All
i have a simple farm buggy vehicle thingy which runs a 55A Landcruiser alternator ( external regulator type ) which is controlled by an early Holden HT regulator. Its basic ,very cheap and works well being cobbled together from stuff i had lying around the shed.

now i am thinking about adding a voltage warning light to this setup , and was wondering if this could be just as simple as using a Zener diode , say 13v , in series with a tiny 12v relay and using the relay to control the dash lamp. So once the alternator produces >13v the relay would turn on.

Yes I could do this using an internally regulated alternator but Toyota versions are expensive ( $300+ ) and hard to get second hand. Wreckers export then to Pakistan of all places lol. Or i could get a cheap internally regulated $100 Holden alternator but they dont run ribbed belts and the mounting config wont work.

Any thoughts or advice thanks ?

[wotnot]

....and I thought, "I wonder if someone makes something like that?"....

...but what you mention would work, circuit would be akin to this;



...you choose the value of RS to limit current through the zener (actual value depends on relay coil resistance)...

[VroomVroom]

Thanks for that , i like it. Since posting ive found some aftermarket Landcruiser regulators for as cheap as $46 !! . Ive even seen secondhand genuine Holden regulators selling for $150 lol.
I'll do some tinkering , thanks again