Voltage drop on relay circuit?, 12v down to 10.5v Options

[IronHillRestorations]

I'm making a harness that needs a power circuit switched via relay.

I've got generic Bosch style 5 pin relays, and I'm seeing a voltage drop on the power out side of the relay.

It's rare that I make a harness that needs a relay, and in the few that I've done with a relay circuit, this has never been reported as a problem.

I'm not an electrical engineer, but I always thought a relay was just an electro-mechanical switch and I should be getting the same voltage on the output.

Just to be clear for those who do know more about this than me, none of the wires that I'm using to test this are more than 24" long and none are less than 14 gauge wire.

The relay power is for a coil pack, so I'm sure that needs a good 12+ volts.

[Spoke]

It is possible that the battery charger is full-wave rectified with no filter caps, not pure dc.Not good if used by itself.

[Dave_Darling]

It is possible that the battery charger is full-wave rectified with no filter caps, not pure dc.Not good if used by itself.

Could that show a voltage drop across a switch like in a relay?

PK could try using a battery instead of a charger/voltage supply box.

I'd be tempted to pry open a relay to see WTF is really going on in there--but I've got bit of the old "destructo" still in my soul.

The round Bosch relays literally have contacts like a set of points do. Should be zero resistance or voltage drop across them unless there is contamination/corrosion of the contacts.

--DD