The Best Way to Perform a Voltage Drop Test

Voltage drop testing allows the technician to monitor voltage loss in a circuit. Voltage drop should be checked with the circuit loaded and a fully-charged battery.

In best case scenarios, voltage drop on a power side or ground side to a component through all connectors, and connections should not exceed 0.1V or 100mV, however most times 0.2V or 200Mv is acceptable. All voltage should be dropped across the load, not in the wires or connections supplying it power or ground.

In this video we will show you how to test voltage drop on a starter motor circuit. This test can be applied to all components in a similar manner.

[joehead]

Best practice; probes at battery should be on actual battery post, probes at starter motor should be on starter motor stud and starter motor housing. This way you are measuring all series connections and wiring in each side of the circuit for voltage drop to the load.

[nickayivor]

Thanks 👍
From Nick Ayivor from London England UK 🇬🇧

[edhermann]

These are good.. but I am looking at a no start with key. I haven’t tried starting it since swapping starter. So it sounds like I need to approach from a different perspective alittle. Just a concern that my ignition switch might be influencing. But then we will see.

[tedlahm]

Kirchhoff’s voltage law for series circuits say the voltage is SHARED with all
the loads. Shared according to the resistance of each load.

[markgrove]

Good clip. Clear, audible, useful info. Suggestion? That's a nice Fluke you have; I have one similar. I'd guess many guys who have less expensive meters (without autorange) could benefit by (either get one with AR) or some info from a future video as to which voltage range to use on a cheaper meter. Most circuits (I presume) would be best set at 20V DC but some others could light you or your meter up nastily. Again tho, excellent work. Do more!

[dariomendoza]

thank you for Sharing im hoping i can use this knowledge to fix my p30 rv SLOW CRANKING new battery new starter its a ghost problem!!

[codycampbell]

So what is causing the voltage drop to increase ? Is it a measurement of resistance through the circuit at connectors or resistance I’m this case within a starter motor ?

[marioeid]

So you subtract those to readings he got .46 and .52 and thats your voltage drop?

[amana]

0:30 If each terminal has dropped 0.1v, why does it show 12.4v dropped total at the starter motor? What happens if you have to use extra long cables for the multimeter, because the starter is far away from the battery terminals? Does this cause a problem by introducing voltage drop through the long multimeter leads?

[XCell]

Those cable are no good. Tahoe's had that problem and it lead to intermittent no start conditions.

[myviews]

You guys fail to mention the most important part of your video what the heck is the setting for standard meter