Best voltmeter power source

[Topsterguy]

Which would be the best and most accurate power source to attach the wire from the voltmeter to? I was told to go right to a terminal on the firewall where a direct lead from the pos side of the battery attaches to for the best reading, but this would mean the voltmeter would be on all the time. Possibly a drain?

[wayne petty]

accessory terminal of the ignition switch usually..  depending on the fuse box. there may be switched ignition empty terminals and switched accessory terminals..

please print this test..  stick it to the wall in the shop.. or with magnets to the side of the tool boxes..

http://i.imgur.com/WMDprhm.jpg     best performed with a hand held digital volt meter that costs over 12 bucks.. the 15 to 25 buck versions are more accurate at the tiny fractions of a volt.  i use the HF37772 daily  for this..

if you pass the six steps of the voltage drop test. you should be able to ground the volt meter to anywhere on the inside of the firewall or floor pan..  or even do the dashboard framework.. depending on how it's mounted.

because alternators put out electrons on the negative side.. the engine block and negative battery terminal need several connections..

negative battery cable to the engine block.

negative battery terminal to the body/inner fender..

engine block/heads to the firewall ..  why the firewall. as many devices are powered off the body/firewall.

just thought you might want to know..

[WZ JUNK]

Thanks again Wayne.

John

[Rochie]

Thanks Wayne. I have printed a bunch of these to give to the many who can't figure it out.