Volt meter reading
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The in dash volt meter either digital or analog does NOT actually read true battery voltage. It reads the voltage that is being applied thru the IGNITION SWITCH.
Does that make a difference?? YES!
How much difference?? Depends on a number of factors. Primary being the condition of the contacts inside the ignition switch. If there BRAND SPANKING NEW, there will be minimal differences between battery voltage and ignition switch output voltage.
If the contacts are in poor condition (YES they do get burnt and pitted) the voltage that you see will be LESS than actual battery voltage):
PROVE IT!
- Read the actual battery voltage (AT the battery terminals) with a digital volt meter. = XXX
- Read the alternator OUTPUT VOLTAGE on the terminal on back of the alternator "under the black boot" to chassis ground = XXX
- Read the digital & analog meter voltage reading = XXX
If everything is 100% they should all match.
They wont!
If there way different, let me know and I will tell you why..
BC
Does that make a difference?? YES!
How much difference?? Depends on a number of factors. Primary being the condition of the contacts inside the ignition switch. If there BRAND SPANKING NEW, there will be minimal differences between battery voltage and ignition switch output voltage.
If the contacts are in poor condition (YES they do get burnt and pitted) the voltage that you see will be LESS than actual battery voltage):
PROVE IT!
- Read the actual battery voltage (AT the battery terminals) with a digital volt meter. = XXX
- Read the alternator OUTPUT VOLTAGE on the terminal on back of the alternator "under the black boot" to chassis ground = XXX
- Read the digital & analog meter voltage reading = XXX
If everything is 100% they should all match.
They wont!If there way different, let me know and I will tell you why..
BC
Last edited by Bill Curlee; Oct 20, 2009 at 08:39 PM.
