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> Voltmeter Behavior, Verify Accuracy
Superhawk996
post Jun 24 2024, 07:28 PM
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Starting a new thread in response to @emeryGT 350 comment in another thread as follow up

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emerygt350
post Jun 25 2024, 06:23 AM
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I think of it more as a dummy light or perhaps a 'general suggestion' about the charging system. However, I have found mine does some disconcerting things that don't allow me to even use it that way. If it's sitting on 12 that scares me, but then I check the voltage and its 13.4. another day it will be at almost 14 and the voltage will be 13.6. That's not helpful. The original lines to the gauge now operate a relay which has a direct (fused) connection to the battery. Hmmm.... I should double check my ground shouldn't i?
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Superhawk996
post Jun 25 2024, 06:32 AM
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QUOTE(emerygt350 @ Jun 25 2024, 08:23 AM) *

I should double check my ground shouldn't i?

Yes! Especially since you’ve previously had issues with the starter & hot starts.

A bad negative battery cable from Batt negative to chassis will cause all kinds of grief as will a bad ground strap from chassis to transmission. The most reliable way to judge the state of these grounds is to measure the voltage drop across the cable while cranking. Visual inspection and appearance is meaningless. Anything more than about 0.2v of voltage drop while cranking is too much - replace the cable / ground strap.

Required reading:
https://www.fenderbender.com/running-a-shop...ircuits-part-11

[Edit] check battery positive cable the same way! Its condition is no less important than the negative cable.


Have you painted your fan shroud or any of the alternator mounting brackets? These are the in the ground path for the alternator.

I’ll get some video of the gauge damping behavior up later tonight. There is nothing in the damping behavior that would explain the variance your mentioning between voltage and/or any sort of extended delay in the voltmeter reporting proper voltage within +/- 0.5 volt.
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Superhawk996   Voltmeter Behavior   Jun 24 2024, 07:28 PM
Superhawk996   I have two gauges, tested both at a variety of vol...   Jun 24 2024, 07:34 PM
Superhawk996   Gauge #1   Jun 24 2024, 07:36 PM
emerygt350   Very interesting! Could you do some readings ...   Jun 24 2024, 07:39 PM
Superhawk996   Yup will do Here’s 14v.   Jun 24 2024, 07:42 PM
Superhawk996   RE: Voltmeter Behavior   Jun 24 2024, 07:46 PM
Superhawk996   Gauge #1 at 13.7v Gauge #2 at full scale - wa...   Jun 24 2024, 07:54 PM
Superhawk996   Gauge #2 12v nominal   Jun 24 2024, 08:09 PM
windforfun   What's the problem? How exactly do you expect...   Jun 24 2024, 08:11 PM
Superhawk996   What's the problem? How exactly do you expec...   Jun 24 2024, 08:20 PM
windforfun   Copy that. The power supply reads out to one plac...   Jun 24 2024, 08:40 PM
Superhawk996   Copy that. The power supply reads out to one pla...   Jun 24 2024, 10:18 PM
windforfun   Copy that. The power supply reads out to one pl...   Jun 25 2024, 09:03 AM
Superhawk996   Recognize anything? @windforfun Nice test ...   Jun 25 2024, 09:33 AM
emerygt350   I was interested in the behavior of the voltage me...   Jun 25 2024, 04:46 AM
mb911   Good data. Unfortunately mine is right on.   Jun 25 2024, 05:17 AM
914Sixer   60's-70's are what I call ball park gauges...   Jun 25 2024, 05:53 AM
emerygt350   I think of it more as a dummy light or perhaps a ...   Jun 25 2024, 06:23 AM
Superhawk996   I should double check my ground shouldn't i...   Jun 25 2024, 06:32 AM
GregAmy   Unless you want to rewire it directly to the batte...   Jun 25 2024, 07:11 AM
emerygt350   Unless you want to rewire it directly to the batt...   Jun 25 2024, 08:44 AM
technicalninja   Thanks, Superhawk! The dash meters are FAR mo...   Jun 25 2024, 08:08 AM
emerygt350   Just checked the grounds engine to body engine to ...   Jun 25 2024, 09:25 AM
Superhawk996   Just checked the grounds engine to body engine to...   Jun 25 2024, 09:29 AM
Superhawk996   gauge #1 Delay and damping behavior related to in...   Jun 25 2024, 09:53 AM
ClayPerrine   For what it is worth, I use the stock voltmeter as...   Jun 25 2024, 10:31 AM
emerygt350   For what it is worth, I use the stock voltmeter a...   Jun 25 2024, 11:17 AM
rjames   emerygt350 might just have a bad gauge. Mine gave ...   Jun 25 2024, 10:47 AM
Superhawk996   emerygt350 might just have a bad gauge. Mine gave...   Jun 25 2024, 11:06 AM
emerygt350   [quote name='rjames' post='3153039' date='Jun 25 ...   Jun 25 2024, 11:20 AM
Superhawk996   [quote name='rjames' post='3153039' date='Jun 25...   Jun 25 2024, 11:24 AM
Superhawk996   Gauge #2 Slightly different damping behavior. P...   Jun 25 2024, 05:18 PM
emerygt350   It is interesting how in both cases they behaved b...   Jun 25 2024, 07:19 PM
Superhawk996   It is interesting how in both cases they behaved ...   Jun 25 2024, 07:54 PM
emerygt350   I finally dug into the console. I had compared th...   Jun 26 2024, 05:02 AM
Superhawk996   :trophy: Now those delays and variable voltage d...   Jun 26 2024, 06:08 AM
emerygt350   :trophy: Now those delays and variable voltage ...   Jun 26 2024, 06:13 AM


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