Charging System Help

oude geit said:
I have a constant voltage dash mount gauge so I see all the time. Installed because I didn't like all the variables. I can turn on my auxiliary high beams, or grips and see the voltage jump up to 14ish. Shut them off and watch it trickle back down.....idk ive never liked it but another alternator is a lot of money and it works so as I say...if it works dont fix it....
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As I wrote it surprises me because it is not that type of alternator. Modern ECM controlled alternators do that but I would expect the ST1300 alternator to remain in the 14V range like automobile alternators of that era. You can't argue with succes if it is working for you.
 
Andrew Shadow said:
I have never seen less than 13.9 V at idle, and at anything above idle I always see 14.2 V or above.
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And how likely are use of dodgy multi-meter and other measurement errors in the above process... :unsure:
"wer misst, misst mist", local proverb... (he who measures, measures rubbish)...
A well-known saying from measurement technology and physics... ;)

Especially at low voltages a "dollar-store" grade multimeter might/will give iffy readings... (by bodged design or when its batteries are low...)
Corroded contact surfaces at the battery terminals, combined with holding worn probes on with unstable/shaky hands vary results even further...

If results/equipment are somewhat important I grab my trusty Fluke clamp meter, switch the leads to rigid laboratory ones with gator-clamps, so shaking hands won't alter the results, and possible make even use of the LOW and HIGH memory featured by the instrument...
(like when adjusting the step-down modules for onboard 5V USB supplies for the SENA BT audio interface on the ST...)
 
ST1100Y said:
And how likely are use of dodgy multi-meter and other measurement errors in the above process...
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I'm not sure to what, or to whom, the above question was directed. If it is directed at me the answer is not likely for either the equipment or the process. I have done this test with multiple testers, both with good quality calibrated and certified ones and with lesser quality testers from big box stores. The results that I have seen have been consistent over the years. They are also what I expect to see from an alternator of this era. These are not computer controlled alternators like those that are common on modern vehicles where both the amperage and voltage output can be varied, so I would not expect to see a large variance in voltage output like is the case with the modern alternators.
 
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Andrew Shadow said:
I'm not sure to what what, or to whom, the above question was directed.
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Actually to the entire community...

I've seen cheapo multimeters that couldn't even properly measure an AA or AAA battery voltage...
So errors of 1.5V or more would mess up alt and VRR checks...
 
ST1100Y said:
Actually to the entire community...

So errors of 1.5V or more would mess up alt and VRR checks...
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That is for sure. I went through that two years ago trying to figure out if I had a charging system problem on my truck. It has a computer controlled alternator. I knew nothing about that type of charging system, or how to check them. A 1.5 V swing on a regular alternator is a problem, so the readings that I was getting made no sense at all to me. Turns out that they made perfect sense for that system, and that my alternator is fine.
 
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