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Offline evlove

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Chasing Shorts - Low Voltage
« on: February 19, 2017, 05:40:28 pm »
Been on a few trips the past few months and have had a blast. While spending some time in Pagosa Springs I made a quick drive to a grocery store I came out to a dead battery in the parking lot.  Fortunately a quick jump from the house battery got me back to the condo. Since then I've been monitoring the battery voltage religiously (not just on Sunday) and have been getting some odd readings.  For the past month I haven't seen anything above 12.5v and as low as 9.7v.  The house battery varies from 12.5v-10v depending on useage. 

Logically thinking it must be the voltage regulator on the alternator, I replaced the alternator and have seen a constant 12.5v.  Advance Auto tested the old alternator and passed with flying colors (so another swap and took the new one back).  They tested the entire electrical system and found the battery to be fine too (engine battery is 13 years old, house battery is 6 months).  Im a bit suspect of the old battery, but since the house battery doesn't get a high charge voltage either it doesn't make sense to replace it right now (prove me wrong). 

Before I start from the alternator and work my way to all the grounds, anyone have any trouble spots I should check first? 

Paul

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Offline evlove

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Re: Chasing Shorts - Low Voltage
« Reply #1 on: February 20, 2017, 02:41:15 pm »
Update:

Alternator bench tested at 14v+.
Different/new battery hooked up, same charge of 12.5v coming from the alternator.
Tested electrical system for parasitic drain - no draw above 50 milliamp
Grounds ohms checks - alternator, engine, transmission, frame, body panels all within acceptable range
Positive ohms checks - alternator, starter all within acceptable range

Still getting a reading of 12.5-6v with no load, 11.34v under load.  When van is turned off with no load, the battery reads 10.8v.

Any suggestions? 

Fortunately I can still start and drive the car, the battery doesn't die, but eventually Ill be churning through batteries and don't want to be doing that.  Not to mention, short drives with high loads will leave me with a dead battery. Love to hear some advice.
Paul

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Offline robinson1509

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Re: Chasing Shorts - Low Voltage
« Reply #2 on: February 22, 2017, 06:37:18 pm »
If your alternator bench tested okay it has to be either the belt / tensioner, or the field voltage. The small wire on the alternator supplies voltage to the alternators field coils to create the magnetic field. You should replace the old battry.
« Last Edit: November 24, 2017, 07:09:46 pm by robinson1509 »

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Offline erik.wahlstrom

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Re: Chasing Shorts - Low Voltage
« Reply #3 on: April 21, 2017, 02:37:39 pm »
I'm curious as to how you are monitoring the voltage?