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Intermittent Electrical Voltage readings?

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Old Dec 14, 2016 | 01:07 PM
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Intermittent Electrical Voltage readings?

Of course this started after my turbo work and when it started getting cold. Coincedence, I hope so...

My Volt gauge on the dash has started reading around 10V with the key on waiting on the GP's. Batteries read +/- 12.6V with a DVM in a static state, no key.
Trying to get readings with a DVM solo in temps that chill you to the bone isn't all that fun or easy. I'll have to get better readings this weekend with a helper.

But, quickly as best as I could see the reading on the DS battery drop to around 10V with the key on, GP's cycling. Cranking drops down around 8Vish.

After starting the reading on the DS battery is back up to 10V. This lasts anywhere from 30 seconds to a few min. Then it jumps up to the expected 14.6V reading.

I'm kinda lost where to start troubleshooting this and all ideas are welcome.


P.S. I cleaned up the battery terminals and clamps while doing my turbo,and all the connections are tight.

Thanks!
 
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Old Dec 14, 2016 | 01:21 PM
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As cold as it has been here in CO recently, I suspect this is pretty close to normal. GP and AIH running longer. Battery capacity weakened by cold.

This is hard on battery and alternator, so short trips or excessive idling will take a toll. I try to allow a couple minutes KOEO (glow plugs running, ignore WTS idiot light) on cold mornings.

Plugging in when below 20F for a few hours before starting will help.
 
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Old Dec 14, 2016 | 01:31 PM
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How old are the batteries?
 
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Old Dec 14, 2016 | 01:43 PM
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Originally Posted by Colorado Horseman
As cold as it has been here in CO recently, I suspect this is pretty close to normal. GP and AIH running longer. Battery capacity weakened by cold.

This is hard on battery and alternator, so short trips or excessive idling will take a toll. I try to allow a couple minutes KOEO (glow plugs running, ignore WTS idiot light) on cold mornings.

Plugging in when below 20F for a few hours before starting will help.
I expect the slight drop for the GP cycle, but expect to see the voltage jump up to 14.x immediately after it's running. The delay is throwing me off.
Where you at in the front range? I'm down here in Elbert, NE El Paso cnty. Haven't been able to ride in a few weeks because of work.

Originally Posted by RV_Tech
How old are the batteries?
I believe they are about 1.5 yr old.
 
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Old Dec 14, 2016 | 01:55 PM
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The voltage does not immediately rise when the engine starts. The GPR stays on for up to 2 minutes and the voltage will stay low during that time.
 
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Old Dec 14, 2016 | 02:09 PM
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All of the posts are correct in that what you are seeing is Voltage under a Load. The GP system can use 100 Ah draw on the system easily. And, when colder, the on-time duration lasts up to 120 seconds. In extreme cold, it will reactivate itself after a 15 second delay.


In lieu of a second person to assist, you can easily make one of these for about $25













Here is a time vs temp chart for GP activation




 
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Old Dec 14, 2016 | 02:13 PM
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Originally Posted by ZachinCO
My Volt gauge on the dash has started reading around 10V with the key on waiting on the GP's. Batteries read +/- 12.6V with a DVM in a static state, no key.
I could see the reading on the DS battery drop to around 10V with the key on, GP's cycling. Cranking drops down around 8Vish.

After starting the reading on the DS battery is back up to 10V. This lasts anywhere from 30 seconds to a few min. Then it jumps up to the expected 14.6V reading.


Everything you describe is perfectly normal. The only issue worth paying attention to is the 8 volt reading on crank. This suggests that your batteries are being cycled too deeply when having to produce cranking amps after powering your glowplugs, and as such, your batteries may not last as long.
 
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Old Dec 14, 2016 | 02:17 PM
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Originally Posted by pirschwagon
All of the posts are correct in that what you are seeing is Voltage under a Load. The GP system can use 100 Ah draw on the system easily. And, when colder, the on-time duration lasts up to 120 seconds. In extreme cold, it will reactivate itself after a 15 second delay.


In lieu of a second person to assist, you can easily make one of these for about $25













Here is a time vs temp chart for GP activation




I've saved this to my F250 folder! Thanks and Reps!

Originally Posted by RV_Tech
The voltage does not immediately rise when the engine starts. The GPR stays on for up to 2 minutes and the voltage will stay low during that time.
What is odd is that it has never done this in the 15+ years I've owned it, even in previous winters. Unless my GPR is heading south.
 
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Old Dec 14, 2016 | 02:30 PM
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Have you been monitoring voltage during the last 15 years? During the winter? Have the winters been as cold? Have you been located in the same area? (The PCM uses barometric pressure as one of the parameters for determining length of glow plug on time).
 
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Old Dec 14, 2016 | 02:44 PM
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Originally Posted by ZachinCO
I expect the slight drop for the GP cycle, but expect to see the voltage jump up to 14.x immediately after it's running. The delay is throwing me off.
Where you at in the front range? I'm down here in Elbert, NE El Paso cnty. Haven't been able to ride in a few weeks because of work.



I believe they are about 1.5 yr old.
Your alternator is struggling to overcome the high amp draw at low idle speed (normal for cold climates), but I would not be overly concerned unless you cannot get back to normal voltage output fairly quickly. It will take a good 30 minutes at >1500 RPM for the batteries to recover. I am on my 3rd alternator in 14 yrs, some of which may be due to the snowplow I ran for a few years.

I'm in Thornton now, but spent 20 years on the Rampart Range. Work 3 days a week east of Brighton helping at a small training facility where my daughter and daughter in law keep their pasture ornaments.

I don't ride much since my Appy passed 2 years ago. Sure miss that guy!
 
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Old Dec 14, 2016 | 03:11 PM
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Originally Posted by Y2KW57
Have you been monitoring voltage during the last 15 years? During the winter? Have the winters been as cold? Have you been located in the same area? (The PCM uses barometric pressure as one of the parameters for determining length of glow plug on time).
Been in CO the last 10 years, and yeah I pretty much watch the dash every time I start it up. I don't recall it doing this during the winters in similar temps. I'm on about my 3rd or 4th alternator.
Originally Posted by Colorado Horseman
Your alternator is struggling to overcome the high amp draw at low idle speed (normal for cold climates), but I would not be overly concerned unless you cannot get back to normal voltage output fairly quickly. It will take a good 30 minutes at >1500 RPM for the batteries to recover. I am on my 3rd alternator in 14 yrs, some of which may be due to the snowplow I ran for a few years.

I'm in Thornton now, but spent 20 years on the Rampart Range. Work 3 days a week east of Brighton helping at a small training facility where my daughter and daughter in law keep their pasture ornaments.

I don't ride much since my Appy passed 2 years ago. Sure miss that guy!
I'll have to keep an eye on it, take a video and see. If it's warm enough this weekend I'll be cleaning all my battery cable connections aside from the battery terminals.
My daughter rides an Appy. We just picked him up earlier this year. 6 y/o gelding. His previous owner wasn't able to ride any longer. We ended up getting him, an older mare and 2 mini's from them. Only a few pasture ornaments.
 
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Old Dec 14, 2016 | 07:02 PM
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The Harbor Freight carbon pile battery load tester is cheap (just over $40 with a 20% coupon) and after opening it up and tightening the various connections it is a great tool for load testing your batteries. Add a hydrometer to that for serviceable batteries and you will know in a few minutes if your batteries are up to the job. A few points:

1. Test them individually, not connected to the truck
2. Fully charge before checking specific gravity and do not add water before checking SG.
3. Fully charge before load testing.
4. Use a DMM while load testing for better accuracy than the HF gauge and use temperature compensation on the result.
 
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Old Dec 14, 2016 | 08:24 PM
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Originally Posted by bigb56
The Harbor Freight carbon pile battery load tester is cheap (just over $40 with a 20% coupon) and after opening it up and tightening the various connections it is a great tool for load testing your batteries.
I've had a 100A tester for smaller batteries for a while. I was looking at carbon piles last week and then researched the newer electronic testers. It looks like I could get more bang for the buck getting a Solar BA9 or better a Foxwell BT705. Have you had a chance to compare the pile to electronic testers? I don't want to derail this thread, feel free to PM me instead if you like.
 
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Old Dec 14, 2016 | 08:46 PM
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Originally Posted by blckjck
I've had a 100A tester for smaller batteries for a while. I was looking at carbon piles last week and then researched the newer electronic testers. It looks like I could get more bang for the buck getting a Solar BA9 or better a Foxwell BT705. Have you had a chance to compare the pile to electronic testers? I don't want to derail this thread, feel free to PM me instead if you like.
I looked at the electronic ones as well and I did a lot of research from which I concluded the electronic hand helds were good for someone testing a lot of batteries for say a parts store warranty etc, they are simple to use but they don't really tell the whole story, just pass or fail. I feel the carbon pile puts a realistic load on the battery and a qualified operator can interpret the result and get a true picture of the battery condition. A 100 amp tester is not enough to put a realistic load on an 850 CCA battery, needs to be loaded to 1/2 of it's cranking amps to get the whole picture.

Here's some interesting reading: http://www.vehicleservicepros.com/ar...f-load-testers
 
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Old Dec 14, 2016 | 08:58 PM
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Originally Posted by bigb56
A 100 amp tester is not enough to put a realistic load on an 850 CCA battery, needs to be loaded to 1/2 of it's cranking amps to get the whole picture.

Here's some interesting reading: Tech Tip: The advantages of load testers
That is completely correct, which is why I said smaller batteries, motorcycle, electric lawnmower, UPS and such. Looking deeper into the newer electronic ones seemed to be able to give more information. I understand how to troubleshoot with the more traditional approach. I actually just used my old Sears engine analyzer a month ago to watch the output of an alternator, via a shunt. on a VW Cabby when I loaded up the system with my 100A load tester.

Maybe I'll keep researching.... I do like the ability to do a trend analysis on them from when they are new. Maybe I'll just have to get both, lol
 
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