Low voltage at startup
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More Turbo
Joined: Jan 2011
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Low voltage at startup
my 06 just rolled 227k miles. I have been noticing that when the truck is cold the scanguage is 12.7 on the batterys when i turn the key the glow plugs pull the voltage down to 10.8-11.3 When the glowplug light goes out I hit the starter it will dip down around 10-10.5 (seen as low 9.8) for just a second or less when the truck starts voltage pops backup to 12v until glowplugs kick off then it goes on up to 14-14.5v
Starter is brand new napa. Batteries have been load tested good and are only 6 months old. I have a 190amp DC Power alternator. Added 2/0 wire from alternator to passenger battery. Added 4/0 ground from alternator to battery. Just added a 1/0 wire from driver side to passenger battery. Nothing has really made a change. Do these voltages look low to you?
I am wondering if there is way to test the glow plug relay? That seems to be pulling a lot.
Daniel
Starter is brand new napa. Batteries have been load tested good and are only 6 months old. I have a 190amp DC Power alternator. Added 2/0 wire from alternator to passenger battery. Added 4/0 ground from alternator to battery. Just added a 1/0 wire from driver side to passenger battery. Nothing has really made a change. Do these voltages look low to you?
I am wondering if there is way to test the glow plug relay? That seems to be pulling a lot.
Daniel
Hotshot
Joined: Apr 2010
Posts: 19,056
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From: Saratoga Springs,UT
Yes that's low
What you reading with
Dvm
ObdII
I would also hydro test battery cells if possible unless you have that newer gel batteries
What you reading with
Dvm
ObdII
I would also hydro test battery cells if possible unless you have that newer gel batteries
Last edited by BLADE35; Nov 29, 2014 at 07:47 PM. Reason: My bad sgii
Logistics Pro
Joined: Dec 2004
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From: South Weber, Utah
Do you always wait for the glowplugs to completely shut off before you start it? Disregard that I went and reread it. I see you start it after the glow plug light goes out.
FTE Leadership Emeritus
Joined: Sep 2003
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From: Houston, Texas
The way they test them at the auto parts stores isn't the best while they're connected to the vehicle.
I was working on an '06 F250 that would drop to as low as 7 volts while cranking. The owner put a battery charger on both batteries but it would stop at 80%. When I disconnected both batteries, the passenger side gel battery was fully charged and the driverside battery was an old maintenance battery that was dead.
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More Turbo
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yes they were cold soaked and pulled from the truck. I had a no start that ended up being a bad crankshaft sensor pigtail. I pulled both batteries and had them checked and both were good. They are matching pair I bought 6 months ago.
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Add .2-.4 volts to all those specs to match what the batteries see and those voltages do not look bad.
I will say the DC Power 190 looks like it barely matches the 130 3G and 140 6G in regards to voltage while the glowplugs are on.
Josh
I will say the DC Power 190 looks like it barely matches the 130 3G and 140 6G in regards to voltage while the glowplugs are on.
Josh
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Fleet Owner
Joined: Apr 2012
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From: Spanaway
I find that the SGII is off by about 0.5 Volts
at the batterie post with a DMM. You might
check the voltage at the posts and also do
a voltage drop test on the cables during a startup.
Sean
at the batterie post with a DMM. You might
check the voltage at the posts and also do
a voltage drop test on the cables during a startup.
Sean
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this morning went out and the truck was sitting at 12.6 on the fluke. It dropped to 11.0 while cranking then popped up to 12.5. Numbers definitely look better than they did on the Scanguage it was .4-.5v low. I'll keep a eye on it.
Junior User
Joined: Dec 2013
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From: Metro Detroit, MI
I had the same issues, checked batteries and alternator with a fluke and all looked good. I usually don't look at the scangauge for volts but this time I did and noticed the "low" voltage during start up. I check it every once and awhile when it's really cold just out of curiosity.
Junior User
Joined: Dec 2013
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From: Metro Detroit, MI
Digging this back up
I noticed the other day after work when I went to start the truck it cranked slow and long but it did start. Sitting outside 8+ hours @ 75 deg F and by long crank I mean only an extra 3-4 seconds.
Once started I checked the voltages (SGII), 12V glowplugs still on (light off), 13.8 - 14.2V glowplugs off and stayed that way the whole drive home.
This morning (52 deg F) I checked voltages before I turned the key to start, 12.5V. Turned the key to start, 10.5V glowplugs on, waited for glowplug light to go out and slow and long start. During cranking the voltage was at 10.2 - 10.5V. Once started the voltages were the same as before, normal 12V glowplugs still on (light off) and 13.8 - 14.2V glowplugs off.
I'm not sure if this is a glowplug related issue or starter or what?
Once started I checked the voltages (SGII), 12V glowplugs still on (light off), 13.8 - 14.2V glowplugs off and stayed that way the whole drive home.
This morning (52 deg F) I checked voltages before I turned the key to start, 12.5V. Turned the key to start, 10.5V glowplugs on, waited for glowplug light to go out and slow and long start. During cranking the voltage was at 10.2 - 10.5V. Once started the voltages were the same as before, normal 12V glowplugs still on (light off) and 13.8 - 14.2V glowplugs off.
I'm not sure if this is a glowplug related issue or starter or what?
FTE Leadership Emeritus
Joined: Sep 2003
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From: Houston, Texas
I agree, this is also a good time to pull and test the alternator as well. I say this because the alternator will destroy itself trying to charge batteries that won't hold or take a charge.
Saw this too many times on my 7.3...
Saw this too many times on my 7.3...
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Joined: Dec 2014
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From: Jersey Shore
Let's see if my first upload to YouTube works .....
The SG readings drive me crazy. I've contacted SG and never got anywhere on a good explanation of where the readings are coming from or why the variation. I've gone through cleaning pin contacts on the PCM and other connections, but still have not achieved the stabilization I would like.
There is also the question of how much dampening is in the circuit of my Fluke 77, more dampening less variation.
Here is a segment of a video I've been working on about our electrical system although it does have the narrative laid on top as yet. At this time the truck has the 140a Bosch alternator, a 12ga additional wire between the alternator and passenger battery terminal, as well as the addition of a cable between the drivers battery negative cable frame mount and the engine block.
The SG readings drive me crazy. I've contacted SG and never got anywhere on a good explanation of where the readings are coming from or why the variation. I've gone through cleaning pin contacts on the PCM and other connections, but still have not achieved the stabilization I would like.
There is also the question of how much dampening is in the circuit of my Fluke 77, more dampening less variation.
Here is a segment of a video I've been working on about our electrical system although it does have the narrative laid on top as yet. At this time the truck has the 140a Bosch alternator, a 12ga additional wire between the alternator and passenger battery terminal, as well as the addition of a cable between the drivers battery negative cable frame mount and the engine block.