batt volts
Fleet Mechanic
Joined: Jul 2013
Posts: 1,330
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From: 'Pitlock, Maine
Logistics Pro
Joined: Dec 2004
Posts: 4,138
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From: South Weber, Utah
It really depends on how low the voltage drops during the starting/glow plug cycle, with the factory 110 amp alternator and good batteries its not uncommon to see the system voltage drop into the high 11's to low 12's as read from the OBDII port and while I don't believe this damages the FICM it is very rough on the batteries and the alternator and is the reason the batteries rarely last more than a couple of years.
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Lead Driver
Joined: Sep 2003
Posts: 5,241
Likes: 3
From: Other side of the sunrise
Anyway, in your opinion, would a higher output alternator be easier on the batteries and make them last longer? If true, that is another incentive to invest in a better alternator.
Hotshot
Joined: Apr 2010
Posts: 19,073
Likes: 243
From: Saratoga Springs,UT
Josh did some tests on the alt at startup to see if it was on while GP cycle
IIRC was the I Circuit
Yes the Alt charges while GP is on just Looks was deceiving since while GP are on theres BIG Voltage drops especialy with OEM Alt that ONLY puts out around 80-85 amps at Idle and the truck Needs 225+ Amps right at First it trickles down Fast to 140amp so that why I suggest 140 amp alt Minimum
My 190amp DC puts out 140amp at Idle so
An OEM Alt Rated at 110 amp only puts out 80-85amp at Idle so BIG Diffrence
When you buy an Alt they Listed at MAX output and Idle output will be Lower
Your Original bat last lots longer because the Lead in them is New But most anything you replace with will be recycled Lead Batterys and they Die Faster
The senereo you have Now is how Folks are Killing the FICM
The volts you see is NOT all going to the Batterys some goes to run the truck
Anything under 13 volts is Bad JUJU
Yes get a High Output ALt it helps all batterys and FICm last Longer at minimum a 140am alt
When I went to a DC Power alt my truck ran better when cold I could tell the FICM wasn't as stressed with a High output alt
IIRC was the I Circuit
Yes the Alt charges while GP is on just Looks was deceiving since while GP are on theres BIG Voltage drops especialy with OEM Alt that ONLY puts out around 80-85 amps at Idle and the truck Needs 225+ Amps right at First it trickles down Fast to 140amp so that why I suggest 140 amp alt Minimum
My 190amp DC puts out 140amp at Idle so
An OEM Alt Rated at 110 amp only puts out 80-85amp at Idle so BIG Diffrence
When you buy an Alt they Listed at MAX output and Idle output will be Lower
Your Original bat last lots longer because the Lead in them is New But most anything you replace with will be recycled Lead Batterys and they Die Faster
The senereo you have Now is how Folks are Killing the FICM
The volts you see is NOT all going to the Batterys some goes to run the truck
Anything under 13 volts is Bad JUJU
Yes get a High Output ALt it helps all batterys and FICm last Longer at minimum a 140am alt
When I went to a DC Power alt my truck ran better when cold I could tell the FICM wasn't as stressed with a High output alt
Hotshot
Joined: Apr 2010
Posts: 19,073
Likes: 243
From: Saratoga Springs,UT
And it helps to also do the Wire upgrade with the High Output alt
here are some pics you can make your own or DC Power sells them
Ford Truck Enthusiasts Forums - BLADE35's Album: DC Power Alternator & Wire Upgrade
here are some pics you can make your own or DC Power sells them
Ford Truck Enthusiasts Forums - BLADE35's Album: DC Power Alternator & Wire Upgrade
Hotshot
Joined: Apr 2010
Posts: 19,073
Likes: 243
From: Saratoga Springs,UT
Oh 1 more thing
If your taking Voltage at the OBDII Port it has a Voltage drop there due to the Resistence in the wire
So it really puts out 0.2-0.4 tenths More at the Alt
so this is some the reason for the wire upgrade it helps the system but you will always see the voltage drop at the OBDII PORT
You will see this when you probe with a DVM at the ALT vs OBDII Port
If your taking Voltage at the OBDII Port it has a Voltage drop there due to the Resistence in the wire
So it really puts out 0.2-0.4 tenths More at the Alt
so this is some the reason for the wire upgrade it helps the system but you will always see the voltage drop at the OBDII PORT
You will see this when you probe with a DVM at the ALT vs OBDII Port
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Elder User
Joined: Apr 2012
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How the heck did that rumor start, anyway? I've been scratching my head on this one ever since I first read it on a thread a couple of weeks ago... Thanks for straightening that up.
So which DC Power alternator will have high enough amperage to service the glow plugs and still provide adequate charge to the batteries?
So which DC Power alternator will have high enough amperage to service the glow plugs and still provide adequate charge to the batteries?
with the xp, as it's sturdier than the spx, and the windings are better.
anyone with guages can see that the voltage is being maintained
higher than it would with a total loss on the batteries.
100 amp static load on the batteries would drop voltage into the
low 10's after a couple seconds.
there is a huge amount of misunderstanding about electricity,
and how it works. it's not limited to people with ford diesels.
i've put some long winded screes on here about power generation,
rectification, etc... i'll not bother to beat that dead horse again.
Cargo Master
Joined: Oct 2005
Posts: 2,599
Likes: 2
From: Farmington NM
ok I was not part if the rumor discussion. BUT the PC-ED says that the alt is not on during the GP cycle, So this morning, I put a meter on my alt field wire, during the GP cycle there was 0 V until the cycle was over. I have a early 03. So now i am confused.
Certified Thread Hijacker
Joined: Aug 2001
Posts: 14,441
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The "A" circuit is always hot, key off or on.
Myself and Mustang_309 have both demonstrated the alternator is always commanded to charge key-on and during cold start, but we are 05+ trucks.
Josh
Cargo Master
Joined: Oct 2005
Posts: 2,599
Likes: 2
From: Farmington NM
The I circuit, single alt.