2005 MY. Stock FICM and stock Motorcraft alternator, batteries are about a year old.

Battery volts on my dashboss are around 13.5 during the day, fluctuating from 13.3 to about 13.79.
With the headlights on, the volts drop to low end of 13 and once in a while will hit at 12.99 or so.
I had the alarm set at 13 volts and the alarm would flash on every so often, so I changed the alarm to 12.75 to avoid having to listen to the alarm.

I thought it should be a little higher, but I do remember reading that it will show a little lower at the OBT2 port than it would checking voltage directly.

Does this voltage sound OK? Normal at OBT2?

 

Sounds about right, Mine runs around there

 

Thanks Steve. I feel better now. My alarms are now set for 1st alarm (yellow): 12.75. 2nd alarm (orange): 12.5 and 3rd alarm (red) at: 12.0... Does this sound like good alarm settings.

 

it matches the voltage i got with my OEM alternator.

is it ok? not to my way of thinking. it'll not keep the batteries fully
charged... and the lower operating system voltage means the
ficm pulls more current to make it's output voltage. more current
means more heat. more heat kills ficm's.

ed at ficm repair has this on his web site....

"I've heard that heat and vibration are the real FICM killers. True?

We used to believe that heat and vibration took the top spots,
but have since come to the realization that low supply side voltage
should take the top spot."

when my van is idling, stone cold, 30 seconds after start up, my
system voltage is 14.8 volts, and my batteries are showing a charge
going into them. this is while the glow plugs are on, headlights are
on, and a 1,800 watt stereo is on, pulling peaks of up to 180 amps
primary 12 volt current, with an average of 120 amps to the stereo
alone. i've tested.

turning on the stereo that loud early in the morning when cold is
not recommended to be done near your own house, fyi.

DC power is the alternator i use. no complaints.

 

Thanks. I've pretty much decided to go the DC Power route when the time comes to change out the OEM one. I remember reading that the OEM alternator stops charging, or something like that, while the glow plug cycle is going. Is there any truth to this, or similar?

 

yes, the alternator is not charging during the glow plug cycle.

 

The alternator is "charging" but is unable to provide 200 amps at idle, therefore all you see is battery voltage until the GP have cycled off.

This rumor needs to die already.

Josh

 

Actually your seeing the battery voltage nose dive because of the load. That's why you need healthy batterys.

 

Or a real alternator...

Josh

 

Tim, I would check the Batts separate ,some batteries only go 2/3 yrs , at least this will give you alittle piece of mind on where they sit . I still have the stock alt in and I look at 13.8 to 14. running at cold start 12.8 after glo plugs then back to charge, saveing my $$$$ for a new alt and Batts.

 

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?

 

My volts run about the same as the OP, I have the original OEM alt. Although they are a bit better after start up around 13.7 to 14.2 back and forth within a couple of minutes after the engine is running.
My question here is when you state that the glow plugs pull the batteries down I believe that would have to be the case considering the engine SHOULDN'T be running during the glow plug cycle or at least I have been waiting for the indicator to go out before cranking my engine so I am assuming they have shut down BEFORE I start the engine.
However, I haven't had the truck during the coldest weather we get here in Maine just the fall temps so far the lowest being around 30*. Are you saying as the temps get colder the glow plugs will be cycling even after the engine is running? or to put it another way will the engine have to start and warm up the glow plugs before they stop heating? I ask this because if this is the case I will probably need to be thinking about a new alternator or at least new batteries before it gets much colder here. If I am going to keep my voltages up that is. I hope this isn't too confusing to figure out what I'm asking,lol. Thanks for any input I get. Mcrafty1

 

Just because the pig tail is off (Glow Plug Lamp) does not
mean that the glow plugs are not still on. The plugs
will stay of after the lamp goes dark for a given time
that the PCM sets with some input from the sensors.

As to the not charging rumor. I think it came for people watching the
battery voltage and not seeing it climb for the first few minutes that
the truck is idling at cold start.
Someone posted a video that proves that it does start charging at first
with no delay. I also have proven this to myself here at home.

Ti's just that the starter and glow plugs make so large a deficit that
it hard for the little 110 alternator to catch up. Even the 140 6G
from the dual alternator setup has to run a bit. Just not as much.


Sean

 

The glow plugs are active up to 120 seconds, just because the wait to start light ( glow plug indicator light ) goes out doesn't mean the glow plugs are off, it just means the glow plugs are hot enough to start the engine.

 

Thanks, that may explain why it doesn't jump right up to the 14 volt range sometimes when it is just idling after a cold start.