Battery voltage and charging.

[FMTRVT]

There has been a number of threads on this forum and other Ford diesel forums about failures of batteries, alternators, and FICMs, with FICMs being sensitive to failure due to low battery or charging voltage.

Batt voltage can be easily checked with a voltmeter, and there are relatively cheap cigarette lighter readers that allow you to observe what the voltage is while running. Some of us also have AE or ScanGauge to pull readings as well. When not using AE, I put in a Radio Shack cigarette to banana plug adapter and use my voltmeter to pull the readings.

Usually threads call out what someone has measured for voltage which can vary in our trucks due to the glow plug drain or delayed engagement of the alternator. So maybe it's time for a survey of operating voltages so we can see what the norm is.

To me, a suggested series of reading would be post overnight soak, but before starting, voltage during GP warm-up (which may vary with ambient temps), drop during starting (which is deep), voltage after 15 secs (batt recovery but before alt kick-in), 2 minutes of idling (alt will be in), 2 minutes and 1500 rpm, and voltage after 30 minutes of running. There seems to be a reporting of a drop in voltage after underhood components warm up while driving, and I have noticed that too.

I've not had any electrical issues, but my truck is getting up there with 120k+ miles in over 5 years of service. But maybe if we get a collective average it will help people to find out if a problem is about to raise it's ugly head. Batteries, alternators and FICMs in these trucks are expensive.

Winter's coming and the cold weather can cripple our batts, so this is a good time to check things out.

Here are mine at 72°F ambient:

Overnight 12.6vdc; GP Warm-up 11.3vdc; Start Drop 9.9vdc; Start Recovery 12.0vdc, post Alt kick-in at idle 14.2vdc; 1500rpm 14.2vdc, 30 minutes 13.8vdc.

[glsurratt]

Looking at a Bullydog monitor plugged into the OBD port, I have 12.8 after overnight (key in run position, not started so this could be the glow plug reading?), 12.8 after startup and 13.2 when the alternator kicks in.

[bismic]

I think this is a great post!

Here is my info (BTW, my batteries are 10 mos old and my alternator is original at 52k miles on truck) .......

Overnight.................. 12.3 vdc
GP Warm-up.............. 11.7 vdc
Start Drop................. 11.7 to 11.8 vdc
Start Recovery........... 11.9 vdc
post Alt kick-in at idle.. 13.3 vdc
1500rpm.................... 13.5 - 13.8 vdc
30 minutes................. 13.6 vdc

FMTRVT - I think you may have a bad cell on a battery! Your "start drop" is WAYYY too low IMO.

[FMTRVT]

I agree. May be more then one.

Kicker is a year ago I had all the instrumentation at my facility to test the batteries under load and a refractometer to accurately measure the acid. Not anymore ......

I was thinking of posting over at the garage too.

Hopefully with enough data people will be able to take quick readings and know if something is wrong before they get into winter. It gets very cold in the cab during the winter mornings when the truck won't start.

[mountaintech]

I read your post this morning before leaving for a job and decided to check it out.
cold 12.3
GP 11.4
starting 10.6
after start 12.6
altenator kick in 13.5
while driving 13.6-13.8

I drove about 65 miles and the voltage was steady between 13.6-13.8.
My situation is that in the morning or after the truck sat for 8 hours, it starts fine but when I start to drive it has no power and surges like crazy. After about 5 or 6 miles it clears up and runs great.
I was told it may be the EGR valve so I took it appart and cleaned it, made sure everything moved freely. No change the next day.
Last night I pluged it in just for the hell of it, and this morning it started great and ran better out of my driveway than it has for a long time!!!!
On another Thread they were saying it may be my FICM. Stopped in at Ford today and found out that the warranty expired on Nov '08.
I'm trying to check anything else it may be, before taking it in.(On a tight budget these days)
Any other ideas would be appreciated.
Thanks

[bismic]

Personally I think 10.6V is low for starting. I would begin w/ a load test on each battery - individually.

[Djanzen]

Originally Posted by glsurratt

Looking at a Bullydog monitor plugged into the OBD port, I have 12.8 after overnight (key in run position, not started so this could be the glow plug reading?), 12.8 after startup and 13.2 when the alternator kicks in.

I have a outlook monitor also. I noticed that it does read correctly 13.2 is what mine shows but i also have a high quality fluke multi meter and it shows 13.6. I believe that the outlook is not calibrated 100%. not that it really matters but just check yours to make sure! you might be thinking that something is wrong when is actually correct. btw I have done two alternators and two new battery's in the last two years. second alternator failed two months after i bought it from a dealership (ford rebuild) they would not give me warranty because i misplaced the receipt. so i found a local alt. shop and put in a 190amp 3g case alternator for a little bit more then the $300 that ford would have charged me.

[jimmy]

"There seems to be a reporting of a drop in voltage after underhood components warm up while driving, and I have noticed that too." All late models I know of have decreased voltage after a period on purpose. On some it is a complicated setup involving battery temp sensors and on others it is no more than a ptc resistor in the internal voltage regulator. A diminished voltage output after a time scenario allows more charging after a start but with less evaporation of electrolyte after battery temp comes up and after the assumption is made that battery has attained its full or near full state of charge. The vehicles using battery temp sensors take the guess work out of charge rate based on battery temp.

I agree that the starter engaged voltage is too low for healthy batteries. I checked that a couple of weeks back on mine and it had 10.7 V at its lowest just before engine fired off. That was what this truck did on a similar ambient temp day 2 years ago. My rest voltage was 12.66 V for one battery and 12.65 v for the other.

But most importantly, my green dots do show on each battery....... ha ha ha....

[mountaintech]

I checked my voltages with a Fluke, brought the leads inside and monitored for about 1 hour.
I did a load test on each battery, they came out good.
This morning I had the truck plugged in again and it fired up and ran great!!
Is the FICM influenced by a engine temp sensor that may have gone bad?
Thanks

[OT]

OEM Batt's/Alt. 40K orig. mi. (have 2nd ride)

Used adaptor (jack mentioned) plugged into dash p.port to power my digital v. meter. Certainly not a hi end model. Accuracy @200V 1.0% +/- 1D. Would loss be less at 14+ v. I don't know?

Outside temp...+ 61 deg. Truck sit's outside/yr. round.

Overnight................12.30V (*12.22V w/hood light on)
GP Warm up....................11.32
Start drop................10.68 (quickly jumped to 11+V)
Start recovery...................11.74
Post alt. kick in at idle..14.25/.28
1500RPM.....14.30/.32
30min....still to do.

Any opinion's? TIA Just replaced tire's & new's batt's are on list to do cause I'm really stretching it.

* previous day before v. was 12.22 at batt. BUT, hood light was on (overlooked) Took me a minute to figure out why 12.30V

[69cj]

Originally Posted by OT

OEM Batt's/Alt. 40K orig. mi. (have 2nd ride)

Used adaptor (jack mentioned) plugged into dash p.port to power my digital v. meter. Certainly not a hi end model. Accuracy @200V 1.0% +/- 1D. Would loss be less at 14+ v. I don't know?

Outside temp...+ 61 deg. Truck sit's outside/yr. round.

Overnight................12.30V (*12.22V w/hood light on)
GP Warm up....................11.32
Start drop................10.68 (quickly jumped to 11+V)
Start recovery...................11.74
Post alt. kick in at idle..14.25/.28
1500RPM.....14.30/.32
30min....still to do.

Any opinion's? TIA Just replaced tire's & new's batt's are on list to do cause I'm really stretching it.

* previous day before v. was 12.22 at batt. BUT, hood light was on (overlooked) Took me a minute to figure out why 12.30V

Your over nite reading is questionable and points to bad or weak batteries. I am at 12.7 after over nite and the hood lite doesn't change that reading. For a couple of minutes that lite means nothing to two healthy batteries.

[FMTRVT]

You may be down a little on water level, but the battery still looks like it has good reserve as it's not dropping deep like mine did on start-up. Alt looks like it brings everything back up well.

I had kept my batteries over the winter and not much changed on those values. This spring I did pick up new Motorcraft aftermarket batteries, which are not perfectly identical to the OE units. I'm not expecting the same life.

One think you could do if your in the market for a small charger is get one that has a desulfation mode to it. I have found that using that process once a year has kept, and brought batteries in use far longer then they would normally be.

Oh, and even with those voltage drops I still have my OE FICM. But I also still have my '03 split-shot programing that does not heat up the injector spools.

[greasyfingers]

Good thread going here. I figured I would add my numbers too.

I have the lowest cranking voltage in this thread and I didn't even notice anything out of the ordinary when starting up!

Here are the voltages from my OE, 4-yr-old, 750 CCA, Motorcraft batts (that had one dead cell in one of them), and the new voltages from my maintenance-free, sealed, 880 CCA, NAPA batteries from the first startup right off the shelf with no additional charging. They eash cost me $104 at cash pricing. Things are looking MUCH better now! I also added a final measurement 2 mins after shutdown to use as an indication of the overnight drain-down.

__________________ Old batts / New batts / Next Day
Overnight................... 12.30 v / 12.55 v / 12.75v
GP Warm-up............... 10.47 v / 11.74 v / 11.78v
Start Drop................... 8.62 v / 11.00 v / 11.15v
15 sec after startup..... 11.90 v / 12.16 v / 12.49v
2 mins at idle.............. 13.98 v / 13.92 v / 14.22v
2 mins at 1500rpm....... 14.00 v / 13.96 v / 14.25v
30 minutes running....... 13.65 v / 13.95 v / (no measurement)
2 mins after shut down.. 12.65 v / 12.97 v / 12.92v

*Notes: Measurements taken with Fluke multimeter from power port in dash with a DIY plug-to-alligator clip adaptor. Headlights were on for all measurements (overlooked the automatic setting). Approx .1 v drop was noted with lights on. Radio was off. HVAC was off. Cabin lights off. Ambient temp 62deg in the garage. Engine was warmed up for the "New batt" 1st run. "Next day" voltages are the average of two cold startups at approx 50 degrees (one lights on, one lights off).

[johnny87]

Alternators on Trucks with single alternators are on from the moment that the engine starts the only reference to switching an alternator on was in the case of a dual alternator setup. I think that the observed indication of voltage rise after startup is entirely due to the glow plugs switching off. I found this on another site. A tech posted it from the shop manual...


In the single generator system, with the key in the ON position, voltage is supplied through the instrument cluster warning indicator I circuit to the voltage regulator. The regulator grounds this circuit and the charging system warning indicator is illuminated. When the engine is started, the regulator removes the ground on this circuit and the warning indicator turns off.

On the dual generator system, the PCM controls the charging system warning indicator and commands the lamp on if the PCM detects a concern on the monitored circuits.

The dual generator system is also monitored and controlled by the PCM. The PCM monitors both the upper and lower generator I circuits to determine the output of both generators and sets possible diagnostic trouble codes (DTCs). The PCM controls the lower generator by turning it off when the glow plug system is commanded on by the PCM to avoid possible damage (excessive voltage) to the glow plugs. As soon as the glow plug system stops cycling, the PCM powers up the lower generator.

[bismic]

Originally Posted by johnny87

Alternators on Trucks with single alternators are on from the moment that the engine starts the only reference to switching an alternator on was in the case of a dual alternator setup.

That is not true. Put a clamp on meter on the alternator wire at start-up. It will not be charging at first. It definitely does not get a signal from the PCM (as you stated), but it is kept off while the glow plugs are on via the electrical wiring design (and not the PCM).

It is in fact the HEC that controlls the alternator, not the pcm.
The "I" circuit is not turned on till the gpcm timer goes off (up to 2 min depending on eot).

Here is a good thread:
http://www.ford-trucks.com/forums/10...ml#post9569196