Mu FX2 has stranded me a couple of times over the past couple of weeks. It would crank slowly then start at times, but on two occasions, it wouldn't start at all. It started immediately both times with booster cables attached.

Throughout all of this, I had no idiot lights or error codes.

I changed the display on my Evolution CS so that I could monitor battery voltage.

I noticed the voltage varying between 12.3 and 14.0. This told me that the alternator was capable of charging properly, but wasn't doing it all of the time.

According to everything I read, even at idle with all accessories on, the voltage should be 13.5 minimum.

I took the truck to an auto electric place today. Of course, on the 20 minute drive there (as well as for the last day or so), the voltage was at 14.0 steady.

They put their meter on it and found no issues with the alternator, but one dead cell in the original battery. He assured me that this was my culprit. He replaced it. $130...better than a new alternator in my opinion. Apparently 3 years is the new expected lifespan of a battery.

On the way home, the voltage again was at 14.0 bang on.

I took the truck out later in the day and the voltage started fluctuating again. 12.5-14.0 with no apparent correlation to headlight or defog status or engine RPM.

I'm probably fooling myself when I say this. I'm hoping that the ECM is actively regulating the charging voltage as the battery needs it. I'm hoping that this fluctuation is normal and that I'm not about to cook another battery.

Can someone with a volt gauge installed on a current gen F150 please tell me that I can breathe easy or else tell me that I've still got a problem?

There's no worse feeling than not being able to rely on your vehicle.

Thanks for any and all replies.

PC

 

I have a 13 now, however my 2009 battery died just over a year old.
now- I tend to watch the battery voltage closely, there is a TON of draw these days.

when I get in, and start the truck up. voltage is around 12.x and quickly climbs to 13.7-13.9 then tapers off around 14.2-14.4 continuous. if I drive for lets say an hour it might go back down to 13.8 or 13.9

if its fluctuating that much, I would think the alternator is starting to go bad. but them having checked that? seems strange. I would check all cables, with the battery being replaced I would think those ends would be tight. follow them and make sure the ground is also tight.

I also have an edge. and it shows right along with my radar detector which shows batt voltage.

one other thing to make sure of is if your battery was truly bad, did you before it was replaced , or even now leave the key in the ignition? that will leave some devices powered on, and put a decent drain on the battery. if the battery is weak. usually a two day period like this and it will not start the truck.

 

Thanks for the info. No, I have never left the key in the ignition. I guess I'll be headed back to the auto electric place. I can't get there until Monday. At that point, they can check the condition of the battery. If it's down, then there's definitely an issue to find.

 

OK, a little research has turned up this.

It looks to me that everything might be working normally. The dead cell in my battery may actually have been the only problem.

I'll still take it back to the shop on Monday and have him test the battery. If, after a weeks normal use including heated seats, rear defog, wipers..., the battery is still normally charged, then I'm ready to call it good.

 

Is your edge set on fuel economy? Mine has done the same for 10,000 miles. I returned to stock for the last 1500 and in has gone back to full charge. I think it's related to the edge economy mode,

 

It's nothing to do with the tuner. If you read the article I've linked to above you'll see that it's acting perfectly normal