It's cold here, real cold (-31C without wind, -40s with) and naturally my truck wont start. The issue is even when my truck is warm and I've been driving 30 minutes to work and I turn off my truck, if I try to start it right away all I get is clicks. I have an Edge Evo and have been monitoring my voltage. When I attempt to start the truck warm it's at about 11.5. Low but still startable in my opinion. When I try to start it, it instantly drops to ~5.5 and of course wont start. It idles at 14.5 so that makes me think it's the battery but is there another issue here? This would be my 4th battery at my truck isn't turning 7 until May.

 

You might want to get the alt and bat tested....

Batteries don't last like they used to....try a die hard gold for your next one....

 

I had the battery tested in the spring or summer, the last time this happened and it tested fine. I've only backyard mechanic tested the alternator so far with the spark test.

 

It would be best to get the alt tested professionally....

 

A battery at 11.5 VDC is only 20% charged, well beyond "low", and you should not be using the alternator to charge a battery that is in this much of a discharge state.

When you say you "spark tested" the battery, do you mean you shorted the terminals together with something like a screw driver ?

Not too sure which came first the dead battery, or a possibly a toasted alternator, but you should actually test them both.

If you want to do a backyard battery test that will indicate something :

Quick go / no go test at home if you have a charger and meter :

Have the battery stand alone ( at the very least have it disconnected from the truck's system ).
1. Charge the battery on a 2A setting until fully charged.

2. Once charged, take a voltage reading and record it.
2.1. This should be in the 13.n range.
2.1.1. on the low side, 12.9 / 12.8.
2.1.2. 12.6 could be acceptable for a battery that is getting to its last legs.

3. Let the battery sit for 3 to 4 hours and take another reading
3.1. Should be within 0.2 / 0.3 VDC of the 1st reading.

4. Let the battery sit overnight and take another reading
4.1. should be what the 2nd reading was +/- 0.10 / 0.20 VDC of the 2nd reading.

This should put the overnight ( unhooked ) reading within ~0.4 VDC of the fully charged reading.
If the battery is 1.0 VDC + off the 1st reading, the battery is not holding a charge on its own, and should be replaced.

As 88racing posted, have them professionally tested. A real load test on a battery requires charging the battery, so if you are having Autozone test it, don't take that as sound advice. I have yet to see a single person at Autozone perform a real load test. They put some load on the battery ( without making sure it is charged ) and hit it with some fixed load size ( which chances are is too low of a load for your battery ).

 

There's some very useful information, thanks guys.
I'll have to pick up a charger before I can test that one out though, all I have is a booster.

 

What size/brand battery have you been using? 4 batteries in 7 years is a problem. Either you have a drain on the system causing dead batteries or your alternator is under/overcharging them. Do you have a 2003 or 2004 MY truck? In 2004, F150's went to a smart charging system where the PCM controls the voltage based on a battery temp algorithm. Previous, it was the alternator regulator dictating voltage which wasn't all that accurate. In extreme temp ranges, the alternator controlled temp systems were even worse.

 

It's an '05.
I went back to the place I got my last battery and they replaced it under warranty. It's a series 65 but I'm not sure of the brand or the CCA. The one they put in this time was different than the last one but I didn't get a chance to look at the make.
Now I need to test the alternator and I'll also double check any parasitic draw when it warms up a little. I've done it once before and didn't find anything but I'll double check. Is there a way I can check if the alternator is under/over charging the battery or is the only test for an alternator working/not working?

 

Group size 65 battery is a good size and is around 650 - 800CCA rating with good reserve minutes. The 2009 F150 was released with a group 59 battery which I believe is a tad small for the truck market but did meet testing requirements.

You need to check battery mfger's they are using, they are not created equal. The two main battery suppliers for auto batteries are Johnson Controls and Exide. Try to avoid Exide if possible, they were de-sourced from Ford a couple years ago.


Overnight cold weather start-up like the temps you are discussing, I woul expect voltage to be 14.5v or higher until the battery begins to warm up. Hot summer re-start, battery voltage should be down to 13.1 - 13.3v. But it all depends on the assumed battery temperature which is dictated by engine operation and duration.

Overcharging occurs in the summer months when you can boil out the battery charging above 13.7v so can really only be checked during those conditions.

Undercharging occurs in the winter time by not having a high enough voltage, usually well above 13.7v and actually should never see it below 14.1v in these type of winter conditions. Undercharging weakens the battery, does affect battery life and can sulfate the battery by not being at a high state of charge.

To determine PCM assumed battery temperature, you'll need a diagnostic tool used at the dealership. But this is the same programmable feature used basically in all Ford NA vehicles with the smart charging system so I would definitely dis-count a voltage control problem.

You should be well below 50mA for a key off load after about 20 minutes.

 

So if I was to go outside right now at -25C (it warmed up!) and test the voltage to the battery it should, in theory, be around 14+V. If it's not it's being undercharged, correct?

 

That's probably a little over simplified, but close enough. I NORMALLY like to test the voltage at the battery at 15-1700 RPM rather than idle. It's not going to make a lot of difference, but a little. Since you don't normally drive at idle I prefer simulating driving. Turn off any excess load. There are variables that are hard to put into the test that will have SOME effect on it. A good fully charged battery will HOLD approximately 12.6 V. A smart charger will push a starting battery to around 13.2-13.4V, but it won't hold that. A good carbon pile load test, or waiting till the next day will drop it to about 12.6-12.8V. You have to (should) run 14.+ to make up for starting loss etc., and keep it fully charged. I would also do a diode test if you have access to a tester that will do that.

 

Yeah but as I also stated, "But this is the same programmable feature used basically in all Ford NA vehicles with the smart charging system so I would definitely dis-count a voltage control problem."

If the alternator is not putting out the right voltage it will trip a DTC and display a battery warning symbol on the dash. That is not your problem.

 

What do you think the problem might be then? Some elusive parasitic drain?

 

My guesses:
Battery drain
Poor connection
Bad battery - What brand are you using??? Even good brands have problems
Non-ideal driving conditions to maintain battery charge

All the above problems are exasterbated in cold temperatures.

Did you do any battery voltage testing which Scully pointed out???