As the temp gets colder the battery has less power, and the engine requires more power. For every vehicle there is a temp where the two meet and the engine won't crank. As temp1 pointed out, as the battery ages it puts out less amps.

 

I tried to start my car one time but it would not crank. The terminals were not corroded but they were dull greyish black or dark grey. I cleaned the battery post's and the connectors till they were shiny and tightened them back down. The car started right up!

 

Thanks again you guys your advice is professional and to the point and I really appreciate it.

 

During some recent cold weather (-25F) My 2001 4.6 would not start even when plugged in. You could hear the starter solenoid engage but not the starter motor. It would take ten to twenty tries or more before it started. Battery terminals looked good. In warm weather it was no problem starting, and the battery seemed pretty strong (Truck only has 20,000 miles).
Took it to the dealer who found a Ford technical service bulletin that described corrosion on the starter solenoid wire connections. Sure enough the starter solenoid connections were quite corroded (from road salt and water) and once it was cleaned no more problems.

 

Originally posted by Pestco1
... Saw guys wearing ski hats and ear muffs and it was 49... geez!

LMAO. Must be a dude from Texas heh. It's barely in the 30s right now and I see people with ski masks and other gears looking like they're getting ready to rob a bank.

About the hair dryer trick, does that actually make a difference? Once when I had fluid in one of the cylinders I left a hair dryer on for over 1/2 hour and it barely warmed up the plug threads. An analogy would be a person trying to warm a cold glass of water by blowing on it. Minuscule change at best.

 

Ford V8's have to meet a cold crank requirement of 60 rpm's at -40 degrees. The test is performed with a fully charged battery. The F150's can start at about 46 cranking rpm's, but they are not happy.

Far as battery corrosion, can't tell you how many times we have tried to remedy this problem. F150 starters are located at the bottom of the bell housing with no splash protection. Add the corrosion effects from disimilar metals (zinc plated steel battery terminal on a copper stud) doesn't help. This issue gets compounded in colder weather where you need just about every ounce.

 

Thanks Stromsearch!!!!
I have often wondered what the cranking rpm was for these ford motors.

On a side note (you seem to be well informed) ever hear of a ford diesel not starting because of low cranking rpms. Was told that there is a low oil pressure switch that has to be happy during cranking before the injectors will get fuel. Fresh batteries has always fixed the problem. Batteries would last about 1 year in this unit. We switched to optima batteries three years ago and are still on them. The batteries we took out would still load test good and were given to Dept. members to use in there personal vehicles and give good service. We were told that in the ambulance the batteries were not getting topped off on the charging system and the motor needed just a few more cranking rpm's to start.

T-man

 

Heh, folks used to put a bucket of hot coals under the old Model Ts to get em started. Don't ya wish we still had hand cranks. I have not had my arm ripped off in a long time. LOL

 

Hey triumphman,

Not sure about the oil switch on diesels. I can check when I get back to work on Monday. Cold crank requirements are different on diesels which I do not have much knowledge of but will check.

 

Okay, the jist is you cannot create any oil pressure until the engine is running. Didn't find out anything from a fuel cut-off because of it. There is simply not enough crank rpm's to increase any amount of oil pressure, which are around 60 rpm's compared to idle rpm's of over 600 to more than 1000 rpm's.

I believe you had a weak battery system or poorly spec'd out for the system that would not crank fast enough to turn over the engine. I believe Optima batteries have a much better discharge rate over time than standard wet cells, meaning they can provide full output over a longer period of time and also can easily be nearly fully drained w/o much problems. With a wet cell, when getting down 10 - 20% of full charge, output begins to drop.

As a side note, most ambulance systems run a dual alternator/battery setup to handle all of the load and still crank. As you know there are dual batteries in most diesels. Diesel engines are roughly 120% harder to start, on average.