Hey fellas.

Last year I found that the truck (99 f-250 psd) was draging when starting when it was cold. I figured it was because the cold, and plugged the truck in and gave the truck a full charge on the battery. It did fine as long as it was plugged in but if I left it for 8 hours in 25-30 deg weather it would drag and run out of juice before not starting.

Well the weather warmed up and I didn't give it anymore thought until saturday morning when I got up the truck would not start again and after 2 attempts to let it crank it died compleetly. These were just normal cranking no hold it down til it starts.

SO I thought the batteries had gotten weak. So I charged it full and it cranked really fast, so much so it startled me. I then was concerned that it was not charging properly. I took the batterys in and had them tested and they tested fine. one seemed a bit slow to recover under load bt not anything like others I have seen.

The truck has been fine since cranking better than normal.

My question is since the batteries were fine, I asume the only thing left on these is the alternator?

I will put a volt meter on it tomorow, but what is the "correct" charging output for the alternators on our trucks?

And Yes I need a FSM.

Lastly have you guys seen issues like this that turned out to be anything but a battery issue?

I don't mind putting a new set of batteries into the truck but don't want to if it is not necessary.

 

Truck running full charge on the batteries the alt should put out 14.5 volts. Batteries should be 12.5-12.7 engine off with the surface charge removed I/E lights on for 30 sec's. You may have a drain that lowers the batteries over night...


Dick

 

Batteries should be around 13.5 to 14.0, if it gets lower then 13 then that's when I would change them. I have a voltmeter hooked up right on the batteries and I get inbetween the range that I just gave. If your getting it from the trucks computer(ie monitor or diag. scanner) then it's going to be closer to 13.2 then having something hooked directly to the battery.

 

If you do some research you will find that I am correct for standard lead acid batteries.


Dick

 

You need to replace your batteries. One battery that is "slow to recover under load" when at room temp is going to prevent you from starting the truck when it is 35 degreees outside.

Diesel engines demand you have two good batteries. Your "no start" condition when cold is because one is failing.

You MUST replace the batteries as a set.

You should have your alternator tested, but I suspect it will be OK.

 

Your talking about when the engine is off and your testing it when the truck isn't running, I'm talking about when you have the truck running, if what you said is correct for the truck running then either my voltmeter is really really off by a volt or the Ford factory batteries are some really good "stuff".

 

I recommend also checking all the battery cables and their attachments at both ends. On my old '85 F350 many years ago I had a similar problem and it turned out to be corrosion where one of the negative cables bolted to the engine or frame. I had checked the batteries and the alternator and the upper connections, all to no avail.

Good luck.

 

Everything I said is correct. My truck charges at 14.6-14.7 volts with a high charge regulator..stock is around 14.5 volts..I have been doing auto electric for almost 40 years plus I'm an electronic tech...


Dick

 

I'm just saying what my gauges are telling me and it has never yet reached 14 and I'm talking about the batteries not the alternator(you said the batteries charge at 12.5 - 12.7 in your first post, I don't know why you switched now). My gauge is hooked up to the batteries, I don't know what my alternator is putting out and I never once claimed to know, I was talking exclusively what my gauge was telling me my batteries are putting out as my truck is running down the road. As to what is in bold, that certainly lends more weight to you being correct, it however, does not mean that in of itself you are correct in all things electrical(in regards to auto electrical that is), which makes saying that irrelevant unless you are telling me that I am wrong because I don't match your 40 yrs experiance as an electronic tech(it's called an ad hominem fallacy and I'm sure alot of people here are tired of my saying that however, it doesn't make it any less true), I know what my gauge is telling me, now if the gauge is faulty that's one thing and it could very well be, but if it has been it's been that way from the start(which is possible).

 

Read again

I try not to say anything that isn't absolutely true and correct. I've been on here a while only to provide accurate info for all who need it..you need a good digital meter to measure your alt and batteries correctly and measure at the battery..

Dick

 

I can appreciate that, and I don't mean to give the appearance of my trying to cast some type of doubt over that, I'm just telling you what my gauge tells me and it doesn't mesh with what you had said, now the gauge could very well be hinky that is possible, I don't know for sure because it has been consistantly that way since I installed it in the spring. However, let me remind you that my readings are being taken while the truck is running and in motion with various operations going on(ie a/c, radio etc.) which is going to be different then the readings that you are talking about. Your talking about when it's hooked up on a charger(where I do believe the 14 plus volts are coming in) and when you just turn the truck on but are not turning the engine on(I believe thats where the 12 plus volts come in), while my readings are for when the truck is running and in motion. I do believe all three of those scenarios are going to yield different readings, please correct me if I am wrong in that but I believe you are talking about two different scenarios both of which are different from the one that I am talking about.

 

I'll try again...
A fully charged good battery will read 12.7 volts engine off after removing the surface charge...12.5volts = 1/2 charged. 12 volts about dead...

Engine running voltage should be real close to 14.5 volts measured at the battery with a meter. This reading would be with a fully charged battery. If the battery in the vehicle isn't fully charged then you may see 14-14.5 volts or so.

Whatever your gauge reads needs to be backed up with a good digital meter.

Dick

 

Just so I'm not going to commit the strawman fallacy, are you saying just with the engine running you should be seeing that, or is that with the normal load on the batteries(ie. radio, a/c, lights or any combination thereof etc.)? Because with a load on the batteries I'll see(and I'm guessing as this is analog however, I do know it's not right at 14) 13.7-13.9(fluctuates depending on what accessory combination I'm running). I will however in the morning see what my gauge says just with the engine running just in case that's what those numbers should be. I would think it would probably be closer to 14 then 14.5 as the batteries are two yrs. old and I've got a lot of electronics running through them so I'm sure they took it's toll on the batteries.


On my charger, I just have an analog gauge, at the time I was getting it I felt no need to splurge the extra money for a digital one as that was not my business, so I can't verify my in cab gauge reading to your satisfaction. For just the home do it yourself person it does fine for me though. I do understand the reasoning though for a digital one.