My 05 ex has taken up a habit of randomly not starting and acting like it's a dead battery. I hook it up to the charger and assume I left something on or didn't drive it enough. Now it's happening when I know I'm not at fault.

Sunday I drove it about 100-150 miles with plenty of highway time and 15 or engine off stops and starts. Then yesterday I drove it about 5 miles with a couple engine off and ons.

Today I go to start it and it acts like the battery's dead. Dash lights flashing when the injectors buzz, click but no starter motor action, etc . When I hook up a multi meter I'm getting 12.75 v woth key off. Key on I drop to about 7.8v. Batteries are about 6 months old and and recently charged and tested at auto parts store. Voltage draw tests look like 25 milliamps woth everything off. This happens randomly, some times i can go a week without driving and it will fire right up, but last night it died over night. If I leave it on the charger overnight it's good to go in the morning. Any advise?

I also have a p 1102 code but can't see how the two would be connected. Any help would be appreciated!

 

Pictures of the top of your batteries, please. We need to see the cables and attachments. Show where you are hooking up the voltmeter, too.

After the engine has cooled down, have you noticed if the alternator or glow plug controller is hot?

 

If your batteries aren't bad now, they will be soon.

They are not getting fully charged for whatever reason.

You will not get a reliable start at 7.8 volts

 

During engine cranking it’s preferred to keep the volts at 10.5VDC or greater. You got an issue, either bad batteries or your cables are exhibiting some very high resistance connections.

 

I'll take pics in the morning. 3 of the 4 connectors look stock. 4th is a lead generic battery connector. All connections are clean, vtight, and corrosionfree no corrosionvisible anywhere.

Batteries are 12v when key is off. It is only with key on that i have the reading drop to 7v. When I do the draw test I take one battery out of the equation and measure draw off negative post with multi meter bridging connection from post to battery cable. Positive stays attached.

Never get a battery light, as long as it starts for the day I can drive without battery issues all day. I agree though this behavior will eat those batteries at some point. I had them tested 2 weeks ago and they passed.

 

Does turning the key on (not to start) open some relay to a new ground? Starter maybe? Battery readings are take from both battery posts.

Any way to test batteries at home?

 

We have been through this a lot over the years!!! A vehicle battery at 12.0 volts is essentially dead. You have quite a bit to learn about batteries and battery charging if you think otherwise (hopefully you don't)!

Your vehicle processors will not work properly at 8 volts. In fact, you may be doing damage to them - especially the Fuel Injector Control Module.

 

I was typing fast, 12.75 v 12.8v battery readings.

 

Ah. That is better. Then the battery (or both) are bad if they start out fully charged (12.8 V) and drop to 8 volts with only the key on.

If the drop to 8 volts is when cranking, then you MIGHT also have a short somewhere, but that will generate a lot of heat as posted earlier!

 

That's a significant drop, from ~12.75 to 7.8. So either these batteries are compromised, there is a connection issue with one battery, or there is something that draws down the reserve. Something is goofy here.

I did a video of how my batteries drop over a week for someone on the org. I don't think you need to review it, but here's the chart. Tenths matter.




The batteries may be good; you said they were tested at the auto parts store. Do you have the capacity results? My gut is a battery cable, possibly with something else. When you go key-on, you'll draw 200 amps initially. Even that should not bring one battery down to 7.8v at key-on unless your key-on means starter engagement, not wait-to-start.

 

This morning after a night on the charger I'm at 13.05 and when key on I'm at 12.36 and truck starts. Going to go see about warranty replacing the batteries just to rule that out. If it is still not fixed I should know about it in the next 2 to 3 weeks as this is hard to repeat.

Pic of battery's. 850CCA

 

>>Pictures of the top of your batteries, please. We need to see the cables and attachments. Show where you are hooking up the voltmeter, too.

A picture of one battery and the terminal covered accomplishes nothing.

I am about done trying to help in threads where it takes post after post to try to get answers when trying to help people. I just went through his crap in two threads over at the org.......

 

Earlier you asked about a way to test batteries at home.

There was a recent thread on this, I'll find it and post the link. It may or may not be worth the money for you to invest in a battery tester. Note that in the video linked above, Jack mentions the battery tester that he uses.

In a way, cranking this engine is a load test. The main drawback is that when you crank/start the engine, both batteries are connected, so it is not going to help you identify a single bad battery. Personally, I wouldn't recommend to try starting with only one battery either. You can do it, and it should start with only one battery, but it is adding extra stress and strain on systems that don't need to be exposed to it (again - IMO).

When you turn the key on, the glow plugs come on. Even if the glow plug light goes out, the glow plugs will stay on for a period of time determined by the PCM (oil temperature plays a role in the length of time). The glow plugs are certainly a significant current draw, maybe up to 200 amps at first (as mentioned above) ...... but they should quickly settle down to only draw about 80-100 amps. Jack knows way more about the typical behavior (time based) of the glow plugs and electrical system than I do.

The system voltage should not drop below 10.5 volts when cranking (assuming the batteries are fully charged). If the system voltage drops to 10.2 or so, I still would probably call that OK. I hate to see it at 10V or less!!! There is a problem if it is!

Just be aware that short drives do NOT do a good job at re-charging your batteries.

Years ago, I made a comment that drew some fire. I said that IMO the alternator was not a good battery charger.
What I meant by that was "several-fold":

• Normal engine operation is with both batteries connected to the alternator (captain obvious). A single bad battery can cause problems with the alternator operation AND the effective charging process - so it does not necessarily help the good battery.
• Unless you have an upgraded alternator, you may not have a lot of extra amps available to replenish the charge lost when starting.
• Lastly, at idle you do not typically get many amps out of the alternator.

You probably know all that, but just some things to consider.

I have an old style carbon pile load tester and it works well. I have wanted one of the electronic testers, I just haven't been able to justify it yet!

 

The discussion on battery testers was on another forum:

https://www.powerstroke.org/threads/...-tips.1401613/

 

Just to be thorough (and the 6.0L certainly does challenge us in that department), what does the positive terminal look like under that cover? Also, what do the terminals look like under the other battery? (post #2 and #12)

Lastly, you were asked to show where you hooked up your terminals?

Just might help reduce future frustration.