98 Intermittent Start Problems

[KD0JZI]

I have a 98 Moutaineer that just recently started to have intermittent starting problems.
Just a couple weeks back I was out chasing storms and had lots of frequent lightning (any time I touched something electrical in the vehicle {Ham Radio, Scanner, Car Radio} I'd get a small static shock). The vehicle started up and drove just fine for another 2 days. Then I took a trip to see family 90 miles away and after about a 7 hour visit went to start the truck and acted like the battery was almost dead, real slow cranking, and finally got the click click sound. Tried a couple minutes later fired right up.
A couple days later slow to start again, drove to work just fine, shut it off. Went out on lunch 5 hours later and it started just fine, ran it for 30 minutes to sit in the a/c/ 5 hours later again acted if battery was drained.
Started fine for 3 days no problems, then acted up again, drove a little ways, shut it off, ran into Wal~Mart about an hour and started fine.
And just tonight after starting fine 36 hours before, all I got was a real slow turn over, but no go. Checked the battery with my multi-meter and read 10.1 volts. Placed on charger and fired right up.
Once I get it running, all gauges are in normal range, no alt. light, no low oil, doesn't over heat.
Thinking something is leaching my battery but what? Don't see dome lights on, no hood light installed, ham radio is off, only thing on is the anti theft.

[shorod]

Since sometimes it starts up fine after sitting several minutes, I'd be more inclined to think the issue is a loose connection at the battery.

When you measured 10.1 Vdc at the battery, was that on the cable connectors at the battery or through the center and on the battery terminals directly?

-Rod

[autojoe]

make sure the meter leads are on the battery posts and not the terminals......fully charged battery should be 12.6 volts dc.check all your connections at battery and starter and make sure tight and no corrosion buildup.I would also have battery load tested....autozone and advance auto do for free..this would eliminate battery as the culprit.....a load test is the only way to test a battery.if battery and connections are fine charge to 12.66 volts and let set and then check battery voltage before starting and see if voltage is low.....if so then you probably have a parasitic drain.computers on vehicles are supposed to go into sleep mode afer so long and if they dont it could also cause this.most of the time it is a partial short in a circuit.I have also seen leaking generator diodes and starter motor windings do this also....that is after eliminating all the fusable circuits.it is just a process of elimination.start with battery and connections first.if you had an ammeter you could check key off current draw.I use an inductive one.

[KD0JZI]

When I checked the battery Vdc it was on the connectors first, then I checked the battery posts directly and both read 10.1. Did it that way to rule out any possible corrosion on the connectors.
I did charge the battery last night to 12.6, and am planning on letting it sit awhile to see what happens.
I have double checked the connections and all seem tight.

Got an oil change planned for Thursday, so will have a load test done then.
And will try the other ideas as well, especially if the battery is low after sitting awhile with me not attempting to start it.

Thanks gentlemen for the ideas.

[shorod]

If the shop doing the oil change has a true load tester, like a carbon pile load tester, that could help determine if the battery is somewhat healthy. Some of the electronic load testers still need some development. I've seen a couple of times where the electronic load testers showed a battery as good under load, but the battery voltage dropped considerable in the car and a new battery in fact fixed the starting issue.

Where I struggle with a parasitic load being the issue is you mentioned that one time it wouldn't start, then just a few minutes later it started no problem. That would not be consistent with a parasitic load.

The more I think through this, the more I suspect you have an intermittent connection inside the battery to one of the cells. The battery has 6 cells, each of nominal 2V. If one cells were dead when you made your measurement, it would drop your voltage by about 2.1 Vdc. Add that one cell back in and you're at 12.2 volts which is about right depending on how long the truck had been sitting. And if the cell happens to be behaving when the load test is performed, the test may not identify an issue.

-Rod

[KD0JZI]

Originally Posted by shorod

Where I struggle with a parasitic load being the issue is you mentioned that one time it wouldn't start, then just a few minutes later it started no problem. That would not be consistent with a parasitic load.

The more I think through this, the more I suspect you have an intermittent connection inside the battery to one of the cells. The battery has 6 cells, each of nominal 2V. If one cells were dead when you made your measurement, it would drop your voltage by about 2.1 Vdc. Add that one cell back in and you're at 12.2 volts which is about right depending on how long the truck had been sitting. And if the cell happens to be behaving when the load test is performed, the test may not identify an issue.

-Rod

DUH!!!! 6 cells in the battery, each at 2v =12v. Tested last night at 10v. 12v - 10v = 2v. Possible bad cell.
Why didn't I think of that, basic Ham Radio electrical knowledge. (Slaps self around a bit).
Thanks Rod!!!

Now my wife did remind me about the dimmer switch for the dash and dome lights as well. I do know that it has a short. Dome lights don't illuminate when doors are open, or when I hit the remote unlock. Did notice if I wiggle the switch can get them to work just fine. Dash lights are not a problem, those work just fine. But I did notice this issue awhile back, so thinking this may not be the problem, as the starting issues are just recent.

Was planning on a new battery soon, either way. Just didn't want to buy a new one and have problems, still, with it going dead. (After all they aren't cheap) But the more I think about it, the more your idea, Rod, makes perfect sense.

[autojoe]

you can test individual cell voltage with meter and junk test leads to pinpoint bad cell.do you know how to do this?

[KD0JZI]

It's been awhile, so don't recall the entire procedure.

Now I did check the volts and after sitting 16 hours still at 12.2.

[autojoe]

if memory serves me well...hook neg meter lead to battery neg terminal start probing cells near battery neg terminal and ending at positive battery terminal....should increase around 2 volts per cell depending on battery charge....then reverse leads positive meter lead to positive battery terminal and neg meter lead probe each cell starting near positive battery terminal should increase around 2 volts....i think that is what is involved.when you charge a battery to 12.66 volts the battery is not fully charged because there is a positive surface charge.....so you have to charge well past and monitor until it does not go below 12.6 volts or put a load on it for 30 seconds to remove positive surface charge.
I would just have battery load tested.....that would be the true test.my electronic tester will detect a bad cell.

[KD0JZI]

Checked the cells, and also checked the volts at the leads and reading 12.02vdc. (original after charge 40 hours earlier was 12.2) Assuming anti theft of course would drain some.
Going to take her out for a drive and see what happens after I shut her off. Do a vdc test just after I shut her off, and another before I start her again, to see if the battery is staying charged or becoming drained after sitting.

[KD0JZI]

Did my little test drive and everything was ok. Charged just fine, held charge, etc.
Did take it in yesterday and did an oil change and got a new batt. to be on the safe side. And all is well.

Thanks for the help everyone, and fingers crossed the batt. was the problem.