battery questions....

[steph74]

Hi everybody
let me start by saying that I will get the battery checked as soon as I have time but I would love some input on battery functioning.

my jeep won;t start, it sounds like the battery is dead but all accessories (radio/lights...) are working fine.
So I went under the hood, and put my trusty voltmeter (if you have a renix that is your tool of choice) on it.
12.4V it is low but it is also in the 10to 20 F out there so I was expecting around 12.6 V

I can jump start and it reads 14.5V when the engine is running that would tell me that the alternator is working OK right ?

If I turn off the engine after running it for a while, it won;t start back. Voltage goes down to 11.5V and then slowly goes back up to 12.3V (????)

I am assuming that since I can jump start it, all other parts are working OK like starter, CPS and what not...

So I came down to the diagnostic that the battery (5 month old) is just not charging or that it is not holding a charge....
I hope that NAPA will change it because this is already a replacement.
I am also going to see if instead of giving me the same (it is their NAPA 65) they will allow me to just pay the difference and upgrade to the premium...


I am wondering what kind of battery you guys living in cold country are using / recommending for good measure.

[Mudderoy]

Hi everybody
let me start by saying that I will get the battery checked as soon as I have time but I would love some input on battery functioning.

my jeep won;t start, it sounds like the battery is dead but all accessories (radio/lights...) are working fine.
So I went under the hood, and put my trusty voltmeter (if you have a renix that is your tool of choice) on it.
12.4V it is low but it is also in the 10to 20 F out there so I was expecting around 12.6 V

I can jump start and it reads 14.5V when the engine is running that would tell me that the alternator is working OK right ?

If I turn off the engine after running it for a while, it won;t start back. Voltage goes down to 11.5V and then slowly goes back up to 12.3V (????)

I am assuming that since I can jump start it, all other parts are working OK like starter, CPS and what not...

So I came down to the diagnostic that the battery (5 month old) is just not charging or that it is not holding a charge....
I hope that NAPA will change it because this is already a replacement.
I am also going to see if instead of giving me the same (it is their NAPA 65) they will allow me to just pay the difference and upgrade to the premium...


I am wondering what kind of battery you guys living in cold country are using / recommending for good measure.

I like my Red Top Optima battery, but I don't know how well they work (if any better) in cold climates.

You might want to remove the cables, clean the connections with one of those special wire brush thingies, charge the battery and see if it does better, but I betcha you have at least one dead cell = bad battery.

[prerunner1982]

I would agree with cleaning the connections and checking the water in the battery if you are able.

[steph74]

yes I didn;t mention that but the connections are clean (maybe will clean again just to be sure) and the levels of fluids are good to me... right under the top

[cantab27]

5 months old , take it back .....

[steph74]

I will take it back for sure.. but these lazy people are open when i am at work lol so unless i am off it is not possible.
That is the second time since I have the jeep that I have to go change the battery start getting annoying lol

[4.3LXJ]

You said you have 12.4V, which is good. Also 14.5V charging. There is an easy test to perform to confirm a bad connection. Turn on the headlights and then hit the starter. If the headlights dim significantly or go out, it is a bad connection. You might have one at the starter also.

[steph74]

You said you have 12.4V, which is good. Also 14.5V charging. There is an easy test to perform to confirm a bad connection. Turn on the headlights and then hit the starter. If the headlights dim significantly or go out, it is a bad connection. You might have one at the starter also.

I will try that tonight

So 12.4V is good ? I thought it was supposed to be more like 12.8.... i checked on my other car and the battery gives 12.87V exactly and they are parked side by side outside lol

No correct me if I am wrong to think this way. Since I can start the jeep with jumper cables connected to a different battery, I will assume that the starter connection are good right ? (I don;t want to crawl under the car to test the starter... there is way too much snow lol)

And I am already all over the article about the starter on this forum... just getting info on how it works and maybe decide to take it out to clean and help there


Would putting a thinner oil help by reducing the power needed to turn everything ? I am running a little thick (15W40 rotella so maybe with that cold it is not the best)


like I said I will have the battery checked, I just don;t like no understanding how it works

[XJ Rat]

You might also want to make sure the connection at the starter is clean and corrossion free. It will make a difference. Ask me how I know.

[pvt.tadpolxj]

With my 1991 XJ all of my starting problem's were the result of Heat from the engine block Causing my IGN. COIL'S to fail. I had to make a very tough heat shield for my coil. I did not want to relocate my new coil to the fender.I hope thois will help!:smiley-scared002:

[pvt.tadpolxj]

And you do not need a thinner oil. Your XJ will alway's run better and smoother with the oil you are using.Look at the thread in OEM/Factory Called ENGINE KNOCKING....:thumbsup:

[4.3LXJ]

Maybe I should ask a question here. Does it crank over?

[prerunner1982]

No correct me if I am wrong to think this way. Since I can start the jeep with jumper cables connected to a different battery, I will assume that the starter connection are good right ? (I don;t want to crawl under the car to test the starter... there is way too much snow lol)


If there is a bad or corroded connection.. with enough juice being pushed enough may be able to get by to start your Jeep.

[steph74]

Maybe I should ask a question here. Does it crank over?

what do you mean exactly by crank over (sorry mechanically challenged here ;))
When I turn the key, it looks like it wants to turn but does not turn totally (if that makes sense...)

but then really quickly everything shuts off including lights on the dash board... bringing me to think bad connection maybe as you suggested above

[steph74]

If there is a bad or corroded connection.. with enough juice being pushed enough may be able to get by to start your Jeep.

totally makes sense.... I'll double check that then....

[steph74]

You might also want to make sure the connection at the starter is clean and corrossion free. It will make a difference. Ask me how I know.

and that also could be a reason, because with all that snow and mud, something might have happen....
I know what I am doing tonight lol

[prerunner1982]

I changed the starter in my XJ in 6-8" of snow... So I feel your pain.

[XJ Rat]

and that also could be a reason, because with all that snow and mud, something might have happen....
I know what I am doing tonight lol

Mine acted the same way. Removed and cleaned both ends and presto, started right up. Battery was 6 years old, so I initially suspected that.

Good luck crawling around in the snow tonight.:thumbsup:

[bigjim350]

I had problems with a battery in one of my trucks last year. Using the volt meter it showed 12.6v but still would not start the truck. I took it to a buddy at Intersate battery and he tested it. It showed to have enough volts, but not enough amps. Therefore the battery had a dead cell and had to be replaced.

[ice_cold]

Have a load test done on the battery. It may have the initial voltage but not enough over time.

[steph74]

Well problem solved.... was the battery....
I got it exchanged and started right away.....
Jeep is all happy now ;)

that doesn't mean I am not going to give a good cleanup to the connections

thanks all for the inputs I guess it will help diagnose problems in the futur and remind everybody to keep them clean ;)

[Mudderoy]

Well problem solved.... was the battery....
I got it exchanged and started right away.....
Jeep is all happy now ;)

that doesn't mean I am not going to give a good cleanup to the connections

thanks all for the inputs I guess it will help diagnose problems in the futur and remind everybody to keep them clean ;)

Yeah it's easy to do and removes that issue from the list of things it could be. Doing it prior to a good cold snap is a good idea. :thumbsup:

[Horsehide]

My 2000 XJ came with a smallish battery. Since it was leaking a bit, I replaced it with a 700 CCA Interstate and I have had no issues starting it up at -13F.
On the other hand, I also switched to Rotella T6 5W40 and the synthetic oil might have also helped some. Have you checked/cleaned your spark plugs recently?