At 7:00 this morning, it was 9*F ( -13*C) here in New Jersey. The car barely turned over.

I checked the battery voltage this afternoon at 4:00 pm and it is 20*F ( -6.7*C) outside, voltage is 12.1 vdc, not too good. I notice sometimes when I start the car the rear defroster is on for some reason, and once sport mode button was lit...voltage related?

I purchased a new battery last month and it was at 12.4 volts.

I am wondering if I might have a drain while the car is off, or the cold weather is affecting the battery ( I would think not, but who knows), or my alternator is going bad.

Note lately I have been using the auto setting for the headlights, lights function normally in this mode but maybe it has something to do with this voltage?

Thanks for any input!

 

Are you regularly driving a long way so it has a chance to charge?

Have you tried charging it with a separate device?

 

Could be a combination of both. Might be worth investing in a C-Tek trickle charger to use during the colder months..

 

I'm driving the car 70 miles per day, round trip to/from work, five days a week, and sometimes on weekends.

I do have a Deltran Battery Tender, and will charge the battery and take note of the voltage and see if it drops again.

On the way home today, I got the restricted performance message with an amber light which went out after a few minutes, and an engine malfunction " check engine" light.

I will have to check codes and see, but I'm guessing right now that its low voltage related, we'll see...

 

2003 S type 4.2 Had the same happen to me this morning in Chicago. The car would not start just the ticking noise. Had it jumped and ran 'till I turned of after 3 hrs did not start again. My battery has this immobilizer on the positive terminal of battery. I just purchased the car last Sunday, it came with a separate smaller fob as well as the original fob. The small one has 2 buttons on it a red lock or arm button, and a unlock or disarm button. My car also seems to be clearing memory of clock and radio presets, nearly everyday. I'm not sure if it's alarm thing or not. Need help to find a solution to this. Battery voltage checks ok at 14.03vDC when running.

 

If you are checking voltage across the battery terminals with the car running, you are getting the voltage output from the alternator, not the battery.

 

Yep - need to leave it 8+ hrs, engine off, before checking volts.

Could be that extra immo - can't see any point at all in it.

 

+1. Probably the cause of the clock radio presets disappearing.

For the OP- it's normal for the defroster to come on by itself in cold weather.

 

Thanks for all input. I checked the battery non running this morning and it's reading 10v not good. The immobilizer needs to come off. When I push the button of the immo it stays depressed a reads 10v, then clicks off and reads nearly nothing off the battery. So i'm going to take the immo off the battery, and just hook the positive lead straight to the positive terminal of the battery. I may still need a jump start and let it run. If the car sits and still measures low reading then it's not holding a charge and will have to replace battery.

 

When turning the car on, only the rear defrost ( defog) button is lit, even with the climate control system off. Seems strange.

Will post codes later.

 

10V - ouch!! You want at least 12.5V

 

Yes. Same with mine. Rear defrost always comes on. It may just have an auto "on" feature when temps are cold and senses rear window frost?.

 

For sure, hoping for 12.45 - 12.5v

What's good CCA rated battery for these cars? Mines CA 910 and CCA 730, Battery visually looks near new.

 

Those crank ratings are fine. These batteries usually look new even when they are 10 years old because they aren't sitting under the hood getting dirt and grime slung all over them. There should be a date code on the battery somewhere (typically engraved); but regardless of how old it is, if its bad then it should be replaced.

 

Ok, removed the immobilizer, got car jumped and running. How long do I need to run car before turning off?

Battery date: Nov 13 I'll assume that's 2013.

Edit: I know it's testing fine with car running at 14.4v, but the true test is that after I let it sit for some 8+ hrs.

Thank you Quartz

 

@dcjag64 and Jimmy68, as already mentioned in one of the posts above, get yourselves a CTEK smart charger. It will be the best money you ever spend on your cars and will help to keep them "electrically gremlin" free.

Jim

 

If it was about 10V then
1. it may never recover
2. if it does it'll need 12+ hours on charge, preferably with a smart charger suited to lead-acid

 

[QUOTE=jimbov8;1135659]@dcjag64 and Jimmy68, as already mentioned in one of the posts above, get yourselves a CTEK smart charger. It will be the best money you ever spend on your cars and will help to keep them "electrically gremlin" free.
Thanks, but as I stated above, I own a Deltran Battery Tender Plus smart charger already.

I've used it on my idle Mustang, but didn't think I'd need it yet for the Jag, of which I put 350 miles a week on at the least, and the battery is not even two months old...

BTW, code is P0174, lean condition engine bank two.

Will investigate to see if theres a real cause or if not its low voltage related.

 

Definitely will look into that purchase.

 

That's probably what will happen, but I'll take it a step at a time to be sure.


Thanks