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Discussion Starter · #1 ·
Dumb question, but... here's the long story:
I have a 2010 R/T that I replaced the battery first in 2015. After installing it, I started the car and figured I was good to go. Well, it was a couple days before I used the car again and it wouldn't start. Took the battery out to return it but the store said it was at 80% and looked like it wasn't charging. Put it back in the car and charged it for a couple hours and it started so I drove it to the dealer (still under warranty). They checked the car out and kept it overnight and said everything was fine; I must have left something on.
Fast forward to this past Wednesday; the car was cranking slow so figured it was time to replace the battery again. I removed it at the store, installed the new one, drove to another place before going home and everything seemed OK.
Well, this morning I went to unlock it to check under the hood like I do every Sunday and the car was dead - wouldn't unlock or open the trunk with the remote. Opened the door with the key and the window didn't drop.
Put a charger on it and the remote opened the trunk and the window dropped when I opened the door, so it looks like its low again. I'll let it charge for a few hours and see if it starts.
Since this is the second time experiencing a dead battery after replacement, I figured I must be doing something wrong. I didn't see a procedure in the manual for replacing the battery, and I have disconnected it a couple times working on the airbag/steering wheel, but the battery didn't drain at those times.
Any suggestions as to what I'm doing wrong?
 

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The Bacon Hauler (‘12 Cop Charger)
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Sounds like a charging issue may be the culprit. That year model was under recall for their alternators a while back. Have you checked your VIN to see if there are any outstanding recalls on it?

If there is an alternator recall open on it, have that done first before further troubleshooting efforts are invested.
 

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Discussion Starter · #3 ·
Thanks. Is there a link on this site where I can check for recalls?

Never mind; found one. Looks like there were 2 recalls and 1 'campaign' against my VIN, none for the alternator.

Something I just remembered that I wanted to include in my original post. A couple hours after parking the car on Weds (after the battery replacement), I noticed both windows were down and the doors unlocked. I know I didn't leave it that way. I used the key on ACCY to raise the windows and re-locked the car.
My car has the 'auto down' window feature activated by the remote, so I'm thinking something caused the windows to go down and whatever that was may have drained the battery?
Its still on the charger, I'll let know know what happens.
 

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The Bacon Hauler (‘12 Cop Charger)
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Never mind; found one. Looks like there were 2 recalls and 1 'campaign' against my VIN, none for the alternator.
You should still verify the charging system is doing its job before indicting the battery again.

Do you have a multimeter or some other way to get a reading of the charging system’s voltage while the engine is running?
 

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I’ve heard these horror stories before. I’d like to know wtf. Will a trickle charger help to maintain power while the exchange is made? What’s the best AGM replacement battery. It shouldn’t be this hard. Sold my 09 last month with the original battery.
 

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Discussion Starter · #7 ·
Just started the car; it was on the charger a little over 2 hours. With the engine running, I measured 14.5 VDC between the charging post and ground.
After shutting it off, I checked for any lights etc. that may be on including the trunk and didn't find anything.
I might start it tomorrow just for grins...
 

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Try leaving the battery on charge until the charger indicates it is fully charged. If it does not have an indicator leave it on charge for 24 hours. Frequently new batteries are not fully charged and many vehicles exhibit strange behaviors when the battery is not fully charged. Just a stab in the dark but worth a try.
 

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Discussion Starter · #10 ·
jtrotsky - no aftermarket stuff.
Rob - I'm trying to follow what happened last time I changed the battery in 2015. After charging for a while I drove to the dealer and while I don't know exactly what they did, I doubt they disconnected the battery or put a charger on it and after I took it back I never had an issue. (They might run it for a while, however, while checking the charging system.) I'll probably start it tomorrow and depending on what happens as next step I might leave it on charge for 24 hours as you suggest.
 

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The Bacon Hauler (‘12 Cop Charger)
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Yes, I do. With the engine running, would I just measure between the positive charging post under the hood and ground?
Yes, get a DC voltage reading there and another at the battery. Actually get several at the battery, touching the posts, the terminals, etc.

All the readings should be within 0.1 volts of each other. Anything larger indicates a problem

Just started the car; it was on the charger a little over 2 hours. With the engine running, I measured 14.5 VDC between the charging post and ground.
After shutting it off, I checked for any lights etc. that may be on including the trunk and didn't find anything.
I might start it tomorrow just for grins...
14.5v is more than I would expect for an idling car. If you had the headlights, A/C, rear defroster, and wipers all going when you measured that, I could see the car needing 14.5v. But it sounds like the battery was already low on charge so the PCM was amping up the alternators output to compensate.

After you have shut the car off for the last time tonight, cycle the headlights to bleed surface and then take a voltage reading on the battery charge. Before starting it in the morning, take another reading. Those two numbers should not be far apart, if any.

If there is a significant decrease in the voltage measured in the morning, you have a parasitic draw depleting the battery when the engine is off. Those will keep the battery in a perpetually undercharged state, and that will kill a battery quicker if it’s always asked to start the car without a full charge (12.6v)
 

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I’ve heard these horror stories before. I’d like to know wtf. Will a trickle charger help to maintain power while the exchange is made? What’s the best AGM replacement battery. It shouldn’t be this hard. Sold my 09 last month with the original battery.
I replaced my battery with a vented Bosch Platinum, H7/L4/94R. It is built with glass mat technology and lasts longer. Also, it has more cranking power than the OEM (800 CCA and 960 CA Reserve). It also comes with a 48-month free replacement warranty.

1007651
 

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Here is the battery replacement procedure:

Replacing your trunk-mounted battery is an easy project that takes very little time. Of course, you are dealing with batteries and electrical systems, so it is important to be careful, review proper safety procedures and manufacturer instructions.

Here's how to do it:

Required Tools

10mm Wrench
10mm Socket Wrench with Extension

Parts List

Vented, Top-Post Battery
Anti-Corrosion Fiber Washers
Battery Terminal Protector
Battery Replacement Instructions

1. Open the trunk and lift the base to expose the spare tire and battery compartment.
2. Remove the spare tire (if equipped) to gain additional battery access for safety.
3. Use the 10mm wrench to loosen the connector from the negative terminal. Carefully remove the black cable from the battery terminal and set it aside where it cannot reconnect with the battery.
4. Repeat step 4 with the connector on the positive terminal.
5. Remove the vent tube from the hole by the positive terminal.
6. Using the 10mm socket wrench with extension, remove the battery hold-down plate, followed by removal of the tie-strap that wraps around the side of the battery.
7. Being careful to avoid connecting or otherwise grounding the battery terminals, as well as to avoid any leaked battery acid or other chemicals, remove the original battery from the vehicle and dispose of it according to your local regulations.
8. Use the plug provided with the battery to close the vent port by the negative terminal, if necessary. This is the one farthest from the Challenger vent tube. For safety, be sure to leave all terminal covers on the battery until ready to connect the terminals.
9. Carefully place the new batter in the Challenger battery compartment, being careful to slide the base under the lip on the battery stand.
10. Secure the battery using the hold-down plate and tie strap.
11. Connect the vent tube to the unplugged battery vent port on the positive end of the battery. You will be using the existing parts. There should be a 90* elbow connector (black plastic) that is connected to a rubber hose that passes through the floor of the trunk, to the outside...this vents the hydrogen gas out of the trunk/ interior. Push the positive cable away from the battery to get some access to push the 90* elbow connector back into the vent port. The other end of the hose passes through the battery tray and through a rubber grommet in the floor of the trunk (to outside of the body).
You don't want hydrogen gas / sulfuric acid fumes building up inside the car.
12. Remove the positive terminal cover, install a positive anti-corrosion fiber washer (if desired), and connect the positive red battery cables, securing the connector with the 10mm wrench.
13. Remove the negative terminal cover, install a negative anti-corrosion fiber wash (if desired), and connect the black negative battery cable, securing the connector with the 10mm wrench.
14. If desired, spray battery terminal protector in accordance with the manufacturer’s directions – avoid inhalation and over-spray.
15. Replace the original red terminal cover over the positive terminal. If this does not fit, an appropriate after-market cover is recommended for safety.
16. Close up the trunk floor and start your car. You are done!

See photos:

http://vanderbiltautogroup.com/2013/03/20/challenger-battery-replacement/

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Discussion Starter · #14 ·
Thanks, Cuda. So there's nothing in the procedure related to re-setting anything? I noticed that my radio presets were still there but I had to re-set the clock.
In my experience with this specific vehicle, twice now, something got turned on or left on and drained the battery in a couple days. I'll try the car later this morning and let you know what happens.
 

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Thanks, Cuda. So there's nothing in the procedure related to re-setting anything? I noticed that my radio presets were still there but I had to re-set the clock.
In my experience with this specific vehicle, twice now, something got turned on or left on and drained the battery in a couple days. I'll try the car later this morning and let you know what happens.
If there was something that needed resetting after a battery R&R the owners manual would cover this.

The problem reads more like a charging problem. While you checked the voltage at the battery with the engine running you probably checked it right after engine start. My limited experience with a bad charging system has been mixed. In one case -- not my vehicle but one I came upon in a dealer service bay -- the alternator started out strong but in just a few minutes was not putting out enough electricity to meet the vehicle's needs and after another minute or two of the vehicle and engine manifesting various issues the engine died.

With one of my cars the battery voltage started out ok not quite 14V. But after some minutes (~30) of driving around -- in the day time -- I noticed the battery voltage was getting close to 12V. Realizing this was not good I made a dash for the dealer and made it with no problem. Left car and tech confirmed later the alternator was bad.

But with the both windows down and the doors unlocked, while that might be the result of a low battery, it might also be due to a problem with some electrical component in the car's door lock/window circuit. Some years ago I had a car manifest odd behavior with the passenger window failing to drop when it should or worse dropping normally when the door was open but going up once the door was open. At other times the doors would lock on their own shortly after driving off from a cold start. I'd push the unlock button on the dash but often the doors would lock again on their own.

Could have been water in the door but it wasn't. It was a bad door lock controller. Now this in my car's case never affected the battery but if something like this went bad in such a way it kept part of the car's security system alive and powered up this would drain a healthy battery in no time.

With some cars there can be a problem with water in the wet side of the door getting into the dry side of the door -- the two "sides" being separated by a water barrier, a membrane. If this can happen a 10+ year old car is certainly a candidate to develop this problem. The membrane ages. If this water problem exists door lock and window gremlins can appear.
 

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Discussion Starter · #16 ·
Nuke - I got your reply about 4 hours after I posted my measurement of 14.5 volts, so I got another reading at that time; 11.47 volts at the post under hood (not running, no charger). So that was last night about 4:30 pm my time.
This morning the car unlocked with the remote so I immediately took a measurement: 11.26 volts (9 am my time). This was with the headlights on as it was within the 30 seconds or so that they come on after unlocking the car.
Car started fine. Let it run 10 minutes and took a reading after shutdown: 12.2 volts.
I decided to put it back on the charger to make sure it was fully charged; after 2 hours on the charger the reading was 12.3 volts.
I'll leave it over night and check it again tomorrow.

BTW, regarding battery life, I live in Phoenix AZ and I've never got more than 3 years out of a battery. I attribute the 5 years I got out of both the OEM and first replacement batteries to the fact that it resides in the trunk.
Rockster - I can't read voltage in my car and my next trip is Weds (appointment) so if the voltage is about 12 volts tomorrow am I'll leave it and check it/start the car on Weds. I'll check it again after I get back to see if there was a drop. Regarding your comment about moisture, I acknowledge anything is possible but we haven't had any rain in literally 90 days.
 

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The Bacon Hauler (‘12 Cop Charger)
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Something ain’t stirring the kool-aid here. A battery with only 11.26v should not be able to start the engine. Where was that measurement taken, under the hood?

Also, keep in mind a fully charged battery will have 12.6v (2.1v per internal plate; 3 plates total hooked up in serial fashion). 12.2v is considered an undercharged battery, and continually asking the battery to start the engine when undercharged will kill it very quickly.
 

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The Bacon Hauler (‘12 Cop Charger)
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Should power be maintained to the car while changing the battery? Will this make a difference?
no difference with this issue.

How handy are you with that multimeter? If you’re pretty handy with it, use it to check current draw at the battery hot connection while engine is not running and ignition is in OFF position.

Anything more than 500 mV is a problem and will likely have to be tracked down and addressed to resolve this problem.
 
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Discussion Starter · #20 ·
Yes, all measurements were taken at the charging post under the hood. Tomorrow am I will check current draw.
Is that merely measuring current between the positive battery post and ground?
 
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