OK, I know that I should've fixed the HHR long ago, but life gets in the way sometimes....I just kept putting off the original problem(s) Now I have no power, key stuck (until I just now remembered the removal button), shifter stuck in park...etc. I had not addressed the original problems back in 2016, and just drove it until the tags expired 12-1-15, when I started driving my 2500HD to work. I had assumed that I would fix the HHR once I had the time (after I retired 1-1-16). Health, finances, and major home repairs (never had the time before retiring...too tired after 60-70 hour work weeks). So, I parked it, kept it on trickle charge, and only started and drove it in the drive way a couple of times a month. Then, last month, the charger failed, but since I was in the midst of a rafter-down remodel of the bedroom, I failed to replace the charger until too late. Neither of my key pods would open the door (though I repaired both and replaced their batteries last summer, so I used my key to open the door and put the new 1.5amp trickle/maintainer in the car (plugged into the 12v dash receptacle). I heard some "relay"-type clicking sounds from under dash, or hood, for a few seconds, but they stopped before I could locate them. I checked for any functions at that time, but no lights or anything. Put the key in, and nothing worked either. Shifter wouldn't move, either. The key stuck as well. As it was dark-thirty, and the Zikas were in full bloom, I locked the doors with my spare key, and quit. This morning, the battery charger said the battery was up to charge (haven't verified with meter yet), and still nothing works. Removed the key. Started searching the forum for similar cases, and guess I'll have to crawl inside to open the tailgate (I assume the main fuse is blown?). Once I determine the main power situation, I'll proceed from there. Suggested steps? What was the underdash/underhood clicking when I plugged in the charger? Will hooking up (jumping with my truck) give me power (even if the main fuse is blown)? I'm going to unhook the trickle charger, and see if I even have minimal power for relays (isn't that about 10.5v)? I at least need to be able to unlock the shifter, so I can roll it out into the driveway or garage to work on it. Just checked: only have 2.25 volts to the underhood cable...therefore the main fuse is still good, battery dead. I'll hook up my truck, and see if any functionality returns. Just need to replace the battery and go from there?

 

I'd start with a new, fully charged battery. Probably all you'll need.

The "clicking" noise you heard is most likely a relay or something that is reacting to the low voltage. May have even been the park switch solenoid trying to engage.

 

X2 dead battery! Whilst you have the old one disconnected and removed, check all the ground wires and the fuse box halves for tightness! And remember don't close the rear hatch! and connect the positive first then the negative to avoid sparks ,shocks and damaged computers!

 

I read in the manual that 9v was needed to power relays, switches (not 10.5 as I mis-remembered), so I jumped the HHR, now running on alternator power, and drove it to my garage (not into, but at)- where I could more easily work on it. Before I shut it off, I opened the hatch! Once the engine was off, I tried the ignition and heard the clicking underdash, just as all power faded again. I'm going to try multiple stage recharging with my garage charger, to see if I can save the battery. I have brought two batteries back that way, one an Optima from 2.5v, and a lead-acid from 4v. Probably not in this case, but what can I lose? Thanks for the help!

 

Well ok give it the old college try! Then get the correct size battery! Some swear by the AGM batteries, I've had great service out of my now 6 year old AAA battery, but I'm keeping an eye open for a sale at Sears

 

It charged up to 12.3v after 4 charging cycles yesterday: 2 hours @ 15amps, then 2 hours @ 40amps (voltage up to 14v, no more), cooling for 2 hours, then 1 hour each at 15a then 40a again. This morning, after it sat for 14 hours, I used my fob to open the hatch (never took the battery out), and metered the voltage at 8.2v. I'll repeat this cycling for 3 days (as I have done in the past), and see if it comes back. Otherwise, I'm pricing new batteries...the cheapest I find is about $120 @ Wally world.

 

Before you spend that kind of money on an old technology battery, check out this thread, for a few more dollars you could have AGM. https://www.chevyhhr.net/forums/comm...battery-52505/

My AGM is going strong no hint of problems.

 

I told you people swear by AGM batteries! I'm leaning that way next battery, for sure!