Another stupid question, from what I have seen the battery is the key to many problems. Does the HHR need a better alternator? More amps?
just a wild Quess? Don’t know of any options for different alternators?

 

It looks like the electronics are very sensitive to voltage loss.
I would think the 130 amps the alternator can put out is sufficient.
Going below 12.4 volts when the battery is at rest looks to be a warning sign that sensors and the like can act up.

 

I asked that same question a few years back when replacing the alternator and they range from 115 amps to 130
https://www.rockauto.com/en/catalog/...generator,2412

I opted for the 130 amp unit, just because I could. Now That HHR was my 2007 2.2 litre, no extra electronics or towing/trailer harness.

Now my 2011 2.4 litre shows only 130 amp units listed

https://www.rockauto.com/en/catalog/...generator,2412

 

Never new the amps, 130 should be enough for sure. One thing I learned from working on aircraft is that maybe you need to replace all electrical components. Not sure if it has a voltage regulator, ? Probably a module now days, but still a regulator. I have chased this mouse more than once, never believed it. Until I tried it. It may seem like a shotgun approach, but solved a lot of problems. The service manuals recommended this, but I didn’t believe it. Why replace something that works? Beats me. Could save money and trouble on the long road
just my two cents which is about as worthless as stock.
the new toilet paper is stocks

 

Computer, no regulator. That funny black plastic ring around the battery ground cable is a current sensor the software constantly varies the alternator exciter depending on current demand.

 

If you are gonna leave it parked for an extended periods of time, invest in a decent Battery MINDer®

I have a few, mine are the BM1500 units which are 1.5mA charge rate, then they float. Set it & forget it,

 

I got the HHR in 2014, and parked the Neon. Took the battery out, put it on a battery MINDer in the garage. Had it tested almost a year ago, has a dead cell. Moral of the story, even on a float charger, it won't last forever.

 

I hear ya. how long do you think it would have lasted if you did not have it on a MINDer ?

I got almost 11 years out of my HHR battery & it still worked good, but going into winter I didn't feel like pressing my luck.

 

It probably would not have lasted long at all.

 

I agree, once they are not activated, they begin the sulfation process.