[hellsop]

True or not, why go through that effort? More capacity for what? The 12V doesn't turn the gas engine, it just boot's up the computer systems. Go with the standard AGM battery. Don't forget to reattach the vent tube.

All it would likely impact in the long run is how many times one can push the radio power button to turn the music back on every 10 minutes before the car can't start again.

 

[vap3]

True or not, why go through that effort? More capacity for what? The 12V doesn't turn the gas engine, it just boot's up the computer systems. Go with the standard AGM battery. Don't forget to reattach the vent tube.

your right I'm just getting greedy when I just wanna idle in 12 volt mode versus idle at park.

I think I found it!
MotoMaster CanadianTire not a bad price!

Since my 2012 volt is over 11 years old, I'll be sure to take a cold reading after 24 hours on its original 12 volt battery!

 

[hellsop]

your right I'm just getting greedy when I just wanna idle in 12 volt mode versus idle at park.

What gains? The APM will just have to charge the aux battery back up again, so it might as well do the "idle" from itself in the first place and "idle" means you get climate control as well as listening to the radio. (Heater and AC don't work in Service Mode because those run off the HV system, which won't be connected.)

 

[Steverino]

your right I'm just getting greedy when I just wanna idle in 12 volt mode versus idle at park.

why go at this half hearted, maybe add two or three more 12V AGM's back there? Sure, extra work for no real gain but you'll feel better, lol

Under the same "more must be better", I would also add extra A/C capacity

 

[sbachman7117]

why go at this half hearted, maybe add two or three more 12V AGM's back there? Sure, extra work for no real gain but you'll feel better, lol

That's all good fun, and I think I understand that more "capacity" (energy) is not necessarily going to be needed. But what about more voltage?
I ask because I'm trying to determine the cause of "Initializing, Wait to Shift" issues. That DIC message haunts my dreams. I've seen it for years on my 2011; mostly in cold or really hot weather, but lately even in mild temperatures. Based on my experience with it, I've come to expect that the very appearance of it on the display indicates a problem. If it lasts more than a second or two, the car is not going to allow propulsion. If it goes away quickly, you're okay and the computers all eventually synched up and decided to play nice. But the fact that it appears at all (I THINK) is a result of some or all of the computers (modules) not getting as much voltage as they desire.
I bought a new H5(47) size AGM battery from Costco about a month ago. It didn't consistently stop the problem, so I checked the voltage and it was often around 12.5V with the negative terminal disconnected. I called Interstate and spoke with a helpful engineer who confirmed what Google had told me earlier: New off-the-shelf AGM batteries should read 12.8V+ at open circuit. I checked my cheap meter against my neighbor's Fluke and mine was within .05 volts. So I went back to Costco to swap my battery. Oddly, all 5 batteries on their shelf read 12.53v!
This made me wonder if all AGM batteries deliver enough voltage, even when new, to satisfy older Volts with likely connection point corrosion (=resistance=voltage drop.) I'm thinking that, independent of the energy capacity, I need a battery that has 12.8+ voltage when close to fully charged and not under load.
There are some good threads or this forum about chasing down and improving ground points, which can be responsible for voltage drops. I've recently gone down that path and hopefully improved things, but I didn't find any obviously compromised ground points, so I'm not sure where the presumed voltage drop is occurring.
So anyway, getting to the point: Have others closely monitored voltage and also concluded that close to 13V is the safe-range for starting older Volts, and that less than 12.5V is the danger-zone?
Thanks!

 

[hellsop]

Looks like Costco isn't maintaining the AGMs any differently from the flooded batteries. If you worry about that, maybe stop buying them there.

 

[sbachman7117]

Looks like Costco isn't maintaining the AGMs any differently from the flooded batteries. If you worry about that, maybe stop buying them there.

Yeah, I returned mine instead of swapping it when I saw that all of the ones on the rack were below spec on voltage. I'm limping along on a spare non-AGM battery right now (it read 12.8v), until I find an AGM that reads 13v+. The Costco supervisor said she was going to check with the Interstate rep. I'll call her tomorrow and see if she learned anything. I hope my local Costco gets it worked out, since they have a good warranty and their price is decent.

 

[Cloudnine]

Steverino, thanks for this sticky post. I replaced my 10 yo original battery today. Nothing was very wrong, although the displays would occasionally freeze and I got a "fob not detected" error message twice. That was enough to have me get out my wallet and buy a RockAuto AC-Delco AGM. We will see whether that makes any difference.

Anyway, the replacement process only took about 45 minutes with some interruptions, but no blood our bad words, so I do appreciate your postings on this topic.

 

[Steverino]

Anyway, the replacement process only took about 45 minutes with some interruptions, but no blood our bad words, so I do appreciate your postings on this topic.

I've gotten faster after screwing up and having replace the 12V battery twice, Cloudnine. I killed the first new install by not keeping the car on an AGM battery tender during the long Covid shutdown, grr. Just me being stupid. As with many things, the second replacement went faster. And now I have a CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer that I engage when the car sits for a few weeks. I have it's two eyelet leads attached to the terminal screws so I only need to snap in the unit and plug in the extension cord. Very convenient. Only downside is it costs about half as much as a new battery.

 

[vap3]

i heard you need to reset the software when replacing the 12 volt battery, so when changing it I should tender the current 12 volt so i don't lose power right?

 

[JuneBug]

i heard you need to reset the software when replacing the 12 volt battery, so when changing it I should tender the current 12 volt so i don't lose power right?

No, absolutely not. I didn’t lose any settings when I changed my 12 volt. The only things affected were the compass and tpms readings. They reset after driving a couple of blocks.

 

[wordptom]

i heard you need to reset the software when replacing the 12 volt battery, so when changing it I should tender the current 12 volt so i don't lose power right?

Many Volt drivers report no issues, no resets at all when the 12-volt battery is changed. I had only one.

In the fall of 2022 I thought it prudent to have my GM dealer install in my 2012 Volt a new 12-Volt AGM battery (the original battery had been serving me well for over 10 years, but I was about to start on a 4,000 mile road trip). As I drove to the end of the dealer’s lot that Wednesday afternoon (perhaps about a half-hour after the battery had been installed), I noticed the clock read 12:31 am, so I corrected the time of day setting. I didn’t check the configuration menu to see if any other personalized settings had been changed, but everything else seemed normal. Two days later as I started my Volt (it was then Friday, August 12, 2022), I noticed the date said Sunday, June 26, 2011, so I updated that, too.

IOW, changing the 12-volt battery in August of 2022 reset my 2012 Volt’s center console display clock to midnight on a day in June of 2011.

 

[Ergolad]

For those dealing with a 12V in 2025, I just replaced my original 2013. Car was totally dead, started easily with a jump, but 12V wouldn’t hold a charge. I looked at ordering from the often recommended RockAuto, which would have run about $200 all told. Considered that, waiting for delivery, returning the core, and using all the wrong tools for the job, OR go to my dealer. For $75 more, AAA (which I already pay for and rarely use), came out and did the job in less than 30 mins. They had a compatible AMG battery w/ 3 yr warranty. I got the tech on the phone before he came out to make sure the service call was worth it. He confirmed stock, but was a little hesitant, needing to make sure that he could service a 2013 Volt. Turns out he could and quoted me the total of $275. Seemed like an extra $75 well spent. And… the tech tolerated me watching the whole process, so my inner geek was satisfied.