[Blobby]

Originally Posted by Gunkk

Unlike flooded cell batteries, AGM batteries recharge VERY SLOWLY. Driving the car 1+ hr may not charge it fully. Ask me how I know. Get a proper AGM battery tender on the car. If you have excessive parasitic drain, an AGM tender might throw a false positive error. If so, disconnect the negative terminal and charge the battery directly with the tender without the car drawing power.

One of these can help avoid with this as well as avoid premature battery death due to parasitic drain if the car sits for extended periods. Just make sure you don't fully close the trunk after you disconnect the battery or you'll be popping the lid off the door handle to get back in.

My battery charger is on loan to my parents atm. It’s not the cheapest one Walmart sells, but definitely not the most expensive. No clue if it was advertised for AGM. Do AGMs need a specific charger?

The fella at Oriley said their warranty requirements are pretty nonexistent unless you have a clear habit of killing batteries. I was afraid they’d want to blame the car and not warranty it.

[Gunkk]

Originally Posted by Blobby

My battery charger is on loan to my parents atm. It’s not the cheapest one Walmart sells, but definitely not the most expensive. No clue if it was advertised for AGM. Do AGMs need a specific charger?

Yes you want an AGM-capable charger/tender with a selectable mode and/or indicator light on it. A regular charger can do "bad things(TM)" to an AGM battery.

I use this one because I also own two non-AGM cars.

https://www.amazon.com/gp/product/B00CD44RQO/

Caveats: It doesn't like the 20mA the car drains while sleeping, and the tender itself can keep the car awake in my experience, raising the drain to 200+mA. So I use the knife switch to disconnect the car while it's on the tender. I'm sure there are other models out there more tolerant of the car's natural "drain-while-asleep".

The fella at Oriley said their warranty requirements are pretty nonexistent unless you have a clear habit of killing batteries. I was afraid they’d want to blame the car and not warranty it.

When I replaced my OEM battery in my car last year, I thought the replacement was bad at first because it couldn't seem to hold a charge ... but it just needed to be charged fully (and driving 2 hrs didn't do it). After 24 or so hrs on the tender it was obvious it needed to be charged. Since then has been just fine.

[ctrlz]

Originally Posted by Gunkk

I use this one because I also own two non-AGM cars.

https://www.amazon.com/gp/product/B00CD44RQO/

You can get a NOCO 10 amp which doubles as a maintainer for $20 more. NOCO chargers are always highly rated.

[Blobby]

Update. New batt installed. First start attempt failed. Turned over once and stopped. Second attempt cranked up. Orileys said the alt tested good but the starter failed. And I assume the starter is not covered under powertrain warranty.

Edit: 1.5 hrs on the charger and it’s at 1.5 amps. It started at 15A. It started around 80% and still says the same. Wonder how accurate that meter is.

[ctrlz]

Originally Posted by Blobby

No attempt to crank, lights dim and flickering, kept getting worse, wipers started wiping incredibly slowly. Tried to jump under hood and no change. Tail lights and DRL stayed on constantly, dim, and flickering. Got the battery exposed and jumped from there. It tried to turn over but no joy. Electricals came back tho. Acted normal.

There's a bit too much going on here for this to be a bad starter.
A bad starter relay can give you difficulty cranking. But once started, that goes out of circuit and everything should be ok. Dim lights and slow wipers means something in circuit is dropping the voltage, or the voltage is already low (e.g. bad battery or alternator).

A new battery should be charged enough to start the car. The meter on the charger is not something I would trust. If you have a Harbor Freight nearby you can pick up their cheapie Cen-Tech $2 meter which is more than adequate to check voltages on your battery and charging system.

[IceGoaliePaul]

I've drained my battery several times over the past few months due to abnormal parasitic load. I have to remove the battery to charge it and I can tell you that the first start after reinstalling the battery always fails. It'll turn over for 0.5seconds and then stops. I assume it's aomething in the software.

[Blobby]

Originally Posted by ctrlz

There's a bit too much going on here for this to be a bad starter.
A bad starter relay can give you difficulty cranking. But once started, that goes out of circuit and everything should be ok. Dim lights and slow wipers means something in circuit is dropping the voltage, or the voltage is already low (e.g. bad battery or alternator).

A new battery should be charged enough to start the car. The meter on the charger is not something I would trust. If you have a Harbor Freight nearby you can pick up their cheapie Cen-Tech $2 meter which is more than adequate to check voltages on your battery and charging system.

Everything checks out good now. Running voltage, off voltage, starting enthusiasm. Could it be that the starter is going bad (heat soak issue) and damaged the battery? Maybe after multiple high draw starts, the alternator can’t keep up? Original battery lost confidence at 5 years. This one kicked the bucket at 6 mo.

[Gunkk]

Originally Posted by IceGoaliePaul

I can tell you that the first start after reinstalling the battery always fails. It'll turn over for 0.5seconds and then stops. I assume it's aomething in the software.

As someone who uses a knife switch (in my post #14 above) to completely disconnect battery from the car on a routine basis, I've seen this and also believe it to be a "design feature." I'm sure someone here more familiar with the sleep-state logic can chime in here but in layman's terms...

Normally when the car is off with a healthy battery connected, the anti-theft, remote key access part of the BCM, onstar and probably a few other computer modules are in a sleep state and draw about 20-30mA. In this state the car can be started with a single button press as we all know and expect.

But when battery power is completely disconnected, all of the car's modules are obviously completely offline and dead. When battery power is first reconnected to the car (or via jumper cable), you will notice that some of the relays click and interior lights come on, HMI backlight may light up, etc. But the car isn't fully awake yet and won't like to go from completely offline to completely car-start-and-run in one button press. It has to wake up first. Trying to start the car will do it, but I've seen some instability with this approach.

So what I found to be the best way to start the car after a power outage is:

1. Connect battery power to the car.
2. With your foot OFF the brake pedal, hold the start button for 5-6 seconds until the car wakes up. Release the button. Wait another 10 or so seconds until the dash animation stops. You will see a steady yellow check engine light and any other typical "key on engine off" lights. The car is now in key-on-diagnostic mode.
3. Put foot on the brake and start the car as you would normally. CEL light should go out (presuming you don't have any active codes).

[ctrlz]

Originally Posted by Blobby

Could it be that the starter is going bad (heat soak issue) and damaged the battery? Maybe after multiple high draw starts, the alternator can’t keep up? Original battery lost confidence at 5 years. This one kicked the bucket at 6 mo.

I don't think there have been that many reports of "bad" starters here. The heat soak issue has been attributed to poor grounding of the starter causing it to pull more amps than usual, or not crank at all. That's a connection issue, not a real starter issue.
I think the start relay is internal to the starter. If the contacts on that go bad (no reports of that), then you get reluctant cranking every time.

I think the only way a bad starter could damage a battery is if it contained a dead short.

Assuming you had another bad battery and replacing it solved 95% of your issues, I would just keep an eye on things. I daily drive my car and it takes a bit longer to start maybe 1 out of 30 times. it is not 100% perfect.