[Gunkk]

Originally Posted by tommcd24

Does this seem legit that my battery could truly have drained that much?

Yes. Our cars will draw ~20mA or so while asleep. 70 Amp-hours / 0.02A = 20 weeks by the numbers, but in reality you're more likely to get only half that before the battery can't start the car. So yeah 10-12 weeks will usually kill a completely charged battery.

Re-charging by driving doesn't work well because AGM. Not like the old flooded cells. You really need to get a good AGM charger/tender on it for a couple days.

Is my NOCO underpowered or do the front battery terminals have too much resistance or something for trickle charging?

Probably not, but it might take a week to completely charge a dead battery, or a few days to top up a half-dead one. My 5 amp Ctek needs about 48 hrs to charge a dead AGM battery. About half that for a regular flooded cell. So your 2 amp NOCO would need 250% that time... close to a full week for a Camaro.

In the meantime, if anyone has "been there, done that" and has pointers for me, I'd appreciate it.

My Ctek doesn't play well with the modules in the car. If one of the modules is awake and pulling 100-250mA during the "health check" cycle, the CTEK will see the high drain and error out, thinking the battery has a short. You can watch the car go to sleep by measuring voltage drop across the fuses in the front engine bay fuse box using a chart. I've seen some odd sleep/wakeup behavior with the modules in my car when there's a stored CEL, and your remote unlock Chevy app can obviously also wake up the car. Using the Ctek on the front posts seemed to want to trigger more weirdness. Might be the desulfate cycle, might not.

I wasn't interested in troubleshooting all of that BS, so I got one of these old-school battery disconnects. And I disconnect the car from the battery while the tender is clamped to the battery. Just have to lay a towel over the latch to keep the trunk ajar so I can get back in the car without having to take apart the door handle. The vert's trunk configuration makes access to the battery terminals a breeze. No wrestling with trunk interior panels required. Disconnects are not for everyone, but the Ctek works just fine with the switch. The Ctek's dual mode is also good for the 3 other family cars without AGM batteries. It's surprising sometimes how a daily driver battery can drain down after a few weeks of nothing but a few <5 min trips.