New Costco Battery, run down to 1.9 Volts, is it damaged?

[samven]

You can get a pigtail with an SAE connector that you can leave connected to the battery, then you just plug the charger into the pigtail and into the wall. And you can get pigtails with SAE to Clamps and SAE to cigar lighter so you can use it on other batteries. If you want to leave a charger hardwired under the hood you will need to look for a marine grade on board charger that can tolerate being splashed and handle the constant vibration.

 

[y_p_w]

When you buy a new battery the voltage may look OK but it is not charged fully. If you then drive a short distance home and park it, it will drain. Its likely that the 2v you see when connecting your charger is not the true battery voltage. If its still connected in the car it still has a load on it. If you disconnect it and give it an hour to recover you will be able to measure the real battery voltage although I doubt that it will come up to more than 6v or about 1v/cell. It may still take a charge but it has been damaged and will never come back to 100% and when connected will drain even faster than before. If you take it back and they give you a new battery make sure you put it on a charger when you get home and leave it on for 4 or 5 hrs min. and then recharge at least weekly when in hibernation or like you were planning disconnect it. Running the engine at high idle for 15 min wont charge a dead battery, it may leave a surface charge that reads 12v but that will be gone in a few hours and your battery will continue to sulfate.

There's not much of a voltage drop due to load when the engine is off. I suppose it might be possible if there's something like a massive competition car stereo setup, no way would a normal parasitic load (even something like map lights on) really cause that much of a drop in voltage. It should be pretty close to being an open circuit voltage.

The internal resistance of a lead acid battery is somewhere around 10 milliohms. An incandescent map light on might be around 800 millions, and that might take over a day to drain down a battery.

 

[samven]

There's not much of a voltage drop due to load when the engine is off. I suppose it might be possible if there's something like a massive competition car stereo setup, no way would a normal parasitic load (even something like map lights on) really cause that much of a drop in voltage. It should be pretty close to being an open circuit voltage.

The internal resistance of a lead acid battery is somewhere around 10 milliohms. An incandescent map light on might be around 800 millions, and that might take over a day to drain down a battery.

There is not much of any voltage drop when the engine is off with a charged battery that can supply 1000x the current that is being requested but if the battery is so dead it cant supply 75 milliamps but has an open ckt voltage of 6 or 7 volts and you put a 50 milliamp load on it the voltage will drop to near zero. Its just like the voltage drop you see on a fully charged battery when you hit the starter. The battery can provide 600 or 700 CCA but put a 200 amp load on it and the voltage drops to 10v until the starter disengages and the voltage bounces back.

 

[y_p_w]

There is not much of any voltage drop when the engine is off with a charged battery that can supply 1000x the current that is being requested but if the battery is so dead it cant supply 75 milliamps but has an open ckt voltage of 6 or 7 volts and you put a 50 milliamp load on it the voltage will drop to near zero. Its just like the voltage drop you see on a fully charged battery when you hit the starter. The battery can provide 600 or 700 CCA but put a 200 amp load on it and the voltage drops to 10v until the starter disengages and the voltage bounces back.

I thought that the discussion was about the voltage around 2V as read out by a charger before it was enabled to charge - obviously not when it's starting. My 3A/12A charger does that. When initially connected all it does is read out the voltage. I have to select both the charging current and then wet or AGM, and then it give a little click before it starts. Then it just flashes between just 12 (assuming that it's charging a 12V battery) and then an estimated charge percentage.

I've got a charger that would probably start charging it at 2V, but thinking it was a 6V battery and then stop at the set voltage for a 6V battery. There's no 6V/12V setting/switch. That would be rather interesting what it would do.