Any battery gurus

Truck has been sitting for years and for some reason I didn't pull the battery. It's beyond dead.
Google shows AGM batteries can be revived by running them in a parallel with a charger and another good battery. For some people you have to do this a few times. For me I'm on my 10th+ time with no luck but I think it's the charger i'm using. It won't get past 7v. I understand the charger is thinking it's likely a 6v battery but even when it reads as being fully charged it quickly drops back to 7v




Anyone else have any advice?

 

That's not a guaranteed fix for all batteries. You said "for years" which is probably well past the point of resuscitation. The idea is that most chargers won't charge if the target battery is almost completely flat. The second battery is primarily there to trick the charger. However it does take some current to even attempt this, your charger might be marginal on output.

 

Use an old style charger if available, the new ones are too smart. They sense the dead battery somehow.

 

Buy a new battery.

Ran AGMs for years in my Z cars and Miatas. While they are good, and meet a specific purpose, they are not lifetime, nor magical.

 

I'll add this. If the battery was frozen while at zero charge the chances of a future are greatly diminished. That's in addition to the other factors.

 

That looks like a scene from one of the Back to the Future movies for rigging power for the Flux Capacitor.....yikes!!

 

I had success bringing an optima battery back from the dead using one of the newer smart chargers. The trick was I had to set the charger to assume it was a 6v battery until it was charged and then tell the charger that it was a 12v battery. It then charged to 12v and all was good. The instructions on the charger actually mentioned doing this for fully discharged batteries. The charger I used was a noco genius charger. Battery lasted a good 2 years after this. The battery probably would have lasted longer but my alternator started to die which caused the battery to never fully charge and that eventually killed the battery.

 

New battery as a person who forgets batteries all the time.

I am getting better only had to buy 3 since May