Dead battery charging attempt
Looking for some advice, I have a pair of 12v lead acid batteries which are reading 2.5v. I appreciate that they're likely junk at this point. I have an old industrial charger with an infinitely variable voltage adjustment. What would be the best voltage to set it at, to see if these will take a charge? It also has an ammeter, so I can keep an eye on both gauges for any changes... and again, I understand that they will likely need to be replaced! Thanks in advance.