6 volt deep cycle

[Britcanuck]

One of the 6 volt deep cycle batteries from my Rv is on the bench. It is obviously sulfated as I cannot get it to accept a charge with an older 'dumb' 6v charger. When connected to a Schumacher smart charger is shows in the display as a 12 volt battery. I started the charging procedure and after 10-15 mins it went into the desulfate mode. At this time I checked the voltage across the terminals and it was almost 17 volts and strong activity in the cells. It appears that the 6v battery thinks it's a 12v one but how can that be? I'm lost-any ideas-thanks.

 

[snoobler]

The resistance in the battery is so high even the slightest current causes a huge voltage spike.

That battery is done for.

 

[Britcanuck]

Thank you. Not what I wanted to hear but just like there is no sorta pregnant there is no sorta nearly dead.. At least I have the core value.