I connected 2 6v batteries in series to be able to charge them with my nautilus 12v smart charger.
They are very, very large.
The problem is that the charger never stops, it always displays between 70 and 90%.
I have a small module that displays the capacity, it tells me that it is at 100%.
I got myself a 6v charger to see if the problem wouldn’t come from the fact that it’s in series. But still it does not display 100%, it loads and indicates between 80 and 100%.
I don’t know what else to do, leave my 12v charger until it stops on its own? I’m afraid of overcharging the batteries. I noticed that they boil. I went to check and it seems normal when they are almost full