This charger is very poor with respect blocks 9 V main function for which I had bought (square 9V batteries for my many musical instruments). The discharge function is not provided for these batteries. Once the full stack, continuous load (no switching to trickle charge for these batteries). Nothing is clear in the manual, we do not know if you can put batteries already used and not unloaded recharge, I am very disappointed with my purchase, I did it based on comments, So that would have been more precise and avoid me this misstep.