A 26D is 2600maH and a 35E is 3500maH. You will reduce your batteries capacity by 0.90AH.

Even though you're only doing one cell, the battery capacity is determined by its weakest cell group. This cell will pull the other cells around down faster, and the group that it's in will hit the low voltage limit sooner, and shut the battery down. When you recharge it, the group will spring back to full voltage but will again be the first group to run out. The math is easy. It's 900AH lower,