4.5 amps sounds kind of high for a regular charge on 3300 packs. The way I understand it is the temp on a charge should not exceed 120 degrees. If your charging 3300 mah packs, I would think a 3.3, or 3.0 would be optimal. How low of a charge rate can you select with your piranha? Can it charge below 1.0 amp? You made just need to "form", or in this case, "reform" or "balance" your packs you've built. If you can charge them slowly at a .33 amp rate, it will take 10-12 hours, but it will balance all the cells in the pack. Do you have a temp probe or a non-contact thermometer?

When you say you "put it at" 3350. Do you pre-select the mahs when charging? You should be able to get up to 125% of the rated capacity on a charge before exceeding 120 degrees, or in this case, 4187 mahs.