So I have a handheld vac that has internal rechargeable batteries and charging stand and it won't hold a charge anymore. I opened it up easy and it has several sets of unbranded rechargeable AA batteries where two batteries are in parallel with some soldering between their ends with a small rectangular piece of metal soldered to each and then wires going to next set in series. I don't have much experience with this but feel like it would be an easy project to improve my skills and include my kids on. Can someone more knowledgeable confirm this should be an easy project and maybe recommend which inexpensive soldering iron, solder, etc... I should use and any tips you might have. Am I going to blow up the batteries or something with the heat from soldering iron if not careful and need face mask or something? Ha. I was planning to just buy random AA rechargeables. I think the current ones are only 1400mah so the new ones could be higher and increase runtime too.... Thanks.