I made a homemade 9.6 v battery pack with duracell 26500 mah Ni-MH batteries, using wire for the connections and shrink wrap to hold the pack together and I connected them together in series. I charged the battery pack correctly and it wasn't to hot after the charge so I decided to put it in my super sportster ep to give it a test fly. When I landed and took the battery out of the plane I noticed that some of the shrink wrap had melted and some of the coverings on the individual battery cells had burned off. Is there any way that I can reduce the heat caused by this battery pack? Perhaps wrapping it in something before I cover it with shrink wrap? Any suggestions would be greatly appreciated. You can e-mail your suggestions to [email protected].

Thanks,

Strongman

Hi, welcome to RCU. You sound like you're very handy. I don't know the plane or what size cells, but it sounds like they are too small or at least can't handle the current required by your set-up. Shjrinking or wrapping will make things worse since the heat is coming from inside the cells.

If you have any idea what amps the plane pulls or what the specific size cells are then a comparison may show that the cells are lower than required. I'm guessing the battery ran out very quickly? like 6 minutes or less. Perhaps propping down, gearing down, or dropping 1-2 cell will lower the current draw.

It definitely sounds like the amp current is more than the batteries can handle.

What can I do to reduce the heat? The flight time was around 10 minutes. You can look the Super Sportster EP up on greatplanes.com for the specifications.

The cells were AA size. I used 8 of them connected in a series hence the 9.6v battery pack.

There's your problem, AA cells cannot be used for anywhere near the amperage you are asking of them, you need high discharge capable, low internal resistance Nimh cells and the AA size is anything but that, those cells are only suitable for powering electronics where long duration at low current is the goal.
Pete

As pilotpete2 said: AA-batteries are not for motor-use. Motorbatteries are typical "fat", not "tiny" shaped. Look for KAN or GP-cells.

Anyway: don`t forget to make sure there is enough airflow over all the components in the driveline; Motor, ESC and batteries have to be cooled by a proper airflow through the fuse. Good inlets is not enough, remember some good outlets behind the gadgets. And never run the setup static on the ground for more than a few seconds...