battery back up

Dan,

I'm assuming you intend to connect the packs in parallel, right? ALL the receiver's servo connections for power (battery plus & minus) are connected in parallel, with the plus & minus battery pins on the RX.

In other words, connecting a battery pack can be done on any RX channel.....provided polarity and proper pin connections are noted.

With the relatively cheap prices of 2000+ma/h "AA" cells however, unless you needed a few ounces for model balance with an extra pack, perhaps it would be prudent to simply purchase a larger capacity pack for the Katana.

With anything...a good practice is....fewer components to fail...mean fewer failures...regarding R/C airplanes, that usually equates to fewer "mishaps".

I also have a problem charging packs in parallel, as the load (internal resistance) between different packs is not the same, and the packs will charge unevenly.

Mike

| In other words, connecting a battery pack can be done on any RX | channel...

Yup. Plug them into any channel. Use a Y connector if you have to.

| With the relatively cheap prices of 2000+ma/h "AA" cells however, | unless you needed a few ounces for model balance with an extra pack, | perhaps it would be prudent to simply purchase a larger capacity | pack for the Katana.

Actually, two packs gives you a nice backup. One pack can fail (they almost always fail open rather than having a cell short out) and you've still got power.

| I also have a problem charging packs in parallel, as the load | (internal resistance) between different packs is not the same, and | the packs will charge unevenly.

Yes -- if you set up your plane with two NiCd/NiMH receiver packs, you'll need to charge them seperately. This means two charge jacks, and two switches.

I have several large birds set up like this

If you run out of empty ports on the RX plug a "Y" connector into one position, plug the servo into one leg of the "Y" and your switch into the other leg

bob