For those that may need it. Here is a link to the updated DA manual which gives the minimum battery requirements. I also have a DA50 mounting template.

The manual is also available from TBM (TroyBuiltModels)

http://www.hiddenhangarrc.com/da/

From this manual it states:

We recommend a 1500 mAh or larger pack. With this size pack, the ignition pack should last longer than your receiver pack will. If a meter shows 5.0 volts or less, don’t fly. Re-charge. Use a 5.2 to 6.0 volt regulator on packs rated above 6.0 volts.

So, like Exeter, I'm also curious about the size 4.8 pack you are replacing. I use Fromeco Li-ION's regulated to 5.2 volts on mine