Yaesu folks want you to buy the 9.6 vdc battery pack and do not recommend you attempt to charge batts. from the included "stock" alkaline pack.
They have even rigged the pack so it will not charge. Poking around with a VOM I discovered that there is a way to make the alkaline pack charge. Pull out the pack and peel the tape off of the end with the wires.
You will find 2 red wires, 2 black wires and a green wire. cut and insulate the green wire. Put Nicads or NiMh Batteries in the the pack and set up the charge time circut. I have done this with no problem. This keeps you from breaking the bank buying alkaline cells and give you portable batt. power.
Two words of caution:
As with all mods, the warranty is affected, do so at your own risk.
By during this mod you have now disabled the protection feature and can re-charge alkaline batts.
This could be dangerous and messy...be careful not to do that. Of course with this mod, you will have little reason to use alkaline cells.
Enjoy. I look forward to hearing about other ft-817 mods for this nifty little rig.