Step-up dc-dc converter

[FB]

I need some help in creating a dc-dc converter with the following specifications:

Input voltage: 1.2V
Output voltage: 9.6V
Output current: 3.5A

The input source will be one rechargable NiMH D-cell with a capacity of 7000mAh.

I know this is a lot to ask from a single NiMH cell, but it can easily handle 30A.

 

[electricuwe]

I would like to suggest to consider an alternative approach:

For a step-up ratio from 1.2 V to 9.6 V a simple boost converter would require a large inductor. A converter using a transformer with mid-tap on the primary would a better approach. This would still be a challange to an experienced designer. What are the disadvantages of connecting more smaller cells in series and using a simple boost converter?

 

[FB]

At the moment I use 8 cells connected in series.

The reason why I would like to use one larger cell instead is simply that it's much cheaper. I can get a single 7000mAh cell for about 1/5 the price of an accu pack with 8 cells.