Originally Posted by cmarti
Please give us more information about your double battery mod and also post the link for the eBay auction. (Or provide your eBay ID)
I intended to make all information available, however hesitating in give out instructions on the double battery mod, because this mod involving soldering (heat up) the lithium battery tabs without protection circuit and can be very dangerous if anything goes wrong,
For the double battery mod you will need:
1. To arrange the mSATA SSD on the side, existing zif cable will need to be extended by a straight zif cable, I did it with a hot plate & solder paste, Soldering iron will be difficult.
2. Get two piece of stock lithium ion battery, fully discharge them to the same voltage under 3.5V. took off the protection circuit and soldering their tabs together, then connect to one protection circuit. Try to avoid lithium polymer batteries, they have higher internal resistance and are more prone to damage & dangerous than the metal casing lithium ion battery. I did the soldering work with eye goggles on, a bucket of sand underneath my desk, windows open - in case something happen, I can throw the bomb out of the window. :-)
Since the mSATA adapter available now is not of that high quality, I am thinking about make a new adapter with SSD in horizontal position, this will provide space for a single high capacity battery, and even room for a build in head Amp. TA6120 is a good candidate, I should be able to patch up rockbox so config Wolfson DAC output as differential lineout, which can be fed into TA6120's differential line-in without the need of any coupling capacitor. Volume control can also be done through TA6120's i2c interface, by modifying rockbox firmware.
My ebay ID is windandbeyond. Thanks.