Hello,
I've posted the draft battery model reference manual. You can find it here, under "Photovoltaic Models":
sam.nrel.gov/performance
Thanks for the suggestion to add a tag for battery-related support questions. We chose not to because technically the battery model is part of SAM's photovoltaic performance model (the CSP models have a separate model for thermal energy storage), but perhaps PV with storage is a big enough topic to merit its own tag.
Best regards,
Paul.