I found a source for a much larger, single Lipo battery, http://www.all-battery.com/li-ion3-7v15600mahrechargeablebattery31059.aspx. Assuming this is legit, which I need to check. This battery would be one 57.72 Wh battery, replacing two 24.42 Wh batteries. This would give a better battery life and eliminates one boost converter module. I think that I will order one of these as one of Adafruit solar lipo management modules and make sure that they work without dying before I put things together.