Custom size lipo battery in 1S2P configuration that fits in 4xAA battery compartment and can be used in many projects!
Dimentions are 58x51x13.7mm, 120mm long leads with JST PH 2.0 connector (fits Adafruit Powerboost, Kite's boards and many other boards) and capacity is 5000+mAh - tested and confirmed.
Price per battery (inside a solar light) is €25.00 and priority shipping is €1.99 (+€0.99 for additional battery).
Order from Dextech's store: https://bllutech.com/products/4aa-size-5000-mah-lipo-battery
Discussion in the forums: http://www.sudomod.com/forum/viewtopic.php?f=7&t=2320