Battery Replacement
SARK-110 original battery model is PR-384160N or PL-403860; see the datasheet below. The basic specifications are the following:
Chemistry: Li-ion Polymer
Nominal Rated Voltage: 3.7V
Safe voltage range: 3 - 4.2V
Nominal Capacity: 940mAh
Dimensions: H=3.8mm W=41mm L=63mm
Connector: Molex 51021-0200 (pitch 1.25mm)
Operating Temperature: 0 ~45°C (Charging) / -10~60°C (Discharging)
There are some vendors of Li-Ion batteries offering similar batteries. These batteries are normally supplied without a connector, so it will require the original connector being cut off and re-joined to the new battery.
3.7V 1500mAh Li-Ion Polymer
This higher capacity battery is slightly thicker than the original one, but it fits inside the SARK-110 housing.
Model: 504050
size: H=5mm W=40mm L=50mm
voltage: 3.7 V
capacity: 1500mAh, 2C discharge
Sources:
3.7V 1200mAh Li-Ion Polymer
This higher capacity battery offered by Adafruit is slightly thicker than the original one, but it fits inside the SARK-110 housing.
Model: LP-503062
size: H=5mm W=34mm L=62mm
voltage: 3.7 V
capacity: 1300mAh
Note that the provided connector is not compatible; also check shipping restrictions
Sources:
3.7V 1000mAh Li-Ion Polymer with JST 1.25mm Plug
This one includes the JST connector.
Model: LP-503450
size: H=5mm W=34mm L=50mm
voltage: 3.7 V
capacity: 1000mAh
Sources: