Alkaline Manganes Dioxide Military Battery BA-3791/U
 Alkaline battery  non-rechargeable
The batteries exceed Military Standards MIL-B-49030(EL). 
The intercellular connections are done by resistance welding and were assembled in a molded plastic case.
Replacement for TNC-2188, see also BB2791 SMART Battery Replacement.
Nominal Voltage:15 volts
Maximum battery voltage (O.C.V.):16.5 volts
End test voltage:10 volts
Cell connection:Serial and parallel
Socket: 2-hole socket
Maximum Weight:1.65kg
Dimensions (H-W-D):70 x 186.5 x 64.8mm