Tattu (Marke von Grepow) Semi-solid State 330Wh/kg 25000mAh 10C 44.4V 12S1P

The Tattu Semi-solid State 330Wh/kg 25000mAh 10C 44.4V 12S1P is a semi-solid lithium battery from Tattu, a Grepow brand, for heavy multicopters. Twelve cells in series give a nominal 44.4 V at 25 Ah; the connector is an AS150U-F.

44.4 V and 25 Ah give 1,110 Wh; at 3,788 g that is about 293 Wh/kg at pack level. Figures of 330 and 350 Wh/kg are quoted; both are above the calculated pack value, which is the one that counts for comparison. The 10C applies as a peak for less than 3 seconds, which is 250 A. For hovering, the continuous current counts, which should be read from the data sheet of the version supplied, not the peak.

1,110 Wh is far above 160 Wh. Under the IATA passenger leaflet (February 2019 edition) the pack travels only as dangerous-goods cargo, not as a spare in hand baggage; UN 38.3 testing is the precondition, and airline rules may be stricter. At about 3.8 kg the pack fills almost the entire 4 kg take-off mass of EU class C2; it belongs in heavier aircraft of classes C3 and C4 (below 25 kg).

In selection the current demand of the aircraft in hover must lie clearly below the continuous current of the pack; the short peak is meant only for load changes. The AS150U-F is made for currents around 150 A and must match the wiring. Wear shows as lost cycles, growing voltage sag and deformed cells; the twelve cell voltages are checked at the 13-pin balance lead. Storage is in the middle of the charge range as the maker specifies, in a cool place and protected against pressure.