ANDE POWER SYSTEM ENERGY BUDGET 1 Apr 2004 ---------------------------------------------------------------- Bob Bruninga This revision adds in the drain of the backup side B currents. Also, as of first power of prototype the nominal currents are higher than expected. The original (Oct 2001) baseline was 30 mA average current for the life of the mission. TNC/RX draw 78 mA. Removing audio amp chip saves 12 mA down to 66 mA instead of the designed 45 mA. TNC is drawing 32 mA instead of 15mA as designed. Timer circuits are drawing 10 mA instead of 1mA. This average current increases average load by 50% reducing life by a third unless fixed. BATTERY SYSTEM: Lithium-primary Battery Mass: 11.2 Kg Battery Construction: 112 Cells Tadiran TL-5930 Each cell is 93 g and 33 x 62 mm Battery volume: 7562 cu cm Battery configuration: 28 4-cell strings in parallel Battery volts: 12 volts (14.4v no load) Battery safety: Every 4-cell string fuzed individually Battery capacity: 532 AHrs (7448 WHrs at 14 volts) ANDE Telemetry/Command system: nominal dutycycle 10% ontime result Average Percent System current standby with-users USAGE CURRENT ------ ------- --------------- ---------- ------ -------- ------- Rcvr A 35 mA 10% [1.5s ON ] 10% 20% 7 mA 20% TNC A 20 mA 10% [15s off] 10% 20% 4 mA 11% XMTR A 600 mA 20% 2% 12 mA 34% LASERS 350 mA 3% over Maui 10% 0.3% 1 mA 3% Timers 3 mA 100% 100% 100% 3 mA 9%] Volt TLM 0.2 100% ea (2) 100% 100% 0.4 mA 1%] Temp TLM 0.7 10% ea (6) 100% 20% 0.4 mA 1%] 5v ref 0.9 10% 100% 10% 0.1 mA 0%] Counter 1.2 100% 100% 100% 1.2 mA 3%] Rcvr B 35 mA 3% [1.5s ON ] 3% 1 mA 3% TNC B 20 mA 3% [45s off] 3% 0.6 mA 2% XMTR B 600 mA 0% backup only 0% 0% 0 mA Timers 3 mA 100% 100% 100% 3 mA 9%] Volt TLM 0.2 100% ea (2) 100% 100% 0.4 mA 1%] Temp TLM 0.7 3% ea (6) 100% 3% 0.1 mA 1%] 5v ref 0.9 3% 100% 3% 0.03 mA 1%] Counter 1.2 100% 100% 100% 1.2 mA 3%] --------------------------------------------------------------- Total 35.5 mA Growth compared to original proposal 12% NOTE: 30% of our power is in the on-always timers, counter and TLM. We must re-design to reduce this substantially. As of 20 March we will do the following design changes: 1) Note the Speaker Amp and RS-232 go away in flight configuration 2) Double Voltage divider resistors (saves .4 mA always) 3) Quadruple the Counter D/A resistors (Saves 1.8 mA always) 4) Double Temp Sensor impedance to 10k for R2 (saves 0.6 mA) 5) Install CMOS 555 timers (saves 6 mA) Actually, these later measured a whopping 6 and 8 mA each (spec says 15 mA so clearly a CMOS version is necessary. Battery life: 532 AHrs/36 mA = 15,000 hours = About 600 days. The total life is drastically dependent on the usage duty cycle. The above figures assumed a worse case scenario. Typical and target values could allow for more than 1.5 year life and still support nominal communications via the PCsat-style operations... The side B is dormant except for its 1.5 second wakeup every 45 seconds. Unless the A side fails, the B side is not used for transmitting otherwise. Bob Bruninga USNA Satellite Lab