I did some experiments to see what the discharge rates where for various loads.

These are my observations of the battery times for submerged travel.
Submerged depth was around 20 - 30 meters in a straight line.

Testing was based on the battery current meter (not motor RPM) to see what the general battery discharge rate was for
1kA LOW POWER
2kA MEDIUM POWER
3kA FULL POWER

1. stationary, rudders centered, surfaced, full compressor, fully charged batteries, engines off and decoupled, electric motors off, screws engaged.
2. mark position on map.
3. stationary dive order to 30 meters.
4. start timer.
5. start both electric motors forward.
6. run until drained to zero
7. order to surface right as lights are turning off (so the dive panes are in correct position to surface when power goes out)
8. power out, timer off.
9. mark position on map when velocity reaches zero.

After the test
1. disengage screws
2. recharge the batteries to full
3. recharge compressor and prep the ballast tanks.
4. repeat the test at a different power level

Battery current draw: 3 kA.

Total run time: 24 minutes.

Speed: 7.7kn

Distance traveled: 5500 meters


Battery current draw: 2 kA.

Total run time: 34 minutes 45 sec.

Speed: 6.6kn

Distance traveled: 7070 meters


Battery current draw: 1 kA.

Total run time: 1 hour 8 minutes.

Speed: 5.2kn

Distance traveled: 10760 meters

• Going full power (full speed) over medium power (great speed) provides almost negligible benefit in speed (1 knot) at twice the battery burn rate. It should only be used in a dire emergency to dodge depth charges.
  
  
• A grid square is a good reference for the submerged range at full power. I circle with the radius of 5500 meters fits nicely into one grid square.
  
  
• Two full power tests where done with lights on and lights off. Shutting off power to lights did not seem to have an effect or the effect was negligible. Time was the same for both, 24 minutes. I did not test lights on/off during low power run.
  
  
• UPDATED: ship systems are consuming electricity. But at an unknown rate. Uboat was left idle for about 4 hours with engines off. Started with full batteries. Only ship systems online. About 700 Ah were lost during this time when I came back. There are 3 voltage regulator dials: two in the back, one in the control room. According to the dials (if they are correct) the uboat was consuming: 320 amps in the control room, 320 amps of power on rear port side, and zero amps on starboard. Making it 740 amps total. I should have consumed almost 3000 Ah. Unanswered questions....There are two charge indicators.....did each bank consume 700Ah in those 4 hours for a total of 1400Ah?....that is still half of what should have been consumed. There are three voltage regulators...which ones work with which battery bank?
  
  
• Control room voltage regulator controls starboard interior lights. Rear starboard regulator (always showing zero amp current) controls the hydrophone power. Rear port regulator controls the port side interior lights.
  
  
• RECHARGING TAKES 6 MINUTES AT DUAL ENGINE MAX RECHARGE RATE.