Tweet
This past weekend I finally had a chance to perform a test on the boat that I've been wanting to do for a while.
I want an honest assessment of my current draw while underway. So I set up a static test stand and
operated the model at various bells to define the power use curve.
As a static test, the aft end was lowered into a pool and the model remains in place. Since she is NOT moving forward
as in a dynamic test, the data I recorded should be "worse case scenario".
Some stats on the boat:
LOA: 63" (1600 mm) Beam: 8" (203 mm)
Draft: 6.5" (165 mm) Weight: 26 lbs (11.8 Kg)
Battery(s): 2x (in parallel) 12V 7.5Ah SLA
Drive train: JOMAR Nautical Throttle, 10A fuse inline w/Redmond PE20270 12VDC Motor (RV HVAC Blower), Direct Drive, 7 Bladed 3 1/2" RH Scimitar Prop (Prop Shop UK)
FWIW, the model at rest, no throttle or servo command draws .18A @ 12.51V (2.2W).
My standard bell, surfaced or Persicope Depth is at 50% throttle. So you can see from the curve below,
the numbers came in at 12.3V 0.98A here. Cycling several servos brought it to 1.18A. All things being equal I should theoretically run
for 14 hours at this speed.
Burn 'n Churn!!
Test setup
I'm fortunate enough to work with EE's at a company known for Power as well as Data Distribution in both Military and Aerospace applications.
So I have quite a few folks to leverage for help when the fuses pop.
They told me that jump in he graph regarding current and Voltage drop it due to "Back EMF"
Granted, the easy way to do this is to just run your model at your favorite speed until you need to swim to get it's run time.
But that's why they call me "Special Ed". I'm happy with the results giving me a warm and fuzzy on what I draw as well as what I should and should not do.
FWIW, Bob was correct in stating we really run at the low end regarding amp draw when we cruise. Even this "baby"
I want an honest assessment of my current draw while underway. So I set up a static test stand and
operated the model at various bells to define the power use curve.
As a static test, the aft end was lowered into a pool and the model remains in place. Since she is NOT moving forward
as in a dynamic test, the data I recorded should be "worse case scenario".
Some stats on the boat:
LOA: 63" (1600 mm) Beam: 8" (203 mm)
Draft: 6.5" (165 mm) Weight: 26 lbs (11.8 Kg)
Battery(s): 2x (in parallel) 12V 7.5Ah SLA
Drive train: JOMAR Nautical Throttle, 10A fuse inline w/Redmond PE20270 12VDC Motor (RV HVAC Blower), Direct Drive, 7 Bladed 3 1/2" RH Scimitar Prop (Prop Shop UK)
FWIW, the model at rest, no throttle or servo command draws .18A @ 12.51V (2.2W).
My standard bell, surfaced or Persicope Depth is at 50% throttle. So you can see from the curve below,
the numbers came in at 12.3V 0.98A here. Cycling several servos brought it to 1.18A. All things being equal I should theoretically run
for 14 hours at this speed.
Burn 'n Churn!!
Test setup
I'm fortunate enough to work with EE's at a company known for Power as well as Data Distribution in both Military and Aerospace applications.
So I have quite a few folks to leverage for help when the fuses pop.
They told me that jump in he graph regarding current and Voltage drop it due to "Back EMF"
Granted, the easy way to do this is to just run your model at your favorite speed until you need to swim to get it's run time.
But that's why they call me "Special Ed". I'm happy with the results giving me a warm and fuzzy on what I draw as well as what I should and should not do.
FWIW, Bob was correct in stating we really run at the low end regarding amp draw when we cruise. Even this "baby"
Comment