Thanks for all the help. As I stated before my new charger is stopping charge before the battery is fully charged. So instead of 50 seconds run time I actually got 10 minutes. Charger put ~3600 mAh back in.
20" mono electrified, 15T speed gems 2 (4006 kv), X432 prop, 7.2V 3800mAh NiMH battery, 35 max amp Astroflight ESC
Perfectly flat water so ran wet, not as fast as expected. However I ran later with a little chop and it scooted across the tops of the chop beautifully. Could run at full speed with no controllability issues.
Max rpm= 4006 x 7.2 = 28,800 rpm, 20,200 RPM loaded (per OSE calcs)
Amps=(3600 mAh/1000)/(600 sec/3600)=21.6 Amps
Watts = (amps) x V = 21.6 x 7.2 = 155 watts
Top speed per OSE calcs= 33mph
I confirmed numbers on OSE speed calc link.
At the end of run:
ESC barely warm
Motor very hot
Battery was slightly warm.
So now I want to pick a brushless motor/LiPO combo to put into 4 more boats. Must be inexpensive and hopefully a bit more boat speed.
Turnigy 36-56-04 2600kv Inrunner on 3S 5000 mAh, $20 http://www.hobbyking.com/hobbyking/s...idproduct=6527
Max RPM=2600x11.1=28,860 RPM (same as current boat), 23,100 RPM loaded
Rated Watts=475 therefore max Amps=43 on 11.1V
Run time =7 minutes
Top speed per OSE = 38mph
Is this a good replacement combo? Numbers seem to work but I have no idea if it is the best combo. Are the rated wattages accurate for these motors? There are plenty of other Turnigy choices.
20" mono electrified, 15T speed gems 2 (4006 kv), X432 prop, 7.2V 3800mAh NiMH battery, 35 max amp Astroflight ESC
Perfectly flat water so ran wet, not as fast as expected. However I ran later with a little chop and it scooted across the tops of the chop beautifully. Could run at full speed with no controllability issues.
Max rpm= 4006 x 7.2 = 28,800 rpm, 20,200 RPM loaded (per OSE calcs)
Amps=(3600 mAh/1000)/(600 sec/3600)=21.6 Amps
Watts = (amps) x V = 21.6 x 7.2 = 155 watts
Top speed per OSE calcs= 33mph
I confirmed numbers on OSE speed calc link.
At the end of run:
ESC barely warm
Motor very hot
Battery was slightly warm.
So now I want to pick a brushless motor/LiPO combo to put into 4 more boats. Must be inexpensive and hopefully a bit more boat speed.
Turnigy 36-56-04 2600kv Inrunner on 3S 5000 mAh, $20 http://www.hobbyking.com/hobbyking/s...idproduct=6527
Max RPM=2600x11.1=28,860 RPM (same as current boat), 23,100 RPM loaded
Rated Watts=475 therefore max Amps=43 on 11.1V
Run time =7 minutes
Top speed per OSE = 38mph
Is this a good replacement combo? Numbers seem to work but I have no idea if it is the best combo. Are the rated wattages accurate for these motors? There are plenty of other Turnigy choices.
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