rfg06

My Feedback: (8)

Will the cc Phx 25 cut power to the motor if the motor is drawing too much current for the batteries to handle? I have an axi 2808/16 with an Apc slo-flyer prop 9x3.8 with a phoenix 25 and an 8 cell 600 mah Ni-Cd pack. I think the amps being drawn is around 20-25 amps. Can the battery handle this discharge which i beleive would be 40C?
What batteries besides lipos would do the job? I'm still looking to use 9.6 volts.

jooNorway

The ESC will cut the motor if the voltage drops below the programmed value.
When it comes to current you can program the way it reacts to high current, even switch off all safety in the ESC and fly until it catch fire... If you leave the current settings at "normal" it will cut when the current is too high compared to the ESC`s ability to handle current, not taking care of the batteries.
I think your current-consumption is appr. 28-29 Amp with that prop... A bit on the hard side for the motor, and close to 50C for your batteries...
Sorry, but I don`t know enough about NiCd/NiMh to give you any advise here, but you propably will get better advices from others

rfg06

My Feedback: (8)

joo,
Thanks for the advice...I should really buy a whattmeter!!! Do you think moving to a smaller 8" prop would bring my amp draw down to safer limits or should I consider reducing the voltage?

Glacier Girl

My Feedback: (4)

I may be wrong but I don't think dropping voltage is going to change amp draw at all.
Motor will still drawl, same amount of amps. Dropping prop size may lower amps some what.
For what you're doing I don't think packs are going to handle the load for long.
BJ

jooNorway

With a 8x3,8SF your Amp is reduced to appr 23 Amp... But you loose 20% of the thrust. A 8x4E is the best choise i think, same current and at bit more thrust.
In fact dropping the voltage also reduses current, at 7 cells and 9x3,8SF the current would be appr 23 Amp as far as I can see from the tables... And the thrust close to the value at 8 cells on 8x3,8.

wreck_em_all

According to Ohm's Law, I (current) = V (voltage) x R (resistance). Reducing voltage will reduce current since motor resistance and prop size are not changed.

-pkh-

My Feedback: (2)

40-50C!!! I don't know of any cells that can do that! The best Sub-C NiMH cells I've seen are around 30C. The LiPos I've seen are about 12C max. I think you need a parallel cell pack and much higher capacity. You realize a 40-50C draw will give you about 60-90 seconds of flight time? For a 20-25A draw, I'd get a 2S2P or 3S2P Lipo pack with 2000mAh+ capacity and 12C+ discharge rate...