Amp Draw

[HVAC25000]

Hey guys. Running a brushless motor in a 4wd, what kind of amp draw can I expect from a 5.5 and a 6.5? I want those new trakpower 3200 saddles but I don't know if they can handle it. I was told that 6.5 pulls an average of about 80-90amps, which is getting close to the limit for the trakpowers.

Thanks
Chris

[Hog]

Which Trakpower saddles? I ran a 5.5R in my ZX5 on Trakpower 4800 saddles and had no issues at all.

[HVAC25000]

Forgot to mention, the 3200s.

[Dunc]

I've run a 3200 saddle and sintered 6.5 (Speed Passion) in my B4 and was using 1500 mAh, at most, on high traction astro turf.

I would imagine that so long as you're not a complete animal those cells will be okay for 4wd too.

Hope that helps a little.

[pugboy]

The current output of the battery is the 'C' rating of the battery multiplied by the capacity in mAh/1000, i.e. if it's a 25C continuous 3200 mAh Li Po then the max continuous current output would be 25 x (3200/1000) = 80A

I'm not clever, I've just done some research because I wondered the same thing myself. See this link

http://www.flyingsites.co.uk/features/lipo.htm

Cheers

Chris

[HVAC25000]

Umm, the discharge capacity of the battery was never in question, that's why I asked what kind of amps the motors can draw, not how many the battery can handle (if you see, I even mentioned how many the battery can handle, 3 hours ago). Basically, you didn't tell me anything I didn't already know, and didn't already say myself. You're right, you aren't clever

[Richard Lowe]

The Nosram/LRP sintered 6.5's are rated at ~370 watts.

370/7.4 (voltage) = 50 amps (max), assuming the cells can hold 7.4v under load.

[stegger]

Originally Posted by Richard Lowe

The Nosram/LRP sintered 6.5's are rated at ~370 watts.

370/7.4 (voltage) = 50 amps (max), assuming the cells can hold 7.4v under load.

Good old OHMS law

[Jonny_H]

But is that 370 W electrical input (current × voltage), or 370 W 'brake' mechanical output (torque × speed)?

If it's the latter then the current required will be quite a bit more...

[Richard Lowe]

Originally Posted by Jonny_H

But is that 370 W electrical input (current × voltage), or 370 W 'brake' mechanical output (torque × speed)?

If it's the latter then the current required will be quite a bit more...

Not a clue

The 6.5 claims to be 91% efficient, although that must vary with the temperature of the windings/rotor?

Lets try 370w power output with 91% efficiency, that'd be 407w input and the remaining 37w released as heat/noise. That gives 55 amps draw, not including esc/power wire resistance losses...

To the original question...
The 3200's will be fine, in my experience the 3200 gives a similar feel to a good NiMh pack in terms of punch but is lighter