Mtroniks esc questions

[tim slocum]

I was thinking of replacing the Proboat esc in my Bismarck with a Mtroniks Marine 40. If Im running the Biz on 6volts and the Mtroniks runs on 6-12v then would a partially drained battery result in the Mtroniks shutting down? Also, would two 550sized motors running two 1.5in props direct drive be too much for the 40amp Mtroniks? Finally, do different esc's allow for different ranges of speed?ie one allows a higher top speed than another? Thanks

[patmat2350]

I can only guess that if it's designed to work on 6v systems as advertised, it has been designed for the inevitability of a low battery (5.5v?).

On 8.4v, my Speed 600's draw about 10A each driving props near that size... I gotta imagine that 550 motors intended for 7.2v (?) operation will draw significantly less current on 6v. Ought to be fine if it's a >real< 40A ESC.

Finally, no. The most any ESC will deliver is (nearly) full battery voltage and whatever current the motors want to draw. Very nearly like if you just wired the battery straight to the motors. They can't inject anything extra, they can only minimize resistive losses in the FETs (field effect transistors, effectively the "switches" inside the ESC).

Pat M

[Rob_P]

Tim,

I can't answer your question directly but I'll share my experience.
I'm running a Marine Viper 40A, I had some questions and sent them an email & they responded pretty promptly.

I noted that the old models on their web site stated 6-12V (10 cells). The new Viper 40 only stated 6-12V & no cell count.

They responded -

"You should be fine running 10 cells, just make sure that when fully charged that your pack does not go over 13.2V maximum".

Wouldn't a 10 cell pack be more like 14V???
I have emailed again for a clarification & currently await a response.

Rob

[tim slocum]

Rob,10cells should be around 12v. Patmat, I was thinking a higher quality esc might get you closer to full voltage, resulting in a higher top speed? The Proboat is not very smooth with the application of throttle and I wasnt sure if it was allowing for full voltage to pass through. Maybe there would be more resistance with a cheap esc, costing you top speed. I hope Im explaining my question clearly. Thanks

[patmat2350]

No, you're right... better ESCs have FETs with lower resistance, and/or more FETs in parallel which will further lower the "on" resistance. We're talking the difference of a few milli-ohms though, which is more important to the ESC itself. High current passing through even that low resistance will generate significant heat.
Racers might notice a difference, doubt any scale boater will.

What you're seeing is not how good "on" is (e.g., "full throtle"), but how well the ESC ramps up to "on". The Proboat ESC starts at like 1/4 throttle, where good "scale" ESCs will ease in at a much lower throttle point.

Pat

[Kmot]

The higher the operating frequency of the esc, the slower you can turn a motor.

[tim slocum]

Thanks for clearing that up.

[Ghost 2501]

i thaught the proboat 50 was a bloody good esc, I plan to upgrade the robbe esc in the E-boat with a proboat 50 or two