ESC voltage Astroflight 212d

[xlandguy]

Rated 14 volts or 12 cells (with bec) it says on web site, but on the actual esc it says 25 volts??? So if I use the onboard bec I am limited to 14 volts? If I run an external bec then I can run up to 25 volts. What happens if I run 4s with the bec? Fry the RX?

http://www.astroflight.com/index.php?main_page=product_info&cPath=17&products_id=94

Astroflight_212d_MarineESC.jpg

From the website:

Voltage range	6 to 14 Volts
Turn on Voltage	6 Volts
BEC Cut off voltage	5 volts
Number of Nicad NIMH Cells	6 to 14 Cells
Continuous Current Rating	75 Amps
PWM rate	3 KC
BEC rating	1 Amp at 5 Volts
Length	2 inches
Width	1 inch
Height	1/4 inch
Weight	40 grams
Servo Connector	Universal
Power Cables	13 gage
Power Connectors	Astro

[xlandguy]

Nobody eh?
really a bump

[LarrysDrifter]

I have no idea, but I say call or email them. I think Traxxas make brushed speedos too, but im not familiar with brushed stuff.

[m4a1usr]

The 25 volt rating of the 212D is the max voltage rating of the FET's on that speedo. Not the true max input voltage of the esc. I know its a bit confusing and not sure why AstroFlight printed that on the exterior of the case. Do not run it up at 25 volts. 14 nimh cells fully charged are up to appox 17 volts. But under load are down to about 15 volts and loosing voltage rapidly. With lipos there is much less voltage sag under load. I doubt AstroFlight ever intended that speedo to be used with lipos.

Now back to your questions,..........If I remember right the 212D has a linear bec. That means that it uses a design of heat dissipation to over come higher voltage (battery) input. All it wants to do is output 6 volts. If you stick 14 volts into it, then it will have to remove 8 volts of what is in escence waste heat. Thats the weakness of a linear bec. You end up with more heat. Newer speedos use a switching bec and it doesnt suffer the same heat issue. So the moral of the story is stick to 12 or less cells if you plan on using the bec. Also you can get a pretty robust inexpensive UBEC for your setup and just remove the red wire connecting to your speedo. That way the speedo will see the 5/6 volts off your Rx.

Heres some good reading about it. Hope the mod's are alright with the linky? http://www.publicrc.com/pt/ESCs-Line...-BECs/blog.htm


John

[xlandguy]

Thank you so much, very useful.