 |
 |
|
 |
 |
 |
Jun 01, 2003, 04:17 PM
|
|
|
East Sussex UK
Joined Jul 2002
14 Posts
|
400 Amps From SCR's and 500 size motors !!!!
I was in my LHS today and one of my sons was looking at the RC Car controllers, he asks the man behind the counter which is the cheapest. He points to one and says that one adding it will only do down to a 17 turn motor. How many amps is that, says I.
70 comes the reply. When I can speak coherently again I ask how many amps do they go up to then. That one will do 400 comes the reply as he points to one on the end of the shelf. From SCR's I enquire. Yes comes the reply. How long do they last I ask. About 15 minutes comes the reply. That explained it I thought 1 charge and 1 run! and Bang!. But you can recharge them a thousand times or more he added. Surley they can't be drawing that kind of current from SCR's and what are those buggy motors made of? Can anyone out there explain |
|
|
|
|
|
Jun 01, 2003, 05:14 PM
|
|
San Diego, CA, USA
Joined Mar 2001
3,067 Posts
|
It's marketing baloney.
If they were drawing 70A from 2400mAh cells, the'd only run for a maximum of about 2 minutes, assuming 100% efficiency and assuming that you really get the rated capacity at that current. Neither one of which is going to happen. 400A, if nothing else melted, would drain the same cells in about 20 seconds. Of course, this is impossible because the cells just won't deliver any significant voltage under that kind of load. Oh, and they'd vent and start leaking their guts. The FETs are what the car ESC ratings are based on... and even there it's a joke. They ignore the rest of the controller. The best RC car controllers for brushed motors are only good for about 40-70A continuous. -David |
|
|
|
|
Jun 01, 2003, 05:14 PM
|
|
Bundaberg, Qld, Australia
Joined Jun 2002
1,365 Posts
|
Methinks he knows not of what he speaks.
|
|
|
|
|
Jun 01, 2003, 07:48 PM
|
|
In Heli Wonderland
Joined Aug 1999
22,744 Posts
|
F5B's pull 100 amps for 2-3 seconds, for just a few bursts to climb.
They maybe stating up the startup amps that only last a few miliseconds. |
 |
|
|
Jun 01, 2003, 08:25 PM
|
|
United States, MA, Cambridge
Joined Jul 2002
309 Posts
|
Startup amps mean nothing....
Startup amps on a plane are just as insignificant. George |
|
|
|
|
Jun 02, 2003, 02:50 AM
|
|
|
N. Staffs, UK
Joined Jan 1997
5,654 Posts
|
As davidfee says, car controllers are typically rated at a theoretical current based on what the output devices WOULD stand if you had them on an infinite heatshink and the current lasted no more than 1/1000th of a second. Don't ask me why.
If you divide by somewhere around 5 to 8 you'll get the real constant current rating which is used for aircraft controllers. I'd guess the "70A" controller at around 15A and the "400A" at around 50-60A. Steve |
|
|
|
|
Jun 02, 2003, 03:06 AM
|
|
Mostly in Norman, OK
Joined May 2002
1,840 Posts
|
Just about everything in R/C cars is over-hyped and over-prices fwiw ...
|
|
|
|
|
Jun 02, 2003, 01:42 PM
|
|
|
East Sussex UK
Joined Jul 2002
14 Posts
|
Ah Ha!
This all makes sense now. I always thought those R/C car guys talked out their exhaust pipes. Thanks for the replys |
|
|
|
|
|
«
Previous Thread
|
Next Thread
»
| Thread Tools | |
Similar Threads
|
||||
| Thread | Thread Starter | Forum | Replies | Last Post |
| what's the longest you can pull 200+ amps from your pack? | e-sailpilot86 | High Performance | 3 | May 14, 2005 08:27 AM |
| Cobri 28 aluminum Gearbox for Mega and other 400 size motors | Splash | Power Systems | 21 | Jul 01, 2004 07:08 AM |
| 15 amps from 4.8v speed 400? | FLL | Power Systems | 5 | May 12, 2003 03:55 PM |
| Any experiments done with Goldmine 400 size motors (g4032) | kit basher | Power Systems | 1 | Nov 25, 2001 08:18 PM |
|
|