R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric Off-Road

Thread Tools Search this Thread
Old 11-23-2008, 02:09 PM   #1
Tech Fanatic
blanks596's Avatar
Join Date: Mar 2005
Location: Los Angeles Dojo
Posts: 813
Trader Rating: 14 (100%+)
Default Science of batter, motor, and speedcontronls

could someone please explain to me the science of batteries, motors, and speedcontrols; specifically their relation to each other in terms of numbers? for example mih, Amp numbers on speedcontrol, and amp draw from batteries? I'm about to dip into electric racing and just need a bit of help
Thanks in advance
Serpent/Desoto Racing
Max S
blanks596 is offline   Reply With Quote
Old 11-23-2008, 02:25 PM   #2
Tech Master
Join Date: Apr 2008
Location: Christchurch, NZ
Posts: 1,063

Not sure how up to speed you are with electrics in general, but i'll start it off.

The motor draws power from the battery. The speed controller is there to regulate how much power it will receive. It does this by limiting the amount of power that can pass trhough it to the motor. Kind of like a tap on a water pipe.

The current (amps) is a representation of how much power is passing through at any one time. Kind of like how large a water hose can be. A little hose can't pass a lot of water, a big one can pass lots.

So, if you have a high powered motor that wants to pull through a lot of power, you need an ESC that can allow this without too much resistence, or you will blow the seals on your valve.

If the battery has a lot of internal resistance, it won't let a lot of power through. Think of a water tank with a small hose coming out of it. If it has very low resistence, it can let a lot of power through, think bigger hose.

Hope that helps a little towards it.

BTW, I may have bits wrong, but there will be a fair few replies to correct me no doubt
JR007 is offline   Reply With Quote
Old 11-23-2008, 09:36 PM   #3
Tech Addict
Brandon A's Avatar
Join Date: Jul 2008
Location: Corvallis, OR
Posts: 557
Trader Rating: 1 (100%+)

Just to add a little more detail to the above without getting too in depth...

Batteries-mah=capacity (higher number means more runtime.)
Nimh cells=7.2 volts(slightly less punch) lipo=7.4volts (slightly more)
-Lower internal resistance also gives more punch

Motors-generally, the lower the turn the faster the motor.
-clean motors are always faster ones
-hotter motors draw more amps and mah
-different motors are good for on-road and off-road

speed controls-turn limit on speed control must be lower or equal to that of the motor being used with it (i.e. 15t motor can only be used with a speed control rated to use 15t or hotter/lower turn motors)
-max amp draw is the highest amperage that can be put through the control before it cooks.
-nominal/average amp draw is the average amperage the control will pass when in use.

hope that helps
RCAmerica/Xray <> Panther <> RW Mods
Brandon A is offline   Reply With Quote
Old 11-23-2008, 10:40 PM   #4
Tech Regular
Gliptal's Avatar
Join Date: May 2007
Location: Portland, OR
Posts: 258

JR007’s analogy is right more of less but he got the current and power a bit backwards.

Power is current times voltage, the speed control regulates the current and thus controlling the power to the motor. Voltage is like the pressure in the pipe, if there is any resistance to the current in the pipe you lose pressure (voltage) and lose power since less water, err, power, is flowing to you motor…

Lower turn motors draw more current and therefore need a speed control that can handle more current and a battery that can supply it.

Current is measured in Amps.
Gliptal is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

All times are GMT -7. It is currently 09:50 PM.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net