Glossary of non-hub motor drive/RC terms

[Miles]

BEC: Battery Eliminator Circuit.
CVT: Continuously Variable Transmission.
ESC: Electronic Speed Controller.
HV: High Voltage.
WOT: Wide Open Throttle.

See also the Glossary of EV terminology

[spinningmagnets]

Kv:
in plain language, how many RPM's a motor will deliver PER VOLT. A 20-volt battery powering a 180-Kv motor will have an unloaded RPM of 3600 (20 X 180 = 3600).

LiPo:
One of the desireable characteristics of powerful RC motors is that they are very small, and they are sometimes found with batteries made of Lithium Polymer (LiPo). These are smallest batteries per a given wattage. They will catch on fire if not managed properly.

10C from 3S4P:
Naming conventions explained. How fast a battery can discharge is it's maximum CURRENT capacity. Current is generally rated in C's for the battery. C is how long it takes to discharge the battery in fractions of an hour. 2C discharges the battery in 1/2 or half an hour. 4C in 1/4 of an hour.

All RC batteries are rated in milli-Amp hours. If a battery is rated at 2000 mAh and you discharge it at 2000mA (or 2 amps, 1 amp = 1000mA) it will be completely discharged in one hour. The C rating of the battery is thus based on its capacity. A 2000mAh cell discharged at 2 amps is being discharged at 1C (2000mA x 1), a 2000mAh cell discharged at 6 amps is being discharged at 3C (2000mA x 3).

All batteries have limitations on how fast they can discharge. Because of this many LiPoly batteries are put in parallel to increase the current discharge capacity of the battery pack. When 2 batteries are wired positive to positive and negative to negative they become like a same-voltage battery with double the current volume discharge capacity.

If you have two 2000mAh cells and you wire them in parallel, then the result is the same as one 4000mAh cell. This 4000mAh cell has the same C rating as the original 2000mAh cells did. Thus if the 2000mAh cells could discharge at a maximum of 5C (or 10-Amps) then the new 4000mAh cell can also discharge at 5C (4000mA x 5) or 20 amps. This method of battery pack building allows us to use LiPoly batteries at higher currents than single cells could produce.

The naming convention that allows you to decipher how many cells are in SERIES and how many are in PARALLEL is the XS/XP method. The number in front of the S represents the number of series cells in the pack so 3S means it's a 3 cell pack. The number in front of P means the number of cells in parallel. So a 3S4P pack of 2100mAh cells has a total of 12 cells inside.

It will have the voltage of any other 3S pack since the number of cells in series determines the voltage. It will have the current handling of 4 times the maximum C rating of the 12 individual cells. So say our 3S4P pack had a maximum discharge of 6C. That means that it has a nominal voltage of 10.8 volts (3 x 3.6V) and a maximum discharge rate of 50.4 Amps (2100mAh x 6C x 4P).

PS I am still learning, I will eagerly edit any mistakes that are pointed out, text copied from RC sites, bits chosen by what I was personally confused about. Corrections may be posted below, or sent directly to velmis1450bc@aol.com, or mailed to (#41, Chino state correctional facility for men)

[spinningmagnets]

BMS:
Battery Management System. To get the optimum life from an expensive battery pack, some batteries need to use a smart charger of the type that charges it and monitors each cells state of charge (SOC) and continually adjusts the charging rate after occasionally sensing its Depth Of Discharge (DOD). The closer a battery gets to being fully charged, the less amps should be used. Battery pack heat should be monitored and the charging should be adjusted to prevent the batteries from getting overheated, especially LiPo's

Inrunner:
The type of motor that most people are familiar with. The end caps, outer shell, and copper wire coils are fixed to the base, and the only part that spins is the shaft and the internal armature with the magnets attached to it.


Outrunner:
Small RC motors are capable of incredibly high RPM's. If the magnets were on a conventional inrunner armature (like above), at a certain very high RPM, the magnets may detach and fly off. On an outrunner, the magnets are attached to the inside of the outer cylinder shell so centrifugal force is not a problem. Of course the non-spinning Stator coils are attached to the end cap because the shell spins.

Miles pointed out to me that an outrunner also has the magnetic flux interaction farther away from the motors center than an inrunner. In this way, an outrunner of a given diameter can have the same torque potential as a larger diameter inrunner.

[Miles]

Spinning,

Maybe you could add something to the effect that:

The most significant difference between an outrunner and an inrunner is that due to the magnets taking up less space than the armature, the airgap is at a greater radius in an outrunner. So, for a given case diameter, the turning moment and therefore the torque produced is greater in an outrunner than an inrunner.

Also, it should be "Kv" not "kV" It's velocity constant not voltage constant. kV stands for kilovolt.

[SoSauty]

I don't understand some terms/brand names in common use here, yet ever so often I conclude a new definition. Plan to return here and add definitions 2010/11.

(Eno) freewheel; ie: fits around shaft/axle to permit idle in one direction and power transfer in the other; a racheted type freewheel capable of handling greater than standard torque
http://www.whiteind.com/singlespeedgearing/freewheels.html
gb; ie: gear box
(Extron) sprocket; ie: a racing go-kart type sproket, sometimes made of composite or kevlar
http://shockwavekarting.com/miva/merchant.mvc?Screen=PROD&Store_Code=SK&Product_Code=SPKT
Nuvinci: fits as rear bike hub, acts as torque converter; a variable speed pwer trans http://www.fallbrooktech.com/nuvinci.asp see CVT in 1st post above,
Singleator; brand of chain tensioner http://www.jensonusa.com/store/product/RD707Y01-Surly+Singleator.aspx
Shunt: a low resistance resistor to aid Cycle Anaylst (or other meter) in measuring amps, maybe inside a controller or external inline with batteries. http://solar.altestore.com/search/?w=shunt&p=Q&ts=v2
HOBO: ie, High Output Brushless Outrunner

Burning issues not understood:
As motor winds get higher, say 6wind(6T) to 10wind(10T), yet the 50volt Castle HV160 caps voltage, what are the performance trade offs?
ie; how does a 3220 10T motor perform with 40-50volts, will it accept extra amps to compensate for low voltage? (48V & 94amp),
ie; is motor heat determined primarily by watts(voltsXamps) or by amps,
ie; if a 10T has >2X the resistance, is it still 90-93% efficient?

[Hillhater]

Be carefulwith those "definitions"..
Eno and Extron are both "brand" names, rather than generic descriptions and are associated with those products only because of their dominance in the field.

[spinningmagnets]

ESC Electronic Speed Controller

HV High Voltage, such as 8S (28V), 10S (36V), 12S (44V)....lower voltages, such as 5S (18V) and 6S (22V) are not considered HV in the RC world. However, they very common.

"Optically coupled"
An opto ESC just means that it doesn't have a 5V power supply to run the servos or servo tester throttle (if used on an ebike). Many high voltage ESCs don't have a 5V supply, which means you need to find another way to power a servo tester to use as a throttle. (edit: from the catalogue: "The throttle signal is transfered through optically coupled system to avoid the electromagnetic interference")

BEC
A BEC is a Battery Eliminator Circuit, another name for the 5V supply that is needed to drive servos, an RC receiver or, in the case of an electric bicycle, a servo tester to be use as a throttle. BEC is usually used to describe the built-in 5V supply inside an ESC. This "eliminates" having to use a second battery for the servos. A BEC could also be called by the generic term DC/DC-converter, as it converts the main batteries 18V/22V into 5V. An ESC without a BEC can still be used on an electric bicycle with a servo-tester as a throttle if you use a small second battery to power the servo-tester, such as 4 AAA NiMH batteries in series (among other throttle options)

UBEC
It is a Universal Battery Eliminator Circuit and is a separate module that connects to your battery pack and provides the 5V needed to drive other parts of an RC system, like the servos (a servo is an electrically moved piston or turning-screw that might be used to move a planes rudder, for instance) or other accessories. The thing to watch when using them to drive a servo tester as a throttle on an ebike is the input, or battery, voltage rating. Not all of them will accept high voltages (over 28V) safely.

Rx
it is just an abbreviation for the RC receiver used in models.

[liveforphysics]

Hobo or HOBO motor.

High Output Brushless Outrunner

[usurper]

thanx just today i was wondering why this didnt exist as a newcomer iv had to pick up a lot of rc slang etc having this glossary has sped up the learning process