The Language of Electrics

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frddyj

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Electric R/C is different from Nitro and uses its own unique language. I came across this article which will be usefull to those interested in electrics
Please note that it is broken up into 3 posts: ESC, Battery & Motor.

Electric r/c terminology

This is from RC Car Action Sept 2009, pp 74-76
Article written by: Lito Reyes

Speed Control Lingo:

Firmware: The program on a speed control, radio or receiver that can be updated.

Why it matters:
Manufacturers of ESC's often release software updates to make the products more reliable or add features and functions. This is usually performed by downloading firmware updates from a website & uploading to the device via USB cable.

Linear & Curves: "Linear" means the t/b work in the exact same proportion as the transmitter's trigger is pulled or pushed. Pull 50% trigger, get 50% throttle. A "curve" is used to increase/decrease that relationship. A typical throttle curve will decrease the throttle response at the low end.

Why it matters: Curves are 1 of the best ways to tune your truck for driveability. Adding a gradual throttle curve can be used to tame high-power brushless systems for off-road use.

LiPo Cutoff: A speed control setting that automatically cuts power to the motor if the battery voltage drops below a certain voltage; this is to prevent LiPo batteries from becoming damaged.

Why it matters: Lithium-based batteries can be permanently damaged if the cells are allowed to be discharged to about 2.6v per cell. If your speed control doesn't have this feature and you want to use LiPo's, then get an external cutoff or at least an audible alarm that lets you know when its time to end the run.

Punch/Traction Control: Speed control setting that basically limits the amount of current that's passed on to the motor during acceleration.

Why it matters: Adjusting punch to the highest setting that you can use without breaking traction will gain you more run time and more control. Remember that too much punch control can also limit top speed.

Start Power: The amount of current sent to a motor to get it to move from a standstill.

Why it matters: If the motor hesitates, then decrease the setting. If it still hesitates at the lowest setting, batteries with a higher "C" rating might be needed.

Trigger Dead Band: the amount of trigger travel needed before the motor responds.

Why it matters:
Sensored brushless motors are incredibly responsive, so sometimes a larger dead band is needed to prevent unwanted car movement.

Drag Brake: Speed Control (ESC) setting that applies an adjustable amount of braking when the trigger is in the nuetral position.

Why it matters:
Use Drag Brake to make it quicker to lock up the tires and rotate the rear end for tight turns. It also makes your brushless motors feel more like brushed motors when off-power.

 
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Battery Lingo p 2 of 3

Battery Lingo:

Amps: Short for Amperes and is the unit of measurment for current.

Why it matters:
Most speed controls (ESC) are rated by how many amps they can handle and all batteries are rated by how much energy they can store in amp hours (or milliamp hours Mah).

C-Rating: Equivalent to the capacity of the battery pack in amps; also, part of a formula that lets you know how many amps a battery pack can be safely discharged at (cell capacity multiplied by C-Rating equals continuous amps). So, if you have a pack with 5000mah capacity and C-Ratingof 25C, it can output 125Amps for whatever time period the mfr. states.

Why it matters:
The higher the C-Rating, the more punch from the battery pack. However, higher-rated packs are also more expensive.

Charge Rate: The recommended charge current setting for a battery pack.

Why it matters:
New battery technologies have different SAFE charge rates. For most lithium batteries, a charge rate of 1C is safe.

Li-Ion: The general name for the family of older lithium-based batteries.

Why it matters:
This older technology requires pressure as part of the cell construction, meaning a hard case.

LiPo: The general name for the family of soft-cased, lithium-based cells.

Why it matters:
LiPos come in different formulas, but whether they come in hard shells or not, the cells are made of soft "pouches."

Li-Fe: More commonly known as A123, MaxAmps Green Series Cells or lithium nanophosphate batteries, these batteries have a cathode made from a combination of iron, phosphorus and oxygen (Li-FePO4) & have a nominal voltage rating of 3.3v per cell.

Why it matters:
Li-Fe batteries are known to be very durable and can sustain very high charge rates. The voltage isn't as high as standard LiPo batteries. They can also be safely charged in a fraction of the time compared to a LiPo battery pack.

Li-Mn: Known as Lithium Manganese (LiMn04), these batteries have a cathode made from manganese and oxygen. They have a rating of 3.7v per cell, and do not produce as violent a reaction when shorted as LiPo cells.

Why it matters:
Apogee Batteries is best known for using Li-Mn cells. They are durable and safer than other LiPo cells, and also come in large capacities. They can be safely charged at 2C.

Mah: The standard for rating battery capacity; short for "Milliamp" output per hour.

Why it matters:
A 5000Mah battery pack can also be called a 5AH pack, but we always use the milli-rating because it sounds bigger. This means this pack can deliver 5 Amps of power for an hour when fully charged.

Ohms: The measurement of how much a circuit resists voltage.

Why it matters:
Copper wire of a specific diameter and length will have a calculable resistance. Knowing that, motors of all types can be tech'd by measuring the Ohms resistance between the winds.

Voltage: The measurement of potential difference of electricity between two points.

Why it matters:
Nickel-based batteries output a nominal 1.2v per cell, while the magic number for lithium cells are 7.4, 11.1 and 14.8, referring to voltage of 2-, 3-, and 4-cell lithium packs are usually 6-cell (7.2v) or 7-cell (8.4v). Higher voltage usually means your car will be faster.

 
Motor Lingo p 3 of 3

Motor Lingo:


Ar-Ma-Ture: The rotating spindle assembly on a brushed motor that contains the motor shaft, the wire-wrapped stack and the commuator. It's supported by bearings or bushings.

Why it matters:
If the performance oon an old brushed motor has dropped off, you can usually just replace the armature, rather than the whole motor.

Cogging: The resistance felt in a motor armature as the stator or armature passes through different segments of the can's magnetic field. Brushless motors often have less cogging than brushed motors.

Why it matters:
This term is often mistakenly applied to the motor hesitation that can occur when a battery pack can't output the current load needed in a brushless motor system.

kV Rating: Motor rating that states how many RPM it will run per volt of electricity.

Why it matters:
The closest thing to a common brushless motor rating standard we have is by kV. For example, a motor rated at 5700kV will run at 42,180 rpm at top speed on a 7.4v battery pack (5700 x 7.4) - no matter how many winds it has or whether it sensored or sensorless.

Stack: The frame, usually made from iron, that the motor windings are wrapped around

Why it matters:
In a brushless motor, its inside the walls of the can; in a brushed motor, its part of the rotating armature.

Stator: The fixed, non-rotating portion of a motor.

Why it matters:
In a brushless motor, it's the winding structure inside the can; in a brushed motor, it's the magnet structure.

Watts: A measure of electric power calculated by multiplying the volts and amperes used in a circuit.

Why it matters:
Some companies rate its motors by their wattage, instead of winds or kV ratings.
 
jeez freddy I'm going to need a weekend to read this lol
 
A round of applause for Freddy. This is exactly why I said at the WF that the hpisf is one of the friendliest and most useful sources of info on the net.

Bryan @ SMC
 
Why it matters: Lithium-based batteries can be permanently damaged if the cells are allowed to be discharged to about 2.6v per cell. If your speed control doesn't have this feature and you want to use LiPo's, then get an external cutoff or at least an audible alarm that lets you know when its time to end the run.


Just a note. 3.0v is a good cut-off point.
 
I have a lot of experience to add Fred...do you mind?

Not at all Chris. Again, the information i posted is a direct quote from RCCA (which i posted) i have little experience with electric and no experience with b/l (yet).

id like to see the knowledge-base in the electric-side of our forum grow.

so please, any experience you would post is gonna make this section that much better for all of us.
 
Not at all Chris. Again, the information i posted is a direct quote from RCCA (which i posted) i have little experience with electric and no experience with b/l (yet).

id like to see the knowledge-base in the electric-side of our forum grow.

so please, any experience you would post is gonna make this section that much better for all of us.

You got it!
 

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