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Electric Guide


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Here is a guide for all your questions you have to do with the electric side of R/C cars.

This guide is written by Garry, Nick, doom56 and c0sie of the MSUK forum, and is NOT to be reproduced in any way, shape or form without expressed written consent from the author.

To find what you are looking for easily, use Ctrl+F and type the word, phrase or number in the box that pops us.

=====[Table of Contents]=====

A. Basic information.

- (A01) What is a battery pack?

- (A02) What is a motor?

B. Brushed Motors

- (B01) What is a brushed motor?

- (B02) What is a Turn/Wind?

- (B03) What is a Stock/Super Stock motor?

- (B04) What is a Modified motor?

- (B05) Why is there difference in prices of motors?

- (B06) What's a 'skim', and how often should I do it?

- (B07) How do I tune a motor?

- (B08) What are 'caps'?

C. Brushless motors

- (C01) What's a brushless motor?

- (C02) What does 'Kv' mean?

- (C03) How do I maintain one?

- (C04) What is 'cogging'?

D. Batteries

- (D01) Whats the difference between NiCD, NiMH, LiPO etc?

- (D02) What what do the numbers on a battery mean?

- (D03) What is a 'matched' battery?

- (D04) Does more cells equal more power?

- (D05) What's the difference in pricing mean?

- (D06) What's the deal with LiPo?

E. Charging and Chargers

- (E01) Do all chargers charge any battery?

- (E02) What charge rate should I use?

- (E03) Why is the battery warm/hot during a charge?

- (E04) What is 'discharging/equalizing/cycling'?

- (E05) How do I look after my new battery?

- (E06) How do I look after a LiPo pack?

F. Radio Equipment

- (F01) What does the radio equipment consist of?

- (F02) Which is better, sticks or wheels?

- (F03) What are 'crystals'?

- (F04) Is any frequency available?

- (F05) What is 'interference'?

- (F06) Which servo is best for me?

G. Electronic Speed Controllers

- (G01) What is an Electronic Speed Control?

- (G02) Why are some more expensive than others?

- (G03) Should I buy one with reverse?

- (G04) Are brushed and brushless ESC's the same?

- (G05) What does the 'turn limit' mean?

- (G06) What is a 'power cap'?

I. Update notes

- Created July 1st 2006.

- Made available 4/6/2006.

- LiPo informationa dn charging guidelines added 11/01/2007

- Updated with latest technology, ideas and guides 04/05/2009


A. Basic information.

- (A01) What is a battery pack?

A battery pack is several individual cells soldered together to create a pack. The most common type and form are six 1.2v sub-C sized Nickel Metal Hydride cells soldered together to create what is known as a 'Stickpack', as it resembles a stick:




There are other styles of battery though, which include side-by-side:


and the 5-cell hump pack (used as reciever batteries in nitro cars):



Depending on the application, battery packs can consist of anywhere between 2 and 14 cells, with some custom cars and trucks using even more.

- (A02) What is a motor?

A motor can best be described as a mechanical device used to move the car under an electrical current. In the past 10 years, the technology used to create them is astounding, and you can make an car very quick, fairly simply.

Most motors used in RC share the same basic idea as motors found in real cars (Starter motors), or PC's (disk drives etc). There are two specific types of RC motors used today, which we will go into further detail about below.

B. Brushed Motors

- (B01) What is a brushed motor?

A brushed motor is exactly that - a motor using rectangular faced brushes, but not the kind you sweep the floor with. ;) They are a metal mixture of compounds that wear out, but can be replaced to alter performance. It is a fairly complicated thing, but can be easily understood with practice.

In general, a motor consists of the following components:

Armature (with 3 stacks of windings)

Can (with either 2 or 4 magnets)

Endbell with brush hoods and timing ring



Ball bearings/bronze bushings

Each of these combine to make the motor rotate the armature, which turns the pinion. The power from the ESC goes into the positive side of the endbell, through the brush hoods and brushes, and into one side of the armature stack, via the copper commutator. The magnet repels that side and turns the armature round, whilst the power does the same to the next stack. This happens thousands of times a minute! On a lot of motors, the timing can be changed to increase performance, but also the wear.

In addition to this, there are 4 main types of brush design, what give difference perfomance and lifespan characteristics.

'Laydown' brushes are where the longest edge of the brush face is 'laid down' across the width of the commutator, these are usually found on 27t motors.

'Standup' brushes are where the longest edge of the brush face is 'stood up' along the length of the commutator, these are usually found in 19t and modifited motors.

'Checkpoint' brushes are a round or octagonal faced brush screwed into the brush hood and gives the best characteristics of both laydown and standup brushes. They are found in the Checkpoint range of 19t and modified motors.

'V2' are similar to Checkpoint brushes, but have an oval face, and are inserted at a 45deg angle to the commutator. These are similar in perforamce to standup brushes, but much less wear, and are found in Peak and Orion 19t amd modified motors.

- (B02) What is a Turn/Wind?

Turns are the number of times wire is wrapped around each armature stack. Less turn means a faster motor and more means slower. But thats not all of it.

Motors are classified in a certain number order. For example:


This means that the motor in question a 19 turn single. The second number is the power delivery of the motor. This usually ranges from 1 to 6 (single, double, triple, quad, quint, hex). With this number, lower means more punchy, higher means smoother. You will see motors with as few as 6 turns and as many as 35 or more.

- (B03) What is a Stock/Super Stock motor?

In the UK (touring cars especially), there are 3 classes of racing. Stock, Super Stock and Modified. Mod will be discussed below.

Stock racing is simple. The motors have to be rebuildable 27t's, with fixed timing and bushings.

Super Stock is similar, but are rebuildable 19t's, with fixed timings and ball bearings.

Both can be tuned for give lots more power than factory, and companies such as Demon, Team Br00d, EA Motorsports etc offer ready to use tuned motors.

- (B04) What is a Modified motor

Modified is another class of racing. The basic motor is similar to Super Stock, but has adjustable timing and any armature turn can be used. At nationals, you can regularly see 7t or 8 turn motors. Thus, this is the quickest class of UK racing.

However, any motor that has adjustable timing is usually classed as a modified motor, so you can 13t, 16t, 20t modifieds etc.

- (B05) Why is there difference in prices of motors?

As with many things, you get what you pay for. If you don't spend a lot on a motor, you won't get much in the way of performance.

For example, you could buy a modified motor with bushings, low power/long life brushes and

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  • 2 weeks later...

A great guide.

my son is running an e-maxx on 2 8.4 3000 nimh packs

i didn't no about cycling packs so they aran't given good run times anymore.

could i run an e-maxx on 2 lipo packs, would this give longer run times and would i need 2 cut offs one for each pack

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  • 2 months later...
  • 2 weeks later...
  • 1 month later...

Yeah, they have to be in what is known as, side-by-side saddles, where the cells sit across the pack and the next one is soldered in line.


Much More made one for NiMH stick packs, but it wasn't that popular and I haven't seen one on sale for a long time, it involved making holes in the heatshrink of the pack.


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  • 4 weeks later...

i have a 60a aeolian esc, and an unknown brushless motor in a ftx enrage, i think the motor is on its way out, whats the best suited brushless motor and the fastest, im using 7.2v saddle packs at 3800maph. thanks

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  • 1 month later...

Hi, welcome to the forum!

Its an OK car, nothing special but it'll do the job. Yep you can go brushless but you'll need a brushless ESC to run the brushless motor too. Most shops will sell an ESC and suitable motor as a combo, depending how quick you want to go.

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That topic used to be covered in one of the links at the bottom of the guide but since rebuildable brushed motors stopped being used in competitions, the links were broken. They are fairly simple to maintain though with the right tools.

Checks -

1. Remove the spring from the brush endbell, and pull brush out of the brush hood.

2. Look at the colour of the brush face and the commutator on the armature. If the colour is black, then its time for new brushes and a comm. skim. If they are not the usual coppery colour (they are red/purple/blue), then the motor has overheated and the oils have left the brush, time to replace.

3. If the grooves in the brush are still there, then they are usually fine if not discoloured.

Stripping -

1. Make a mark of the timing direction of the motor, as if you build the motor with the endbell rotated 180degrees, it'll run backwards. Make the mark going across the can and endbell edge, with a knife blade or a spot of nail varnish.

2. Remove the springs and brushes as above. Make a note to which side each came from, as some motors have a weaker spring on the negative side of the endbell.

3. Loosen the two screws which hold the endbell on, and twist the endbell off the motor can. Be careful not to lose any shims which are on the armature as they may temporarily stick to the endbell.

4. Pull the armature ouf of the can, the magnetic force may make this a bit tricky but try not to touch the commutator itself. Shims may be on the bottom of the armature too.


1. Find someone with a motor lathe suitable for 540-sized motors. Ebay normally has some cheap ones, look for quality brands such as Hudy, Eagle, Team Cobra.

2. Ask them nicely to skim your motor, they'll use the lathe and a diamond (or carbide) tip to literally skim a fraction of a milimetre off the commutator face, leaving it shiny and new. Or do it yourself (see point 1), but be prepared for a few expensive mistakes when learning how to do it.

3. Unscrew old brushes from the brush hood (or unsolder them, if soldered in the first place).


1. Rebuild is the reverse of disassembly. Make sure all the shims go in the right places and take your time.

2. Drive the car!

Hope this helps!

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  • 1 month later...

Hi I`m interested in the FTX Carnage Brushless(i owned a grasshopper in about 84 ? ) but have just read the guide and it says Lipos are not for newcomers Can I run the brushless Carnage on Nimh and if so what do you recomend batt size to get the best performance and runtime ??? i`m only messing about at the mo not racing but maybe interested in lipos in the future when i get braver.

Also could you recomend a charger so that i can cycle these batts I wanna get about three batts so i can keep going.

Or do you recommend i go for the brushed version?

Many thanks in anticipation.

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  • 2 weeks later...
  • 3 weeks later...

Its to do with channel allocation and responsible use of the band. 40mhz crystals ending in zero interfer with crystals on either side of it.

If someone uses something outside of permitted channels then when something goes wrong and the investigation turns out that you're using illegal frequencies, then you're looking at prosecution and a heafty prison sentence. There are scanners in use at MOD bases in the UK and they have a large area of operation, but its a massive massive gamble to run anything illegal and not worth it.

There's a lot of information on http://www.ukrcc.org/

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  • 2 weeks later...

Fantastic guide, cheers all contributors !!

I've been out of the RC scene for over a decade & haven't ran electric for about 20 years. Things have changed A LOT in that time, and this guide's just 'learnt' me loads :)

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  • 3 weeks later...
  • 3 weeks later...

came in here looking for some more detailed info on what series and parallel actualy do, didn't find it.

sincle found that info i was after but may be an idea to add this info to the batteries section of the guide as people seem to be using series and parallel more often these days (lipos in perticular)

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