Competition Electronics Turbo35-GFX User manual

Competition Electronics, Inc
3469 Precision Dr.
Rockford, IL 61109
Competition Electronics, Inc
Turbo35-GFX
User’s Manual
and
Guide to
Electric R/C Racing

T BLE OF CONTENTS
INTRODUCTION TO THE T35-GFX A TOOL TO MEASURE AND CONDITION
YOUR CELLS 4
WARNING 4
HOW TO USE THIS MANUAL 5
QUICK START A STARTING LINE VIEW OF THE T35-GFX 5
PREPPING THE T35-GF FOR USE .......................................................................................................... 5
POWERING UP THE T35-GF ................................................................................................................. 6
GETTING FAMILIAR WITH THE T35-GF MENU SYSTEM ........................................................................... 6
THE HELP LINE .................................................................................................................................... 8
LOADING FACTORY SETUPS .................................................................................................................... 9
CONNECTING YOUR PACK AND MOTOR ....................................................................................................... 9
QUICK START CHARGE ..................................................................................................................... 10
QUICK START DISCHARGE ................................................................................................................. 10
QUICK START CYCLE ........................................................................................................................ 10
QUICK START MOTOR RUN .............................................................................................................. 11
LEARNING ABOUT CELLS AND PACKS FOR R/C RACING 11
TYPES OF CELLS USED IN R/C RACING .............................................................................................. 11
RC RACING IS DIFFERENT FROM OTHER BATTERY APPLICATIONS ............................................................ 11
HOW CAN CELL AND PACK CAPACITY BE MEASURED AND COMPARED? ................................................. 12
SETTING UP TESTS AND COMPARING DATA ............................................................................................. 12
TO RECAP… .................................................................................................................................... 14
USEFUL PARAMETERS FOR MEASURING PERFORMANCE ............................................................................. 14
MAXIMIZING PERFORMANCE WHAT HELPS, WHAT DOESN’T .................................................................. 16
UNDERSTANDING CELL RATING AND MANUFACTURER’S SPECIFICATIONS .................................................... 16
HOW TO DETERMINE STARTING POINTS FOR CHARGE RATES, DISCHARGE RATES, AND PEAK DETECT SETTINGS
......................................................................................................................................................... 16
USING SIMULATED DISCHARGE PROFILES TO CONDITION PACKS ................................................................ 20
ZAPPING: WHAT IS IT AND WHAT DOES IT DO? ......................................................................................... 21
ETREME DISCHARGE/EQUALIZING ........................................................................................................ 21
GETTING THE MOST OUT OF YOUR CELLS DEPENDS ON DRIVING SKILL ...................................................... 21
HMMM: IT SOUNDS COOL, BUT IS IT USEFUL? GIMMICKS, TRENDS AND SUPERSTITION .................................. 21
FINAL ADVICE (FOR NOW…) .............................................................................................................. 22
RESOURCES ON THE WEB ................................................................................................................... 22
THE T35-GFX IN DETAIL 22
2

WHAT CAN I DO WITH MY T35-GFX? 22
THE MODE BUTTON ........................................................................................................................ 23
THE PAGE BUTTON ......................................................................................................................... 24
THE START/STOP BUTTON ........................................................................................................... 24
THE ROTARY DIAL SWITCH AND THE CURSOR ..................................................................................... 25
REINITIALIZING NON-VOLATILE MEMORY .............................................................................................. 25
CHARGE MODE .................................................................................................................................. 25
CHARGE POWER DISSIPATION LIMIT ...................................................................................................... 26
SETTING UP A CHARGE CYCLE ................................................................................................................ 26
DISCHARGE MODE ............................................................................................................................. 29
DISCHARGE POWER DISSIPATION LIMIT .................................................................................................. 29
SETTING UP A DISCHARGE CYCLE ............................................................................................................ 29
CYCLE MODE .................................................................................................................................... 33
SETTING UP A CYCLE ........................................................................................................................... 33
MOTOR RUN MODE ........................................................................................................................... 33
SETTING UP THE MOTOR RUN CYCLE ..................................................................................................... 34
DATA MODE ...................................................................................................................................... 34
COMM SETTING ................................................................................................................................... 35
USING THE GRAPHING FEATURES ........................................................................................................... 40
SUPPLY VOLTAGE ................................................................................................................................ 41
SETUP MODE ..................................................................................................................................... 41
WHAT SETTINGS ARE SAVED/RECALLED IN A SETUP? .............................................................................. 41
STORING/RETRIEVING SETUPS ............................................................................................................. 42
LOADING SETUPS ................................................................................................................................ 43
SAVING SETUPS ................................................................................................................................... 43
NAMING/RENAMING SETUPS ................................................................................................................. 44
EDITING SETUPS .................................................................................................................................. 44
BEEPER .............................................................................................................................................. 44
MACHINE ........................................................................................................................................... 45
USING THE PC AND HELPER PROGRAMS ................................................................................................. 46
HYPERTERMINAL QUICK START ............................................................................................................ 47
CAPTURING AND SAVING DATA ............................................................................................................. 48
SPECIFICATIONS 56
POWER SUPPLY REQUIREMENTS .......................................................................................................... 56
WHEN IT DOESN’T WORK 57
COMMON PROBLEMS AND QUESTIONS .................................................................................................. 57
NONVOLATILE MEMORY CORRUPTION ...................................................................................................... 57
FAILURE TO POWER UP CORRECTLY; GARBLED DISPLAY ............................................................................. 57
FUSES ................................................................................................................................................ 58
VOLTAGE DROP, RESISTANCE, AND THE PROPER USE OF SENSE LEADS ...................................................... 59
SHOULD I SEND MY T35-GF IN FOR CALIBRATION? ............................................................................. 59
SENDING YOUR T35-GFX IN FOR REPAIR ........................................................................................... 59
FIRMWARE UPDATES .......................................................................................................................... 60
***LIMITED WARRANTY*** .............................................................................................................. 61
3

HOW TO CONTACT COMPETITION ELECTRONICS .................................................................................. 61
4

Introduction to the T35-GFX: Tool to Measure and
Condition your Cells
Congratulations on your purchase of our Turbo35 GF ! The T35-GF is a state-of-the-
art, competition-grade battery charger/discharger/motor run machine. If you are new to
the T35-GF it will take a while to become fully familiar with its many advanced
features. However, the T35-GF is designed so that its basic functions are easy to use,
right out of the box.
If you’ve used other CEI products, you’ll feel right at home with the T35-GF . However,
if you’ve used earlier CEI products, you’ll find that the T35-GF also has many new,
exciting and useful features that you won’t find on our competitor’s products.
In order to get the most out of your T35-GF , please take a moment to familiarize
yourself with this manual.
Warning
To reduce the risk of injury, use only rechargeable nickel cadmium or nickel metal cells
and packs with the T35-GF . Any other type of battery may burst and cause personal
injury.
DO NOT leave the T35-GF unattended. The remote possibility of an electronic failure
could cause extreme overcharge. This could cause a cell to burst and cause a fire hazard.
The T35-GF is designed to provide data about rechargeable nickel cadmium and nickel
metal batteries. In order to simulate high discharge rates obtained during racing, the T35-
GF is designed to discharge at high currents. While the methods used in the T35-GF
are common in selecting cells, excessive heat generated during the process may cause
damage to the cells or cause them to vent battery acids. To reduce the risk of injury,
ALWAYS WEAR SAFEY GLASSES when operating the T35-GF . Since the cells are
extremely hot, be careful not to handle the cells until cooled.
Always make sure all the cells in the pack are in the same state of discharge before
charging a pack. Otherwise, the cells that are partially charged before charging will get
extremely hot and may be damaged or vent battery acids.
Check your battery pack occasionally for overheating. If the cells are too hot to touch,
there is something wrong and the pack must be disconnected from the charger.
Competition Electronics, Inc. shall not be liable for any property damage or personal
injury which may result from the failure to follow these instructions or other improper
use of this product.
How to Use this Manual
This manual is divided into several parts.
•Quick Start If you can’t wait to use your T35-GF , go here. Come back later
when you want to get into the details.
•Learning about Cells, etc This section contains useful background information
about cells and packs, and how to get the most out of them.
•What can I do with my T35-GFX? Look in this section for more detailed
operating instructions.
5

•Specifications This section contains a concise technical summary of the T35-
GF capabilities and requirements data.
•When it doesn’t work In this section you learn how to tell if your T35-GF is
broken, and what to do about it. Also, look here for information about how to get
your T35-GF upgraded, calibrated, etc.
Quick Start: Starting Line View of the T35-GFX
This section of the manual will get you up and running fast.
Prepping the T35-GFX for use
If your T35-GF is new out of the box, you will need to configure the power and output
lead wires. CEI supplies heavy duty alligator clips for these lead wires; they must be
soldered to obtain a good connection. Alternately, you may choose to install some other
type of connector, such as a Dean’s® connector for the power connections.
When soldering, be sure to heat the conductors enough so that you get a nice shiny solder
joint. Use enough solder to fully wet the conductors, but not so much that it forms a big
ball, or glob.
Good solder joints are shiny, not dull. Dull solder joints are usually referred to as “cold”
solder joints. The usual cause is not heating the conductors to be soldered sufficiently
before applying the solder.
Figure 1. Soldering an alligator clip.
6

Remember to put the alligator clip insulators on the wires before soldering the alligator
clips, and make sure they’re far enough away from the solder joint so that they don’t
overheat and melt.
Powering up the T35-GFX
The 14 gage 4 foot long pair of leads on the left side of the T35-GF are to be connected
to the DC power supply. The other leads are used to make connections to your pack or
motor.
Avoid using the switch on an outlet strip or the line cord plug on the AC side of your
power supply as a means control power to the T35-GF . Instead, always make the final
power connection to the T35-GF AT THE DC INPUT WIRE on the power cable of the
T35-GF .
After terminating the lead wires, connect the T35-GF power leads to a 12V-16V DC
power supply. Obviously, the red lead goes to the positive terminal; the black lead to the
negative terminal of the supply. This DC supply should be capable of 20 amps if you
want to utilize the full motor run capacity and 12 amps to realize the full charging
capacity of the T35-GF . See “Power Supply Requirements,” below, for more details.
Getting Familiar with the T35-GFX Menu System
Like many digital electronic devices, the T35-GF has an LCD display that
communicates the status of the T35-GF to the user. By this means, the T35-GF menu
system is displayed. Below is a “menu tree” showing the navigation pattern for the T35-
GF menu.
7

CHARGE
MODE
MAIN SCREEN
PAGE PAGE PAGE
PAGE PAGE
PAGE PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
PAGE
MODE
MODE
MODE
MODE
MODE
MODE
MODE
DISCHARGE
MODE
MAIN SCREEN
CYCLE
MODE
MAIN SCREEN
MOTOR RUN
MODE
MAIN SCREEN
PAGE 1
1ST PAGE
SETUP
PAGE 2
2ND PAGE
SETUP
PAGE 3
TRICKLE
DELAY START
PAGE 1
SETUP
PAGE 1
SETUP
PAGE 1
SETUP
PAGE 1
GRAPHS &
READINGS
PAGE 2
READINGS
PAGE 2
LOAD, SAVE
AND NAME
10 SETUPS
DATA MODE
MAIN SCREEN
SET MODE
MAIN SCREEN
Figure 2. T35 GFX Menu Tree.
8

When you first turn on the T35-
GF , the display will show the
sign-on message, including the
firmware revision number.
This number corresponds to the
version of software in the T35-
GF . From time to time, CEI
upgrades this software, either to fix
firmware “bugs” or to add new
features. The firmware revision
number may be important if your
T35-GF needs service; see “When
it doesn’t work” for more details
about this.
The T35-GF has three buttons on the front panel, as well as a combination rotary
dial/push button. The buttons are as follows:
Start/Stop used to start and
stop the selected function.
Mode This button is used to
cycle through the six main
functions, detailed below.
Page This button will cycle
through the various screens
associated with each function.
Use the Mode and Page buttons
to navigate to the desired page,
or screen containing the
parameter(s) you want to view or
change. In either case, when you
get to the last Mode or Page,
pushing the button again will go
to the first Mode or Page of the
series.
As you advance from page to page, individual lines appear on each page. Upon entry to a
page, the top line will be highlighted, indicating it is the currently selected line.
To navigate to individual lines on a page, use the large rotary dial; just push it in to
navigate to the next line on the display.
Some values are adjustable, and some are simply informational and cannot be changed. If
you are on a line that can be adjusted, in general, rotating the dial CW or CCW will
increase/decrease the value.
The Help Line
As you highlight the various lines, a context sensitive, scrolling help line will appear at
the bottom of the display. You can always see the details for the selected line, such as
what range it can be adjusted over, etc. Also, if applicable, you will see additional
9
Figure 3. Sign-on Screen.
Figure 4. T35-GFX front panel controls.

directions for adjusting the highlighted line, such as when you are creating names for
setups, for example. Use of the buttons varies from the norm on some lines, and details
are given for use when it is appropriate. So, you never really need the directions, once
you’ve got a grasp of the basic use of each function. Just refer to the help line.
Loading Factory Setups
A lot of users have questions about how to set up their T35-GF for different types of
packs and motors. In order to get you started, the T35-GF comes from the factory with
a number of standard setups already in the unit. The setups are good starting points for
many common needs. This is the quickest way to get started.
Use the Mode button to navigate to the “set mode” display (shown in the upper right
hand corner of the LCD display. The top line will be highlighted; by rotating the dial, you
can select one of the presets and by pressing the “start” button, you can load it into the
T35-GF memory for use.
The factory settings are:
1. 6CellNimH: for a 6 cell, 3300mAHr pack.
2. 8CellTx for a 8 cell transmitter pack
3. 4CellRx for a 4 cell receiver pack
4. 4CellNimH for a 4 cell 3300mAHr pack.
5. 6CellCyc setup to run a charge/discharge cycle for a 6 cell 3300mAHr pack.
6. 4CellCyc same thing for a 4 cell 3300mAHr pack
The remaining 4 setups are left unused by CEI and you can use them for your own
custom setups. You can also edit and save the factory setups; just be aware that if you
need to reload the factory setups, anything you have saved will be lost. However,
normally you only need to do this if you want to return to the factory setups, or if the
onboard non-volatile memory gets corrupted, which is rare indeed.
Load the factory preset cycle that most closely matches what you want to do. Then,
if necessary, adjust individual settings to “tweak” the setting to your liking. If you don’t
know much about how to set the various parameters, the preset cycles are a good starting
point. As you learn more about the charging and discharging of cells, you can make
adjustments as you wish.
If you are using the T35-GF with something other than these more standard cell types,
the charge and discharge rates will depend on the mAHr rating and the application the
cells are being used in.
Connecting your pack and motor
First of all, you’ll notice that your T35-GF has four leads. This is no accident. One of
the things that set your T35-GF apart from the competition is that it has a set of
separate, smaller “sense leads”. Why? Ohm’s law tells us that where there is a higher
current flowing, there will be a greater voltage drop across any resistance in the circuit
under observation. In this case, most of the unwanted voltage drop occurs directly at the
mechanical connections between the large, hi-current leads and the battery pack. This can
be minimized by making better connections, but the fact is that there will always be a
voltage drop at the connections, because of the high current flowing during charge or
10

discharge. That is why we have the additional
small sense leads. These leads are designed
specifically for measuring, and will have
essentially no voltage drop at all, because the
current flowing through these leads is
relatively low. The advantage of this is that
they can measure the voltage far more
accurately. So in general, it’s best to always
use the sense leads. However, the sense leads
are not absolutely necessary for a charge cycle.
Although the readings will be slightly off, it
will not affect the amount of charge
delivered to the pack.
And another thing: it is critical that the
sense leads be connected directly to the
pack/motor solder tabs, and not clipped
or soldered to the large leads. If you do
this, you will defeat the purpose of the
sense leads and they will do you
absolutely no good.
Quick Start: Charge
1. Load a setup from the T35-GF memory, or use the currently loaded setup, if
appropriate.
2. Navigate to the “chg mode” screen.
3. Make any adjustments that might differ from the stock factory setup.
4. Connect Power and Sense leads to the pack.
5. Press “Start”.
Quick Start: Discharge
1. Load a setup from the T35-GF memory, or use the currently loaded setup, if
appropriate.
2. Navigate to the “dcg mode” screen.
3. Make any adjustments that might differ from the stock factory setup.
4. Connect Power and Sense leads to the pack.
5. Press “Start”.
Quick Start: Cycle
1. Load a setup from the T35-GF memory, or use the currently loaded setup, if
appropriate.
2. Navigate to the “cyc mode” screen.
3. Make any adjustments that might differ from the stock factory setup.
4. Connect Power and Sense leads to the pack.
11
Figure 5. Motor Connections.
Figure 6. Pack Connections.

5. Press “Start”.
Quick Start: Motor Run
1. Navigate to the “mot mode” screen. There are no specific factory cycles for motor
run, although values are saved and included in all setups.
2. Using the “Page” button, go to the “1 of 1” motor parameter screen and select the
motor voltage and run time.
3. Connect Power and Sense leads to the motor.
4. Press “Start”.
After you get up and running, be sure to read the rest of the manual. Do it while your
charging those high capacity NimH packs; you’ll be glad you did.
Learning about Cells and Packs for R/C Racing
One of the hurdles for beginning R/C racers is gaining a basic understanding of these
power sources we call cells. It turns out that the cells we use, and how we treat them has
a huge effect on racing performance. The objective of this section is to give you that
basic understanding.
The technology that makes R/C racing possible is the advent of rechargeable cell types
that are capable of sustained high rates of discharge. It is probable that R/C racing as we
know it could not exist if this technology had not been discovered.
Types of Cells Used in R/C Racing
There are two main types of cells used in R/C racing today.
NiCd NiCd stands for Nickel-Cadmium. Until the last few years, NiCd was the most
popular cell used for R/C racing.
NiCd cells have a typical cell voltage of 1.2 volts. Among their disadvantages is the fact
that they have a “memory” and if they are not routinely discharged completely and
recharged fully, their capacity diminishes considerably.
Another disadvantage of NiCd chemistry is that they require special disposal procedures
because of their cadmium content.
They are a bit more durable than NimH cells and can stand a bit more abuse, but their
mAHr capacity is considerably lower than NimH types. They are more consistent in their
charge/discharge characteristics from cycle to cycle.
NimH NimH stands for Nickel-metal-Hydride. NimH is by far the predominant cell in
use today for R/C racing. NimH chemistry does not suffer from any of the disadvantages
of NiCd. It is less toxic, does not have a memory, and now comes in higher mAHr
capacity than the NiCd types.
Today’s NimH cell voltage after “zapping” (we will discuss zapping a little later) have
significantly higher average voltages.
NimH cells should still be recycled at the end of their useful life.
RC Racing is different from other battery applications
If you talk to a cell manufacturer about the way R/C racers charge and discharge their
cells, he or she may tell you that you are abusing these cells. The fact is, to a certain
12

extent, this is true. However, the goals of an R/C racer are different than the goals of an
average user. In the case of the R/C racer, there is the need to balance cell longevity with
performance. It is an inherent tradeoff racers make, so you should understand from the
beginning that racers don’t treat their cells “nice”. As a result, they cannot be expected to
last as long as they might in a less demanding application. If you are interested in
ultimate performance, plan to relegate older packs to practice duty after they have been
used for a while. Exactly when you do this is a function of your skill level and how much
you are willing to spend on cells.
ow can Cell and Pack Capacity be Measured and Compared?
Pack performance is one of the crucial make-or-break factors in R/C racing. The best
drivers can use every extra bit of voltage and current available from the best packs.
Because NimH and NiCd cells can vary considerably from cell to cell, and because their
performance can degrade or change depending on how we treat them, how old they are,
etc, we need a way to measure and compare our cells in order to identify the best cells, as
well as the best procedures for charging, discharging, and using them. The T35-GF is
designed to do just that.
Setting up Tests and Comparing Data
The best way to test and measure cell performance is to set up defined conditions for
charge and discharge, and then run these tests on cells to see which cells are the best.
When you do this, it is also important to be aware that the very conditions under which
they are charged and discharged have a direct effect on their performance.
Basically, the idea is to run these tests on cells, looking for the ones that have the highest
average discharge voltage, the lowest internal resistance, and the longest run time.
In general, when charging, you’ll want to strike a balance between a high charge rate
(which minimizes charge time) while keeping cell heating within bounds.
When discharging, you’ll want to try to use the highest discharge rates applicable to the
cell type you are using, in order to test it under conditions similar to actual use. The T35-
GF can sustain a 35 amp discharge rate.
Racers often ask what will be the effect of increasing the charge current, lowering the
peak detect voltage, etc. The T35-GF is the perfect tool for getting answers to all these
questions! Which manufacturer’s cells perform better? What rate should we charge at?
All these things can be tested and answered by the racer using the T35-GF .
You can use it to test single cells or packs.
13

Single Cell Testing
Figure 7. T35-GFX with Single Cell Holder.
If you’re planning on doing a lot of single cell testing, you will want to get a cell holder
from CEI, #CEI -2090. See our website for this and other products.
To use the optional battery box, connect the large alligator clips to the bare 14 gauge
wires on the battery box, (red to red and black to black) or install a high quality connector
of choice. Whatever connector you choose should be rated for continuous current
capacity of 35 amps if you intend to discharge at full rated capability. Then, connect the
small red alligator clip to the small red lead on the cell holder, in like manner, connect the
small black alligator clip to the small black lead. The small voltage leads must be
connected to get accurate discharge readings. DO NOT increase the length of the battery
box high current leads, or introduce any type of additional connection other than the main
connection formed with the end of the leads. To do so may cause discharge current to
taper off at the end of the discharge, due to additional voltage drops introduced by the
additional series resistance.
Mount the end of the battery box with the springs to a flat surface with the holes
provided. The other end of the box is left free to move. Do not tighten the screws all the
way, otherwise the battery box will not move freely.
The battery box may be forced open by squeezing the spring at the end of the rods and
the box between the thumb and the forefingers. This is useful for placing the cell in the
box. The positive terminal of the cell goes to the red lead end of the box. Rotating the cell
back and forth a few times after placing it in the box will insure good connection between
the contacts and the cell. To remove the cell, place your finger underneath the cell and
push up.
14

The contacts used are tin-plated contacts. The contacts can be (and should be) cleaned
using a model train track cleaner for brass tracks such as Rail Zip® made by Pacer Tech.
To Recap…
So, start with the appropriate factory preset. Talk to other racers. Do your research on the
internet. Then, take an old pack and start to modify the settings, and keep track of the
changes in a notebook. Log the charge settings and the results when you discharge. And
don’t forget to try it in your car! That’s where “the rubber meets the road,” so to speak.
Look for a change in your personal performance. Over time, you’ll find what works for
you.
Useful Parameters for Measuring Performance
The T35-GF can make a number of useful measurements that will help you to evaluate
your cells. Here are some of the most useful.
Actual Internal Resistance
The actual internal resistance measurement made by the T35-GF conforms closely (not
exactly) to the ANSI standard C18.2M-1997 for sealed rechargeable batteries. It is a
measure of the internal resistance of the pack or cells and will correspond to the packs
ability to deliver power. It is presented in units of milliohms (1/1000 of an ohm) and it is
measured during the discharge cycle. A lower number is better. There is no hard and fast
rule concerning at what rate to discharge cells when making this measurement, but in
general, to get the best comparison data, it’s a good idea to discharge packs at the same
current rate.
It is good to keep in mind that this measurement will include resistance in the
connections between cells, etc. Make sure that you test packs and cells under similar
conditions. For example, use the same method of connecting to cells for all the packs or
cells you want to compare.
Peak Charge Volts
In a general way, a higher peak charge voltage means that it took more volts across the
pack to induce the setpoint current through the pack during charge, for a given charge
rate. This is an indication of the pack’s internal resistance and age; higher voltage means
the pack is less desirable.
Discharge Average Volts
Discharge average volts is simply that, the average voltage over the discharge curve,
measured at intervals, from the start of the discharge cycle until cutoff. Of course, a
higher number is better because it means that the cells will deliver a higher average
voltage to the motor. More volts means more power.
Discharge Average Volts at 1V
This parameter is useful in this way; that most people won’t care about the average
voltage after the per-cell voltage drops below 1 volt, because the cells are too discharged
15

to provide useful power. It will result in a higher number than Discharge Average Volts
and represents the voltage over a more useful range.
Run Time
How long from the start of discharge until cutoff at the set discharge current? Longer is
better, if you need the time. If your races are short, that means that the pack could have
delivered more power if it was required. Maybe changing to a higher current motor, or
changing the gearing might give you more performance by allowing you to utilize more
of your pack’s stored power.
mAHr
mAHr (milliAmpere-Hours) is the capacity
of a cell or cells expressed as the product of
the discharge current in milliamperes times
the time it delivers this output current in
hours. (a mA is 1/1000 of an ampere.)
Manufacturer’s mAHr rating on the types
of cells R/C racers use is typically printed
right on the cell jacket. mAHrs can flow
into or out of the cell; in other words, we
can use mAHr to describe the rate of
charging or discharging. Due to the built-in
inefficiency of power transfer into and out
of the cell, it will always take more power
to charge up a cell or pack than the cell or
pack can deliver into a load.
You can use this to figure out how long a
pack can supply a given current before it is
spent.
mWHr
mWHr (milliWatt-Hours) is a measure of the power the cell can deliver over time. It is
measured and calculated in the T35-GF by making a measurement of the output voltage
for a periodic mAHr rate, and multiplying the voltage measurement times the mAHr for
that time period, and totaling the result for the duration of the discharge period until
cutoff.
Relative Internal Resistance
Relative internal resistance was developed by Jeff Pack (a programmer and racer) as a
way of making cell comparisons related to the internal resistance of a cell. You can use it
to compare packs; a lower number is better.
In order to measure this parameter, a full charge/discharge, also known as a Cycle, must
be run. In order to get comparative numbers, you must use similar settings for charge and
discharge current across packs to be compared.
16
Figure 8. Close up of 3300 mAHr cells.

It has been largely replaced by Actual Internal Resistance, another CEI innovation in R/C
racing competition-grade equipment.
Maximizing Performance: What helps, what doesn’t
Understanding Cell Rating and Manufacturer’s Specifications
If you buy your cells from a distributor or matcher, you may not have thought about the
fact that they are a middle man to the manufacturer. Google for the manufacturer’s
website; you may find valuable information concerning the cells you are using.
Charge and Discharge Rates and the “C” Rating
For instance, manufacturers of storage cells rate their cells by giving them a “C” rating.
Below is a graph of cell voltage vs. percentage of full capacity charge input for a 1C
charge rate for a 3300 mAHr sub-c cell. This is related to the rate of discharge current
which will empty the cell of charge in 1 hour. So, a “1C” charge rate is the current
necessary to charge a dead cell to full capacity in 1 hour.
Figure 9. 1C charge profile for 3300 mAHr NimH Cell.
How to determine Starting Points for Charge Rates, Discharge Rates,
and Peak Detect Settings
Charging
So, at what current should packs be charged? For more normal applications (not R/C
racing!), the manufacturer might recommend a 1C charge rate, which should result in a
life expectancy of >500 charge/discharge cycles, according to the data sheet.
17

For smaller capacity cells, it’s probably a good idea to stick to 1C charge rates, but as the
cell capacity gets larger, the cell can handle higher rates.
For another, there is some evidence to indicate that a higher charge rate will result in
better performance on the track. Racers routinely charge these cells at 5A (5000mA) and
better. One racer likes to charge his high capacity NimH cells at 10A (better than a 3C
charge rate) because he claims that it improves the performance!
Peak Detect
Notice the little voltage “hump” at the 1C point in the graph above, followed by the drop
in voltage. This is called “peaking” and this is the method used by many chargers,
including the T35-GF , to determine when the charge is finished. When you set the peak
detect voltage in the T35-GF , you are telling the T35-GF to terminate the charge
when the voltage drops back from the peak, or maximum voltage seen during the charge
process, by the peak detect amount. If you use the T35-GF graphing feature to look at
the charge curve, you will be able to see this hump for yourself.
The actual peak rate of change and the magnitude of peak negative dropback voltage are
highly dependent on the charge current. At charge rates of, say, 0.5C and below, the peak
negative dropback voltage may be too small to serve as a reliable indicator of charge
completion.
A typical value for peak detect for a NimH pack is 0.007 to 0.010 V/cell, or 0.04 to 0.06
volts for a 6 cell pack. The value for a NiCd cell will be somewhat higher, typically 0.008
to 0.013 V/cell, as the NiCd cell exhibits a larger peak negative dropback voltage than a
NimH. CEI recommends using the lowest value required to reach a temp of 130° to 140°
F.
False Peaking
As you can see from the graph, the voltage at the start of the charge cycle will jump up
some amount as current is applied. Then, the voltage will “level out” for a while, or
slowly rise. It is at this point that NimH (and NiCd) packs often exhibit a characteristic
called “false peaking”. The pack voltage will actually drop, even though the pack is not
yet near full charge. This effect can be magnified if “dead shorting” or deep discharging
the battery. If you are not aware of this, you may think your packs are fully charged, but
in reality, they are only partially charged. If your pack appears to have peaked too soon, a
quick test is to feel the pack to see if it is warm. If it is not good and warm, that means
that the pack false-peaked and is not fully charged. If the T35-GF indicates something
less than the 1C mAHr rating has been delivered to the pack, it is almost a certainty that
the pack has false peaked.
False peaking can be overcome in the T35-GF by using the “Long Lockout” feature to
cause the T35-GF to ignore voltage drop across the pack at the beginning of the charge
cycle. It will automatically re-enable its peak detect monitoring after the time for false
peak rejection has expired. This has proven to be quite reliable as a method to avoid false
peaking. It eliminates the hassle of having to restart the charge cycle because the pack
false peaked.
Cell Heating
18

When charging properly functioning NimH packs, during the first part of the charge
process the cells will self heat slightly. NiCd cells do not exhibit this self-heating
behavior before peaking. For both types of cells, temperature will rapidly rise as the pack
nears full charge. Normally, for good cell longevity, it is desirable to minimize cell
heating as much as possible. However, in R/C racing, there are definite advantages to
heating your cells! It turns out that the performance of warm cells is noticeably superior
to cold cells. It will then be better to peak your cells right before a race, so that they are
warm when you use them. Also, some racers thermally insulate the pack while charging,
to cause the pack to build more heat during the charge process, while maintaining a lower
peak detect voltage.
Another factor that will heat the pack is a higher charge rate. A higher peak detect
voltage will also result in a hotter pack. But don’t forget that excess heat does damage the
cells and will shorten their life. Normal treatment of NimH cells would dictate as small a
peak detect voltage as possible, to avoid as much heat as possible during charging, but
R/C racing is different!
Cell “Venting”
Both NimH and NiCd cells have vents at the positive electrode end that will release
pressure (and electrolyte) when the cells are charged. This venting is normally to be
avoided. It will occur at higher charge rates. Repeated venting will certainly degrade
cells.
TurboFlex: W at is it and w at does it do?
Your T35-GF includes a feature called “TurboFlex”, also known as “burping”.
TurboFlex is only intended for use with NiCd cells. The rationale behind TurboFlex is
this: Charging NiCd cells can cause crystalline deposits to build up inside them, resulting
in performance degradation. Periodic discharge pulses delivered during a charge cycle
can reduce these deposits, thus improving performance. Using the TurboFlex feature is
not beneficial when actually charging for use in a car, but rather should be regarded as a
conditioning procedure. Do not use TurboFlex when charging your cells for racing.
The T35-GF is set up for variable adjustment of the TurboFlex feature. The settings go
from 1 to 9, with 1 resulting in the lowest ratio of discharge to charge time, and 9 the
highest. In the case of the T35-GF , the TurboFlex discharge rate is fixed at 5 amps.
TurboFlex will not take place, regardless of the setting, if the charge current is <= 3A.
This is built into the T35-GF .
Discharging
The T35-GF includes a discharging function that can discharge at rates of up to 35
amps. With this feature, you can test your cells and packs and measure their performance.
You can tell when the performance is falling off, and you can extend the performance of
your packs by re-matching cells and combining similar cells into packs.
Disc arge Rate and It’s Relations ip to Performance
Over the years, CEI has repeatedly increased the discharge rate of our
charger/dischargers. This is because our customers demanded the higher rates. One
19

reason for this is the fact that cell capacities have increased. Another reason is that R/C
motors these days draw a lot of current, so it takes a higher discharge rate to emulate
these high currents.
The discharge function is the main tool that you use to compare cell performance. You
can discharge a cell or a pack to a defined cutoff voltage at a fixed current and observe
the discharge voltage over time as a graph, as well as time the discharge duration.
Obviously, a rather simple application of this, and one that is used most frequently, is to
run the identical discharge procedure on several similar packs and compare the results.
More run time is better, of course, but a higher output voltage is better, as well.
Cell Matc ing and it’s Effects
For the best performance, you’ll want to obtain what is known as a matched pack. This
means that the cells in the pack have similar discharge profiles. This is desirable because
cells with similar discharge times and similar discharge profiles will tend to deliver
similar output power over the same time period. They will reach the end of their power
output at the same time. Matching prevents the condition where some cells in a pack are
still delivering current to the load while others are fully discharged.
Figure 10. TurboMatcher 4/35.
As we have already stated, individual cells vary widely, both in output voltage and
discharge, or run time. Cell matching companies go through many cases of batteries in
order to separate out the best ones, and match them into packs for top racers. The lesser
quality cells are also matched into packs, but they are sold for less money. Most matcher
companies use the CEI TurboMatcher 4 (a special charger/discharger that is designed to
grade 4 single cells at a time) to test cells and match them.
You can do the same thing with a T35-GF ; the only difference is that you will have to
do one cell at a time.
20