DELTA PEAK AND SUPER
LINEAR CURRENT ON THE CELL MASTER
By far, the most common questions from owners of the MuchMore Cell Master
concern the delta peak settings. Some do not realize that the Cell Master
utilizes significantly lower delta peak settings for peak detection compared to
other chargers.
For example: While you may use a 0.03V (30mV) delta peak setting on a CE Turbo
35, you will use somewhere around a 0.006V (6mV) setting on the Cell Master.
The reasons behind this can be complicated, but they all root from the Cell
Master’s unique Super Linear Current, the most pure and constant linear
current available to the RC market.
The overall purpose of this article is to explain why the Cell Master
utilizes lower delta peak settings. In order to accomplish this, though, I must
explain the causes and effects of the Cell Master’s Super Linear Current.
What is Delta Peak?
The most common way a charger will peak a battery is by utilizing a delta peak
setting. The term “delta peak” refers to the negative change in voltage. For
the most part, a battery’s voltage will increase through a charge cycle until
it reaches its peak voltage. From there, the voltage will begin to decline as
the charger essentially overcharges the battery. The delta peak setting
is the amount that the voltage decreases before charging terminates. This
setting is measured in millivolts (mV), either per cell or per pack.
On the Cell Master, the input delta peak setting is for the entire pack.
Data Conversion Table:
|
Delta Peak Setting
|
Decimal
|
Fraction
|
Input Setting on
CM
|
|
30mV
|
0.030V
|
30/1000 of a volt
|
30
|
|
3mV
|
0.003V
|
3/1000 of a volt
|
03
|
***To get the mV per cell, divide by the number of
cells. For a 6 cell pack, 30mV equals 5mV per cell, and 3mV equals 0.5mV per
cell.
Why is it necessary to set lower delta peak settings on the Cell Master
compared to other chargers?
The reasons for this all root from the CM’s advanced Super Linear Current (SLC).
When designing the Cell Master, MuchMore Racing made every effort to create a
charger with a very pure and constant linear charging current, knowing that it
would result in batteries with more power. As a result, when you are charging
at 6.0 amps with the Cell Master, the battery pack is receiving a pure,
constant, and uninterrupted current rated at exactly 6.0 amps.
This Super Linear Current (SLC) is unique to the Cell Master. It is the SLC,
in fact, that makes the Cell Master so popular among factory-level drivers
(rather than convenient functions).
Both the software and the hardware of the Cell Master contribute to the SLC.
The advanced charging software is programmed to take into account all of the
factors that can influence the charging current (including the LCD screen,
cooling fans, etc), while the state-of-the-art hardware is built fully with
low-resistance connections to make it as accurate and consistent as possible
(how many other chargers feature gold-plated alligator clips?).
The primary purpose of the SLC is to generate more power. Linear charging (as
opposed to pulse and flex charging) has been shown to generate the most power
in today’s racing cells, and the more strong and constant the current is,
the more power it will yield.
On the Cell Master, the combination of the SLC and step-charging is known as
“CTX Charging”. With most chargers, step charging will yield higher
run-times and less power drop-off…but with a slight decrease in power. When
CTX Charging with the Cell Master, however, racers can reap the advantages of
step charging without the power loss. The SLC “makes up” for the slight
power loss naturally created by the process, allowing the racer to have added
run time and less power drop-off without sacrificing power.
Skeptical of the SLC? See the Seeing the Super Linear Current in Action
section later in this article.
Just having the SLC is not good enough, though; a charger must also have
advanced peak detection abilities to prevent the SLC from hurting the
batteries.
With most chargers, a battery will gain most of its heat and power as its
voltage drops when it is peaking. Subsequently, raising the delta peak setting
is a common way to gain more power. Going from a 0.03 setting to a 0.04
setting on a Turbo 35, for example, will give your battery more power. Doing
this, though, will generate more heat and hurt your NiMH battery.
A battery charged with the Cell Master, on the other hand, will gain much of
its power and heat during charge as opposed to at the end of charge
(due to the SLC). It is for this reason that the CM requires lower delta peak
settings. The power and heat have already been generated during charge, so
excessive overcharge is not necessary to create power (and would make the
battery pack very hot). The power gained from the SLC easily outweighs the
power “lost” from lower delta peak settings.
It is due to all of this that MuchMore Racing created advanced 16bit AD peak
detection for the Cell Master. Here are the options for setting delta peak:
1) 3-99mV (0.003-0.099V) Delta Peak Detection— Ultra-fine delta peak
detection adjustable in increments of 1mV. 3mV (0.003V) is the most sensitive
delta peak threshold offered to the RC market.
or…
2) Zero Delta Peak— If the voltage does not change for 7 seconds
during final 30% of the user’s set capacity, the battery will “zero
cut”. If this condition is not met, the charger will peak cut at 3mV
(0.003V).
Because you are able to set these lower delta peak settings without a loss of
power, there is significantly less overcharge of the battery pack. By itself,
super linear charging would hurt the life of a battery pack more than industry
standard linear charging. But, when you take into account the peak detection
settings required by these two methods, super linear charging is actually
better for the life of a battery pack because it does not require the battery
to be excessively overcharged to generate power.
Increasing the delta peak will still result in more power. However, since you
are able to adjust the delta peak by much finer increments (1mV as opposed to
10mV with most other chargers), you can do so more safely with the Cell
Master.
We usually start with a 05 or 06 (0.005V or 0.006V) setting for NiMH batteries
on the Cell Master, adjusting the value from there based on different ambient
conditions and applications.
Seeing the Super Linear Current in Action:
It is normal for a battery’s voltage to fluctuate some early in a charge
cycle. This is because the battery has not yet stabilized and adjusted to the
incoming current. Dead-shorted or stored packs fluctuate more because they are
inherently less stable and less used to incoming current. Later in the charge,
though, there are only two things that can cause voltage fluctuation: a
nonlinear current or some kind of resistance (either due to a bad connection
or bad cell).
It is very common with most other chargers, however, for a battery to
fluctuate in voltage as it peaks. For example, a Turbo 35 set with a 0.03
(30mV) delta peak may peak a 6 cell pack with this pattern:
9.14 - 9.13 - 9.14 - 9.13 - 9.14 - 9.13 - 9.12 - 9.13 - 9.12 - 9.13 - 9.12 -
9.11 - PEAK
As you can see, the voltage is not constantly decreasing.
When charging a battery with the MuchMore Cell Master, however, you will
rarely see any voltage fluctuation as the battery peaks. A 6 cell battery set
with a .006 (6mV) delta peak would follow a voltage pattern similar to this:
9.140 - 9.139 - 9.138 - 9.137 - 9.136 - 9.135 - 9.134 - PEAK
Even showing voltage to the thousandth of a volt (most other chargers show
only two decimal places), you can see that there is no voltage fluctuation as
the battery peaks with the Cell Master; the voltage decreases constantly.
Because the battery is receiving a constant linear current, the battery’s
voltage does not have a chance to fluctuate.
It is very easy to check if the voltage is fluctuating on the Cell Master. There
is an up-or-down arrow to the left of the voltage that demonstrates whether the
battery pack’s voltage is increasing or decreasing (shown in pic below).
Setting Delta Peak on the Cell Master:
Now that you’ve read the technical information concerning why the Cell Master
utilizes lower delta peak settings, perhaps you would like to know how to
actually input the value.
In the setup menus for each charging profile, there are two digits for setting
your delta peak value. This setting is in terms of millivolts (mV) for the
entire pack. You can think of your setting here as 0.0##V.
So, a value of 06 (as in the above pictures) is equal to 6mV or 0.006V (for the
entire pack).
***There is no setting on the Cell Master for mV per cell. A 06 setting (0.006V
or 6mV) for a 6 cell pack is equal to 1mV or 0.001V per cell (calculation:
0.006/6=0.001).
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