Tech Center
QI bought a used car and the brushless ESC was bad, so
I ordered a new ESC
for it. ;e motor wires
are red, black, and white on my new ESC and the wires
on the old one are blue, black, and red. How do I know
where the new ESC wires go on the old motor?
WHICH
WIRE
WHERE?
ABrushless motors have three wires to them be- cause they have three stages that need to be electrified. ;e key to a brushless motor running correctly
is that each of the three stages fires in the right order. If
they do not, the motor performance will be significantly
reduced if it works at all. ;e stages are usually labeled
A, B, and C. Most ESCs have labels where the motor
leads are soldered into the case, and many motors have
corresponding labels molded into the endbell. Match the
A wire to the A terminal on the motor and so forth and
your motor should be run correctly. If the motor or ESC
is unlabeled, then consult the manual for the product
to figure it out. In reality it does not matter if the letters
match up, as long as they are in the same order. For
example, A wire into B terminal, B wire onto C terminal,
and C wire onto the A wire should work fine too.
QI have a battery charging question. I have a mixed collection of both NiMH and LiPo packs. I have a multi-function charger that can handle both types of packs. However,
when I am charging my packs, the voltage reading on the charger seems much higher
than the rated voltage of the pack. For example, an 8.4V pack may display 9.2 volts on the
charger. Is this normal, and if not, what do I do to fix it?
AIt is normal for NiMH packs to charge up to a higher voltage than they are rated, but it is not normal for the charger to read past the rated voltage for a LiPo pack. Batteries are
rated for a certain output voltage, and this is based on the chemical cocktail that is inside the
cell. In a standard sub-C sized NiMH cell, the quoted voltage output is 1.2 volts per cell. So, in
a 7-cell pack, the voltage for the whole pack is 8. 4 volts. However, the actual voltage output
of each cell is usually higher than what is printed on the label. Environmental conditions, as
well as slight di;erences in manufacturing techniques, will make each cell or pack unique.
It is not uncommon for the voltage in each NiMH cell to be closer to 1.4V, which would
make the voltage of the entire pack 9. 8. So, it is normal to see higher
charge voltages for a NiMH pack. However, LiPos are a
di;erent story. ;ey can only have a charge
voltage of 4.2 volts per cell. Any higher
than this and the chemistry becomes
unstable and they can explode. LiPo
chargers are programmed to charge at
your quoted amperage until they reach
4.2 volts per cell, then they slowly ramp
down the amperage to trickle charge the
remaining mAh into the pack. If you
are charging an 8.4V LiPo and the
voltage reads more than that, you
need to stop immediately and check
your charger settings before continuing. Accidentally charging LiPos on the NiMH setting
can be dangerous.
