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Battery Basics 101!
– Nickel Cadmium abbreviated Ni-Cd, batteries
are the most common rechargeable batteries in the world. It is
important that you discharge these batteries fully before charging
them, or they will lose their capacity and you will get less
run-time in-between charges. This is often referred to as the
“Memory Effect”. In Rc the Ni-Cd battery has the highest voltages
and allow the highest current draw of all the battery chemistry
presently. Making these the cells of choice for sprint racing. It is
also very important that you recycle these batteries because nickel
cadmium is toxic and harmful for the environment.
– Nickel Metal Hydride abbreviated Ni-MH,
batteries have been around for some time, but haven't been able to
take the high current drain of Rc boating. In the last year or so
these problems have been worked out and we to now benefit from the
high capacity cells. Ni-MH batteries have higher capacities (mAh)
than Ni-Cd batteries and are not affected by the “Memory Effect”.
They are more expensive than Ni-Cd batteries, however they will last
longer than Ni-Cd batteries in-between chargers, and will therefore
have a longer life span. These batteries unlike Ni-Cd cells
typically run just as good if not better the second or third run
during the day. You also need to make sure the charger you buy/have
has the ability to charge Ni-MH chemistry batteries. These cells are
the cells of choice for sport and endurance racers.
– Lithium Ion abbreviated LI-ON, batteries are
the newest battery chemistry that exists today. Lithium Ion
rechargeable batteries offer higher voltage and capacity then a Ni-Cd
or Ni-Mh of the same weight. The draw back to these cells is the
very high cost. Also at this date(3/27/03) cant take the high
current drain of Rc boating unless run in parallel. By running in
parallel, we double the weight losing the beneficial gains of LI-ON.
All rechargeable batteries should be charged before use for the
first time.
Before you use your new NiMH batteries for the
first time you must charge them fully. Please note that for new NiMH
batteries, it is often necessary to cycle them at least three to
five times or more before they reach peak performance and
capacity. The first several times that you use your NiMH batteries
you may find that they run down (discharge) quickly during use. Not
to worry, this is normal until the batteries actually form up.
The number of times you can recharge your
batteries will depend on the operating parameters, such as drain
rate, battery care, etc. In general, under the very high drain rates
of Rc boating these batteries wont last as long as say a video
camera. Keep cells charged over the winter and cycle them a few
times. This will help extend the life of the batteries.
You should never fast charge any batteries unless you a have a built
in charger with built-in battery peak detector, or you have
calculated the charge time for your battery pack. If you fast charge
NiCad & NiMH batteries and leave them unattended without the right
charger they can explode and cause fires. We recommend never leaving
charging batteries unattended!
– Lithium Polymer abbreviated Lipo, cells are the latest (as
of this date 7/01/2007) cell technology for rc vehicles. They
are very different than round cell type chemistries like the Ni-Mh
and Ni-Cd.
Individual Lithium Polymer cells have a nominal voltage of 3.7 volts
(vs. 1.2volts per cell for Ni-Cd/NiMH).
Unlike Ni-Cd/Ni-MH cells that self-discharge when wired in parallel,
LiPo cells can be hooked up, charged and discharged in parallel.
Wiring two LiPo cells in parallel doubles the capacity (more run
time), plus an important advantage of wiring in parallel is that
each cell only sees half the total current, which saves the cells
from being overworked in a high amp application. You will hear the
terms "S" & "P" used when people talk about these cells. "S' stands
for series, and "P" for parallel. For example a 2S 2P
battery pack has 4 cells in total. Two cells in series paralleled
with two more cells in series. This pack has 7.4 volts.
All LiPo cells packs should give you a stated C rating or continuous
current rating. This is the maximum average recommended discharge
current for the cell. For example, a 1000mAh pack with a 10c rating
should not be discharged more than 10 amps continuous. To figure
that out 1000mAh x 10c = 10,000mAh or 10 amps. We recommend that if
your application will draw more than 60% of that rating, buy higher
rated cells. Beware of "burst" ratings. Burst ratings are amp rating
for only a few seconds. This is a poor way to judge the cells
ability.
This is a basic overview of LiPo cells. Please search the internet
for information on using and charging these safely. NEVER leave them
unattended. Store them in a safe fire proof container!
Key to terms you'll see used on many pages dealing with batteries.
Amp Hours (Ah) – Refers to the amperage – the
strength of the electrical current expressed in amperes that the
battery can hold. The higher the Ah, the longer the battery will
last in-between charges.
Capacity – Measured in Amp Hours or Milliamp
Hours and is the amount of time the battery can supply the necessary
voltage.
Cell – One individual battery canister. Commonly
arranged with other cells to form battery packs of different voltage
and capacities.
Charge – With the use of a charger, charging a
battery will insert energy into it.
Condition or
cycle– The process by which a battery is discharged and
charged in order to guarantee maximum performance. It works
basically like this. Charge your batteries fully. Allow them to cool
before using them. Then use your batteries as you would normally do.
Not allowing them to completely die (this will kill your batteries)
This is one complete cycle.
Discharge – The process of taking energy out of a
battery.
Life Cycle – The amount of times a battery can be
charged and discharged before it no longer has any power.
Memory Effect – The Effect that represents the
decrease in capacity and voltage in Ni-Cd batteries due to
repetitive charging and incomplete discharging. This results in loss
of run-time in-between charges.
Milliamp Hours (mAh) – Applies to how much energy
the battery can store – the capacity of the battery. The higher the
mAh, the longer the run-time in-between charges. One mAh is the
equivalent to 1/1000 Amps. IE: 2.7 Ah = 2700 mAh
Self-Discharge – If batteries are fully charged
and sit on the shelf for one-two months, they will Self-Discharge.
By Self-Discharging the batteries will lose capacity on their own
without being used or placed in a charger that discharges the
batteries. |