It is important to always
adjust your charger correctly
for the size and type battery
you are charging.
Here is a typical battery label, showing the total capacity in milliamp hours (mAh)
and amp hours (Ah), and both the 6S cell count and nominal voltage of 22.2 volts.
No charge rate is listed, so this one should be charged at 1C.
Charge LiPo Batteries
Using a modern charger safely
Tex T & pho Tos by John KauK
for the batteries, which has been discussed previously in this column.
Second, the balance lead gives the charger an accurate way to count
the cells in a battery and measure the voltage of each cell. If the charger
knows the cell count and it has been programmed to stop charging at an
appropriate cell voltage, it becomes much harder to make a mistake. If the
charger has the cell count and the cell chemistry (LiPo, LiFe [lithium iron],
etc.) has been selected, then all that remains for a balance charge is to set
the charge current. All of the LiPo batteries that I’ve used can be safely
charged at a rate equal to the battery capacity on the label, otherwise
known as a “1C charge rate.” A 5000mAh battery, for example, would
charge at 5000 milliamps or 5 amps. Some manufacturers allow higher
charge rates and will note that on the label as a multiple of C, such as 2C
or 3C. While it might be safe to charge batteries at these higher rates if
Read the LabeL
A LiPo battery’s label has a lot of information on it: cell count, nominal
voltage, capacity in either amp hours (Ah) or milliamp hours (mAh), and a
recommended discharge rate or two in terms of a multiple of the capacity.
This discharge rate is the dreaded “C rating,” which is a topic for another
day. The only things you really need to know to charge a LiPo well and
safely are the battery voltage or cell count and the capacity.
The old-school chargers I started out with had one pair of leads that
connected to the power leads on the battery. Either you selected the
cell count as part of the startup sequence, or the charger would read the
battery voltage and guess at a cell count for you. Both methods were
susceptible to error for various reasons. If you weren’t careful, you could
end up charging a 3S LiPo at a 4S voltage, which would lead to an exciting
Modern chargers have a connection for the battery’s balance lead,
so they can balance the battery’s cells as they charge. This has several
advantages over the older chargers. First, balance charging is much better
When I first began using lithium polymer (LiPo) batteries
in my RC planes, it felt a little risky. I didn’t know a lot
about the batteries, and the labels were more than a
little confusing. The chargers available for me to use back
then were a little on the basic side, and the horror stories
on the Internet about fires scared me to death. Today,
things are better—in part, because I know more and have
more experience with LiPos and, in part, because charger
technology has greatly improved.