Basic understanding of LiPo battery use and
care for
RC models
LiPos (Lithium-ion Polymer) batteries have become more and more useful in RC hobbies.
This is because LiPo are able to charged up to over 100 times without losing
capacity, this provides an ideal energy source to power
RC models. It is more convenient and safer than using nitro/fuel as a source of
power.
A typical LiPo battery consists of one or more cells with a
connector power plug
and a balancer port.
Each cell of a LiPo has a nominal voltage rating of 3.7 volts and a maximum charge voltage of 4.22
volts (4.2V is standard), as such there is a "voltage-window" ranging between 3 volts to 4.2 volts.
You can pack each cell together to increase your voltage or capacity linearly or in parallel,
example 3S LiPo is 3x3.7 =11.1v (fully charged 3x4.2=12.6+v).
It is important to know that if a cell is discharged below 3 volts, this will cause irreparable damage to the cell and therefore a complete charge is no
longer possible, giving your LiPo a short shelf life.
If you received one of our DM drone enabled model aircrafts, our typical flight controller we use has a voltage protection that prevents your LiPo batteries from falling below it's recommended level. Many Electronic
Speed
Controller (ESC) also has a built-in voltage protection. Before the LiPo voltage reaches the critical range, your drone will either try to land or return to launch. At this stage, you can still fly for about
2 more minutes, but should only fly within your landing zone. After the second warning, you should discontinue flying with the same LiPo battery. If you should carry on flying, the cell voltage will fall below 3.0V and be damaged.
During each flight, the cells may discharged differently. For example on a LiPo
with 3 cells, one cell can have 3.4V, the next 3.6V and the third 3.5V. This
adds to a total voltage of 10.5V. To rebalance each cell, you can charge your LiPo with the balancer port
connected during charging. You use the LiPo Balance Charge
function provided by your charger.
You can also buy a little gadget LiPo Battery Monitor and Alarm
for under US$3, listed below (What We Use), which will allow you to measure voltages before each
flight and also acts as an onboard alarm, if left connected to your LiPo balance
port.
If your model aircraft includes an On Screen Display (OSD) and you are flying with video, you can easily monitor your voltage. A good practice is to
not fly below 10.5V with 3s LiPo and begin
your landing protocol. The voltage monitor will
fluctuate during flight, and a sudden burst may drop the voltage lower. You may also notice a higher
remaining voltage upon landing. If you complete your flight with about 11.4V left
upon landing, you can simply store them for future use without completing a LiPo
Storage charge.
Storage: A LiPo should be stored at about 3.8V per cell, if not used for an extended
period of time.
Again, if you don't store your LiPo at the suggested voltage, your battery will get damaged
too. You should store your LiPo batteries in a fireproof containers or sand bags.
Disposing LiPo: When your LiPo batteries cannot be completely charge, a shorter flight time
begins to take it's toll. The capacity of such a damaged LiPo can be reduce by 50% of the original capacity
when used.
To disposed a damaged LiPo, you can just fill a disposable container with table salt and water.
Discharge the battery as much first, fully submerge your LiPo for a week, and you can then dispose it at a battery recycling centre or throw it out. Remember a charged LiPo
when crushed, will cause an intense burst of flames.
Understand your charger limitation: You may have
learned that a LiPo with a capacity of 5000 mAh, allows you to set a charge
current at 5A, and that is theoretically correct. However a popular IMAX B6 Charger is
only a 50W charger. Using the formula P = U * I, you will get I = P / U for a 6S Lipo divide 50w/25.2V= 1.98A. You can charge your 6S LiPo at maximum of
1.9A even if it is a 5000 mAh battery. If you try to charge it higher, as a
safety, the screen goes black, and the entire unit shuts down until you
disconnect your power. Some of the high-end IMAX chargers will automatically
reduce the charge rate, if it determines it cannot charge at the rate you
entered.
LiPo Battery Schematics: There are different types of battery connectors used by different
manufacturers on different batteries and battery accessories such as chargers
and speed controllers.
We suggest you try to choose your own preferred connector type(s) and stick to
those to ensure compatibility with all your own equipment and models.
The main picture shows a range of the most popular battery connectors and
balance / charging plugs. They are labelled and listed as follows :
B1 - Deans (T) type main connector - Female & Male. Used
for main connection to speed controllers and motors. Used for medium to high
current draw. Suitable for up to 60amps
B2 - JST / BEC type main connector - Female & Male. Used
for main connection to speed controllers and motors. Used for low current
draw. Suitable for about 5amps
B3 - Tamiya main battery plug usually used on Car and Boat
batteries (NiCd / NiMh) - Female & Male
B4 - Bullet Connectors - Female & Male. Single wire
connectors, available in a range of different sizes to suit current draw /
load requirements from 2mm to 8mm
B5 - HXT Connectors - Female & Male. Available in 3.5mm and
4.00mm sizes. Used for main battery connectors for medium / high power
applications
B6 - Traxxas Connectors - Male & Female. Mainly used on
high current draw car and boat batteries
B7 - XT60 Connectors - Male & Female. Used for high current
draw battery connections
B8 - EC3 Connectors - Male & Female. Used for high current
draw battery connections
B9 - Flight Power / Thunder Power (FP / TP) LiPo Balance
Charger plug - Female & Male
B12 - JST-EHR (EH) LiPo Balance Charger plug - Female &
Male. Good for 3 Amps.
By understanding the balance plug, it is a relatively easy task to
cut off different plug types and solder / crimp on your preferred type, and
leverage a secondary power source.
While it may seem to be a lot of information and responsibility for a LiPo battery,
I am sure you will enjoy your hobby! :)
DIYdrone Lab ... behind the scenes
Wednesday February 10, 2016
Notes:
While it is good to charge and store your LiPo batteries in fireproof bags, we
actually have our little DM tip;
add another base layer of silicone bake ware. Yes, silicon have been tested
and proven to be high-heat resistant up to 500°F or 260°C. So, visit your kitchen,
you may just have one handy.
Inspect your LiPo carefully after a crash, a punctured LiPo will
begin to bubble at high temperature before releasing a thick smoke and burst
into flames.
and a balancer port.
Each cell of a LiPo has a nominal voltage rating of 3.7 volts and a maximum charge voltage of 4.22
volts (4.2V is standard), as such there is a "voltage-window" ranging between 3 volts to 4.2 volts.
You can pack each cell together to increase your voltage or capacity linearly or in parallel,
example 3S LiPo is 3x3.7 =11.1v (fully charged 3x4.2=12.6+v).
Speed
Controller (ESC) also has a built-in voltage protection. Before the LiPo voltage reaches the critical range, your drone will either try to land or return to launch. At this stage, you can still fly for about
2 more minutes, but should only fly within your landing zone. After the second warning, you should discontinue flying with the same LiPo battery. If you should carry on flying, the cell voltage will fall below 3.0V and be damaged.
DIYdrone Lab
: LiPo Battery Monitor & Alarm
Notes:
While it is good to charge and store your LiPo batteries in fireproof bags, we
actually have our little DM tip;
add another base layer of silicone bake ware. Yes, silicon have been tested
and proven to be high-heat resistant up to 500°F or 260°C. So, visit your kitchen,
you may just have one handy.
