First, the list:
1.
Keeping laptop/phone on charge overnight reduces battery life
2.
Batteries should be drained to 0 and recharged to full
3.
Batteries can swell or even explode due to overcharging
4. My power bank, equal to battery in terms of capacity should fully charge my phone
5.
X type is better than Y type
Yes, these are all myths and we’ll bust them one by one. But
first, keep a few terms in mind. We’ll be using them frequently in this
article:
- Battery life: the time from
first use to last run before recycling/discarding
- Runtime: the running time of
battery in a single complete charge before discharging
- Cycles: number of times the
battery can be recharged from fully drained to maximum
- Overcharge: providing more
voltage than required to charge the battery
- Standby time: the capacity of
battery to hold charge in storage or when not in use
Keeping laptop/phone on charge overnight reduces battery life
There’s some merit in
this one, because about 2 decades ago, the chargers weren’t designed keeping
battery life under consideration. Especially in case of early laptops, the
charger was to keep the battery charged and the computer drew its power from
battery all the time. Manufacturers fixed this issue by switching to power from
charger, when connected. Meaning the battery would be disconnected and laptop
will run solely on main power.
This solution introduced
a new issue. Once battery is fully charged to 100%, charging circuit would
disconnect battery from power source, but as the battery falls to 99% while in
standby mode, the charger kicks back and charges to 100% again. This resulted
in reducing maximum cycles and thus overall battery life.
In order to resolve this
issue, manufacturers provide tools to allow battery to fall to about 80% while
in standby mode before charging again.
So yes, this used to be
an issue once, but isn’t true today at all, since all famous manufacturers now
equip their phones and laptops with digital circuit breakers, which cut-off
charging once the battery is charged, and also run the device directly from
charger.
Batteries should be drained to zero and recharged to full
Most of the smart
devices today use Lithium-ion or Lithium polymer batteries, which have a
built-in circuit. Once the voltage drops below certain threshold (about 2.5v
per cell), then the safety circuit opens and declares the battery dead. It will
then take a special charger to revive the battery. This is one reason why
batteries should not be drained completely.
Similarly, charging to
100% is not the best idea either, because once your battery reaches higher
threshold (about 4.35v) then its oxidation state becomes unstable, thus
damaging the metal holding the charge. This may result in reducing your cycles
by half.
The recommended idea is
to keep your battery between 30% and 85%. But here’s the catch. Keeping battery
at these levels for months causes the inner circuit to forget the battery’s
true runtime, and your phone or computer will show 2 hours of remaining time,
while the actual time would be 3 hours. Therefore, it is good practice to
completely drain your battery to 0% and fully recharge once every couple of
months to keep the estimates accurate.
Batteries can swell or even explode due to overcharging
You’ll sometimes notice your battery getting thicker than normal and reducing their runtime to half or less. This happens to lead-acid and other types of batteries too. The cause is not overcharging, but overheating, which sometimes is a result of overcharging. If you take care of a few things enlisted, you may never encounter this problem:
- Always use the right charger.
Using 3Amp charger, when the recommended charger is of 1.5Amp, may charge
the device very quickly, but can also damage your battery.
- Do not use your phone while
charging. Errrmm!!! Actually, this one’s also a myth, the right way to put
this would be not to use the phone for calling in low
reception area, while charging with high-power charger.
The reason behind this is a high-power charger, say of 2Amps, heats the
battery more and in low-reception area, the phone’s antenna is draining
more power, thus consuming more battery – another plus to heating.
- NEVER hard-press or try to
puncture a battery. It may catch fire.
Now let’s talk about
phones exploding. This became famous and known after Samsung’s Note 7 battery disaster. The reason
behind these batteries catching fire was design a design flaw. The layer
separating negative and positive plates inside the battery was so thin, that
with increase in temperature, the plates collided directly, causing short
circuit. The Galaxy Note 7 was water resistant, therefore there was no escape
for heat. As a result, the phones exploded with fire. Such a risk is rare and
is only with internal batteries, removable batteries tend to have extra
protective layers and are more resilient to damage.
My power bank, equal to battery in terms of capacity should fully charge my phone
My power bank, equal to battery in terms of mAh should fully
charge my phone
Not true. If your
phone’s battery is 1000 mAh (milli-Ampere-hour is a measure of electric charge)
and you just bought a 1000 mAh power bank, then even a top of the line brand
will charge your phone to 93%, while average power banks built with cheap
material may give you somewhere around 75% to 85%. This loss of power is called
conversion loss. Consider a 5000 mAh power bank, which consists of a pair of
3.7v cells of 2500 mAh capacity. This should charge your 1000 mAh battery 5
times, right? Wrong, you’re missing a point that USB works at 5v, not the same
voltage as battery cells. Therefore, there’s a small circuit inside the power
bank to convert battery voltages to 5v; the lost power is used by this circuit.
And oh! Don’t forget the power drained by that blinking LED showing you the
capacity.
X type is better than Y type
This one is for nerds.
Lead Acid > Alkaline > Nickel Cadmium (NiCd) > Nickel Metal Hydride
(NiMH) > Lithium-ion (Li-ion) > Lithium-ion Polymer. This is the sequence
in which someone with a fan-boy-mentality may describe which battery is the
best.
There are merits and
demerits to all of these. While it is true that Lithium-ion and Lithium-polymer
are streamline when it comes to smart devices, not all of the rest are useless
or have become obsolete. Let’s map the differences in a table:
|
NiCd
|
NiMH
|
Lead Acid
|
Li-ion
|
Li-ion polymer
|
Alkaline
|
|
|
Cycles (until dropped below
80%)
|
1500
|
300-500
|
200-300
|
500-1000
|
300-500
|
50
|
|
Fast charge time
|
1h
|
2-4h
|
8-16h
|
2-4h
|
2-4h
|
2-3h
|
|
Overcharge tolerance
|
Moderate
|
Low
|
High
|
Very low
|
Low
|
Moderate
|
|
Standby time (per month)
|
20%
|
30%
|
5%
|
10%
|
10%
|
0.3%
|
|
Voltage
|
1.25V
|
1.25V
|
2V
|
3.6V
|
3.6V
|
1.5V
|
|
Temperature tolerance (0C)
|
-40 – 60
|
-20 – 60
|
-20 – 60
|
-20 – 60
|
0 – 60
|
0 – 65
|
|
Cost per cycle (USD)
|
0.04
|
0.12
|
0.1
|
0.14
|
0.29
|
0.1-0.5
|
Conclusion
- NiCd: low-cost, can be used in
extreme temperatures, shortest charging time and gives more cycles than
the rest. Most widely used rechargeable battery in consumer electronics.
- NiMH: holds more charge than
NiCd, but has low overcharge tolerance and requires quality chargers. Used
widely in digital cameras walkie-talkie phones, voice recorders,
calculators and watches.
- Lead acid: long standby time,
low-cost and can run with low-quality chargers as well. Used in
high-consumption environments like automobile and UPS.
- Li-ion/Li-ion polymer: higher
number of cycles, highest voltage, good standby time and consistent
runtime. Used in almost all smart devices.
- Alkaline: longest standby time
with high overcharge tolerance, but lowest number of cycles
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