5200 mAh Backup External Battery USB Power Bank Pack Charger for Cell Phone,China Apexto price supplier

Q1:  What's Power Bank?

Power Bank aka(also known as) mobile power is small in size, large capacity, convenient to carry, it can be for the service of a variety of digital products. Part of the Power Bank:shells, batteries, circuit boards,wire. And batteries contain ordinary Lithium batteries and polymer batteries.

Polymer lithium battery also called soft bag. Products of well-known manufacturers and secondary manufacturers make no odds. Only defective rate is very different. Soft bag can be customized into various shapes, it is smaller and lighter than lithium batteries ,and it can be charging and discharging at a total of 500 times or so .Soft bag is made from colloidal electrolyte, it is safe, environmental , and it won't explode.

Lithium batteries usually called as 18650 Lithium batteries , because it is a cylinder battery whose diameter is 18mm, length is 65mm . It is made from liquid electrolyte, it is large and heavy, it can be charging and discharging at a total of 300 times or so, its explosion rate is two millionths.

According to the quality and timeliness of the battery,it can be divided into three levels: grade A, grade B, grade C. Grade A power means new polymer battery. Grade B power means the inventory is more than three months, or according to national standards testing,which is one or more substandard batteries, grade B power is cheaper than grade A power but it declines more quickly. Grade C power means used batteries or the batteries removed from devices such as laptop, cellphone, and so on. It is the cheapest one, but it has serious quality problems.

Q2:  Is Power Bank safe?

Capacitance is serious that cannot be ignored, because he will seriously affect the output ripple of power bank , ripple becomes wide will cause cell phone failure, more serious thing is that cellular phone will crack.

Electrolytic capacitor has short life, and it is easy to cracked, tantalum capacitor has long life, but it has possibility of explosion. MLCC ceramic capacitors is safety,longevity,heat resisting. On the market,most of the brands use electrolytic capacitor and tantalum capacitor.

In 2.1 A under load,battery voltage is low to 4.7 xV,this point is very low,steadies less than plus or minus 5%.It is a big advantage for cheap copy factory(Power bank full ripple of cheap copy factory will over 300mV).

Q3:  How to choose Power Bank that I need?

Power bank PCB includes plug-in type and intelligent protection type(Over current, overload and overcharge, discharge protection function)

Refers to the intelligent protection cost,all single section 18650 type lithium electricity power bank doesn't have this function.

Output capacity / Nominal capacity * % = Conversion rate

What is the nominal capacity?

Generally it refers to the nominal capacity of batteries,batteries capacity is calculated according to the volume of the battery.Length * width * thickness,and then,according to a coefficient value can estimate the capacity of a cell,but this is not accurate.Battery can increased to 200-300 mah via fine processing.

Output capacity=power bank capacity*3.7V*the percentage of conversion)/5V,such as a 5000mah capacity power bank, in a standard conversion rate of 85%, 5000*3.7*0.85/5=3145mAh.