Cameras, smartphones, touchscreens, autonomous GPS … most electronic devices now include a micro-USB (or mini-USB) connector. To recharge the battery, connect a USB cable, which is connected to an AC adapter. 


A single charger could therefore be sufficient to recharge the battery of all these devices. Charge speed, potential damage … Here’s all you need to know.

 Cable, AC Adapter, Battery: Principles

  • A charger consists of a cable and an AC adapter.
  • All USB 2.0 cables deliver the same current, 500 mA (USB 3.0 cables, increasingly frequent, can provide 900 mA).


  • The difference between two chargers comes from the AC adapter, specifically its charging power, expressed in watts (W).
  • This power is the product of the voltage (V) by the intensity (A).
  • The adapters of small electronic devices have a voltage of 5 or 5.25 W.

What distinguishes them from each other is intensity, which varies the speed of charge

In Samsung, for example, the charger of the Galaxy S4 smartphone (5 V and 2 A, therefore 10 W) is twice as powerful.


Charging a battery of the same capacity (2,600 mAh, for example) will theoretically be twice as fast with the Galaxy S4 charger (in practice, when the end of the charge is approaching), the intensity will decrease: there is therefore more difference between a 5 W charger and a 10 W charger.

Is It Risky To Recharge The Battery Of One Device With The Charger Of Another?


No, there is no risk of damage to the battery. The chargers delivered with our devices are “intelligent”: they are capable of detecting a potential incompatibility of voltage and then adapt the power they deliver. So much for the theory. In practice, manufacturers protect themselves and advise to use only the charger supplied with the device.


At the slightest problem, admitting that another charger was used could void the warranty. We also advise against the use of low-end chargers of doubtful origin.

Why Doesn’t IPad Load When Connected To The USB Port On My Computer?


The USB 1.1 and USB 2.0 ports on a computer deliver a power of 500 mA (up to 900 mA for USB 3.0 ports). This is little, which explains why the load is long when you connect a device through this. It is even too little to recharge some gourmet devices, such as a large touch tablet, for example. In the special case of an IPad, note that charging is possible if the tablet is in standby.

Is There A Risk In Leaving A Device Connected All Night?


Risks, no, but useless consumption, yes. Firstly because a charger always consumes a little electricity when connected to the mains. Then, of course, intelligent chargers stop charging once the battery is full.


But if the device remains connected, the charger will recharge the battery which will have barely discharged cyclically, hence unnecessary micro cycles of charge. When the charging is complete, it is better to unplug the adapter from the electrical outlet.

Should The Battery Be Completely Discharged Before Recharging?


Some manufacturers advise to fully charge the battery of the new device before using it, and sometimes even to wait until the battery is completely discharged before recharging. These are legacy warnings of batteries subject to a phenomenon called “memory effect,” which reduces performance when the battery is not fully charged before being charged, and then recharged. Ni-Cd and Ni-MH technologies are the most concerned.


Lithium-based (Li-ion) batteries, the most common in smartphones, touchpads, or cameras, are not, or very weak. Recharging the battery without waiting for the complete is therefore not very serious or seriously to be taken. It would even be advisable to prefer to the full charge cycles several recharges of short duration.

Is A Battery Sensitive To Cold, Heat, and Humidity?


  • A battery is sensitive to cold: the battery power/life of your device will decrease as the thermometer slider goes down. But it will regain its level of performance once the temperature has risen.
  • Not all models are sensitive to the same temperatures, but starting from 0 ° C, it is better to keep your device in a warm pocket to preserve its battery/power.


  • Moisture and heat can permanently damage the battery.
  • Beyond 45 degrees C, the battery, under pressure, becomes dangerous. Hence the importance of not leaving your device in the sun or in an environment too humid.