I have a tiny device (similar to a stripped down cell phone), and it has an unmarked battery connected with +/- wires. It also uses an power adapter to charge the battery, the power adapter (with USB plug) says 5V 0.2A

  • A connector / wires for battery
  • A connector that gets power from wall adapter (0.2A)

I wanted to permanently connect it to another power source that is 5V and ~1A and use the battery connectors for that (unsolder the battery).

Is it safe to assume the device can handle more amperage on the battery connector than the 0.2A that it gets from the charger on the charger connector ?

// Maybe there is a way to decide how much amperage it can handle on the connector coming from battery ?


Yes, it is safe to assume that the maximum current rating of the connectors is considerably higher than the typical/max. current they will carry.

Sometimes this is because of derating, whereby components rating exceed maximum stress in circuit by a standard margin. The standard may be a company standard, military/avionics/etc standard or just the personal good practice of the design engineer.

Sometimes it's because the standard connector for the application gives you more than you need. This is true of mains plugs, which in the UK are fused at 13 A and capable of more but where the vast majority carry less than 5 A. All those TVs, phone chargers and lamps and so few kettles and vacuum cleaners...

And sometimes it's because the mechanical requirements of the application require larger metal connectors. This is true of a PP3 battery connector, which has much larger conductors than the practical drawn current of the 9 V battery needs.

Of course, a percentage of the equipment around will be badly designed and not follow these rules. But you're quite unlikely to bump into that stuff that often.


The short answer to your "Do battery connectors handle more amperage than the charger port?" is "NO", since current in a series circuit is everywhere the same.

  • \$\begingroup\$ You've answered the title, not the question. Question says "safe to assume the device can handle more amperage on the battery connector than the 0.2A that it gets from the charger on the charger connector". \$\endgroup\$ – TonyM Apr 2 '17 at 18:40
  • \$\begingroup\$ @TonyM Valid point, which basically breaks down to determining the resistance of the interface between the battery and the connector , the resistance of the connector, and the resistance of the wiring leading to the load. Unfortunately, the OP hasn't specified his load current... \$\endgroup\$ – user144172 Apr 2 '17 at 19:32
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    \$\begingroup\$ That rather assumes that the only thing you ever do with the battery is to charge it. If the gadget itself draws more than 0.2A in use, then it's quite possible that the battery connector is rated higher than the charger port. \$\endgroup\$ – Simon B Apr 2 '17 at 20:37

well charging the battery with 0.2 Amps to get 0.2 amps from a 5V power source you need a resistor of 10 ohms. 5v/10ohm =0.2 amps In your case, you should see if there is any resistor after the charger connector or not if there is you can change the adaptor on the other hand, the components on your board draw the amperage they need but for the battery, you need and current limiting resistor so that it would charge slowly

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    \$\begingroup\$ This doesn't actually answer the question. \$\endgroup\$ – Simon B Apr 2 '17 at 20:38

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