# What will happen, if we charge a battery with current, above its maximum charging current?

If capacity of battery is 50mAh, and its fast charge capacity is 1C, then its maximum charge current is 50mA. If we are using 2500mA charger and charging the battery what will happen? whether we can program the charger to maintain charge current provided to battery?

• Using a 2500mA charger does not mean it will force that much current into the battery, it just means that is the max current it can supply. What battery composition is this about? If you have a specific charger in mind please share that as well. May 14, 2015 at 21:39
• Thermal Runaway can happen. The battery can't physically/chemically store the energy if delivered too fast, so it is dissipated as heat. May 15, 2015 at 8:14
• Contrary to what some comments/answers may suggest, the charger needs to be told the maximum current to deliver. They normally don't/can't 'sense' it. May 15, 2015 at 8:17

The important thing is to use the correct battery charger circuitry based on the chemistry of the battery. You don't mention the type of battery you have.

For many battery types, such as the Li-Poly generally used in cell phones, you need a special battery management IC such as the "bqTINY" bq24013 which regulates both the voltage and current. You can't just hook up a fixed voltage to the battery and expect it to charge properly. Instead, it would likely heat up and worst case catch fire.

The basic algorithm for Li-Poly batteries is to charge at constant current (0.5 C to 1C) until the battery reaches 4.2 Vpc (volts per cell), and hold the voltage at 4.2 volts until the charge current has dropped to 10% of the initial charge rate. In addition, a charge timer should be included for safety.

The desired charging current (0.5C, 1.0C or whatever) is typically set up externally to the chip by a voltage divider or other means.

Cheaper chargers may omit the constant voltage part (Stage 2) but that is not recommended.

So as you can see, the charge current is controlled by the charge management IC, and it doesn't matter how much current is made available, as long as it meets the minimum required by the algorithm.

Other battery chemistries will have different charging algorithms, but in general you should always use a battery management IC suited for the particular battery you have. Here is the list of battery chemistries supported by various battery management chips found on Digi-Key. Multiple types on one line refer to chips that can support all of them in one IC.

If you charge a battery more aggressively it will heat up more, which may reduce the life of it.

• Whether it will reduce the battery life alone, or it will burst the battery if we charge with very large current than charging current?
– SATHEESH RAJA
May 14, 2015 at 11:55
• How much larger are you talking about? I've charged a LiPo that was rated for 2A charging at 3A before and didn't have any issues, although it will likely decrease battery life over the long term. I probably wouldn't charge it at 5A or anything though. May 14, 2015 at 21:27