Can a 1.5 V 0.15A Ni-MH Charger Charge 1.2V 1600mAh AAA Ni-MH Batteries?

The short answer is yes, a 1.5V 0.15A Ni-MH charger can be used to charge 1.2V 1600mAh AAA Ni-MH rechargeable batteries. However, there are several factors to consider, including voltage compatibility, current rating, charging time, and charger type.

Voltage Compatibility

The charger's output voltage of 1.5V is suitable for charging 1.2V Ni-MH batteries. Ni-MH batteries typically require a charging voltage slightly higher than their nominal voltage (1.2V) to effectively charge them. This characteristic is crucial for a successful charging process.

Current Rating

The charger's current rating of 0.15A is generally appropriate for a 1600mAh battery. Ni-MH batteries typically have a recommended charging rate of between 0.1C to 0.5C, where C is the battery capacity in Ah. For a 1600mAh battery, 0.1C corresponds to a current of 160mA. Therefore, a 150mA current is reasonably close to the recommended rate, making the charger suitable for this purpose.

Charging Time

At a charging rate of 150mA, it would take approximately 10 to 12 hours to fully charge a depleted 1600mAh battery. This estimate assumes that the battery has reached its discharge point, which is typically around 1.0V. Given the low charge rate, it's essential to monitor the charging process to avoid overcharging. If your charger lacks an automatic shut-off feature, you'll need to be particularly vigilant.

Charger Type

Ensure that the charger is specifically designed for Ni-MH batteries. Using a charger intended for other types of batteries, such as NiCd or alkaline, can be unsafe. NiCd and alkaline batteries have different charging requirements and can cause damage if used with a Ni-MH charger.

Charging Process and Battery Chemistry

Battery voltage is a relative term. The nominal voltage of a battery, in this case, 1.2V, is a typical value during discharge, but a fully charged battery will have a higher voltage—typically around 1.4V. When charging, the charger will regulate the current, and as the chemical reactions in the battery progress, the voltage will change.

However, there might be issues with the charging time and rate. A 0.15A (150mA) charging rate for a 1600mAh battery is very low. Generally, you should aim to put in at least 1.2 times the battery's capacity to ensure it's fully charged. In this scenario, this would take approximately 13 hours.

Given the 1600mAh capacity of the AAA battery, which is quite high for an AAA battery (typical capacity ranges from 800-900mAh), you might need more time than it would take for a standard battery. Therefore, if your charger has a timer and your batteries indeed have a 1600mAh capacity, you might need to leave them in the charger for a longer duration than a single full charge cycle to achieve full charging.

Conclusion

In summary, a 1.5V 0.15A Ni-MH charger can charge your 1.2V 1600mAh AAA Ni-MH batteries, provided it is designed for Ni-MH battery chemistry. However, it is advisable to monitor the charging process, especially with the low current rate, to avoid potential overcharging or damage.