What happens when you overcharge a AA battery?

There are a few things that can damage NiMh batteries over time: 1) overcharging. This can cause the dreaded ‘memory effect’ over (a long) time. Some fancy chargers can discharge the battery before recharging, but just using the batteries until they’re about empty works as well.

How long do you charge rechargeable AA batteries?

Maximizes Battery Life

	Energizer Recharge Pro Charger	Energizer Recharge Basic Charger
NiMH rechargeable Battery Size	AA, AAA	AA, AAA
# of Batteries	2 or 4	2 or 4
Charging Times	3-5 Hours	7-13 Hours for AA; 6-9 Hours for AAA
Charging Source	AC Outlet	AC Outlet

Why do batteries take longer to charge at the end?

At the end of the charge the charger knows the battery is nearly full and can no longer accept a high charge rate, so it ramps down the current, filling in the last gaps in the battery’s internal structure.

Can you leave batteries in a charger?

Don’t Leave Battery on Charger: Unless your tool instructions specifically say to store the battery on the charger, be sure to remove it after charging is complete. Overcharging can damage a battery and shorten its life, and not all chargers shut off automatically.

Is it best to leave rechargeable batteries in the charger?

Pick the right method. You should always charge rechargeable batteries in the device it’s used in, the charger it came with or a charger recommended by the manufacturer. Chargers are designed for specific battery types; mixing chargers and batteries could result in unexpected problems.

Can I charge Duracell batteries in an Energizer charger?

Yes, in any charger, but Duracell chargers are recommended because they are among the safest in the industry.