NiMH Batteries

"I have some rechargable AA batteries from over 10 years ago. They have never been charged. Will they go bad over time, or will they still be good when I decide to charge them?"

10 years is really pushing it for rechargeable battery storeage. General rule of thumb, 3 years for NiMH, 5 years for NiCD. Beyond that you will likely encounter decreasing capacity and cycle life. Rechargeable NiHM batteries have the disadvantage of loosing power after a period of time, so keep regular batteries as well.


NiMH Battery Care & Tips

* Charge your new battery overnight (14-16 hours) before using it. This is referred to as initializing and will enable you to obtain maxium battery capacity.

* New batteries can be stored up to 2 years without cycle loss.

* Store new batteries, at room temperature, in cool dry area.

* Batteries which have been in storage should be charged overnight.

* When using a rapid charger, leave battery in charger for an additional 1-2 hours after the green light appears.

* Do not leave battery in the charger when not charging. Continuous charging will shorten battery life.

* Only charge batteries when they need it. If it isn't fully discharged, don't recharge it. Use a second battery for multiple/longer duty cycle applications.

* Do not return fully charged batteries to the charger for an extra boost. This action will significantly reduce cycle life.

* Stabilize battery to room temperature (22º C) before charging. Charging below 4.4º C or above 40º C will decrease cycle life.


NiMH Q&A

First Time Usage - Do I need to charge my NiMH batteries. prior to using them for the first time?

Yes, before you use your new NiMH batteries for the first time you must charge them fully. For new NiMH batteries, it is often necessary to cycle them at least 3-5 times or more before they reach peak performance and capacity.

Holding A Charge (Shelf-Life) - How long can the batteries hold their charge if I leave them on the shelf?

At normal room temperature, NiMH batteries can generally retain 70% of their charge after 30 days. Normal self-discharge of NiMH batteries is about 1 percent per day at normal room temperature. Lower temperatures will cause NiMH Batteries to hold their charge longer. Use them within 5-10 days of their initial charge.

Not Holding A Charge - I have not used my NiMH batteries in several months and they are not holding their charge. How can I fix this?

NiMH batteries - like any rechargeable battery - will self-discharge if left unused. Generally, within 30-60 days, batteries will become almost completely drained. When using them, you will need to first recharge them. After extended storage, you may need to cycle them several times to regain normal performance. Conditioning can be performed using the conditioning feature on chargers such as the Maha PowerEx MH-C204F.

Long Term Storage - Are there any special precautions I need to know about if I store my NiMH batteries for several months?

- Always store your NiMH batteries in a discharged state.

- Do not expose your batteries to direct sunlight or temperatures above 35 degrees C during storage.


Care for Maximum LIfe - What can I do to maximize the life of my NiMH batteries?

- Never drop NiMH batteries on a floor or hard surface. If you do drop them, we recommend replacement even if no damage is apparent.

- Be sure to use a well-designed charger that will prevent overcharging. Fastest is not always the best.

- Never carry NiMH batteries loosely in your pocket. Coins , or other metal items could cause them to short, thus causing severe burns, or even a fire.