NiCd battery in Maglite

[U_U]

The Maglite rechargeable has a NiCd battery pack. Those kind of batteries have memory effect unlike NiMH batteries, right? Can you guys give me some advice how to get the most out of those batteries without screwing them up? And what if I charge them before they are empty? Why can't Maglite just use NiMH packs????? /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/banghead.gif

 

[Bullzeyebill]

NiCD batteries running at fairly high amperage in lights such as MagCharger, and Streamlight do not suffer from memory effect. Historically NiCd's have been used in these types of lights because they can take a high discharge rate and still maintain nominal voltage for high light output, over time. In other words, they are, or have been
considered to be more efficient than NiMH cells.

Bill

 

[U_U]

mh... thanks

 

[SilverFox]

Hello U_U,

Both NiCd and NiMh can exhibit the memory effect. However, you have to work very hard to do it.

If you discharge a battery exactly the same amount each time you use it and recharge it exactly the same amount, after a few hundred cycles you will see the memory effect.

In actual flashlight use it is difficult to do this.

NiCd's are more robust than NiMh's. You can leave them on the charger for an extended period of time and they will handle the slight overcharge better. That is why flashlight manufacturers use them. The change to NiMh cells has happened because of the increased capacity of those cells.

NiMh cells pack more power into the same sized package. Their energy density is higher. A high capacity NiMh AA cell is rated at 2300 mAh. By contrast, a high capacity NiCd AA cell is rated at 1400 mAh.

Both types of cells benefit from a full discharge cycle (down to 0.9 volts per cell) periodically. NiCd's like a shorter period like once per month, NiMh's a longer period like once per 3-6 months.

Tom

 

[Techmedic]

NiMH's do not like the cold weather. Use a NIMH pack in the winter (e.g. leave light in car) and it won't deliver near the capacity that a NICAD will. The specifications (MIL-SPEC) always references a temperature range, and NIMH's won't meet typical lower temperatures for performance.

As discussed before, (search...) the high current discharge of the NICAD in a flashlight application goes a long way in eliminating the memory effect.