Emergency lighting unit battery .....NiCd is better than NiMH?

[gophert]

The best emergency battery ive found is Energizer Ultimate Lithium (NON-RECHARGABLE). They come in standard sizes and voltages (9V and AA). They have a 20-year shelf life, no liquids to leak out or corrode, no pressure build up when discharged at high rates. A 9V is spec'ed at 1A (but voltage does drop to about 7.5V when discharging at 1amp rate).

Well documented datasheets available from Energizer.


The problems:
- fairly expensive (but may be considered a cheap solution - depends on the situation)
- cannot be shipped without jumping through the hurdles of shipping Lithium batteries
- one to two ohms of internal resistance at 1A discharge rate.
- not rechargeable so they may need to be changed after several short power outages.

They definitely are worth the hassle in my industrial applications.

 

[KeepItSimpleStupid]

Energizer and a Japanese Ni-MH battery manufacturer say that the modern Ni-MH cells last for 5 years with the recommended low trickle charge that most charger ICs can provide, or last for 5 Years without a trickle charge when they are charged each year.

I'm seeing that too. 5-7 year life Ni-mH in a system designed for Ni-Cd. The charging base is noting more than a current limiter and I'm sure there are more smarts in the cordless phone.

So far, no problems using Ni-mH in Ni-Cd systems.