Pratical battery choices

Been reading up on battery info... Wow, little much for a newbe! Think I've got the basics but please tell me if I'm thinking clearly...
Alkaline -> Use for smoke detectors and clocks. Okay for the flashlight in you're grandma's kitchen drawer.
NiMH -> Use in every day carry light, rotate'em in/out of the charger every few days. Don't use in lights that are being stored 'cause they'll be dead when you need'em. Try not to run'em dead.
Single use Lithium -> Use in lights that are stored for emergencies. Can lay around for 10 years or so.
NiCad -> Old fashion, only good for things like power tools.
Li-ion & other chem's -> Save these for the real flashfreaks.

Looks like you have the right idea, but you forgot to list LSD NIMH, which can be left unused for longer periods of time. Will retain 85% charge after a year of storage. Examples of these: Sanyo Eneloop, GP Recyko, Varta Ready2use, Duracell ActiveCharge, Powerex Imedion...

NiCads aren't only good for power tools.
They are old technology, but they have about half the self-discharge of NiMH cells, on average. I use one in a 1-AA flashlight I use at home, and it works fine. It doesn't have much runtime, of course, but the light sees only occasional use, so that's ok.

fluoronator said:

Been reading up on battery info... Wow, little much for a newbe! Think I've got the basics but please tell me if I'm thinking clearly...
Alkaline -> Use for smoke detectors and clocks. Okay for the flashlight in you're grandma's kitchen drawer.
NiMH -> Use in every day carry light, rotate'em in/out of the charger every few days. Don't use in lights that are being stored 'cause they'll be dead when you need'em. Try not to run'em dead.
Single use Lithium -> Use in lights that are stored for emergencies. Can lay around for 10 years or so.
NiCad -> Old fashion, only good for things like power tools.
Li-ion & other chem's -> Save these for the real flashfreaks.

Click to expand...

Alkaline - Inexpensive, don't handle high current well. Leaks when left in devices causing major corrosion and damage. Change frequently to avoid damage. Use in low current devices.

NiMH - comes in two varieties - Low Self Discharge and Standard. The standard types are available in higher capacity models, but these higher capacity models are often physically larger and don't handle current as well as the medium capacity versions. The new Low Self Discharge types (Eneloops et al) maintain their charge for years. When these cells leak they do little damage, are much safer to leave in a device than alkaline.

Lithium Primaries - Most energy per cell. Highest cost. Very long shelf life, 10-15 years rated. Some fire danger when physically mishandled or shorted causing vent to flame. Great for emergency standby type use. Tend not to leak.

NiCad - Very low impedance, good for high current. Less self discharge than standard NiMH but more than LSD NiMH. Contains poisonus metals so best to avoid, being phased out.

Li-Ion and Polymer - Cobalt LiCoO2 - Laptops, cellphones, etc. High energy density, low self discharge, rechargeable. Vent to flame when mistreated. Live only a few years, generally. Handle with care.

Li-Iron - Phosphate LiFeSO4 - Safer lithium ion chemistry. DeWalt and Black and Decker lithium power tools, coming in electric cars soon. Does not vent to flame when mistreated. Lower energy density than cobalt. The Nano Phosphate sub variety (A123systems) delivers incredibly high current and recharges very fast. Low self discharge, very long life.

Brands and Quality - some lithium cells are not made properly and can fail causing vent to flames or failing to meet life and other performance measures. Choose brands carefully, check on CPF and elsewhere for experience.

-- Alan