theshort description is taken from tis webpage
Cordless power tool batteries: NiCd vs NiMh vs LiIon
Here are the pros and cons of different battery technologies:
NiCd
Pros:
+ charging with very high currents does little or no damage to the battery allowing very fast charging (15 minutes)
+ can provide very high currents, suitable for high-drain application such as power tools
+ work well in cold weather
+ have long shelf life
+ can withstand 400-1000 cycles with minumum capacity loss
+ relatively safe
+ can be stored discharged
Cons:
- has high self-discharge rate (20% or higher per month) 15-20% the first 24 hours, 7-10% the next day
- has low power-to-weight ratio compared to NiMH or LiIon
- very toxic inside and has to be recycled
- can develop internal shorts (dendrites) over time
NiMH
Pros:
+ high energy density compared to NiCD, up to 3600 mAh per cell compared to 2400 in NiCd
+ cheaper than Li-Ion
+ high shelf life
+ can withstand 500 cycles with minumum capacity loss
Cons:
- has high self-discharge rate (30% or higher per month)
- cannot provide as much current as NiCd
- cannot be charged fast without shortening cell life
- freeze at 4 degrees C and must be warmed up to activate catalyst
- must be stored charged
- half the charge/discharge cycles compared to NiCd
Standard Li-Ion
Pros:
+ low self-discharge rate (5% per month)
+ very high energy density (25-33% higher than A123 Systems LiFePO4 Li-Ion aka DeWalt NANO)
+ can be charged fast without damaging the cells
+ can withstand ~1000 cycles with minumum capacity loss
Cons:
- unsafe: can burst into flames and/or explode if shorted or damaged.
- a little expensive compared to NiCd or NiMH
- perform poorly in low temperatures (below 0 C / 32 F)
- toxic and must be recycled
- cannot provide as much current as NiCd
- lower number of cycles compared to A123 Systems LiFePO4 Li-Ion aka DeWalt NANO
A123 Systems LiFePO4 Li-Ion aka DeWalt NANO
Pros:
+ very safe compared to traditional Li-Ion batteries
+ low self-discharge rate (5% per month)
+ high energy density (lower than standard Li-Ion but it's a price of safety and high discharge current)
+ can be charged fast without damaging the cells
+ can withstand up to 2000 cycles with minumum capacity loss
+ perform fairly well in cold weather
Cons:
- very expensive compared to NiCd, NiMH or Li-Ion - up to $16 per cell.
- toxic and must be recycled
- lower energy density compared to traditional Li-Ion.
so in other words:
if you have a LI-ION battery you DO NOT have to fully discharge it, you have to KEEP IT CHARGED all the time.
Cordless power tool batteries: NiCd vs NiMh vs LiIon
Here are the pros and cons of different battery technologies:
NiCd
Pros:
+ charging with very high currents does little or no damage to the battery allowing very fast charging (15 minutes)
+ can provide very high currents, suitable for high-drain application such as power tools
+ work well in cold weather
+ have long shelf life
+ can withstand 400-1000 cycles with minumum capacity loss
+ relatively safe
+ can be stored discharged
Cons:
- has high self-discharge rate (20% or higher per month) 15-20% the first 24 hours, 7-10% the next day
- has low power-to-weight ratio compared to NiMH or LiIon
- very toxic inside and has to be recycled
- can develop internal shorts (dendrites) over time
NiMH
Pros:
+ high energy density compared to NiCD, up to 3600 mAh per cell compared to 2400 in NiCd
+ cheaper than Li-Ion
+ high shelf life
+ can withstand 500 cycles with minumum capacity loss
Cons:
- has high self-discharge rate (30% or higher per month)
- cannot provide as much current as NiCd
- cannot be charged fast without shortening cell life
- freeze at 4 degrees C and must be warmed up to activate catalyst
- must be stored charged
- half the charge/discharge cycles compared to NiCd
Standard Li-Ion
Pros:
+ low self-discharge rate (5% per month)
+ very high energy density (25-33% higher than A123 Systems LiFePO4 Li-Ion aka DeWalt NANO)
+ can be charged fast without damaging the cells
+ can withstand ~1000 cycles with minumum capacity loss
Cons:
- unsafe: can burst into flames and/or explode if shorted or damaged.
- a little expensive compared to NiCd or NiMH
- perform poorly in low temperatures (below 0 C / 32 F)
- toxic and must be recycled
- cannot provide as much current as NiCd
- lower number of cycles compared to A123 Systems LiFePO4 Li-Ion aka DeWalt NANO
A123 Systems LiFePO4 Li-Ion aka DeWalt NANO
Pros:
+ very safe compared to traditional Li-Ion batteries
+ low self-discharge rate (5% per month)
+ high energy density (lower than standard Li-Ion but it's a price of safety and high discharge current)
+ can be charged fast without damaging the cells
+ can withstand up to 2000 cycles with minumum capacity loss
+ perform fairly well in cold weather
Cons:
- very expensive compared to NiCd, NiMH or Li-Ion - up to $16 per cell.
- toxic and must be recycled
- lower energy density compared to traditional Li-Ion.
so in other words:
if you have a LI-ION battery you DO NOT have to fully discharge it, you have to KEEP IT CHARGED all the time.