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Category : How to Choose a NiMH Battery Pack?
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How to Chhose a Battery Pack
- First of all, you must get to know your device:
- What is device's input voltage? ( V)
- What is its power consumption ( Wattage ) ?
- What is Maximum current drain ( A) ?
- What is your expected running time by a battery pack ?
- Decide battery pack voltage you will choose
- Battery pack voltage must be equal or a little higher than your device??s need.
- If you need a exact voltage, which battery pack can not provide, you may consider to use a DC-DC regulator
- Decide Battery pack's Capacity ( mAh or Ah)
- Battery capacity is depended on how long you need to run your device ( hours ), which can be calculated as the follow:
- ( Ah) = Device's Wattage (W) x Time to run ( Hours) / Battery Voltage (V)
- For example, if using a 12V battery pack, and run 10W DC device for 10 hours, you need choose a battery pack with capacity > 8.3Ah, e.g
( 10x10)/12 = 8.3
- 1000 mAh = Ah, higher mAh will provide longer running time.
- Decide Battery pack??s Max. discharging current
- Before order battery pack, you must pay attention on battery pack??s Max. discharging rating on the specification or description. Please don??t think any battery can take any current drain.
- You shall know your device??s max. discharging current. If you don??t know , you must measure it by a multi-meter.
- The battery pack??s Max. discharging rate of the chosen Battery must be higher than that device requires
- Choose Li-Ion, NiMH or Lead acid battery?
- All types of rechargeable battery will work for you. Question is size and weight. The table below lists the advantages and disadvantages of these batteries for your reference
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Chemistry
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Cost
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Weight
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Temp
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Cycle
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Shelf Life
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Volts
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( oC)
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Life
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(months)
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per cell
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Lead Acid
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$$
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Very Heavy
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-65 to 80
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300
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12
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2.0
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Nickel Cadmium
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$$
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Heavy
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-20 to 65
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500+
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6
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1.2
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Nickel Metal Hydride
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$$$
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Moderate
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-10 to 65
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500
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12
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1.2
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Lithium Ion
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$$$$
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Light
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-20 to 60
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500
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12
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3.7
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Lithium Polymer
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$$$$$
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Light
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-20 to 60
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500
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12
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3.7
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- Li-Ion batteries has the highest energy density ( mAh/weight), and become more and more popular. However, Li-Ion may explode and cause a fire if it dose not use properly. Please read our safety warning.
- In current stage, we always suggest customer to use NiMH battery pack for high current application ( < 1C rate ), not Li-Ion , because Li-ion ?®s protection in high current application still is not matured yet
- Choose a Battery Charger
- Please always follow our suggestion to choose a smart charger. So called smart charger must has automatic power cut-off function when battery is full.
- Never use NiMH battery charger for Li-ion battery pack, it will cause battery exploded
- Always charging your battery with attention, and put battery in a fire-proof container ox box to avoid any accident.
- Understand risk to use NiMH and Li-ion battery. Please read our safety warning before buying a battery
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