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photo:batteries

looking after your batteries

Introduction

  • each battery type has unique characteristics and optimised ways to look after them to ensure their life is extended as long as possible, and that the risk of them exploding (this is especially a risk with lithium ion batteries) is reduced
  • life span was particularly a problem with the older technologies such as nickel cadmium (NiCd) and nickel metal hydride (NiMH) as well as the old heavy lead acid batteries.

Lithium ion batteries

  • use the correct charger
    • an incorrect charger may cause serious overheating within minutes
  • don't drain them to zero
    • doing this may make it very difficult to regain maximum capacity and hold charge
  • don't keep them perpetually charging 24×7
    • remove them from the charger once they are fully charged
    • keeping them on a charger risks overheating, swelling and explosion risk
  • supervise them whilst charging
    • don't charge them overnight while you sleep in case they overheat and burn your house down
    • ideally charge them in the same room, or at least have a smoke detector in that room
  • don't store them fully charged
    • this can dramatically shorten their life span
    • it is better to store them at 50% if they are being stored for long periods
  • don't overheat them
    • keep them out of your hot car
    • don't charge them straight away if they are feeling warm
  • don't start charging them while they are hot
    • this will only make them hotter and risk damage to the cells
  • remove from device when not being used
    • devices often leak current even when turned off leading to battery becoming drained

NiMH batteries

  • one can expect 2000 charge/discharge cycles out of a standard NiMH battery
  • use the correct SMART charger
    • Most chargers made since about 2005 charge both NiMH and NiCd batteries. But some newer chargers charge only NiMH, not NiCd.
    • Any NiMH charger will charge both regular NiMH batteries and LSD NiMH's (Low Self Discharge NiMH).
    • Old NiCd chargers can't tell when to stop charging a NiMH battery
    • Use a smart charger! Smart chargers charge each battery separately, giving each one exactly as much energy as it needs and stops charging once it is full.
    • If your NiMH charger manages each cell separately, you can mix NiMh and NiCD, different sizes, and semi-fresh and nearly dead batteries at the same time. If it doesn't you can't. If you insist on mixing them anyway, some of your batteries will be undercharged and some will be overcharged.
    • NiZn batteries require a special charger. NiMH and NiCd chargers will not work.
  • Trickle Charging is the safest method
    • charge at the lowest possible rate that will keep your overall charge time BELOW 20 hours
    • Most would suggest to aim for 4-5 hours - a 4-5-hour charge means about a 500 mAh charge for most 2000mAh AA's, and 200 mAh for most lower capacity AAA's.
    • If the battery charges too slowly, the charger might miss the voltage change and not stop charging.
  • don't keep them perpetually charging 24×7
    • remove them from the charger once they are fully charged, excessive charging reduces battery life
    • Smart chargers will stop charging when charge completed HOWEVER, most chargers give a “trickle” charge after charging is finished. Some chargers give too much of a trickle, and even those which give a reasonable trickle can still overcharge if the batteries are left in the charger too long.
  • almost fully discharge battery prior to charging
    • NiCd and, to a lesser extent, NiMH batteries have a “memory” issue
    • You can recharge at any degree of depletion (you don't have to wait until the battery is mostly discharged), but the sooner you recharge the better, because you'll get more cycle life out of the battery.
    • for a 1.5V battery, it is better to re-charge at 1.1V than wait until 1.0V
    • failing to deplete the battery each time reduces its capacity
    • Newer NiMHs can be restored by “exercising” the battery (fully charging and discharging the battery a few times)
  • there are methods to REVIVE “dead” batteries that won't charge

NiCd batteries

  • use the correct charger
    • Most chargers made since about 2005 charge both NiMH and NiCd batteries. But some newer chargers charge only NiMH, not NiCd.
  • almost fully discharge battery prior to charging
    • NiCd have a major “memory” issue
    • failing to deplete the battery each time reduces its capacity
    • ideally the aim is to charge once the battery is ALMOST fully depleted (voltage will be around 1.0-1.1V for a 1.5V battery)
  • Dispose battery safely - cadmium is TOXIC
photo/batteries.txt · Last modified: 2020/06/21 21:27 by gary1