There are several steps you can take to insure that you get
maximum performance from your Digital Camera Battery:
* Charge your new digital Camera battery overnight (14 to 16 hours) before using it. We refer to this as forming the cells and will enable you to obtain maximum battery capacity.
* New batteries can be stored up to two years ( As long as they have never been charged) without significant cycle loss. If the battery has been charged once, then you have to keep up with the cycling.
* Store new/unused batteries, at room temperature, in cool dry area.
* Batteries which have been in storage should be charged overnight.
* Do not leave your battery in the charger when not charging. Continuous charging will shorten battery cycle life. (Don't use your charger as a stand)
* Do not return fully charged batteries to the charger for an extra boost. This action will Significantly reduce cycle life.
* Stabilize battery to room temperature (72º F) before charging. Charging below 40º F above 104º F will decrease cycle life.
Lithium-ion batteries are the newest technology batteries and offer several advantages over NiMH and NiCd batteries. Lithium-ion batteries are preferred for their lighter weight and higher performance. Lithium-ion batteries are typically 20-35% lighter and will provide 10-20% better performance than a NiMH battery of equivalent mAh rating. Lithium-ion batteries are also unique in that they are not susceptible to the "memory effect". Lithium Ion batteries do require a special type of charger because of their unique charging requirements. To achieve a true full charge , the battery needs to be slow charged the last 10-15% of its end of charge cycle. Most "intelligent" camcorder Lithium-ion chargers provide this capability otherwise overheating could occur and damage the battery.
A new Lithium-ion battery will benefit from an initial "conditioning" of the battery. For the first 3 charge cycles, fully charge the battery overnight and allow it to fully discharge before recharging.Lithium Ions batteries should be stored in a charged condition, and should be "topped off" occasionally. I would make sure to put them in the charger and top them off at least every couple of months, every month would be better. If you allow the cell voltage to drop below 2.5V, you will have irreversible chemical changes inside the cell which will greatly reduce its capacity
Nickel-Metal Hydride (NiMH) Batteries:
NiMH batteries provide the same voltage as NiCd batteries. However, they have at least 30% more capacity than Nicads. While still susceptible to the "memory effect," NiMH batteries are much less prone to this condition than the older technology NiCd batteries. Proper conditioning of a NiMH battery over it's lifetime will greatly reduce the potential negative impacts of "memory effect." This can be done by ensuring the battery is fully discharged before recharging at least once in every 3-5 charge cycles. It is not necessary or reccomended to deep discharge a battery every time you use it
First several times that you charge your new Nickel Metal Hydride battery, trickle charge (slow charge) if possible, this will condition the battery. Using an after market charger that is designed to condition the battery is often times better than the original charger that came with your product. Unlike Nickel Cadmium, the Nickel Metal Hydride battery can withstand random charging. The Nickel Metal battery seems to have a shorter life cycle than the Nickel Cadmium (most common type) battery. These batteries are sometimes twice as expensive as their Nickel Cadmium counterparts. Avoid overheating, heat is a Nickel Metal Hydride battery's worst enemy.
NICKEL CADMIUM (NICD)
Nickel Cadmium (NiCd) batteries are the oldest and most rugged (long service life & solid construction) technology currently available. Withstands a wide range of operating temperatures, and tolerates abuse (over-charging and discharging). IT IS NOT NECESSARY TO FULLY DISCHARGE YOUR CAMCORDER BATTERY BEFORE RECHARGING IT.
Although this exercises all of the cells in the pack, deep discharging also shortens how many cycles you can obtain. By using the battery normally and completely discharging it every 5th or 6th time, you are less likely to build up the "memory effect" and extend you batteries life. Do not leave the battery on the charger for extended periods of time (more than 30 hours), this causes cells to "boil" and will quickly ruin a battery. Also, NiCd batteries should not be subjected to shallow discharge or random charges (i.e. using the battery for a short period of time, then recharging). This type of use may result in dendrites a crystalline formation inside the battery which will diminish performance. To exercise a rechargeable NiCd or NiMH battery safely, first discharge the battery to 1 volt per cell (or until your equipment complains of "low battery"). (NiCd and NiMH batteries consist of 1.2 volts per cell - i.e. a 4.8 volt battery contains 4 cells). Finally, charge your battery with recommended charger until fully charged. When fully charged, a NiCd battery will show approximately 1.35 volts per cell, and a NiMH battery will show about 1.39 volts per cell.
Lead Acid batteries should be kept fully charged in order to ensure their maximum capacity. They are built to stand up to tough operating conditions such as overcharge and deep discharge, and, like NiCd, NiMH and Li Ion batteries, have no memory effect.
These are like very small car batteries and do not have a 'memory' problem. They should be charged frequently (or as often as possible). They should never be fully discharged or they will not be rechargeable again. If stored they should be regularly charged (eg. monthly) to prolong their life. They should not be charged with an automotive battery charger. If an SLA battery shows leakage it should be discarded immediately. Wash any exposed area with lots of water.... and seek medical advice if required. SLA batteries are hazardous to the environment and should be disposed of properly.
Breaking In New Batteries - new batteries come in a discharged condition and must be fully charged before use. It is recommended that you fully charge and discharge your new battery two to four times to allow it to reach its maximum rated capacity.
Preventing the Memory Effect - Keep your battery healthy by fully charging and then fully discharging it at least once every 90 days or between 3 to 5 times of use which ever comes first. Exceptions to the rule are Li-Ion batteries which do not suffer from the memory effect.
Keep Your Batteries Clean - It's a good idea to clean dirty battery contacts with a cotton swab and alcohol. This helps maintain a good connection between the battery and your portable device.
Exercise Your Battery - Do not leave your battery dormant for long periods of time. We recommend using the battery at least once every 90 days. If a battery has not been used for a long period of time (6 months), perform the new battery break in procedure described above and hope that it comes back to life.
Battery Storage - If you don't plan on using the battery for a month or more, we recommend storing it in a clean, dry, cool place away from heat and metal objects. NiCad, NiMH and Li-Ion batteries will self-discharge during storage; remember to break them in before use. Sealed Lead Acid (SLA) batteries must be kept at full charge during storage. This is usually achieved by using special trickle chargers. If you do not have a trickle charger, do not attempt to store SLA batteries for more than three months.
Frequently asked questions
My Nicad (or Nimh) battery died. I was nice to it, what happened?
Rechargeable batteries are not perpetual machines. The do not live forever.
No matter how well one takes care of the cells, they will eventually die. There
are two main reasons Nicad and Nickel Metal Hydride cells fail, other than abuse.
One is separator failure, and the other is degradation of the active material.
The first is far more common, and the result is a shorted cell. Every time a cell is charged, the active material is redeposited on the plates. Ideally, this occurs uniformly across the surface of the plate. However, in reality, there will be bumps and valleys. When there are bumps on both the positive and negative plates are adjacent, separated only by the separator, the resistance between those two points is slightly less than in other regions of the cell. So, the current density there rises. This means that more material is deposited there, contributing to even more "bumpiness".
In reality, needle like formations called dendrites form, and given time, they can force themselves through the separator to short the cell. A cell that appears to self-discharge in a couple of days has dendrite problems, and will soon completely short out. Plan to replace the cell.
Degradation of the active plate material is just a normal aging process of cycling. Both of these mechanisms are very good reasons to avoid deep cycling the cells after each use. NiCd cells should live to about 500 to 1000 cycles if treated properly, NiMH about 2/3 of this. Anything over that is gravy. Typically this translates into about 5 years of usage for a camcorder battery.
Can I zap cells to revive them?
On individual cells this can provide a quick but temporary fix. When cells
short due to dendrites, the piece of material that is actually shorting the
cell is very thin. So, by forcing a huge impulse of current into the cell, one
can vaporize the dendrite. Like blowing a fuse.
This sometimes works, and can revive an otherwise shorted cell. However, it is a stopgap measure at best. First, the fact that one dendrite has formed means that another is not too far behind. Second, the material that was vaporized has now permeated the separator material, forming a resistor that shorts the plates. The cell may no longer be shorted, but will still have a poor charge retention. Besides, unless done properly, this can be dangerous as large currents are necessary.
This technique DOES NOT work Lead acid or Lithium Ion batteries or with a battery pack (a battery with more than one cell) and certainly won't work with a camcorder battery - you have to dismantle the thing first and in view of the temporary nature of the fix and poor charge retention - is it worth the effort?
How about self-discharge?
NiCds have a bad habit of going dead when you just leave them, NiMH are even
worse. Fortunately you can recharge them. The current cells discharge about
1 percent a day, maybe a bit less. Expect them to be mostly flat after 3 months.
If you want to make something to keep your cells from self-discharging, make
a 1 to 2 mA current source. That should more than overcome self-discharge.
NiMH batteries have a horrible self-discharge rate ( between 3 to 10 percent per day- depending on the manufacturer). Self discharge increases with temperature. Higher temperature increases the self discharge rate..
What are battery manufacturers doing to prevent damage from over-charging?
Quite a lot. The demand for rapid charging has lead to a great increase in over-charging abuse. Most NiCd cells can be rapid charged. The trick is to stop charging when it is fully charged. The so called "rapid charge" type of cells just incorporate protection against over-charging at high currents. Most often, this is done with activated carbon inserted in the cell to promote the collection of oxygen and to deliver it to the cathode for recombination. By increasing the rate of oxygen transport, one is increasing the ability of the cell to resist venting. Note however, that heat is still generated. The price one pays for this is reduced capacity. Everything takes space in the cell, and space for carbon means less space for active material. Also, there have been some indications that carbon can cause the cadmium metal to corrode, possibly leading to a shorter life.
What about those super-high capacity cells?
The manufacturers are in a numbers game. It used to be that AA cells were 450 mAh. Then came 500, then 600 mAh. Now, 1700, 1800 and even 2000 mAh and greater cells are available. The highest capacity cells use foamy or spongy backing material for their plates. This allows packing more active material into the plates, but the cost is higher resistance. Recall that one of the great virtues of NiCds is their low internal resistance ,this allows large discharge currents for transmitting power.
What about cell reversal. What is it, and why is it so bad?
In a battery, not all cells are created equal. One will be weaker than the others. So, as the battery is discharged, the weakest cell will use up all its active material. Now, as discharge continues, the current through the dead cell becomes a charging current, except that it is reversed. So, now reduction is occurring at the positive terminal. As there is no more nickelic hydroxide, it reduces the water, and produces hydrogen. Cell pressure builds, and it vents. The cell has lost water and the life of the cell has been shortened. This is the big danger of battery cycling to prevent memory. Invariably, unless one is very careful, one ends up reversing a cell. It does much more harm than the cycling does good. Also, keep in mind that cells have a finite life. Each cycle is a bit of life.
Prepared for the students of Mr. Chuck Dolbeare (Video Chuck)