Rechargeable batteries have been around for many years. With the demand for better batteries, driven strongly by the digital photography market, newer types are being developed and older types relegated to less demanding tasks. One major advantage of rechargeable batteries over primary ones: You’ll save money over the long term. Lets look at some major rechargeable battery types and see how they differ.
Lead-acid batteries have been used in electronic flash units since the first portable flashes were developed. Early flashes used motorcycle batteries for power. Of course these batteries had to be kept upright to keep the liquid electrolyte where it belonged. This imposed no particular restriction since the power pack in most early electronic flash units was separate from the flash head and typically weighed over 20 pounds!
A prime example of this classic setup is the Strobo Research flash developed by my friend and mentor, the late Edward Farber, and shown in the classic photo at left.
The most recent iterations of lead-acid batteries are the gelled acid and “valve regulated” acid types. In these, the acid is constrained in a gel or in a membrane. This allows the batteries to be operated and stored in any position.
Lead-acid batteries are still giving excellent service in products, such as many of the Quantum Instruments battery packs. You don’t usually remove the individual batteries in a lead-acid system when charging them–charging is generally done with the batteries installed in the device.
Nickel-Cadmium batteries have had the widest usage of all easily replaceable, rechargeable batteries in photo gear but their heyday is over. Nickel Metal-Hydride (NiMH) cells are similar in construction and have all but superseded them because of their superior performance and more environmentally friendly components. They are available in many popular sizes including AAA, AA and 9-volt transistor.
AA-size Nickel-Metal-Hydride cells can be charged in anywhere from 15 minutes to overnight – depending on the charger. The best chargers are the two-hours-or-less “smart” chargers that monitor each cell’s charge status separately. A variation on this type of charger is the Rayovac 15-minute charging system, called the IC3 system, that incorporates a charge-shutdown control built into each individual cell.
Lithium-Ion cells are the latest rage in digital camera and video batteries. They are lightweight and available in various sizes to fit cameras of most types from the tiniest digital cameras to pro SLRs. I’m very satisfied with the performance of the ones used in my Nikon D-70. They keep on working even in well-below-freezing weather conditions.
The Care And Feeding of
A large part of caring for batteries is just using common sense. Avoiding the little things you might do that are “just looking for trouble.” Here are a few of the more obvious things.
Don’t ever attempt to use a new set of rechargeable batteries without first giving them a full charge. At best, a new set is likely to be completely run down and won’t work anyway. At worst, each cell will have a different amount of charge left. If so, trying to use them without a fresh charge could reverse charge one of your new cells and wreck it right out of the box!
Another very important thing to do to prolong your satisfaction with your nickel-metal hydride AA’s is don’t run your rechargeables way down! This also goes for Lithium-Ion batteries. This doesn’t preclude getting a lot of shots per set; just don’t abuse your batteries. By the same token, don’t try to recharge a Lithium-Ion battery that was just charged a day or so earlier and not subsequently used. This could stress the battery and shorten its life!
As an experiment I ran down a set of Nickel Metal-Hydride AA’s on my computerized load for less than an hour past their normal rundown point. When I tried recharging them, the one-hour charger balked for almost a minute before recognizing the AAs as chargeable. After charging, a retest in the Vivitar 283 flash I use for testing gave only about 60 shots. In a prior run I got over 190! After another recharge I again got nearly 190 shots.
The moral: Don’t milk the last possible shot out of a charge. Switch batteries sooner or you may be disappointed with the results of the next charge. Fortunately, most digital cameras shut down when the batteries get low and won’t let you abuse them.
As I mentioned last time, with primary batteries, use a Power Pen or similar tool on your rechargeable AAs before using or charging them. Surprisingly, new cells seem to benefit the most from these pens. It also helps to freshen up your flash’s contacts, too.
Keep your cells in sets. Mark them with an identifying number or letter in sets of two, four, or six – whatever number is needed in your gear. Doing so will improve their lifespan, particularly in chargers that charge cells in pairs. This is because every cell in a group will be subjected to the same use and abuse and so will likely need the same amount of charging time.
Charging a half-rundown cell along with fully rundown ones in fast chargers could result in overcharging one cell or undercharging the others. I prefer to use chargers that monitor each cell separately to avoid this problem.
If your flash or motor drive uses four cells, replace all four even though only one is defective. The newer cells will still have a charge when at least one of the others is run down. The rundown cell could become reverse charged by current flowing from the other three. Reverse charging will permanently weaken the rundown cell even further. Save the odd cells for use in portable radios, penlights or other less demanding applications.
Don’t mix rechargeable cells that are of different brands. Most brands have their energy storage capacity in milliampere-hours (MAH) or ampere-hours printed clearly on each cell. Some don’t, so you may not always know exactly what you have. The capacity of a nickel-cadmium AA cell can be anywhere from 450 to 850 MAH, depending on the brand, model and how long ago it was made. Nickel-Metal-Hydride AA cells can have from 1000 to 2400 MAH capacities.
Here, again, mixing cells of different capacities can cause permanent damage to the weakest one in the set. Different manufacturers state a cell’s capacity at anywhere from a ten-hour to a three-hour discharge rate. You shouldn’t simply assume that all 2000 MAH capacity cells will perform identically in your gear.
Don’t leave your batteries in the charger for weeks on end. This, too, can cause them to lose water, permanently reducing their capacity. Charge the batteries when you’re through using them and put them away. Lead–Acid batteries should always be charged before putting them away. Batteries can lose a bit of their ability to store electricity if left unused for several months or longer, but recover quickly from storage losses after a couple of charge-discharge cycles.
Never put a hot or overly warm set of cells into a charger right out of your flash. Let them cool to approximately room temperature first. Temperature rise is a prime indicator of charge status in fast chargers. Putting a hot cell into a charger could result in over- or undercharging. You don’t want this to happen! Similarly, don’t charge your cells in a hot car. This means don’t leave them charging in a closed car in the hot sun. Your cells could be damaged this way too.
Finally, read the instructions before using your charger the first time. This may sound simplistic but it’s quite important. The days of just slapping any old set of batteries into a charger is history. With some chargers, you may need to select a switch setting for the type of batteries you are charging. Other chargers can figure this out themselves.
