We test alkaline, heavy duty, general purpose
and rechargeable cells along with battery
eliminators and testers and come up with some
By David H. Ahl
"In six months, I spend more on batteries than the game cost in the first place."
"No matter how much I yell and scream, he always forgets to turn it off, and, poof, another set of batteries shot. "
"Alkaline, long life, general purpose--they're all the same--they all wear out too soon."
Sound familiar? It's difficult to get along without batteries in this portable electronic age. As a result batteries have become a big business with big ad budgets, lots of hype and not many solid facts.
One maker claims their alkaline battery lasts up to ten times as long as an ordinary battery. Another maker touts the long shelf life of their batteries. Everyone "knows" that alkaline batteries are better and sales figures reflect this bias.
What's the truth? We set out to find out. First we went on a battery shopping spree. Our informal survey of electronic games on the market this holiday season indicated that C-cells were most often required followed by AA, 9-volt and D-cells in that order. Hence, we decided to test C-cells and assume that differences between brands, if any, would hold true for AA, 9-volt and D-cells as well. Furthermore, alkaline cells are the most popular among consumers so we bought seven different brands of alkaline C-cells along with four "long life" and four standard batteries. We also bought a battery charger and accompanying NiCad cells. In addition, we bought three battery eliminators--two with specific voltages and one "universal" type. And, just to be complete, we bought an inexpensive battery tester.
The American National Standards Institute (ANSI) has a standard rating system for batteries and the battery industry also has two "standard" tests: "Heavy Intermittent Flashlight Test" and "Light Intermittent Flashlight Test." In our opinion, none of these comes close to approximating the usage one might expect in a typical electronic game. Even in games, the usage will vary widely. In a chess or backgammon game, for example, the batteries are likely to be in operation for relatively long periods (hours, perhaps, in a chess game). In a handheld action game, usage is more likely to be in short 15-minute or half hour bursts.
Most games give a low battery signal or fail to function correctly when the voltage decreases to about 70-75% of the design voltage. Accordingly, we considered a battery to be dead when its voltage under load dropped to 1.1v. We then calculated the cumulative use time per dollar (average) for each of the four types.
It is apparent from Table 1 that prices vary widely. Two Panasonic C-cells for $1.25 (on sale) are an excellent buy while the regular price of Sears general purpose cells (two for $0.54) has to be considered a bargain. Consequently, although alkaline cells certainly have the longest life, we have derived Table 3 which indicates comparable prices of different types of batteries. One can see from this table that a pair of $2.49 alkaline C-cells is equivalent to $1.34 for heavy duty cells or $ 1.10 for general purpose ones. Hence, two Sears general purpose cells for $0.54 are equivalent to $1.25 for a pair of alkaline cells.
What About Rechargeables?
A word about rechargeables: assuming 1000 recharges as advertised by the manufacturers, they are clearly a much better buy than any conventional cells, even including the cost of the charger. We did not check the validity of the claims of 1000 recharges, as that would have taken nearly three years. However, our experience with rechargeable electric razors indicates that there is noticeable deterioration in performance after about 18 months (about 500 charges). This suggests that the theoretical maximum number of recharges may indeed be 1000, but that 500 may be a more realistic working boundary.
The cost of a charger is about $8-12 while two cells cost $6-9. This means the cost per use plus electricity for operating the charger based on 500 charges is less than 6 cents. Even with only 100 recharges, the cost is under 30 cents per use.
The life of a battery is quite different if it is in continuous use versus intermittent use because the latter gives it an opportunity to recover between uses. Alkaline batteries tend to have less voltage drop in use than others. Standard carbon/zinc cells have large voltage drops after an hour of use, but also rebound substantially overnight.
Our use test was designed to approximate use of the "average" toy or game. We measured the current drain of six representative games. The range was from 35 ma (milliamperes) to 220 ma with generally an additional 20-30 ma when the device played some sort of tune at the beginning or end of a game. Hence, we used a precision 15-ohm resistor as a load which, across 1.5v, provides a current drain of 100 ma.
While every user is different, we tried to approximate a typical use cycle. Day one, say Christmas, we had one hour continuous use. Day two, one-half hour. Day three (friends came over), two one-half hour uses with 1 1/2 hour recovery between each. Day five through battery rundown, alternate between one and two one-half hour uses per day. The discharge curves for the four battery types are shown in Figure 1. This shows the average voltage in each half hour period of use. Figure 2 is a "close up" of a portion of the curves in Figure 1 which shows the decay and recovery characteristics of the four battery types.
We did not run every battery all the way down. Our first one-hour test (Table 1) indicated that batteries within types were roughly similar. Certainly there are differences--the Ray-O-Vac alkaline C-cell had a new load voltage of 1. 50v; it dropped to 1.42v after one hour of use and recovered to 1.44v after another hour. In contrast, the corresponding readings for a Duracell were 1.48, 1.38 and 1.41.
However, we elected to run one representative sample from each battery type all the way down. We chose the Panasonic alkaline, Ray-O-Vac heavy duty, Sears general purpose and Gould rechargeable. Figure 1 shows the results of this test. The graph shows the average voltage under load (it does not show recover time). Figure 2 shows a "closeup" of the first eight hours of use including voltage drop and recover peaks. Note the much larger voltage variations (use and recovery) in a general purpose battery versus an alkaline cell.
Counterbalancing this cost advantage is the much shorter use cycle. What this means in reality is that one must remember to put the batteries back on charge and that it is probably worthwhile to have two sets of batteries to exchange with each other.
Another problem is that for best life, the batteries should not be run down all the way before recharging, nor should they be recharged too soon. Each time into the charger for the required 14-16 hours counts as a recharge cycle. So if one recharges after only 15 or 30 minutes of use, that's still one recharge cycle used up. On the other hand, if one can expect over 500 recharges, then $12 to $18 for two new sets of batteries every two or three years is not at all unreasonable.
At $5 or $6 for the typical battery eliminator, its cost can frequently be justified on the very first set of batteries for an electronic game--rarely would it take more than three sets. Some Selchow & Righter games include discount coupons for an eliminator making it an irresistible deal. On the other hand, the obvious disadvantage of an eliminator is that the device is no longer portable. Eliminators just don't work on buses or at the beach.
We were curious about the purity of the DC voltage from eliminators. Displaying the output on an oscilloscope revealed nasty sawtooth waves from all three eliminators. Fortunately the games we tested weren't at all fussy about well-filtered DC. However, we would strongly advise against using a cheap eliminator with any microprocessor-based circuit such as an Atari video computer system. Although it looks like an eliminator, the Atari power supply has a whopping condenser inside that smooths the output voltage considerably.
One problem we experienced with a so-called universal eliminator is that the four-way plug/outlet had no shanks on the plugs and thus would not work with games that had recessed jacks. More annoying was the fact that about half of the games we tested had no provision for an eliminator.
Most inexpensive battery testers ($4-$10) are nothing more than voltmeters with, generally, five to seven different ranges to accommodate batteries of different voltage. The scale is typically marked with just two zones: replace (red) and good (green). On the 1.5v range on the Radio Shack tester we bought, the division between the two ranges fell at 1.1v.
Since we found that most devices started to malfunction when voltage fell to 1.1, a tester is an accurate indicator of whether or not a battery will work, right?
Well, maybe. The Radio Shack tester, like most others, has three built-in loads for each voltage range. For 1.5v cells, the loads were 10 ma (150 ohms), 50 ma (30 ohms) and 150ma (10 ohms). The instructions recommend using the heavy load with D-cells, medium load with C-cells and light load with AA batteries. However, our measurements showed that some electronic games using AA batteries draw up to 200 ma. Thus a battery might read "good" on the low range (10 ma load) but would not operate in a game with a 200 ma current drain.
In general, we recommend using the medium and high load of a tester for all batteries. There are few devices, even including calculators, that draw as little as 10 ma. Even so, a tester will give only a general indication of condition.
The real test is whether or not the battery will power a particular game, radio or flashlight. And the only way to determine that is to try it in the device.
In tests approximating the use of batteries in electronic games alkaline batteries lasted for 41 hours, heavy duty batteries for 22 hours and standard carbon/zinc cells for 14 hours. Our tests in no way substantiated manufacturer claims for heavy duty batteries (more than twice the life) or alkaline batteries (up to seven times the life) compared to general purpose cells.
Assuming the prices we paid were representative, the cost to operate an electronic game requiring two C-cells would be about five cents per hour using either alkaline or heavy duty cells, just under four cents per hour using standard cells and two and one-half cents with rechargeable batteries.
One of the "laws" of electronic game use is that the game will be left on overnight at least once a month. No matter what kind of cells are being used this will run them down. Hence, because of this as well as the comparative cost we recommend rechargeable batteries as the best buy. Our second choice would be to use a battery eliminator when the game is used at home and general purpose cells for other use. We recommend shopping for the cheapest general purpose cells and buying four or five sets. Manufacturer claims to the contrary, we can find little reason to pay premium prices for either heavy duty or alkaline batteries.
For use in cassette recorders or devices sure to be shut off after every use, alkaline batteries may represent a convenient (fewer battery changes) and economical alternative. But use Table 3 as a price guide. If a pair of standard cells costs $0.79, a pair of alkaline cells would have to cost $1.75 or less to be a better buy. Table 3, incidentally, is applicable to any kind of battery: D, C, AA or 9-volt.
Finally, a word of warning. We purchased one set of Treasury "Long Life" batteries which seemed to be heavy duty cells. It turned out they were simply general purpose cells. Caveat emptor.
|Figure 1. Discharge curves.|
|Figure 2. Discharge curves showing drop during use and recovery.|
|Table 1. Battery voltage measurements before and after one hour of use. Batteries are listed in order of overall use and recovery characteristics, although differences within groups are slight. See article text for discussion and buying recommendations.|
|Table 2. Cost per hour of use of two C-cells
in an electronic game drawing 100 ma.
|Table 3. Equivalent prices of three types of batteries.|