4 minute read

Batteries. Those energy containers that are almost anywhere you look these days. Here are 5 myths about them that you (probably) didn’t know.

Colorful Eneloop Batteries

1. Myth. Alkaline batteries are not rechargeable.

Fact. Just like bottles of water, alkaline batteries ARE rechargeable.

There is a catch, though.

Usually, rechargeable batteries are, well, recharged at somewhere between 0.200 and 2 amperes. In layman terms, that is how fast you are injecting energy back into the battery. The higher the number, the faster the injection.

This injecting back of energy causes heat to build up due to the battery internal resistance, which is one of the main reasons why they get damaged, and in some cases, even explode.

So, how do I recharge an alkaline battery? With care, my dear friend. First, you should go easy with the amperes, keeping them low. Somewhere around 0.150 amperes (That is 150 thousandths of an ampere) is a good number.

Second, don’t lose sight of the bugger while it recharges. If it starts getting hot, STOP. Let it cool down for a couple of hours before continuing the recharge.

Unlike batteries designed specifically to be recharged, regular alkaline ones don’t have any way to deal with the build up heat during the recharge process. There are some rechargeable alkaline batteries in the market but they are only good for about 30 recharges at most if you don’t recharge them before depletion. Don’t expect any better from a regular alkaline one. So, if you actually want to try it, be warned that, if you are not using a proper charger and if it gets too hot, this might happen.

2. Myth. All batteries are the same.

Fact. Not all batteries are created equal.

Even though they can be about the same size (think AA, AAA, C, D sizes and their variants), the voltages and chemical composition vary. A NiMH (Nickel-Metal-Hydride) battery can put out an initial voltage of around 1.4V, stabilizing later at around 1.2V, until the battery is almost depleted. Alkaline batteries, however, put out an initial voltage of around 1.5V, and then it starts to lower in a more or less linear way, all the way until its depletion.

Alkaline batteries discharge with a varying voltage. NiMH batteries discharge with a constant voltage.

3. Myth. Alkaline batteries are better performers than rechargeable batteries.

Fact. In some cases, rechargeable batteries can outperform alkaline ones.

There was a time when alkaline batteries were better than rechargeable ones. Not any more. Technology has gone a long way and there are now batteries with improved capacity and new environment friendly materials. Also, because of the way that rechargeable batteries discharge, specially Nickel Metal Hydride (NiMH) ones, and as counter intuitive as it may sound, they can actually last longer before depletion in some applications, such as camera equipment.

As a side note, Eneloop Pro batteries are among the best and it shows, since they are also among the most expensive ones. If you are into saving money, there are other high quality rechargeable batteries in the market that also cost less. Tip: In a pinch, they might do but, as a general rule, stay away from brand less batteries. Most of the time they don’t hold the advertised amount of charge, not even close (3000mAh? Really?) and degrade in a not-so-graceful way after around 100 recharges. Sometimes even less. Do your own research. Your Mileage May Vary.

4. Myth. You may know precisely how much charge is left in a battery.

Fact. Not always.

The amount of energy a battery can store is usually measured in mAH (milliamperes-Hour), which means how many milliamperes can a battery put out in an hour. So far so good.

The problem is, depending on temperature, humidity, slight chemical variations inside the battery and other factors, this number fluctuates, so it is more of a guideline than a hard and fast number.

There aren’t any battery testers (yet) that can tell you in an instant what the real charge of a battery is. The most they can do is measure the voltage and, from there, estimate the charge. Remember how does a NiMH battery discharge? Voltage lowers from 1.4 volts to around 1.2 volts and stays there until the battery depletes, so there is no real way of knowing at which point of that almost-flat line are you at any given moment.

As Battery University states, there are also other methods of measuring the battery capacity, in a more or less precise way, but all of them have some drawbacks.

5. Myth. You can’t fix a battery with a reversed polarity.

Fact. You can fix a reversed polarity battery (even with BBQ tongs).

In some extreme cases, usually when connected with other batteries, a battery can discharge to a point where the other batteries drive it beyond the point of exhaustion, reversing its polarity. This means that the positive side (the one with the nip) is now acting as the negative side.

To fix it, just connect the positive side (the one with the nip) of a fresh battery to the nip of the damaged battery and the negative side of the fresh battery to the other side of the damaged battery for about 30 seconds. Most of the time this solves the issue. Some people have even demonstrated how to do it with a pair of BBQ tongs.

Take into consideration that every charge/discharge cycle involves a chemical reaction inside the battery, and with every chemical reaction, the lifespan of it shortens a bit. As a reference, you can recharge a high quality NiMH battery at least 500 times (!) before it begins to show wear signs. If you use and recharge it a lot, say every week, it should last you around 10 years if properly taken care of.