When the light goes out, the first thing that comes to mind is flashlights, but having a drained battery in a flashlight in these situations is the worst.
So, yes, flashlights have been known to drain batteries when not in use. After doing some analysis, I came across this flashlight with a unique battery guard feature made by Coleman®. See the image below.
This unique flashlight is designed with a specific mechanism that will prevent the battery from draining and allowing the flashlight batteries to last longer.
Here’s how it works. When the switch is in the off position, it will also disengage the batteries without removing them and losing complete contact with the flashlight preventing the batteries from draining. And that’s all it is; this mechanism will also preserve the battery’s integrity by preventing corrosion.
There are some essential things to know about batteries that will help you understand and better choose or keep your existing batteries in good condition. For example, What are the most common types of batteries used on a Flashlight? What do the numbers and letters on a flashlight battery mean? How often should you charge flashlight batteries? And some other important questions and factors that you need to keep in mind.
Before we go into that, what I want to put in your mind is that you never know when you’re going to need a little extra light, no matter the situation, from power outages to roadside emergencies, having a flashlight ready to go is a necessity.
How Do You Charge Flashlight Batteries?
When charging any battery, it is preferable to get a quality charger for safety reasons. One of the most necessary things to look for when choosing a charger is its independent charging channels. Most lithium-ion chargers have them, but many nickel-metal hydride chargers do not.
I recommended having a NiteCore brand battery charger because it can charge both lithium-ion and nickel-metal hydride cells.
Besides, this NiteCore digital charger is a favorite because it can charge a pair of 26650s side by side and can even work with the longer protected cells.
You should note carefully that some batteries look similar, but fundamentally some of them are very different.
Some flashlights already come with batteries, some of them are rechargeable lithium cells, and others are known as primary lithium cells.
The 1.5-volt lithium batteries such as those from Energizer or the 3-volt CR123 batteries that come in many flashlights are not rechargeable.
And for lithium-ion battery brand recommendations, I like the KeepPower cells; they mark their batteries with realistic capacities, they’re good quality and offer many protected cells.
Probably the best resource I’ve seen to help you choose which battery is best for you is the (HJK website) Google (battery comparator). You can find comparisons for almost any popular cell and useful quality information there.
It does independent tests that show what the discharge curves are for each battery and how high you can discharge them, and pretty much everything you need to know.
For nickel-metal hydride batteries recommendations, many people go for Eneloops because of their reputation for quality.
Another cheaper alternative would be the Duraloop battery, as they are called the Duracell precharged battery; it has a white ring around the top and is made in Japan, not the black ones made in China.
I recently found what I think is an excellent third option is the Powerex Imedion brand.
It is 2500 milliamp capacity sells its low self-discharge and there much cheaper than Eneloops.
Powerex Imedion also performed exceptionally well under load in some of the tests I found after researching.
For larger cells like C & D, I recommend Tenergy Centura for basically all the same reasons as the other batteries.
Should You Remove Batteries From Flashlights When Not in Use?
If you don’t have a flashlight with this unique mechanism mentioned above, you may ask yourself; Should I remove batteries from the flashlight when not used?
The answer is yes; removing the batteries from your existing flashlight is recommended if you are not planning to use it.
What Are The Most Common Types of Batteries Used in Flashlights?
The most usual types of batteries used in flashlights are nickel-metal hydride and lithium-ion batteries.
Nickel-metal hydride: these batteries usually come in sizes that directly replace alkaline batteries, such as AA C&D.
They operate at about 1.2 volts per cell and are an excellent substitute for alkaline batteries and most devices.
The term “lithium-ion”: encompasses several types of batteries, but for flashlights, most are 3.7 volts.
What Do The Numbers on Flashlight Batteries Mean?
Some standard number series on batteries you probably have; for example, some batteries have the number 18650, and some have the number 26650.
The first pair of numbers in that series is the diameter and the second pair is the length.
You can also get lithium-ion batteries to replace standard-size batteries such as AA or CR123 batteries.
For example, a 14500 cell is the same size as an AA, and a 16340 is equivalent to a 3-volt CR123 battery.
Just keep in mind that lithium-ion batteries have a higher voltage than the previous two, and not all flashlights can handle that extra voltage. A fully charged lithium-ion cells are 4.2 volts.
The next set of numbers you will see on a battery is the cell capacity, for example, 5200mAh.
5200 milliamp hours is the battery’s capacity, which means that if we were to discharge this battery to 5200 milliamps, it would run for one hour.
What Do The Letters on Flashlight Batteries Mean?
Moving on to battery letters, some of the standard letters you will see on flashlight batteries are IMR, INR, ICR.
You don’t have to know what these letters stand for; what’s important is that you know how to deal with them.
IMRs and INRs are known as safe chemistry batteries and are more forgiving than others, as you can discharge them at a higher rate.
ICR’s are not safe chemistry that C stands for cobalt or, in other words, be careful.
You can’t test things when using batteries; if you do and try the wrong thing, they can expel toxic fumes or even catch fire.
The best way to know how much a battery can discharge is to look at the manufacturer’s specifications.
For example, with a 26650 battery, you will see a maximum discharge current of 9.5 amps.
Sometimes you will see a rating that says 2c or 5c, which only means two times the cell’s capacity.
Another essential thing to note is the maximum charge current; a 1c is usually the maximum for most lithium-ion cells that flashlights use.
Another variation you’ve probably heard of and lithium-ion cells are protected and unprotected.
This means that a circuit is added to the end of the battery to prevent it from being discharged at too low a voltage.
As is known, too low a voltage will damage the batteries.
Protection circuits also protect the battery from overcharging, and some of them even protect it from discharging at too high a rate.
How Often Should You Charge Flashlight Batteries?
Generally speaking, rechargeable batteries, whether lithium or nickel-metal hydride, as I mentioned earlier, lose a small percentage per month in the form of self-discharge, and if fully charged and allowed to stand, they lose charge over time, the same as alkaline batteries.
So a quick answer on when to recharge your flashlight batteries is early and often.
Over the last few decades, we’ve all been trained with disposable batteries that you want to drain the battery to the last drop before throwing it away.
This is not what you want to do with rechargeable batteries; in general, you never want to discharge that battery fully, so recharge it early and often.
If you pick up the flashlight and wonder if the battery is charged, put it on the charger.
If you have a more advanced charger with a display that shows the voltage when you put it there, you can see how charged or not this is true with lithium batteries.
The nickel-metal hydride battery spends probably 80% of its life while you are using it at about 1.3 volts.
So if you are below 1.3 on the charger, that battery is almost drained; however, when in that middle period you know that 80% is not going to see that you put it in, and it is going to say 1.3, you can’t tell if it is 80% charge or only 10% charge.
So with those batteries, you can try to keep better track or go ahead and charge them again; it’s better to have a full battery than an empty battery, especially when you need it.
But the other right way to illustrate how often you should charge your flashlight batteries is to think of it like filling up your car with gas, so how often do you fill up your car with gas? When you need it; Right?
If you’re planning to go on a long trip with an empty tank, you’ll fill it up first because you’re thinking ahead, and you know you’re going to need it, so the main thing is to fill it up when you know you’re going to need it.
The other thing to keep in mind would be to have spares available; one of the nice things about rechargeable batteries is that you don’t have to have a whole drawer full of extras so that you can have a handful.
Now, if you have rechargeable batteries, one beneficial thing is organization.
What I mean by this is to use Storacell battery holders.
These are great for a couple of reasons, these are made of plastic, and both battery terminals are protected.
You don’t want to have loose batteries in your bag that can cause a short circuit.
These Storacell battery holders are also great when traveling, and you can flip them over to tell at a glance if the batteries in the holder are charged or not.
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