Fechino Files: Understanding Rechargeable Lithium-Ion Batteries

Words: Steven Fechino

Steven Fechino

Recently, I was using a lithium-ion battery powered reciprocating saw with a 5-amp hour battery. The reason I mention the battery size is because it had plenty of power to cut for a decent period of time. By the time I massacred the cut I was attempting (whoever makes precision cuts with a reciprocating saw, I commend you), the battery was pretty hot, enough that I stopped using it till the battery and I both cooled down. I have had battery powered tools through both the nickel-cadmium and the current lithium-ion power sources, and here are a few things that I mention that I hope you can benefit from. This article is written as a way to enhance battery safety and is not designed as a ploy to cry wolf about the batteries or to create any distress, as many of us own many batteries. I just offer information to have a better understanding; that is it!

Nickel-cadmium is the grandfather of battery powered accessories, like your old 14-volt drills, early cellular phones and even computers. The lithium-ion battery is what we can call the next generation of portable rechargeable batteries.

Originating as early as 1912, a gentleman named G.N. Lewis began the science of what was then non-rechargeable lithium batteries. It now has been commonly used as a power source since early 1991 (even before in some parts of the world) and was safe, rechargeable and reliable. Nickel-cadmium typically had about half of the energy density of the lithium-ion batteries of today, which is why the battery powered tool industry, as one example, is able to perform at efficient levels for today’s workload. Nickel-cadmium also required a larger volume of space to create similar power to lithium-ion powered tool, about three times the space. A single nickel-cadmium pack typically would have about one-third the battery capacity and was so much more inefficient for the end user than a lithium-ion pack would produce. This is why the change was made in the industry and worldwide, as the performance for battery powered mobility allowed consumers to purchase their battery powered devices and perform without the cord.  

Lithium-ion battery technology is still being developed and improved. Different versions of metals and chemicals are being tested, and when suitable, improvements are being released to consumers regularly. The drawback to having newer versions being released is that there can be questions about long-term aging of the expensive batteries that we use.

There are many benefits to lithium-ion batteries as they regain full charge quickly, have extended power availability, and have a higher power density for more battery life in a smaller volume, without a charging memory or charging cycle reduction.

When I purchase tool batteries, I want them to last just like you do; however, everyone knows that the day will come when you just “got nuthen’” and have to buy another one. If this is the case, then consider yourself lucky. The battery did its thing with no problems, which is not the case with all lithium-ion batteries. Battery charge capacity reduces during the first year of service, even if the battery is not used, and you may even notice the difference as you find yourself charging more frequently, sometimes failing completely before the third year or lasting until year five. Battery management has much to do with battery life, so does a little luck (luck is really just my opinion and far from found in any research). Lithium-ion batteries do not require daily maintenance.

As mentioned earlier, the discussion of lithium-ion batteries relates to you every day. In the case of my friend Bud Easton, it is his electric bicycle; to you, it may be your laptop or someone’s toy that they are playing with. What is safe nowadays? We really need to exercise care where once we did not.  

So, what do you need to do? Here is my personal checklist:

  1. Keep batteries from total discharge. They will not charge once they are totally depleted. Change out batteries as you are in mid-use while you can.
  2. Removable batteries should not be kept in a hot vehicle every day all summer long.
  3. Removable batteries should not be allowed to be kept in a below-zero climate for long periods; this will really shorten the usable life of the battery. I personally keep all of my batteries in a case and bring them in at night.
  4. DO NOT allow the battery to over-charge and get hot. DO NOT allow the battery to over-charge and get hot. Yup, said it twice! 
  5. Unplug batteries when not in use.
  6. Long-term storage in a slightly cooler than room temperature is ideal (scientists say 59 degrees Fahrenheit). Like I said, I keep mine inside.
  7. When storing batteries, attempt to have at least 50% charge or two lights on the charge indicator when possible. Manufacturers will say it is okay to do less, but in my experience, the better the charge, the longer it will last.
  8. Control long-term storage, keeping all batteries unplugged and off of long-term chargers.

Lithium-ion batteries come with a downside, though, that really should be understood so it can be overall managed.

I know I joke a lot when I write articles, but here I am not. Please read the following carefully, as it can aid you in long-term safety.

The standard lithium-ion batteries are made with flammable materials, all of them. When a lithium battery is charged improperly or allowed to overcharge, heat buildup is the problem. Dangerous heat levels or a circuit short can create a reaction called “thermal runaway,” a reaction that can be the ignition point of a fire. Battery fires burn at 500 degrees C. In order to extinguish the flame, the battery must be cooled rapidly to a pre-ignition temperature. There are three ways to extinguish a lithium-ion battery fire, use of a Lithco LB6 Fire Extinguisher, which is a water-based extinguisher with ‘P Foam’ assisting the fire extinguishing, or the application of an Aqueous Vermiculite Dispersion (AVD) which encapsulates the fire surrounding the battery cells. The third way is to use an electric car fire blanket, which is a bit overkill for the normal reader of this article.

  • This is where laptops placed on a surface like a couch or a bed get very hot, not good. 
  • When you keep your phone plugged in on a long drive, your GPS continues to work and you are fully charged upon arrival, not good.
  • You go on vacation in your camper and leave your electric bike plugged in, not good.

Here is the biggie, 

A lithium-ion battery fire is, for all intent and purpose, an inextinguishable fire. Prevention by the consumer is mandatory, and really, you have nothing to lose by managing the batteries, but longer life and reduced fire risk are not bad perks.

Yes, the battery manufacturers know the dangers of the batteries and have taken precautions. They have the protection limiters on the circuit peak voltage (to minimize the possibility of overcharging) for individual cells during charge and preventing the cell voltage from dropping too low on discharge. In addition, the cell temperature is monitored to prevent temperature extremes. The maximum reduction upon discharge usage (allowing for recharging of the battery) allows for a longer battery life and more recharging cycles. These fail-safes are why you do not hear about battery failures on a daily basis. But let’s face it, everything we own is subject to a bump or a jolt, or in the case of my tool batteries, a fall from a scaffold, all reactions that can loosen a wire or crack a circuit and thus result in a problem.

Now, go check your batteries while my friend Bud goes for a bicycle ride on his electric bike!

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