Battery technology is changing and improving at an incredible pace and will only get better. Battery-powered handheld power tools are becoming more mainstream every day. The most common uses in the fire service are for the reciprocating, circular, chain, and rotary saws; drills; breakers; and vehicle rescue tools.
They also eliminate two big safety issues on the fireground: tripping over stretched cords and hoses and loud noise. The current preferred battery is the lithium-ion (li-ion). The advantages over the older, nickel cadmium (ni-cad) battery include the following:
- Faster recharge time.
- More charge/discharge cycles (most have a rated lifetime between 500 and 1,500 cycles).
- They can be placed in a recharger regardless of the current energy level.
- No charging memory issues.
Keep spare batteries and a charging station nearby.
Most quality li-ion batteries will not let you use them past 40 to 50%; they have circuitry installed that will shut the battery off. Consistently using the battery to zero is damaging to the long life and capacity of the battery. This protects the battery from full discharge (not good for long life of an li-ion) and protects the tool/motor you are operating some; its power source does not run so low that it damages the tool/motor. If you are consistently draining your li-ion battery, consider swapping it out, as it drains down as indicated on the LED indicators showing charge level, at no more than 50% for best results to extend the ability of the battery to be recharged and sustain a charge under load.1
The battery also has built-in protection so that it shuts off when the voltage is too low; as we know, when supply voltage drops, current draw increases to sustain operations. By shutting itself off, the battery is protecting itself from damaging excessive discharges, and this also protects the motor from running in a undervoltage condition. So, as an operator of the tool, you will find it suddenly stops; this is likely not a malfunction but the battery shutting itself off. The tool will not slowly drift down to a stop, taking the battery to zero.
Heat is the enemy of many tools, and this includes batteries. Keep them out of the water. Rain or snow will not hurt them, but being underwater will damage them. Keep them free from moisture as much as possible. Don’t drop or toss them around; vibration shortens battery life.
If you see a battery bulging or feel it getting abnormally hot, this can mean a buildup of gas inside (photo 1). The gases are produced by the electrochemical oxidation of the electrolyte. Such oxidation usually occurs from a faulty battery or battery charger. Stop using such a battery immediately, and dispose of it properly.2
The circuit board regulates the charging and shuts the battery off if the voltage gets too low to prevent damage to the device it is powering (photo 2). Amp hour describes the duration of the battery [C batteries are also known as R14s, or C LR14 batteries, after their designation by the International Electrotechnical Commission (IEC), a prominent electrical standards body.3 This is often referred to as the “capacity” of a battery. A 5Ah battery will power a 5-amp device for one hour. In use powering a vehicle rescue tool, the average duration will be around 15 to 20 minutes. The electric motor in a vehicle rescue tool can draw up to 50 amps from the battery, shortening the working duration.
1 If you see a battery bulging or feel it getting abnormally hot, stop using it immediately, and dispose of it properly. (Photos by author.)
2 The circuit board regulates the charging and shuts the battery off if the voltage gets too low to prevent damage to the device it is powering.
Best Practices for Longer Battery Life
When you feel the power of your tool decrease, stop and change out the battery. It was a standard practice in the past when using rechargeable battering to completely drain them before charging them back up. This is not true of modern rechargeable batteries; do not drain them completely. Older ni-cads can develop “memory” through light discharge and recharge cycles, typically home appliance applications. However, power tools draw higher currents and have more random draw down patterns, which limit any battery “memory” conditioning.
“Battery memory” is a condition associated with ni-cads, not li-ion. This memory condition develops from repeated light usage patterns. The battery loses its ability to provide its fully rated capacity.
Some modern battery chargers (not all, check your manual) have a “maintenance mode,” which allows the battery to remain in the charger even when it is fully charge without hurting the battery. As an example, when you fully charge a ni-cad, it will likely need to be removed from the charger. Once removed, the battery begins to lose power—15-20% the first day, 7-10% the next day. If the ni-cad charger is so equipped, leave the battery in, allowing the charger’s conditioner to maintain the state of health of the battery. None of this past battery practice is applicable to li-ion batteries. They can be stored outside the charger because they have protection circuitry to limit self-discharge (to a degree).
Li-ion batteries that are left idle for more than 6 months could result in your expensive battery going into “Sleep Mode,” resulting in just that—a sleepy, sluggish battery. There are a few things you can do about this.4 For example, if you know that the batteries will be on a shelf for 6 months, drain them to 50% to help prevent “Sleep Mode.” If this has happened or you suspect it, before you throw the battery away, place it in a charger that has a boost or wake-up mode. Again, not all chargers have this capability; it is expensive. This charger applies a small voltage to the battery that activates the protection circuit, allowing it to become recharged. Check the suspect battery voltage; if it is below 50% and your charger does not have a boost capability, using jumper wires, connect the suspect battery to a known good battery in an effort wake the battery up. The voltage level at which the battery goes into “Sleep Mode” is different between battery manufacturers.
The estimated life of a li-ion battery is mostly between 2 to 3 years or within 300 to 500 charge cycles—that is, from the time it was fully charged to fully discharged and fully recharged. Rechargeable li-ion batteries will gradually lose their capacity to hold the charge, as they have a limited life cycle.
An unused battery’s lifespan will depend on how it is stored and other external factors already discussed. Keep in mind that extreme heat is the foremost enemy of the lifespan of a li-ion battery.
Keeping the temperature of your li-ion batteries as consistent as possible is one of the best things you can do for long life. If your charger is in a cold/hot bay or on the apparatus with temperature swings, consider moving the charger into a temperature-controlled room. Before recharging a li-ion battery, allow it to return to room temperature before placing it in the charger. This may take up to two hours, depending on environmental conditions. Too hot is above 104°F. Too cold is below 40°F. Keep in mind that charging a battery is a chemical reaction; for best results, these temperatures should be respected.5
Additional Battery Considerations
Li-ion batteries during their initial commercial use developed a history for starting fires; this has certainly decreased. These batteries have shutters that keep the terminals covered when not in use. This is something the user should check to make sure the shutters are closed and not stuck open. As a result of this history, the Department of Transportation (DOT) has developed regulation when it comes to transporting these batteries. Rule of thumb is to keep the terminals guarded with a nonconductive material and in the original container when possible.6 For more information, consult the U.S. DOT Web site.7
Reconditioning Li-Ion Batteries
Keep in mind that it is not advisable to boost a li-ion battery cell that has a voltage of 1.5 VDC and below. This is because a battery that has been undercharged for an extended period could have developed copper shunts that might cause electric shorts. These shorts are what usually cause overheating in batteries and may cause an explosion. When a battery is grossly (and repeatedly) undercharged, copper is drawn out of the electrolyte and reformed, creating a battery internal short circuit. This can cause the battery to overheat and a decline in performance.
At what point is a li-ion battery dead? The operational life of a battery for a fire service application is different than for the construction or other industry. When one of your batteries is failing to hold an average length of charge (based on a new battery) or is heating up or bulging (buildup of gas) is reason to retire a battery.
Reconditioning a battery may or may not work. Keep newer, fresher batteries as your “first-out” and keep these used batteries as training or backup. When you get new batteries, mark them with the date you place them in-service.
This process requires patience and safety precautions. You can take the battery to a professional to service it. These batteries have a history of catching on fire, so use caution.
Is it possible to overcharge?
Overcharging occurs when a battery is charged to a higher than specified or required voltage. It can be damaging to a battery and even pose a health hazard to a user. Li-ion batteries can receive a partial charge, making it impossible to overcharge. The protection circuit in these batteries prevents the flow of ions when temperatures are too high.
The battery management system in most li-ion battery packs also makes it impossible for overcharging to occur. The internal circuit monitors the charging state of a battery and cuts off the current when the limit is reached. If your li-ion battery overcharges, the charging system is most likely flawed.
How long does an unused battery last?
A battery in a tool or in storage should not be left unused over a long period. If a battery has been left unused for six months, check the battery status (as most batteries self-discharge) and charge it or discard it. If you know you are storing the battery for several weeks, don’t give it a full charge; store it at 30% to 50%, and keep it at room temperature. A fully charged li-ion battery will lose about 20% of its capacity after a year of typical storage.
Replacing the Cells in the Battery Pack
It is cost effective to rebuild/replace the individual cells in a battery pack. It takes a special tool to spot weld the electrical connection because it is not recommended that you apply a soldering iron (heat) directly on a li-ion battery. Make sure your replacement cells fit in the case and that you have the appropriate voltage and amp-hour rating.
Can You Charge Nonrechargeable Batteries?
Nonchargeable batteries are simply not designed to be charged, and attempting to do so could lead to ruptures, overheating, and even explosions. Standard batteries cannot store excess electrons because they have no means to do so; once all the stored electrons have been depleted, the battery becomes inert. By contrast, rechargeable batteries do contain chemicals that can store excess electrons, and these reservoirs are filled by the battery pack during the charging process.
Aluminum-Ion Batteries
The Australian Institute for Bioengineering and Nanotechnology has developed a new battery cell using nanotechnology to insert aluminum atoms inside tiny perforations in graphene planes. The graphene aluminum-ion battery cells are claimed to charge up to 60 times faster than the best li-ion cells and hold three time the energy of the best aluminum-based cells. There is no upper amp limit to cause spontaneous overheating, and they claim to be more sustainable and easier to recycle. Testing also shows these batteries also last three times longer than li-ion versions. First versions will probably be used in cars and cell phones.
ENDNOTES
1. http://pctlc.com/tech-tips/li-ion-battery-care.
2. https://www.quora.com/What-would-cause-a-phone-battery-to-bulge-in-the-middle.
3. https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/c-batteries-guide#:~:text=C%20batteries%20are%20also%20known,a%20prominent%20electrical%20standards%20body.
4. How to Wake a Sleeping Lithium-ion Battery- Methods, Overcharging and Cycle Life_Greenway battery | E-BIKE Battery-Custom Lithium Battery Pack (greenway-battery.com.
5. https://br.dewalt.global/en/dewalt-dna/featured-articles/best-practices-battery-life.
6. Warning | Black & Decker LDX112 User Manual | Page 7 / 40 (manualsdir.com.
7. https://www.transportation.gov/Transporting lithium batteries.
Steve Shupert has 37 years of public service. He retired from Miami Valley Fire District in Montgomery County, Ohio, and serves as a rescue team manager for Ohio Task Force #1 Federal Urban Search and Rescue. Shupert is also the chair of the FEMA Rescue Sub Group and the director of training for 501c3 Crash Course Village in Kettering, Ohio.
