Lithium-ion battery safety
Many of the flashlights discussed/reviewed/modded in Budget Light Forum (BLF) use Lithium-ion rechargeable batteries. Use of Lithium-ion batteries does introduce some risks, and requires more precautions than alkaline batteries. But like any tool, when used properly, the risks can be managed and reduced.
This post outlines safety precautions for users that are new to Lithium-ion batteries. It does not attempt to provide a complete tutorial on Lithium-ion batteries nor the technical reasons for Li-ion dangers. It is intended as a starting point.
There will always be some disagreement about safety rules. Some of these safety rules may not apply to those of you who were lab assistants for Dr. Goodenough, but hopefully they are appropriate for newer users. You have to be aware of your knowledge and experience level.
Lithium-ion rechargeable batteries can be safely used when used properly.
Lithium-ion rechargeable batteries can be dangerous when improperly used.
- Buy quality batteries.
- Saving a few pennies on what may be questionable batteries is not worth it.
- Some cheaper batteries may be counterfeit or may be recycled/reclaimed.
- Experienced users do harvest batteries from battery packs.
- Wait until you have more experience with Li-ion before attempting.
- Battery reviews.
- Buy a quality battery charger.
- This is another place not to go the cheap route.
- An under-performing cell can be safe in a good charger but cell is safe in a poor charger. (SawMaster)
- Read the reviews. Buy a brand name with a good review.
- Things to consider:
- Overcharge protection.
- Reverse polarity protection.
- Independent channels so you can charge different battery types or discharge levels at the same time.
- User interface that gives you what you like. Indicator lights vs. LCD display.
- The charger should charge at 4.2V +/- 0.05V, but the battery may come off at a different voltage.
- Charger reviews.
- This is another place not to go the cheap route.
- Buy and use a multi-meter.
- Many like Digital Multi-Meters (DMM).
- Learn to check your Lithium-ion batteries voltage.
- Note: Not everyone agrees you need a DMM, but many people do recommend them.
- Charging / Discharging
- Batteries can be charged at: 0*C - 45*C (32*F - 113*F)
- Batteries can be discharged at: -20*C - 60*C (-4*F - 140*F)
- Don’t over charge your batteries.
- Max voltage should be 4.2V.
- Only charging to 4.1V may give you more recharge cycles.
- A good battery charger helps prevent over charging.
- Battery chargers may charge +/- 0.05V and still be in tolerance.
- After charging check your battery's voltage with your DMM after a short (~5 min) rest.
- Don’t over discharge your batteries.
- Many people choose to recharge when their batteries reach 3.5- 3.6V
- Batteries are depleted when they reaches 2.7-3.0v. Recharge.
- Batteries begin to suffer damage if discharged to 2.5 volts.
- Batteries should be discarded if they discharge to 2.0 volts.
- Don’t charge your batteries when temperature is below freezing. (0*C / 32*F)
- Don’t let your batteries get too hot.
- If you are going to store your flashlight in your car in the summer, primary batteries are recommended over Lithium-Ion rechargeable batteries.
- High temperatures degrade cells faster, but as long as the temp is less than 60*C (140*F) there is probably not a safety issue.
- For long term storage (months) it is best to store at 40-50% capacity. (3.77-3.87V)
- When not in a flashlight, batteries should always be in a protective carrier.
- This protects from shorting and physical damage.
- Never carry loose batteries in your pocket or bag.
- https://www.youtube.com/watch?v=k1LjSuq0rk8 <==
- Don’t use batteries with physical damage.
- Protected batteries are generally safer than unprotected batteries.
- Protected batteries have a circuit built in which protects from over-charging and over-discharging.
- Protection circuits increase the length and width of the battery slightly. Protected batteries won’t fit in all flashlights. Know your flashlight.
- Some flashlights have low voltage protection and will cut off at low voltage. Know your flashlight.
- Some high draw flashlights will trip the protection circuit in a protected battery and require unprotected batteries. Know your flashlight.
- Multi-battery flashlights have higher risk than single-battery flashlights.
- If just starting out you may want to limit yourself to single-battery flash lights.
- When using multi-battery lights, to reduce the chance of uneven discharge between batteries, it is important that all the batteries:
- are the same type,
- are the same manufacture,
- have the same capacity (Ah) ,
- are charged to the same voltage.
- You may want to mark the batteries so you can use the same set together over time.
- Charge batteries in a location where there are not flammable materials.
- Put your charger on a counter, not on your sofa.
- Never leave charging batteries unattended.
- Check them periodically to make sure they are not getting hot. Warm is ok.
- Note: there are different opinions on how often you need to check.
- Damaged batteries can cause fires!
"Abuse conditions such as overcharge, over-discharge and internal short-circuits can lead to battery temperatures far beyond the manufacturer ratings. At a critical temperature, a chain of exothermic reactions can be triggered. The reactions lead to a further temperature increase, which in turn accelerates the reaction kinetics. This catastrophic self-accelerated degradation of the Li-ion battery is called thermal runaway.2"
Royal Society of Chemistry http://pubs.rsc.org/en/content/articlehtml/2013/ra/c3ra45748f
- In the event of a Lithium-ion battery fire seek medical attention immediately.
- Burning or venting Lithium-ion batteries produce hydrogen fluoride.Symptoms from hydrogen fluoride injuries are not immediately apparent.
- "the battery can release a significant amount of burnable and (if inhaled in high concentrations) toxic gas.4"
- Royal Society of Chemistry http://pubs.rsc.org/en/content/articlehtml/2013/ra/c3ra45748f
- Seek medical attention immediately. Don’t wait until you experience symptoms.
- There are mixed opinions on using magnets to create button-tops from flat-top batteries.
- Don’t get batteries wet.
- Don’t burn batteries.
- Dispose of batteries properly.
- Keep batteries out of the reach of children and pets.
- When swallowed, these small batteries get stuck in the esophagus (throat). The saliva triggers an electric current which causes a chemical reaction that can severely burn the esophagus in as little as two hours.
- A serious issue for children and pets.
Primarily an issue with button batteries, but potential exists with all batteries.
Further reading about Lithium-Ion Batteries:
- A Litany for Beginners: http://budgetlightforum.com/comment/904373#comment-904373
- Search post for “safety” - http://budgetlightforum.com/node/26665
- Li-ion Battery Safety and Shopping Guide - http://budgetlightforum.com/node/16699
- Li-ion Safety Concerns - http://batteryuniversity.com/learn/article/lithium_ion_safety_concerns
- Lithium based batteries - http://batteryuniversity.com/learn/article/lithium_based_batteries
- Battery Chemistry - https://batterybro.com/blogs/18650-wholesale-battery-reviews/18880255-ba...
- Types of Lithium Ion - http://batteryuniversity.com/learn/article/types_of_lithium_ion
Please let me know what I've missed or what I've gotten wrong.
Battery technology changes rapidly. Please check the edit date below.