First things first lets establish the fact that LIPO batteries are not inherently dangerous. It much better to thing of them as being volatile or sensitive. If they are treated correctly they will last a long time and you can keep them for years and have no issues what’s so ever.
Handling Lipos safely
In their own way Lipos are tough however there are a few key areas which are fragile as well. Most of this is common sense but here are a few pointers
- Pick up lipos by the body of the lipo and not the wires. Even though the wires can make a great handle but you can easily break a solder joint inside the lipo and that can cause all sorts of problems. Especially on the cheaper Turngiy batteries the solder joins really are fragile and it’s not good to put unnecessary pressure on them.
- Make sure the LIPO stays away from sharp objects, they have a soft casing which if burst, will almost immediately start self oxidising (burning) at around 600C
- Don’t drop a lipo, even a short distance. Denting/crushing a lipo can cause an internal short and that is a recipe for a fire or a dead cell.,
- Don’t leave a Lipo in the sun as it can over heat the lipo or damage it.
- Keep your Lipos outside of your house or car, preferably in a shed or a garage of some kind.
- Keep LiPo battery packs WELL out of reach of children.
- Do not put battery packs in pockets or bags where they can short circuit.
- Do not store your LiPo pack in extreme temperatures below 0C or above 50C.
- Always store your LiPo pack in a safe and non flammable container away from flammable objects. A LiPo Sack or metal / ceramic storage container is best.
- Always store your LiPo’s partially charged. They will maintain their performance levels over time and there’s no need to cycle them unless stored for periods longer than 3-6 months. The ideal voltage is 11.1V for 3S or 3.7V per cell.
- Ideal Storage capacity is 3.85V or 11.6
- Do not immerse the battery in water or allow the battery to get wet.
- Do not dispose or store near of in fire or heat.
- When mailing or shipping LiPo batteries, always ship them at a 30% charged state for safety reasons.
- When storing batteries for extended periods, store at a half charged state.
- To dispose of a LiPo battery, discharge it fully then place it in a bucket of salt water for one week. To dispose of, follow your municipal battery disposal guidelines.
TIP: Keep your LIPO’s in a bucket of sand, if they were to catch fire the sand will put it out.
DO NOT throw water on a burning LIPO this will do nothing could potentially be dangerous ALWAYS USE SAND
Summery Charging procedure:
- Don’t charge at more than 1C
- Always be nearby
- Always plug in balance port
- Don’t charge near combustible objects
- Have a bucket of sand nearby
- Don’t charge an overly puffed Lipo
- Don’t charge a lipo with a difference of more than 0.5V between the cells
- Make every 3rd charge a balance charge
The most likley time to have a serious issue with a LIPO is when you are charging it, aside from damaging one while in the crash of course. Modern chargers are designed to be safe but they are by no means perfect and there is always a chance, no matter how remote, that something can go wrong. With this in mind lipos should be placed in a location where if there is a problem, it will not grow into a much larger problem like catching your house or car on fire. This does not mean you need to build a bunker in your backyard to charge lipos in but some thought does need put into where lipos are charged.
Make sure you always plug in your balance lead when charging, if this is done then it is highly unlikely that there will be a problem, most new 4 button charges force to put in a balance lead. The reason that this is key is because the most likely cause of a LIPO fire while charging is when the the cell count it too high (e.g. the charger thinks it is charging a 4S when it is actual fact charging a 3S)
The best place to charge your lipos is where there is no combustible material. With that consider all the places you have at your disposal. It could be your garage, your driveway, your bathtub, in your oven … anywhere really, as long as it is not near anything flammable or combustible. Look for any combustible objects within a metre (3 feet) of where you’re charging if there is nothing than you should be okay.
Many people don’t stop at just finding a good place to charge a lipo, they also charge it in something that will contain the lipo if there was a problem. An Ammo box is a favourite in the hobby however something as simple as a commercial Lipo sack. I consider this an added safety step that is not required but is never a bad idea, especially if your location is not perfect. For example if you choose to charge on the kitchen counter, a lipo sack is cheap insurance in case there is a problem. However do not have multiple batteries in the same sack as this can set the others off can cause a chain reaction.
Last, but definitely not least, is the requirement that you be nearby whenever charging a lipo. Obviously don’t pull up a chair and watch the charger for the duration but you should be in ear shot and preferably line of site of the charger the duration of the charge. If you need to leave the charger, simply stop the charge and place the battery somewhere safe while you are away. Then you can start the charge again when you return. If you log the mAh then just write down the amount at the time when you stop the charge and then add the final amount to it for a total.
When transporting lipos do a visual inspection before departure and a visual inspection after arrival. Follow the same general rules as storage. Always been close by to your lipos while travelling just in case something happens. Also avoid taking the Lipos on an underground subway system or Airplane as much as possible as there are obvious inherent risks taking a Lipo somewhere where it cannot be quickly vented should the worse happen.
The 80% rule
This is a rule used to protect Drone LIPOs from over discharging. If you want to know the maximum sustainable capacity of a LIPO battery multiply the mah on the outside by 0.8 (80%).
e.g. 1300mah x 0.8 = 1040.
How do you know your lipo is bad?
This question can sometimes be very easy to answer and other times not. If your pack is folded in half or punctured from a drone crash then it is most definitely bad. But if it looks physically fine and just doesn’t perform well, the question is not as simple to answer. First lets cover what makes a lipo bad in terms of physical conditions and then we will cover other reasons a lipo should be retired.
Anytime a lipo has been physically damaged there is a very good chance it damaged beyond use. If any cell in the pack is punctured, crushed or badly swollen, the pack should be considered damaged beyond use. If any of the wires become disconnected from the pack then most people should discontinue to use the pack. Often times these type of packs can be fixed but the average user will not have the skills needed for the repair and in that case the pack should be considered damaged beyond use.
For packs that look fine but shows signs of other problems? In all honesty multirotors tend to over discharge LIPOs and so if most LIPOs (even high end ones don’t tend to last a very long time. On average a lipo used about once a week for flying will last 6 months if treated well. You can tell the health a lipo by measuring it’s internal reisitence the higher the sicker the LIPO.
These are often great uses for old batteries that are just tired and not damaged in any way. I often use my old 3S batteries for ground stations and goggles. They can also be good on planes which don’t discharge so fast.