Precautions for cordless power tool batteries?

[leecea]

I searched and found a bunch of threads that mostly discussed the best tools or cordless versus corded but nothing specific about precautions people take with cordless tool batteries.

I just read an account of a boat that was lost when their cordless drill battery suffered damage from wave action and burnt the boat. I assume being jostled around or repeatedly banging against something was the issue.

I have read about fire resistant containers but the size of container needed to contain the fire from just one large cordless battery is surprising, and I keep more than one onboard. I have no place to put them, even if cost wasn't an issue.

I wonder about impact protection like a layer of camping pad foam to prevent impact damage. But I don't know if impact is the issue or just repeated shaking due to boat movement.

Does anyone have any insights into this or do they take precautions in how they store tool batteries?

[Iron E]

I would think the biggest dangers occur during charging and from knock off batteries.
Our tools are stored in Pelican's with specific cut-outs designated for tools/batteries/etc. While this keeps them safer, it's most important for me to have well organized tools... everything in its place.

[NorthCoastJoe]

I have been using battery powered tools for over 25 years and never had a problem with batteries. The batteries we used had a hard life. Being tossed in a pile of tools or banging around in a truck bed. I cannot see how being on a boat can be worse than how a contractor or homeowner beats them up.

On board I keep my batteries in a locker where they are not likely to be banged around. In the back of my mind I think about that article but that was a few years back. Hopefully the BMS is better now for tool batteries.

My best hope for failsafe storage would be a steel amo can and welding glove to throw it overboard if it got hot. Oh also keep it in a location that would allow for easy grab and throw if needed.

I would love to hear what others think.

[dannc]

Seems like most of the tool/bike battery fires I have read about, or seen in videos, were when the battery was being charged. My NIMH battery started smoking and sure seemed like it was about to catch fire when I saw what was happening and tossed it outside. The battery was being charged after drilling 3-5 holes in thin, soft plastic. The battery was not dropped or abused and had an easy life before it overheated, melted the case, and was smoking...

I charge all of my batteries where I can watch them, and if they do catch fire, won't burn down the house. On a boat I would do the same. Storage would be in a padded ammo can or some such.

[Jammer]

Interesting question. I look forward to the replies.

I believe that pack construction and underlying cell quality have a significant role in the safety of lithium packs for power tools. A properly designed and manufactured cell should not enter thermal runaway as a result of impact. A properly designed pack should cushion the cells.

I use Milwaukee power tools both at my stick house and aboard. They are widely used by contractors and the packs get dropped all the time. Other than a recall over five years ago on a particular pack size, their track record is pretty good. I also have lithium batteries in other equipment -- my handheld VHF, the "big" flashlight, my phone, and my computer.

The only special precaution I've been taking is to secure the batteries and tools so that they stay in one place and don't bang into stuff as the boat moves.

[Statistical]

1) Don't buy off brand batteries made by companies you have never heard of. Yes batteries are expensive but saving $50 to burn down your boat.

2) Don't charge unattended, don't charge while underway or right before going underway. Batteries are most vulnerable to failure during and right after charging.

3) Don't leave batteries in tools.

4) Secure the batteries from movement and being crushed. A foam cutout inside a metal can works but there are plenty of other solutions.

If you do that is the risk exactly zero? No but given the sheer number of portable batteries out there but on boats and off and the very low rate of fires it is minimal.

[leecea]

I just saw a promotional video of an Elide Fire Ball putting out a battery fire. I wonder if that's true IRL? Perhaps keep one in the locker with the batteries?

[Iron E]

Originally Posted by NorthCoastJoe

I have been using battery powered tools for over 25 years and never had a problem with batteries. The batteries we used had a hard life. Being tossed in a pile of tools or banging around in a truck bed. I cannot see how being on a boat can be worse than how a contractor or homeowner beats them up.

On board I keep my batteries in a locker where they are not likely to be banged around. In the back of my mind I think about that article but that was a few years back. Hopefully the BMS is better now for tool batteries.

My best hope for failsafe storage would be a steel amo can and welding glove to throw it overboard if it got hot. Oh also keep it in a location that would allow for easy grab and throw if needed.

I would love to hear what others think.

I'm a contractor and have never thrown my tools into a pile.

Regarding your ammo box idea, steel ammo boxes rust quickly in the salt environment. I had a couple in a dock box that didn't take very long to show they weren't meant for the sea.

[sailorboy1]

Given the BILLIONS of rechargeable batteries in use..................this topic seems massive paranoia

[Foswick]

Lithium batteries ignite because of a condition called "thermal runaway". A cell heats up and begins to decompose, releasing flammable gases. These gases create pressure which further compromise the cell, create more internal short circuiting, accelerate discharge, create more heat, resulting in more decomposition, etc. Eventually, the gases ignite and neighboring cells are further involved. This can happen very quickly.

As to original cause, it has been stated that the danger is primarily during charging. That is only sort of true.

There are a few causes: overcharging, overdischarging (short circuit usually), manufacturing defects, physical damage, or externally-applied heat (like being near a heat source). Often, the cause is a combination of the above.

Charging is a "dangerous" part of the cycle because chargers are usually designed to charge the battery as rapidly as possible. It will not normally cause thermal runaway, itself, but if the battery is otherwise compromised and/or heat is not allowed to dissipate, rapidly charging can be the last straw that starts the chain reaction.

But, this can happen during use too. If you use your tools at maximum load for an extended period, the batteries WILL heat up and, if the batteries have a defect or damage, you run the same risk as when charging. Charging is mostly considered more dangerous because it is usually unattended.

The bottom line, here, is that heat is the enemy of lithium batteries. So, whatever you do, you need to allow heat to dissipate.

I design battery packs for electric vehicles. These are typically higher voltage than for most power tools, and they are high-power (compared to power tools). The key design considerations for an enclosure think first about heat dissipation, but also just as importantly - how will the ignited gases be managed.

That is, we assume that the battery pack is (for whatever reason) going to ignite. The key is to direct the expanding flaming gases somewhere they will not do serious damage. In the case of these enclosures, the solution is often to enclose them in an alluminum alloy box with a ventilation hole pointed at the ground.

This gives rapidly expanding gases a path of least resistance that is relatively harmless. It is possible for a cell to explode so violently that the entire case is compromised, but the case is designed to survive this with only deformation and not shrapnel.

The problem on a boat is that there is no good direction to expel these flaming gases.

I apologize for the long post with ultimately no answer. This is just a topic near-and-dear to me, so I wanted to explain some of the considerations.

I would recommend watching videos of similar batteries catching fire. This will give you an idea of the kinds of forces involved and may help you come up with a solution you are comfortable with.

Me: I would consider myself an expert on lithium batteries. Even though I have a healthy respect for the dangers of lithium batteries, I honestly don't worry about it when talking about most power tools, cell phones, etc. I just don't abuse them, don't allow them to get unnecessarily hot (like I don't charge my phone under my pillow), and I don't use sketchy batteries. And, when leaving a battery unattended, I give some thought about what would happen if it ignited. Other than that, I don't worry about it.

Now, if I were to put a large battery on board, like a lithium house battery ... that's a different story.

[ohgary]

Originally Posted by NorthCoastJoe

I have been using battery powered tools for over 25 years and never had a problem with batteries. .

I think the big difference is most of the 25 years the batteries were NiCads,
Lithium-ion have only really hit the mainstream tool market in the last 5-7 years. Also note these are not the safer lithium ion phosphate but old school cell phone lithium-ion that tend to act badly when mistreated.

Having had a cell phone or two burst into flames when a battery was damaged care needs to be taken with all lithium-ion batteries.

Proper charging and storage area must.

[dannc]

Originally Posted by sailorboy1

Given the BILLIONS of rechargeable batteries in use..................this topic seems massive paranoia

When you start smelling a funny smell, start looking for the source of that funny smell, and find a battery generating quite a bit of smoke with a melting battery case, and realize that battery is about to catch fire underneath a wall cabinet, you quickly have a Come To Jesus moment about battery tools. If I had not been home, I would have lost my house to a Dewalt NiMH battery failure. A battery that had been lightly used and not abused. I went a decade or so without using cordless tool as a result. I have had to use, and thus buy, new cordless tools and batteries but I learned my lesson and do not trust the batteries even though I buy top brands and do not abuse the batteries.

Once burned, twice shy.....

[Jammer]

Originally Posted by Foswick

Now, if I were to put a large battery on board, like a lithium house battery ... that's a different story.

Well, those are (typically) lithium iron phosphate chemistry, which is inherently safer. Though I guess it's starting to show up in some of the lower performance EV packs also so perhaps you know more than most people about it.

[Jammer]

Originally Posted by Foswick

Charging is a "dangerous" part of the cycle because chargers are usually designed to charge the battery as rapidly as possible. It will not normally cause thermal runaway, itself, but if the battery is otherwise compromised and/or heat is not allowed to dissipate, rapidly charging can be the last straw that starts the chain reaction.

But, this can happen during use too. If you use your tools at maximum load for an extended period, the batteries WILL heat up and, if the batteries have a defect or damage, you run the same risk as when charging. Charging is mostly considered more dangerous because it is usually unattended.

::shrug:: most modern power tools and chargers have thermal supervision for the packs. Safer, and allows the charge/discharge rate to be pushed right to the edge.


This is why I can have a circular saw that will cut 2x4s on a 3-cell 18650 pack.

[Foswick]

I guess this is a good place to talk about what to do with a burning lithium battery.

It is important to note that most fire extinguishers that you are likely to have on board will have little effect. The best they will do is help save surrounding materials. They will not extinguish a lithium battery in thermal runaway. The battery fire is not "out" until all cells are completely discharged and the battery cannot restart the thermal runaway condition.

The best thing you can do is submerg the battery and keep it submerged. This seems counterintuitive, but it accelerates discharge but does not allow uncontrolled thermal runaway.