LI-po battery safety

I'm sure you guys have heard this already but in case you haven't Lipo, or LI-Ion batteries have a very high power density which makes them small and powerful, but they have a nasty habit of catching fire when being recharged, as a model airplane flyer we have them catch fire more often that average as physical damage is one thing that may cause them to go off, so I have learned the hard way, they burn like a magnesieum flare, really hot. It's prudent to charge your batteries in a fireproof container of some kind, ceramic flower pots and corning ware comes to mind for smaller batteries, airplane hobby shops even sell some kind of fire proof plastic bag. when travelling, the bathtub if it's an old fashioned ceramic one is a good place.
Just don't trust the things, even the ones in your cell phone and your laptop.

There have some very notable fires caused by Lithium batteries. A dive scooter in Australia burned, and took out a SUV, and the dive gear of several divers. Another scooter fire in Florida nearly burned down a motel. There have been some dive lights burn as well. FWIW, it would take a pretty big fireproof container to contain a scooter fire. Even dive light batteries are big, compared to RC planes, and cellphones.

Thanks.

Yeah something the size of a scooter would I assume pretty much have to be outside, that is a BIG battery, your not putting that thing in the wifes ceramic cookware. For some reason we don't "balance" charge or monitor battery temp to shut down the charger before a fire. Both are done with the model thing, and some of the model batteries are pretty big, have to be to hover ten lbs of helicopter.
I only brought this up in light of a recent occurence, and the assumption of new equipment being bought being this time of year and all.
It would suck pretty bad to lose your house to a battery fire.

Hence the reason I bought a NiMH can light, even though they're getting hard to find. It seems even SS is abandoning nickel batteries and going only Lithium in their scooters. Scares the bejeebers out of me because I'm lazy and like to plug in my batts and walk away.

Look for lithium iron phosphate batteries. they give great power to weight ratio but don't burn. Even at max charge in a 600 deg environment.

Quote:

---

Originally Posted by a64pilot

Yeah something the size of a scooter would I assume pretty much have to be outside...

---

For me, that might even be worse. I might contain a house fire, but if I set the woods on fire, several houses would go up along with mine :-)

Quote:

---

Originally Posted by FW

For me, that might even be worse. I might contain a house fire, but if I set the woods on fire, several houses would go up along with mine :-)

---

I like all my stuff in one room. So when it goes, it goes big. A house fire? ha. When mine goes it will take out half the block at least. The family fire plan is to run like hell as fast and as far away as possible. Some family's may plan to meet in the yard, or across the street in the neighbor's yard, but my kids have practiced the run to the hospital three blocks away where the plan is to meet in front of the emergency room entrance! Last one there is a rotten egg! The neighbors have been warned too.

skip

Quote:

---

Originally Posted by deepairmike

Look for lithium iron phosphate batteries. they give great power to weight ratio but don't burn. Even at max charge in a 600 deg environment.

---

I've heard of those, but haven't seen them yet. They are the cats ass for bush planes up in AK, work when it's really cold, are safe and light, from what I hear, but I haven't seen them, I gues they aren't common yet?

Just charge you Lithium Ion batteries with your cave filled, double burst disked LP cylinders. That way the exploding tank will blow the fire out (just like a birthday candle, right).

Attachment 5361
Might be whistling in the dark but I built this all metal battery charging bench for our cave diver rental after reading about some of the battery fires.
John Ploegert

I like the bench idea John...thanks for sharing that.

Quote:

---

Originally Posted by kwinter

Hence the reason I bought a NiMH can light, even though they're getting hard to find. It seems even SS is abandoning nickel batteries and going only Lithium in their scooters. Scares the bejeebers out of me because I'm lazy and like to plug in my batts and walk away.

---

NiMh can cause fire as well. Be careful with those. I believe mentioned "motel fire" case had NiMh batts. Unfortunately I have had fire in my house twice during the last 2 yrs, once w/NiMh and second w/Lithium. The second one was 10 times more "entertaining". I have smoke detectors now in gear room, in every fiberglass container where I store them and in a back of my truck too. $9 each - they saved my rear end in the last incident. I charge them in a locked enamel coated pot (again w/smoke detector). Li-Ion so far are still the best by cost-power-dimensions criteria IMHO.

Jill Heinerth posted this video a while back. Her design for an battery charging box/blast shield.

http://www.youtube.com/watch?v=lsqFm4AdpCQ

Quote:

---

Originally Posted by a64pilot

I've heard of those, but haven't seen them yet. They are the cats ass for bush planes up in AK, work when it's really cold, are safe and light, from what I hear, but I haven't seen them, I gues they aren't common yet?

---

I tried putting up my cats butt but, he screamed like hell; at first. There were, however, no fires during the recharging process.

Quote:

---

Originally Posted by John Ploegert

Might be whistling in the dark but I built this all metal battery charging bench for our cave diver rental after reading about some of the battery fires.
John Ploegert

---

Nice!

Quote:

---

Originally Posted by ARY

NiMh can cause fire as well. Be careful with those. I believe mentioned "motel fire" case had NiMh batts. Unfortunately I have had fire in my house twice during the last 2 yrs, once w/NiMh and second w/Lithium. The second one was 10 times more "entertaining". I have smoke detectors now in gear room, in every fiberglass container where I store them and in a back of my truck too. $9 each - they saved my rear end in the last incident. I charge them in a locked enamel coated pot (again w/smoke detector). Li-Ion so far are still the best by cost-power-dimensions criteria IMHO.

---

Nope, the hotel batteries were lithium.

Andrew - I'm assuming your replacement scooter also has lithium batts. I'm interested to know what you do differently now after the incident. Any lessons to learn?

They get charged outdoors!

Quote:

---

Originally Posted by kwinter

Any lessons to learn?

---

Sleep in pajamas to avoid having to bail out of the room bare-arsed and then climb back through the window into a burning hotel room to find something to wear? :)

Quote:

---

Originally Posted by MORGAN

Sleep in pajamas to avoid having to bail out of the room bare-arsed and then climb back through the window into a burning hotel room to find something to wear? :)

---

I'm sure he's wondering when the statute of limitations runs out on that one.

That was a scary story. My rechargeable batteries are all SLA and NIMH, but Andrew's story made me think hard about how I store and charge them.

Funny, I just dropped a lipo light pack while walking the battery upstairs to the fireproof safe I store it in. It hit the ground roughly parallel to the side, and on carpet, but it was still enough force to break the shrinkwrap right in the middle, between the two banks of cells.

Looks like I'll be holding her together with duct tape, and probably seeing if Light Monkey can re-shrink wrap it for me while I pay them to replace a cord on another primary that I managed to pull apart after plenty of torture and abuse...

Lipo scare me just a little, hence the fireproof safe. I'm not sure it would contain a large fire, but I think it will help to slow down the speed at which it destroys all of my possessions... and the safe gets left away from walls or other flammable things, too. I also keep a fire extinguisher nearby, I've even left one at my favourite place to stay in cave country just in case! I like runawaylobster's place too much, figured the $20 fire extinguisher and the $20 fireproof safe were well worth it. It's also a convenient way to carry batteries and chargers, though a bit on the heavy side...

Quote:

---

Originally Posted by JahJahwarrior

Funny, I just dropped a lipo light pack while walking the battery upstairs to the fireproof safe I store it in. It hit the ground roughly parallel to the side, and on carpet, but it was still enough force to break the shrinkwrap right in the middle, between the two banks of cells.

Looks like I'll be holding her together with duct tape, and probably seeing if Light Monkey can re-shrink wrap it for me while I pay them to replace a cord on another primary that I managed to pull apart after plenty of torture and abuse...

Lipo scare me just a little, hence the fireproof safe. I'm not sure it would contain a large fire, but I think it will help to slow down the speed at which it destroys all of my possessions... and the safe gets left away from walls or other flammable things, too. I also keep a fire extinguisher nearby, I've even left one at my favourite place to stay in cave country just in case! I like runawaylobster's place too much, figured the $20 fire extinguisher and the $20 fireproof safe were well worth it. It's also a convenient way to carry batteries and chargers, though a bit on the heavy side...

---

Lipo should scare you.

Lithium batteries increase in volume with respect to state of charge, meaning like a hot dog, they "plump" when you cook 'em.

That however can eventually lead to an internal cell short. No cell protection, PC boards, battery management circuits, fuses etc are of any use if a cell shorts internally.

The swelling of Lipo Cells is exacerbated by over discharge and over charge, and this is usually a direct result of poor cell balancing. Balancing is a complex matter, and the commercial solutions are OK for small capacity cells, and IMO, completely inadequate for larger cells. If cells are not effectively balanced the physical stresses imposed by over discharge and over charge are not trivial.

Cylindrical cells are far more physically robust than a mylar "bag" typical of Li-Po's. Combine good quality graded cells with a topology that provides passive cells balancing and reliability and safety is increased.

In addition 18650 cylindrical cells are produced in the billions annually, compared to relatively few high capacity Li-Po cells. The high production volume lends itself to good SPC QC techniques that simply cannot be realized with low volume, high capacity Li-Po's

The reality is the only benefit for diving applications for using small numbers of High Capacity Li-Po cells is ease of battery pack fabrication. The specific energy and energy density of 18650 cylindrical cells greatly exceeds what is possible with Li-Po's

The 2011 TBM is now available and it makes clear, to those who know how to interpret the results, that good quality 18650's combined with good pack design are very hard to beat.

Tobin

Quote:

---

Originally Posted by decostanza

I like the bench idea John...thanks for sharing that.

---

I wanted a charging bench to support up to 4 cavedivers. Hector suggested starting with 3 tier tool cart from Harbor Freight. My total cost was about $150; $70 for the cart and most of the rest for electrical components (15 gfci protected outlets). I'm a packrat and already had the sheet metal and fasteners.
John Ploegert

Don't you just need one GFCI outlet at the start of the chain, or 1 per circuit? And a nice addition would be a timer to stop charging and reduce the risk of fire due to overchargin.

Quote:

---

Originally Posted by kwinter

Don't you just need one GFCI outlet at the start of the chain, or 1 per circuit? And a nice addition would be a timer to stop charging and reduce the risk of fire due to overchargin.

---

If you are hanging you hat on GFI's and external timers to prevent overcharging you are in deep #@#^#@ already.

Tobin

I believe we have to rely on the manufacturers to begin supplying balance chargers to independately monitor and charge each cell, they way they are being charged now is less expensive to do, but not really optimum. A balance charger is no that expensive really, less than say a mask or a reel for example.
Even if we get decent chargers, I think we need to treat these batteries like they were a can of gas or something similar.
I only know a little about these batteries from model aircraft, if I hadn't played with those things in the past, I wouldn't know anything about them at all, so I think it's perfectly understandable and logical for cave divers on an average to have little understanding about them, we all drive cars, but how many of us actually know exactly what is going on inside of the automatic transmission?

Quote:

---

Originally Posted by TobinGeorge

If you are hanging you hat on GFI's and external timers to prevent overcharging you are in deep #@#^#@ already.

Tobin

---

Well don't leave it hanging there, Tobin. What is the average Joe supposed to do to prevent overcharging other than follow manufacturer's recommendations for charging time? Take the pack apart and check each individual cell on a meter every 10 minutes? How do we make it safe and at least somewhat convenient at the same time? Having a timer to control each outlet seemed like a reasonable approach, and was ok when I discussed the idea with Corey at LM.

Quote:

---

Originally Posted by kwinter

Well don't leave it hanging there, Tobin. What is the average Joe supposed to do to prevent overcharging other than follow manufacturer's recommendations for charging time? Take the pack apart and check each individual cell on a meter every 10 minutes? How do we make it safe and at least somewhat convenient at the same time? Having a timer to control each outlet seemed like a reasonable approach, and was ok when I discussed the idea with Corey at LM.

---

1) Good quality packs. Any Lithium-Ion (Li-Po is just a type of Lithium-Ion) pack will have built into the pack cutoff circuits to prevent overcharging. This transparent to the user.

2) Good quality chargers. Good quality chargers will have multiple means of charge termination including voltage and time.

For an external timer to have any effect you'd need multiple failures in both the battery electronics and the charger. In addition a "dumb" timer will either under charge the battery, i.e. too little time, or overcharge the battery, too much time.

GFI? Really? Pretty much any charger will isolate the output from ground. GFI will do nothing to prevent overcharging.

Tobin

I've been using LiPo packs for years now in my R/C airplanes and helicopters.. (from small 2s receiver packs to 16,000 mAh 120A Discharge packs in the helis)
About 8 months ago I purchased a 35w HID that is Lipo powered and I was surprised at the charging setup. No balance connector and simple trickle type charging.
After less than 20 uses I'm not all that surprised that my burn time on the pack has dwindled to about 20 minutes right after being removed from the charger, and not at all after sitting for a while.
The replacement pack I am putting together is balanced and will be charged properly. Not to mention it will only take about an hour to charge using the right charger for this battery chemistry. (Of which I have many)
Hopefully those putting out dive related products using Lipo power lights (etc) will start utilizing the correct charging schema.
Lipo chargers have come down in price in recent years and the safety margins have gone up significantly.
Before we had chargers specifically designed for charging lipo packs, I had one close friend burn his home down and know of at least 4 others who had similar accidents..
In recent years I've heard of none.. That being said, I never charge Lipo's unattended and I always use flame resistant bags.

While I doubt any of these came close to the fireball Andrew got to deal with when his scooter batteries blew, it'll give those not familiar with lipo fires an idea of what these batteries are capable of..
http://www.youtube.com/watch?v=z3o_2mwRPdw
http://www.youtube.com/watch?v=YCWdnjLqVWw

Tobin is right.. LiPo's should scare you, but like many things in this sport, they are as dangerous as you make them..

My next scoot will definitely be LiPo powered.. In a few years I imagine the vast majority of dive products requiring a fair amount of juice will utilize LiPo, Li-Ion or LiFePO4 cells.

Quote:

---

Originally Posted by kwinter

What is the average Joe supposed to do to prevent overcharging other than follow manufacturer's recommendations for charging time? Take the pack apart and check each individual cell on a meter every 10 minutes? How do we make it safe and at least somewhat convenient at the same time? Having a timer to control each outlet seemed like a reasonable approach, and was ok when I discussed the idea with Corey at LM.

---

Demand that the manufacturers include balance plugs and a proper charger. Then the chargers can properly charge the cells and cut off the charge when the correct balance and voltage has been achieved.
I'd hazard a guess that they have not done so yet because they are concerned that someone might mistakenly set the charge rate above what the battery is spec'd for and possibly blow it..
LiPo's have taken over in the remote control car, airplane and helicopter market, with millions of them in service, charged by kids and adults alike..
I think technically oriented (and other) divers would have no problem safely charging these batteries given simple instructions.

Quote:

---

Originally Posted by Texas Torpedo

Demand that the manufacturers include balance plugs and a proper charger. Then the chargers can properly charge the cells and cut off the charge when the correct balance and voltage has been achieved.

---

Proper active balancing of large capacity packs is extremely hard to do, and most if not all of the "canned" solutions are ineffective.

We use an entirely different approach using passive balancing that keeps the cells from becoming unbalanced vs trying to correct an out of balance condition.

Quote:

---

Originally Posted by Texas Torpedo

I'd hazard a guess that they have not done so yet because they are concerned that someone might mistakenly set the charge rate above what the battery is spec'd for and possibly blow it..

---

?? Not too difficult to "fix" the charge current on most chargers.

Quote:

---

Originally Posted by Texas Torpedo

LiPo's have taken over in the remote control car, airplane and helicopter market, with millions of them in service, charged by kids and adults alike..

---

And this a the source of many of the failures, abuse by RC hobbyists of Li-Po battery packs.

Quote:

---

Originally Posted by Texas Torpedo

I think technically oriented (and other) divers would have no problem safely charging these batteries given simple instructions.

---

You don't really understand this market very well......

Tobin

Tobin, what's your personal procedure when you charge your scooter batteries? In the house? In the garage? In a shed? Do you watch them all the time? Do you just leave them in the open or in a fireproof box?

Quote:

---

Originally Posted by Atom

Tobin, what's your personal procedure when you charge your scooter batteries? In the house? In the garage? In a shed? Do you watch them all the time? Do you just leave them in the open or in a fireproof box?

---

During the first few cycles of newly assembled pack we take reasonable precautions, mostly because we need to verify both the on board electronics in the battery perform as expected, and that the charger performs as expected.

After that I still recommend that our scooter batteries and *ANY OTHER* high capacity rechargeable battery be charged in an open free from combustibles.

If you short circuit a car battery (Pb wet cell) it too can catch fire and explode, all batteries need be treated with respect.

Tobin

Quote:

---

Originally Posted by TobinGeorge

Proper active balancing of large capacity packs is extremely hard to do, and most if not all of the "canned" solutions are ineffective.
We use an entirely different approach using passive balancing that keeps the cells from becoming unbalanced vs trying to correct an out of balance condition.

---

That's understandable with the size packs you are producing for scooters, but not for the packs in lights, etc. My focus here is on the smaller stuff.. Say, under 10S 10k mAh..

Quote:

---

?? Not too difficult to "fix" the charge current on most chargers.

---

What are most chargers? The majority of chargers I own and see (at least in the RC market) are highly variable in both chemistry and charge rate due to the fact that we deal with so many different battery sizes and types.
I have no doubt that a company offering equipment powered by LiPo packs could put together a balancing charger with a fixed rate, however I'd just assume use my own and not have multiple chargers for different battery packs.
Actually, I'd be happy to see them with balance plugs for starters for the option.

Quote:

---

And this a the source of many of the failures, abuse by RC hobbyists of Li-Po battery packs.

---

Considering there are more LiPo packs in use by people in this hobby than any other that I am aware of by a large margin, wouldn't that make sense? If you call abuse crashing a plane / heli and reputing a pack, so be it, however accidents due to improper charging methods are far less now that the right chargers are available and the industry started educating the consumers. The majority of fires you see on Youtube (etc) are all intentionally created, not real accidents.

Quote:

---

You don't really understand this market very well......
Tobin

---

Well Tobin, please explain it to me. As I see it, we have companies starting to utilize LiPo's but not the ideal chargers to go with them.
Again, I'm not talking about scooter batteries.

David

Quote:

---

Originally Posted by Texas Torpedo

That's understandable with the size packs you are producing for scooters, but not for the packs in lights, etc. My focus here is on the smaller stuff.. Say, under 10S 10k mAh..

---

Do you have idea how much power must be switched and dissipated for 10ah pack?

Quote:

---

Originally Posted by Texas Torpedo

What are most chargers? The majority of chargers I own and see (at least in the RC market) are highly variable in both chemistry and charge rate due to the fact that we deal with so many different battery sizes and types.

---

Using "Universal" Hobbyist chargers that claim to be able to charge 3-4 different chemistry's and multiple different cell counts and batteries of widely variant capacity is just begging for a problem IMO.

Quote:

---

Originally Posted by Texas Torpedo

I have no doubt that a company offering equipment powered by LiPo packs could put together a balancing charger with a fixed rate, however I'd just assume use my own and not have multiple chargers for different battery packs.
Actually, I'd be happy to see them with balance plugs for starters for the option.

---

Great idea really. Now a battery will need 3-4-5 more leads. Of course leads on can light batteries are never a problem in the real world. Connectors never get pulled off, broken, corroded, etc.

Balancing Circuits, if used, and properly sized, need to be built into the battery pack. Selling a battery that is dependent on some external balancing circuit is again begging for a problem. What happens when Joe Diver decides to use some other charger 'cuz he forgot to bring his, dropped his overboard, ass ummed all chargers are the same etc. etc. etc.?

Quote:

---

Originally Posted by Texas Torpedo

Considering there are more LiPo packs in use by people in this hobby than any other that I am aware of by a large margin, wouldn't that make sense?

---

Of course it makes sense. I never said otherwise. My other company has built and sold high end rechargeable bike lights. I've sold ~150,000 ~$200-400 bike lights. After making my living designing and selling rechargeable devices for the past 25+ years I shudder every time a customer seeking help opens with "well I used to race RC cars/boats/ airplanes, so I know everything about every battery ever made."

The level of myth, misunderstanding, market hype and outright pure nonsense associated with RC anything and batteries cannot be overstated. For starters the vast majority of RC apps involve very short very high current discharges, and often rapid recharging.
This is simply not true for bike lights, dive lights or scooters. These typically feature long slow discharges and long slow recharges. Layer on a few heaping helpings of market hype and top it off with a generous dollop silly myths and you have an RC battery "expert"

Quote:

---

Originally Posted by Texas Torpedo

The majority of fires you see on Youtube (etc) are all intentionally created, not real accidents.

---

True, just like CBS and the exploding F150's, manufactured "news"

Quote:

---

Originally Posted by Texas Torpedo

Well Tobin, please explain it to me. As I see it, we have companies starting to utilize LiPo's but not the ideal chargers to go with them.

---

The correct approach is robust internal BSM's that function transparently to the user. That makes the charger a simple dumb current source.

Reliability is never enhanced by requiring the user to make more choices. The best charger is one where the user can plug in the battery turn it on do nothing more until the charge is complete.

Tobin

Quote:

---

Originally Posted by TobinGeorge

The best charger is one where the user can plug in the battery turn it on do nothing more until the charge is complete.

Tobin

---

And then what? Nope, the best charger is one where the user can plug in the battery, turn it on and then walk away for a day, or a week, or longer. I know that sounds stupid to you, but this is the real world.

Quote:

---

Originally Posted by kwinter

And then what? Nope, the best charger is one where the user can plug in the battery, turn it on and then walk away for a day, or a week, or longer. I know that sounds stupid to you, but this is the real world.

---

Sure in a perfect world, but try to get off your anti Lithium Jihad long enough to understand that all rechargeable batteries carry some risk.

There is no 100% fail safe charger for any chemistry, *NO* external device can reduce to zero the chance of an internal fault within a cell.

Good pack design, and good charger design, like all other gear choices can reduce the risks, but never make them zero.

I can say that external timers, GFI outlets and thin metal containment stations do nothing, IMO, to reduce the risks.

If you demand 100% fail safe, sell the dive gear, stay home, close the drapes and hum whatever tune makes you happy.

Tobin

Quote:

---

Originally Posted by TobinGeorge

Sure in a perfect world, but try to get off your anti Lithium Jihad long enough to understand that all rechargeable batteries carry some risk.

There is no 100% fail safe charger for any chemistry, *NO* external device can reduce to zero the chance of an internal fault within a cell.

Good pack design, and good charger design, like all other gear choices can reduce the risks, but never make them zero.

I can say that external timers, GFI outlets and thin metal containment stations do nothing, IMO, to reduce the risks.

If you demand 100% fail safe, sell the dive gear, stay home, close the drapes and hum whatever tune makes you happy.

Tobin

---

Don't misunderstand, Tobin. I am not looking for zero risk. Just an acceptable level of risk. And so far I'm not convinced that lithium batteries have reached my comfort level. I know it will get there, and you will undoubtedly be at the forefront. But as of right now, I don't think even you would argue that the risk is higher with lithium cells than with NiMH cells. And as long as I'm willing to live with the shortcomings and lower power of nickel cells, that's the way I choose to go until such time as my safety comfort level is reached. No jihad intended. Just a personal choice.

Ken

Quote:

---

Originally Posted by kwinter

Don't misunderstand, Tobin. I am not looking for zero risk. Just an acceptable level of risk. And so far I'm not convinced that lithium batteries have reached my comfort level. I know it will get there, and you will undoubtedly be at the forefront. But as of right now, I don't think even you would argue that the risk is higher with lithium cells than with NiMH cells. And as long as I'm willing to live with the shortcomings and lower power of nickel cells, that's the way I choose to go until such time as my safety comfort level is reached. No jihad intended. Just a personal choice.

Ken

---

If you think NiMh cells can't runaway, catch fire and burn down your house during charge think again.

Tobin

Quote:

---

Originally Posted by a64pilot

I'm sure you guys have heard this already but in case you haven't Lipo, or LI-Ion batteries have a very high power density which makes them small and powerful, but they have a nasty habit of catching fire when being recharged, as a model airplane flyer we have them catch fire more often that average as physical damage is one thing that may cause them to go off, so I have learned the hard way, they burn like a magnesieum flare, really hot. It's prudent to charge your batteries in a fireproof container of some kind, ceramic flower pots and corning ware comes to mind for smaller batteries, airplane hobby shops even sell some kind of fire proof plastic bag. when travelling, the bathtub if it's an old fashioned ceramic one is a good place.
Just don't trust the things, even the ones in your cell phone and your laptop.

---

Lithium phosphate batteries do not burn and provide the same amount of power/wieght ratio, they use these alot in large model aircraft...hopefully soon we will see them being used in the diving industry to help prevent some of these accidents.

Quote:

---

Originally Posted by gschaut

Jill Heinerth posted this video a while back. Her design for an battery charging box/blast shield.

http://www.youtube.com/watch?v=lsqFm4AdpCQ

---

I like the general idea of Gill's "blast box". However, I would like to have something more portable for my "small" 300Wh LiPo battery that came with a 200W HMI.

I wonder if a carriable metal tool box (or ammunition box) would be suitable? I could cover the insides of the tool box with small ceramic bathroom tiling. The idea is not to make the box gas tight, rather, only to delay and contain the fireworks from immediately spreading to surroundings. Similar concept like the LipoSacks, but, which are far too small for my battery. Since LipoSacks work, wouldn't the same concept work in a slightly larger size? Or would the failure of a 300 Wh LiPo battery be unmanageable in a tool box and sending away metallic and ceramic shrapnel?

The toolbox could also be relatively weather proof allowing charging outside, e.g. on top of a boat deck instead of having to charge under deck. I have in mind week-long boat execursions, so I really need to solve this safety issue. The same would apply to cave excursions, if the motels do not have ceramic bathtubs...

Furthermore, I could fill the tool box with some unburnable but soft isolation/dampening material so the box could double as a transportation box when taking the lamp+battery on rougher RIB boat trips.

Perhaps I could even attach a permanent digital volt meter display on the lid of the toolbox for monitoring charge status.

Comments? Am I missing something?

Quote:

---

Originally Posted by r4e

Comments? Am I missing something?

---

Sounds like it would work to me. I just use a cooking pot for my light battery, but it is smaller. Anything to contain the fire will work. Just don't have anything flamable around it, Li batteries spit sparks when they burn.

Quote:

---

Originally Posted by skip

I like all my stuff in one room. So when it goes, it goes big. A house fire? ha. When mine goes it will take out half the block at least. The family fire plan is to run like hell as fast and as far away as possible. Some family's may plan to meet in the yard, or across the street in the neighbor's yard, but my kids have practiced the run to the hospital three blocks away where the plan is to meet in front of the emergency room entrance! Last one there is a rotten egg! The neighbors have been warned too.

skip

---

Knowing myself, I will likely have many things in the house just as if not more dangerous in a fire than the dive gear...will probably need the same emergency plan when I have kids one day lol.

Quote:

---

Originally Posted by skip

I like all my stuff in one room. So when it goes, it goes big. A house fire? ha. When mine goes it will take out half the block at least. The family fire plan is to run like hell as fast and as far away as possible. Some family's may plan to meet in the yard, or across the street in the neighbor's yard, but my kids have practiced the run to the hospital three blocks away where the plan is to meet in front of the emergency room entrance! Last one there is a rotten egg! The neighbors have been warned too.

skip

---

I am afraid that blasting half a block is too modest. That's why I prefer to load all my O2 tanks and LiPo stuff on my RIB boat in addition to 520 liters/130 gallons of gasoline and then go cruising at 50 knots (55 mph). After hitting an underwater rock or submarine at full speed and flying sky high, it is much more rewarding to swim 100 miles to the closest emergency room. A bit difficult to find dive buddies though. And I dare not take my family with me.

Quote:

---

Originally Posted by CaveMD

Knowing myself, I will likely have many things in the house just as if not more dangerous in a fire than the dive gear...will probably need the same emergency plan when I have kids one day lol.

---

No problem. Just build a small, secure metal or concrete block building at a safe distance from your house and keep the kids in it.

Quote:

---

Originally Posted by MORGAN

No problem. Just build a secure metal or concrete block building at a safe distance from your house and keep the kids in it.

---

:rollguy

Quote:

---

Originally Posted by MORGAN

No problem. Just build a small, secure metal or concrete block building at a safe distance from your house and keep the kids in it.

---

Heres the blast box I built at H2O. Bottom is cement blocks while the top is a HUFFY Steel tool box. Scooters fit in the bottom, cannister light up top. I also wired the power to a 6 hour timer, (similar to the timers for bathroom heat lamps) Now just gotta built the child seats to make your joke be completely true.

Forrest,,
To add insult to injury what happened to my new scoot Sun when we dove was almost certainly a bad cell in the battery, of course that is what usually causes a fire during charging too, so I guess dieing in the cave is better than burning the house down.

How much heat is generated by the battery during the NORMAL charging process?

Do you need to consider ventilation / heat dissipation during charging. Sealing a battery up
in an insulated, airtight container sounds like it "might" present a problem.

That being said, I can vouch from personal experience that plywood is quite fire resistant.
I have had occasion to walk across plywood floors only to find out after-the-fact that
the plywood had direct flame exposure to the underside for several minutes without failing.

Yes, it is flammable. But it will tolerate quite a bit of heat before it fails. Lined with some
fiberglass insulation, a plywood box would be cheap, easy to build in custom size, act as
a shipping container, and suppress quite a bit of flame/shrapnel during a "failure".

just a thought.

Quote:

---

Originally Posted by gschaut

How much heat is generated by the battery during the NORMAL charging process?

Do you need to consider ventilation / heat dissipation during charging. Sealing a battery up
in an insulated, airtight container sounds like it "might" present a problem.

---

The LipoPacks would have the same problem, if there is any problem concerning conduction of any normal heat generated during charging. However they are not airtight - the idea is only to delay the exit of gases and allow them to react with air in a partially enclosed space.

I am guessing that any insulation might possibly speed up a thermal runaway situation. The delrin case of the battery pack is insulation as well. However, if the original problem is a cell chemistry failure or an internal short circuit in a cell and this causing heat, this affects the LiPo chemistry and additionally might cause insulation failures in neighboring cells --> locally fast cascading events and thus probably not affected by external insulation.

A different question is the charger, because this definitely will generate heat due to internal losses. Unless the space is large and/or ventilated, I would not place the charger in the same box.

Monitoring the internal temperature of the box should be easy. Just place a meat thermometer through the box lid. 30 degrees centrigrade is already an elevated temperature, LiPo batteries should not be charged at temperatures over 45 degrees centrigrade, and, internal breakdown of the LiPo battery might commence as low as 70 degrees centrigrade. The temperature zone between these would be heat stress. Perhaps one could build a thermally controlled shutdown for the mains supply to the charger?

If building the box from plywood, I would consider having a loose internal lid in order to make the exit path of gases a bit longer.

The one I built has a shelf on draw slides so it pulls forward and the scooter on bottom is open air. Think of it in terms of a blast shield instead of Box. Plenty of ventilation but if you had an issue it deverted away for the house.

my 2 cents to keep my house from burning...
I use a big metal pot that slips over the battery , a cheap plug in timer that cuts of the power after a set time (i give it 1 hour more that full charge), and a thermostat that cuts the power when it feels any heat.

Thick sock of natural leather is good enough to contain 4-5Ah LiIon fire, just leave gas products relief channel. Pack each individually.

I learned a lot from here.

When I charge my batteries, I make sure I sleep with appropriate clothing. :)

Quote:

---

Originally Posted by Jax

I learned a lot from here.

When I charge my batteries, I make sure I sleep with appropriate clothing. :)

---

You mean like Andrew? :rollguy

On a more serious note, you can buy charging bags for smaller LiPo batteries, like in a dive light. They just don't make one for scooters, yet.

Quote:

---

Originally Posted by MichaelAngelo

Heres the blast box I built at H2O. Bottom is cement blocks while the top is a HUFFY Steel tool box. Scooters fit in the bottom, cannister light up top. I also wired the power to a 6 hour timer, (similar to the timers for bathroom heat lamps) Now just gotta built the child seats to make your joke be completely true.

---

We had a fire in our blast box just about 7 weeks ago. The box contained the fire, and we put it out with extinguishers. Kinda scary. Now, we built a freestanding metal shed on a sand pile about 100 feet from the house, and put two ventilated metal cabinets inside. And extinguishers nearby. Pics to come.

Quote:

---

Originally Posted by RebreatherPro.com

We had a fire in our blast box just about 7 weeks ago. The box contained the fire, and we put it out with extinguishers. Kinda scary. Now, we built a freestanding metal shed on a sand pile about 100 feet from the house, and put two ventilated metal cabinets inside. And extinguishers nearby. Pics to come.

---

Light, or scooter batteries?