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Lithium Battery Explosion

lucaperazzolli

lucaperazzolli

Well Known Member
A friend of mine is really close to the first engine start with an RV-8, he choosed a Lithium Ion battery for weight saving. I'm very conservative about and now I know why ...

This happened at first charge, we were in hangar and the new battery was attached to the charger as per instruction, the charger was approved for that battery. The temperature of the battery during the charging process was normal.

After 30 minutes the battery started to melt with a lot of smoke, an incredible quantity of white smoke. The toxic smell was intolerable, we moved the battery outside of the hangar (wasn't easy) that remained full of smoke for awhile. The temperature of the battery was incredible hight ! Melting continued for 20 minutes, hot battery temperature remained for 2 hours !

I really can't imagine that this could happen into the firewall compartment or, worse, into the fuselage.

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It's interesting that the case isn't even more deformed/melted - having seen smaller lithium-ion batteries give up the ghost, I would have thought a battery this size would have completely melted. Perhaps not all the cells failed?

Anyway, thanks for sharing these! Great reason to either stick with the PC-680 or jump to LiFePO4 batteries!
 
That's a lithium ion battery, not a lithium iron battery. I would never put a battery in an airplane that is 1. lithum ion and 2. without a built-in management circuit.
 
Hi Luke

I think your lesson was also learned by Boeing with the 787 and Lithium-Ion :eek:

As above, in an RV it is not the way ahead - LiFePO4 seems way safer, and there is a lot of experience on this forum with regards to specific types and now years of operation.

Can one ask what research led your friend to this type / model of battery?
 
Thanks for sharing. My reading tells me that most of the failure of Li based batteries seems to occur with over or improper charging. I'm guessing something wasn't as it should have been with this process in this case.

Re. the LiFePO4, most brands I'm familiar with come charged. And further, they hold a charge for a very, very long time relatively speaking. So, you buy one of these, and it sits on the shelf 3, 4 mos, don't assume it needs to be charged.

1 yr 9 mos on Ballistic brand LiFePO4 and pleased with the performance.
 
It does look like it was a LiFePo4 battery. Had it been a standard LiPo, it wouldn't have just melted, it would have burst into flames.

I haven't been able to find on the SkyRich site if these batteries have an internal BMS or not. I'm suspecting that they don't.
 
Was this an "Explosion" or simply a meltdown from heat? Was there any debris or chemicals at any distance from the battery?
 
Lithium Battery Meltdown

You know when everyone started talking about how light/better these new batteries are I started to post something about using extreme caution, but was afraid I'd step on some toes, or get some manufacturer mad at me. My instincts were spot on. While in the military, I had a good pilot buddy that was put in the hospital for a day when a Lithium battery for a military radio sitting on a table near him exploded; and I mean exploded. Everyone there thought that someone had thrown a grenade simulator into the tent. It was that loud. He had a possible ear drum rupture, and shrapnel injuries from the casing. Evidently the casing had sprung a leak and the moisture reacted with the lithium and caused it to explode. I will not be using one of these in any airplane of mine until the technology gets way more proven.
 
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Battery

Hi Luca.

I'm glad this happened ouside of the airplane for sure. Was this Francesco's orange RV-8 that we are talking about?

Tell everyone I said Hi!
 
I've not cut open any of the LiFePO4 batteries. What is located in that top section. It appears from the photos that something in the top failed. It's not clear what happened with the actual cell material.

Can anyone elaborate ?

UPDATE: found this image ...

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Clearly stated on the battery is a MAXIMUM charging rate of 28 amps. I doubt the RV8 had an alternator that put out only 28 amps maximum. I realize this was not the cause of the failure, but may have been a failure later on, like when the engine was started! Why would one just ignore that fact is beyond me.
Also if you go the web site for this battery, it clearly defines it as a MOTORCYCLE battery application (which have a very low alternator output)

BlackhawkSP said:
You know when everyone started talking about how light/better these new batteries are I started to post something about using extreme caution, but was afraid I'd step on some toes, or get some manufacturer mad at me. My instincts were spot on. While in the military, I had a good pilot buddy that was put in the hospital for a day when a Lithium battery for a military radio sitting on a table near him exploded; and I mean exploded. Everyone there thought that someone had thrown a grenade simulator into the tent. It was that loud. He had a possible ear drum rupture, and shrapnel injuries from the casing. Evidently the casing had sprung a leak and the moisture reacted with the lithium and caused it to explode. I will not be using one of these in any airplane of mine until the technology get way more proven.
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When I was in a professional school many years ago, we were taught: "don't be the first person to do the new thing....and don't be the last person doing the old thing". I would sure love to have a lightweight battery in my plane (as anyone would), but I will just wait until lithium battery technology is developed beyond the question of any doubt in any of it's forms or chemistries. So there.
 
I think this is another reason to make sure any LiFePo4 battery you get has a Battery Management System (BMS) built into it. The BMS makes sure the cells are balanced and prevents over charging/over discharging.These new batteries are definitely newer tech, but they need some intelligence on how the cells are managed.

You can't treat your new iPhone like an old motorola. They do the same thing, but work very differently.

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This is EXPERIMENTAL AVIATION. If no one tries the new things, then we'll all be flying 1903 Wright Flyers. And if they had listened to the experts, they wouldn't have flown.
 
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Clairification!!!

...I think this thread is jumping to conclusions that are somewhat incorrect and need to be stated. The potential for heat explosion of lithium batteries varies widely as do the types of lithium batteries. The vary dangerous lithium polymers are extremely prone to this type of issue and consequently should never be considered for our purposes. Second would be the lithium ion units. They can get very hot and melt, sometimes even catch fire if a charging malfunction were to occur. The internal expansion can cause the sealed case to rupture, sometimes with a bang that can be vary loud, but isn't a true explosion in the sense that it wont through high velocity shrapnel everywhere. These two types of batteries I would avoid for aircraft use. The third and most common type and what the Shorai batteries for instance are using is lithium iron. This type is far less prone to these melt downs and doesn't build heat rapidly like the others, thus making them far more stable and more fire resistant. I have this type in my RV-9A with vary heavy electrical loads and a 90 amp alternator. It has performed flawlessly and shows no signs of deterioration. It weighs a mere 4 lb and replaced the 27 lb unit I was using. It also cranks the engine far better that any battery I have used. Don't sell this technology short as they are a big improvement over lead acid in many respects. Thanks, Allan...:D
 
PerfTech said:
?<snip>Don't sell this technology short as they are a big improvement over lead acid in many respects. Thanks, Allan...:D
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This is true, Alan, but there are thousands of chemical combinations of anodes, cathodes, wraps, electrolytes and trace additives. So, just because it has Fe in the name is not a pass on its potential failure modes with an unpleasant result. There are many more factors. We STILL need to be careful until the full envelope of safe operation is quantified for a specific chemistry.

The point is that the envelope must be shown/demonstrated/tested, not assumed. This particular failure probably would have been contained in a stainless box with external venting.

We will get there . . . and hopefully with no collateral damage.
 
Low Pass said:
This is EXPERIMENTAL AVIATION. If no one tries the new things, then we'll all be flying 1903 Wright Flyers. And if they had listened to the experts, they wouldn't have flown.
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True, but remember that the experimentation process involves understanding the physics and technology, then developing a hypothesis or plan, then bench testing, then on-plane testing. If you just go from guess to in the air, that's not experimentation, that's gambling.

Some here are qualified to experiment with these batteries, but I know that I am not one of them. I hope those who are qualified to do so continue to experiment with these low weight battery solutions, but I will stick to the mechanical stuff that I understand.

Tim
 
I think this is another reason to make sure any LiFePo4 battery you get has a Battery Management System (BMS) built into it. The BMS makes sure the cells are balanced and prevents over charging/over discharging.These new batteries are definitely newer tech, but they need some intelligence on how the cells are managed.
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Just for my education here. You are saying that the newer LifePo4 batteries are safe because they have electronics built into them that keep them safe? If so, I've never seen a piece of electronics that can't fail. Are there backups for these electronic fire preventers built in or is it a single point of failure that results in a cabin filled with opaque, toxic gas? In an aircraft, where we have redundancy built in...I have to wonder about these batteries. To save as much weight as a half decent diet would take off the pilot?

I would love to take the battery weight from behind my passenger and make it lighter...but not at the risk of killing myself and anyone with me. Every new version of these batteries that have come out have said they are the safe version....I'm going wait and see.
 
ColoRv said:
Just for my education here. You are saying that the newer LifePo4 batteries are safe because they have electronics built into them that keep them safe? If so, I've never seen a piece of electronics that can't fail. Are there backups for these electronic fire preventers built in or is it a single point of failure that results in a cabin filled with opaque, toxic gas? In an aircraft, where we have redundancy built in...I have to wonder about these batteries. To save as much weight as a half decent diet would take off the pilot?

I would love to take the battery weight from behind my passenger and make it lighter...but not at the risk of killing myself and anyone with me. Every new version of these batteries that have come out have said they are the safe version....I'm going wait and see.
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And, says the Cirrus pilot, you fly an "uncertified" plane built in your garage!

It's all relative, and I do appreciate your warnings and concern.
 
tjo said:
True, but remember that the experimentation process involves understanding the physics and technology, then developing a hypothesis or plan, then bench testing, then on-plane testing. If you just go from guess to in the air, that's not experimentation, that's gambling.

Some here are qualified to experiment with these batteries, but I know that I am not one of them. I hope those who are qualified to do so continue to experiment with these low weight battery solutions, but I will stick to the mechanical stuff that I understand.

Tim
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This logic dictates that all who build an EXPERIMENTAL aircraft are taking on the same GAMBLE! Precious few of us who have built, or are currently building any type of experimental aircraft followed through with . . ."understanding the physics and technology, then developing a hypothesis or plan, then bench testing, then on-plane testing." So, given that you, me, and pretty much everyone else reading this did not follow this advice, what does that say about our decision making process of building these EXPERIMENTAL airplanes?
 
Kahuna said:
Was this an "Explosion" or simply a meltdown from heat? Was there any debris or chemicals at any distance from the battery?
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Thanks, this was effectively a meltdown with a lot of smoke but started suddenly like an 'explosion'. No parts were around the battery but smoke was really toxic and dense. I think a defective brand new battery but it's an interesting experience. I didn't pay the battery :D
 
RVbySDI said:
This logic dictates that all who build an EXPERIMENTAL aircraft are taking on the same GAMBLE! Precious few of us who have built, or are currently building any type of experimental aircraft followed through with . . ."understanding the physics and technology, then developing a hypothesis or plan, then bench testing, then on-plane testing." So, given that you, me, and pretty much everyone else reading this did not follow this advice, what does that say about our decision making process of building these EXPERIMENTAL airplanes?
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Except that the airplane you built is already very well proven, so it has already been tested and you know what to expect.

Tim
 
EarthX lithium batteries

Thank you to all of you that sent this link to us at EarthX and asked us for a response and possible answer to this problem. We have tried to answer each of you individually but our inbox is over flowing so I will attempt to answer the most frequently asked questions here we are receiving.

What exactly happened here, we do not know. It could be an undersized battery, a cell defect, a charger defect, etc. What we do know if there are several things that need to be matched up to choose and use the correct battery for your application. The CCA needed to turn your engine over; the capacity (true amp hours of the battery); and the limitations of the charge current that can be sent through the battery. What we do know is the model used in the RV-8. was the HJTX20HL model.

1. The manufacturer of the Skyrich batteries is a company out of China that is actually named Haijui.
2. They do not have a battery management system, and they don't say that they do either.
3. It is a lithium iron phosphate chemistry.
4. They do not have a manual on their website, that we can find, that lists any of the limits of the battery.
5. They do not have an application chart or recommendation for any type of aircraft use.
6. They list an equivalent capacity amp hour rating of 14 amps, not a true amp hour. (There is no standard for this number and manufacturers can and do list any number here) So the true amp hours of this battery is probably much closer to 4 or possible even less. They have no explanation of how they derive this equivalency number so your guess is as good as ours. We list the true amp hours in our manual as this is a very important number for you as a pilot in the event of your alternator failing. This is the amount of capacity you can run your equipment on.
7. They do not have a maximum amount of charging amps the battery can withstand either. In the RV-8 has up to a 60 amp alternator. We also list the max amps our batteries are designed for on our home page for experimental aircraft use and in our manual. The ETX36 series is designed for 60 amp alternators and the ETX48 series is designed for up to 120 amp alternators.

Batteries are not a one size fits all and lithium batteries are very powerful starter batteries....but you need to match up more than the cranking power of the battery or you can have bad results. An under sized lead acid battery that is over stressed can explode acid every where and an undersized lithium battery can cause cell rupture and extreme heat. The pictures shown indicates extreme heat, not a fire, or it would be a pile of ashes instead. It is actually very hard to get a lithium iron phosphate battery to catch on fire, but if you do, it will also continue to burn.

The technology is not bad or flawed but it does require protection. Can you imagine if cars didn't come with brakes....or trains....or planes? All lithium batteries require protection for them to operate correctly and safely and it is a shame there are companies out there putting out "brakeless" vehicles and people are assuming it is the vehicle's fault....not how it was made.

I hope this response has answered some of your questions. Lithium technology has been used commercially since the 1970's....it is not untested technology. What has happened is now that is it affordable for the masses, companies are putting out batteries in the masses and cutting corners.

Kathy
www.earthxmotorsports.com

[/I]
 
Thank you Kathy ! I posted this story in order to fire some curiosity and you answered us very well. Of course you sell this new technology, but you have a specific web menu voice for Experimental Airplanes. This says a lot.

EarthX Lithium said:
Thank you to all of you that sent this link to us at EarthX and asked us for a response and possible answer to this problem. We have tried to answer each of you individually but our inbox is over flowing so I will attempt to answer the most frequently asked questions here we are receiving.

What exactly happened here, we do not know. It could be an undersized battery, a cell defect, a charger defect, etc. What we do know if there are several things that need to be matched up to choose and use the correct battery for your application. The CCA needed to turn your engine over; the capacity (true amp hours of the battery); and the limitations of the charge current that can be sent through the battery. What we do know is the model used in the RV-8. was the HJTX20HL model.

1. The manufacturer of the Skyrich batteries is a company out of China that is actually named Haijui.
2. They do not have a battery management system, and they don't say that they do either.
3. It is a lithium iron phosphate chemistry.
4. They do not have a manual on their website, that we can find, that lists any of the limits of the battery.
5. They do not have an application chart or recommendation for any type of aircraft use.
6. They list an equivalent capacity amp hour rating of 14 amps, not a true amp hour. (There is no standard for this number and manufacturers can and do list any number here) So the true amp hours of this battery is probably much closer to 4 or possible even less. They have no explanation of how they derive this equivalency number so your guess is as good as ours. We list the true amp hours in our manual as this is a very important number for you as a pilot in the event of your alternator failing. This is the amount of capacity you can run your equipment on.
7. They do not have a maximum amount of charging amps the battery can withstand either. In the RV-8 has up to a 60 amp alternator. We also list the max amps our batteries are designed for on our home page for experimental aircraft use and in our manual. The ETX36 series is designed for 60 amp alternators and the ETX48 series is designed for up to 120 amp alternators.

Batteries are not a one size fits all and lithium batteries are very powerful starter batteries....but you need to match up more than the cranking power of the battery or you can have bad results. An under sized lead acid battery that is over stressed can explode acid every where and an undersized lithium battery can cause cell rupture and extreme heat. The pictures shown indicates extreme heat, not a fire, or it would be a pile of ashes instead. It is actually very hard to get a lithium iron phosphate battery to catch on fire, but if you do, it will also continue to burn.

The technology is not bad or flawed but it does require protection. Can you imagine if cars didn't come with brakes....or trains....or planes? All lithium batteries require protection for them to operate correctly and safely and it is a shame there are companies out there putting out "brakeless" vehicles and people are assuming it is the vehicle's fault....not how it was made.

I hope this response has answered some of your questions. Lithium technology has been used commercially since the 1970's....it is not untested technology. What has happened is now that is it affordable for the masses, companies are putting out batteries in the masses and cutting corners.

Kathy
www.earthxmotorsports.com

[/I]
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tjo said:
Except that the airplane you built is already very well proven, so it has already been tested and you know what to expect.

Tim
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Tim, you're not backing up your argument very well. Actually, just this last weekend, I was contemplating scratch-building my own 4 seat cross country machine (airplane, Exp-AB). Purely my own design. Had much of it worked out after finishing the long drive I had to make. Was thinking composite wood and FRP (fiberglass).

Only time we're not gambling in some form or fashion is that day when we don't wake up in the morning.
 
Low Pass said:
Tim, you're not backing up your argument very well. Actually, just this last weekend, I was contemplating scratch-building my own 4 seat cross country machine (airplane, Exp-AB). Purely my own design. Had much of it worked out after finishing the long drive I had to make. Was thinking composite wood and FRP (fiberglass).

Only time we're not gambling in some form or fashion is that day when we don't wake up in the morning.
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You're right, I am not articulating well at all, which is typical for me. All I am trying to say is, lithium based batteries contain mysteries that I don't have the background or education to understand. In fact, I have seen evidence that indicates that the folks that make them don't quite understand everything about them either. That not only makes me nervous, but as far as I am concerned, There be dragons!.

In your case with building an airplane of your own design using those materials, you are experimenting, sure, but you are using well understood and predictable materials and techniques. You could end up with voids in the layups and other defects, sure, but you should have the information available to you for proper safety factors, design practices, etc. If not and you're just doing what looks right (which I highly doubt), then you're gambling.

The bottom line of what I am trying to say is, lithium based batteries are far too risky for me. Especially considering they only save about 10lb over a PC680, which is just a lead acid battery, no mystery there.

I should have been more precise on my gambling description as well. There is a big difference between being an expert at counting cards at a blackjack table and playing the slots. I am saying that if you don't understand all of the intricacies that Kathy is pointing out and you choose poorly, it's like the slots, even if you win you don't know why. If you use stuff you know and can predict, more like the blackjack table, at least you know what to look for and you can predict your wins and losses.

Tim
 
EarthX Lithium said:
Thank you to all of you that sent this link to us at EarthX and asked us for a response and possible answer to this problem. We have tried to answer each of you individually but our inbox is over flowing so I will attempt to answer the most frequently asked questions here we are receiving.
7. They do not have a maximum amount of charging amps the battery can withstand either. In the RV-8 has up to a 60 amp alternator. QUOTE)

Look at the photo of the battery in the post. The normal charging amps and maximum charging amps are clearly stated on the battery. Sure this is experimental, but why would someone take a battery with stated use for motorcycles, with a max allowable charging amps stated as 28 amps, and install it in an aircraft with an 60 amp alternator? I just don't call that experimental at all.
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Don't be afraid of something new.....

tjo said:
You're right, I am not articulating well at all, which is typical for me. All I am trying to say is, lithium based batteries contain mysteries that I don't have the background or education to understand. In fact, I have seen evidence that indicates that the folks that make them don't quite understand everything about them either. That not only makes me nervous, but as far as I am concerned, There be dragons!.

In your case with building an airplane of your own design using those materials, you are experimenting, sure, but you are using well understood and predictable materials and techniques. You could end up with voids in the layups and other defects, sure, but you should have the information available to you for proper safety factors, design practices, etc. If not and you're just doing what looks right (which I highly doubt), then you're gambling.

The bottom line of what I am trying to say is, lithium based batteries are far too risky for me. Especially considering they only save about 10lb over a PC680, which is just a lead acid battery, no mystery there.

I should have been more precise on my gambling description as well. There is a big difference between being an expert at counting cards at a blackjack table and playing the slots. I am saying that if you don't understand all of the intricacies that Kathy is pointing out and you choose poorly, it's like the slots, even if you win you don't know why. If you use stuff you know and can predict, more like the blackjack table, at least you know what to look for and you can predict your wins and losses.

Tim
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Dear Tim,

I do understand your fear of trying something new and wanting to stick with technology that is over 170+ years old...but since you are using a computer to type this, I am assuming you gave up your type writer in lieu of something a bit more advanced right? And you had to decide to use a PC or a Mac, right? You educated yourself to make the choice that was right for you.

Lead acids are not without problems either, just ask any one who has had acid spill out or worse, had one explode on them. Everything can and will have issues. I truly wish that these "intricacies" were easier for all, including choosing a lead acid battery, but my goal is to help point potential new users in the direction on how to make an educated choice. The rules of choosing a lead acid battery is the same as a lithium by the way. And quite frankly, if the battery manufacturer doesn't address any technical parameters on their sites, they don't have even a manual, that should be an indication of something. Also, read the warranty...that is very indicative of a lot as well.

And to save 10+ pounds........well, I think a lot of people would think the switch to newer technology is definitely worth it.

Kathy
 
Kathy, can you please put up a link to the MSDS for your batteries.

I looked on your website, and could not find it.

Thanks,
 
Having tested both LiFePO and other lithium ion chemistries to failure, It appears the failure was more characteristic of LiFePO. The other chemistries most certainly would have failed with open flame when the case vented. The general description of the failure and manufacturers info supports that this battery did not include a BMS, and thus a classic overcharge failure. As was pointed out fire is not the only hazard, the vented gasses are quite heavy and noxious and if the event occurred during a critical portion of flight, could be quite challenging if the battery is in the cabin.

A good BMS is mandatory. A good, relatively sealed enclosure vented overboard a good idea.
 
EarthX Lithium said:
Dear Tim,

<snip> . .And to save 10+ pounds........well, I think a lot of people would think the switch to newer technology is definitely worth it.

Kathy
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Funny - part of the composite prop attraction is the 15-18 lb saving. The ARE some additional benefits too. The cost/is is a lot more than $15/lb!

Kathy, thanks for continuing to work with the RV group on definition of operating envelope. Let me posit. At OSH, hot day, just finished formation and taxing back to parking. Still hot and ready to depart, trouble hot starting, then long taxi and hot take off. Also the charging system is just below the crowbar trip point of 16.3 volts on charging. Talk with your engineers about this kind of scenario and add 10degC to the battery core temp. Does the Earth fare well? In the same scenario, full SOC. Still ok? - So now just how high can the charging voltage go before an "event"? Was the event contained in a typical RV firewall steel box installation?

These are the kinds of questions your engineers are surely working with. Both at the pack and cell level. We certainly don't need the cell information, so if the BMS/pack design passes all these tests, you will have a long list of instant buyers. Yes, they will take time, and unfortunately, money. Thanks for listening and continuing to provide rational answers even they are "I don't know".
 
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It seems like only yesterday that we were told to scrap our ELTs because of Lithium batteries in them were causing fires. Then we had to buy a newer model at more expense and the ELT wars began.
 
Almost all modern ELTs still use lithium primary batteries as do underwater locator beacons installed on flight data recorders and cockpit voice recorders. The big difference is these are not rechargeable and are very stable unless dented, punctured or exposed to extremely high temperature.
 
I was making reference to primary lithium batteries that are not rechargeable vs lithium ion based batteries.
 
Andy Hill said:
Hi Luke

I think your lesson was also learned by Boeing with the 787 and Lithium-Ion :eek:

As above, in an RV it is not the way ahead - LiFePO4 seems way safer, and there is a lot of experience on this forum with regards to specific types and now years of operation.

Can one ask what research led your friend to this type / model of battery?
Click to expand...


And in addition to this, I just learned Malaysian 370 was carrying 5000 lbs of Lithium batteries. May not mean anything, but food for thought.
 
BillL said:
Funny - part of the composite prop attraction is the 15-18 lb saving. The ARE some additional benefits too. The cost/is is a lot more than $15/lb!

Kathy, thanks for continuing to work with the RV group on definition of operating envelope. Let me posit. At OSH, hot day, just finished formation and taxing back to parking. Still hot and ready to depart, trouble hot starting, then long taxi and hot take off. Also the charging system is just below the crowbar trip point of 16.3 volts on charging. Talk with your engineers about this kind of scenario and add 10degC to the battery core temp. Does the Earth fare well? In the same scenario, full SOC. Still ok? - So now just how high can the charging voltage go before an "event"? Was the event contained in a typical RV firewall steel box installation?

These are the kinds of questions your engineers are surely working with. Both at the pack and cell level. We certainly don't need the cell information, so if the BMS/pack design passes all these tests, you will have a long list of instant buyers. Yes, they will take time, and unfortunately, money. Thanks for listening and continuing to provide rational answers even they are "I don't know".
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Hi Bill, I had our lead engineer look this over and this is his response,

"What type of charging system do you have that has charge voltages as high as 16.3? Typically alternator / regulator would be < 14.5V. The EarthX's battery over-charge protection is effective up to 17V, above which the cells will be damaged. An "event" as you put it would generally be above 17- 20V (like cell rupture, but still contained within our UL-94V-0 case). As for the temperature, the ETX lithium battery has 60 deg C operating temperature range (meaning active discharging / charging). The storage temperature is allowed to 70degC (no charging or discharging). And we conduct tests with the battery above 85 deg C (185 deg F) for short periods like 2-4 hours. The operating temp is defined as continuous operation, not an absolute "not to exceed temp". I know it get hot in the engine compartment after parking the plane, but I would consider that storage temp, for there is not active charging / discharging."


Kathy
 
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EarthX Lithium said:
Hi Bill, I has our lead engineer look this over and this is his response,

"What type of charging system do you have that has charge voltages as high as 16.3? Typically alternator / regulator would be < 14.5V. The EarthX's battery over-charge protection is effective up to 17V, above which the cells will be damaged. An "event" as you put it would generally be above 17- 20V (like cell rupture, but still contained within our UL-94V-0 case). As for the temperature, the ETX lithium battery has 60 deg C operating temperature range (meaning active discharging / charging). The storage temperature is allowed to 70degC (no charging or discharging). And we conduct tests with the battery above 85 deg C (185 deg F) for short periods like 2-4 hours. The operating temp is defined as continuous operation, not an absolute "not to exceed temp". I know it get hot in the engine compartment after parking the plane, but I would consider that storage temp, for there is not active charging / discharging."


Kathy
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An alternator running away is far from uncommon. Are you saying that an over voltage would overcome your protection circuit and cause a cell rupture? Would this result in the smoke described earlier in this thread?
 
Mike H said:
Do you have a link or source for this? I would be interested to read about it.
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Hi Mike, not something I read, but rather on TV. It was called "Ghost Planes", was two hours long, and I think it was on the Military History channel. Might have been Smithsonian, but I'm pretty sure Military History. I've been scrolling thru Military History's menu trying to see it again, but no luck. And then the guy right after you posts an article on 440 lbs of lithium batteries. The TV show said 5000----who knows:confused:
 
So the question is ... the 'over voltage protection circuit' is it an electromechanical switch .. like a Tyco power relay which are used in an EV application or is the over voltage protection pure electronics ? No question that a good / reliable / robust / well designed / fault tolerant ... BMS will protect the Li-battery .. Would be interesting to understand the failure mode of the protection system. I am all for new technology .. working with that all day long ... but having a good understanding of what can go wrong is something I think is worth knowing ...

I am also curios to understand this statement better : (like cell rupture, but still contained within our UL-94V-0 case)

1 - What is a UL-94V-0 case suppose to be able to 'do'. Or put it another way .. What are the benefits of a UL-94V-0 case ?

2 - What is contained in the 'box' and for how long ?? Expanding gas or smoke ?? The battery as it heats up and start to melt ...
 
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EarthX Lithium said:
Hi Bill, I has our lead engineer look this over and this is his response,

"What type of charging system do you have that has charge voltages as high as 16.3? Typically alternator / regulator would be < 14.5V.

The 16.3 VDC is the crowbar circuit trigger point. Obviously as mentioned by rzbill above, over voltage from our alternators are not infrequent. All electrical systems don't have the crowbar nor all use the same trigger point. The nature of experimental. I chose this voltage as we could always specify it as a "requirement" for use of your battery.

The EarthX's battery over-charge protection is effective up to 17V, above which the cells will be damaged. An "event" as you put it would generally be above 17- 20V (like cell rupture, but still contained within our UL-94V-0 case).

a) Is the UL-94V-0 case the standard case for the battery or additional structure?
b) What enclosure is recommended to physically contain the case, as it is assumed that it will soften and deform?
c) Based on your tests, is there an enclosure recommendation for gas venting and/or containment?


As for the temperature, the ETX lithium battery has 60 deg C operating temperature range (meaning active discharging / charging). The storage temperature is allowed to 70degC (no charging or discharging). And we conduct tests with the battery above 85 deg C (185 deg F) for short periods like 2-4 hours. The operating temp is defined as continuous operation, not an absolute "not to exceed temp". I know it get hot in the engine compartment after parking the plane, but I would consider that storage temp, for there is not active charging / discharging."

As an installation verification, should battery case temperature be the measurement point for the user to confirm operation within limits?

Kathy
Click to expand...

Kathy, sincere thanks to you and engineering staff, this is excellent progress to inform a user for safety precautions for use of the EarthX product in an RV.
 
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