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Battery Fire Today

J

Jgibson

Member
Buddy of mine was breaking in his Rotax 503 in his Hawk lite sport plane on the ground today. He had left the master switch on, so the brand new lithium ion battery was low.
We jumped the starter to get it running and observed the volt meter, which sat at 10 volts.
After running approximately 40 minutes of the hour required, the volt meter went to 11 volts, then immediately to 12. At that point, it lit off. As I ran for the fire extinguisher, he fought with disconnecting it and upon getting it free, threw it away from the plane.
It burned and smoked profusely for 5 minutes or so before finally burning itself out. IF this had happened while in the air, there is no way he would have gotten it on the ground before the fire had done serious damage to the plane, IF he could have seen anything through the dense white smoke.
Taught both of us a valuable lesson. I myself will NEVER install one of these until or unless better overcharge protection is in place and unless a low-charge shutoff is in place to prevent it from discharging too far in the first place.
It's just not worth what I saw today, no matter how light and compact it may be.:eek::eek:
 
Yes, please specify brand, model number, and if it is indeed a lithium *ion* battery. If it is, "there's your problem."

I haven't heard of anyone who recommends using a lithium ion battery in an a/c.

Do be aware that there are multiple battery chemistries that include 'lithium' in the name/chemistry. Some are much safer than others.

Charlie
 
ION or IRON?

Jgibson said:
Buddy of mine was breaking in his Rotax 503 in his Hawk lite sport plane on the ground today. He had left the master switch on, so the brand new lithium ion battery was low.
We jumped the starter to get it running and observed the volt meter, which sat at 10 volts.
After running approximately 40 minutes of the hour required, the volt meter went to 11 volts, then immediately to 12. At that point, it lit off. As I ran for the fire extinguisher, he fought with disconnecting it and upon getting it free, threw it away from the plane.
It burned and smoked profusely for 5 minutes or so before finally burning itself out. IF this had happened while in the air, there is no way he would have gotten it on the ground before the fire had done serious damage to the plane, IF he could have seen anything through the dense white smoke.
Taught both of us a valuable lesson. I myself will NEVER install one of these until or unless better overcharge protection is in place and unless a low-charge shutoff is in place to prevent it from discharging too far in the first place.
It's just not worth what I saw today, no matter how light and compact it may be.:eek::eek:
Click to expand...

As the previous repliers said, we need to know the type of lithium battery. Many of us fly EarthX batteries, which are Lithium IRON (not lithium ion). Flying a lithium ion battery is, well, in a word ... risky, no thanks to their trend for high combustibility. We're not seeing this issue with lithium IRON batteries.

I'm really glad he got the battery out of there, and that it happened on the ground.

So, you have our attention: Was it a lithium IRON or lithium ION battery?
 
Thread search?

It seems very similar to a previous thread a while back. Search "A very lucky pilot"... Not sure how to link it..

[...Here you go...try this link It's in the Safety Forum, which is probably where this thread should be...dch...one of the moderators.]
 
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I have a swollen Odyssey PC545 on my bench from a friend's Hawk. It got overcharged due to a bad regulator on the Rotax.
You can't expect any battery chemistry to stand up to overvoltage conditions. It's easily preventable though.

Lenny
 
Battery Brand

The brand of battery was 'Extreme' and was indeed Lithium Ion. Apparently used by many experimental light sport builders and purchased from a dealer.
(Or was it a Samsung?!)
 
So if he jump started it I'm sure it went to full amperage charge, I know these things are sensitive to the amount of current in, they don't recommend jump starting a dead Lithium, rather charge it with the appropriate charger.
 
When Li gets too much heat and pressure

https://youtu.be/b5tmkna-k-U?t=1m17s


Only historic entertainment about the Castle Bravo miscalculation.

I believe the Earth X Lithium Iron batteries are developed to the point that I might try one in my own AC. As with any type of battery it is important to understand the ideal environment and use. More important is to understand what happens in a less than ideal discharge / recharge and temperature/vibration environment.

I like the thought of a sealed SS battery box with external ventilation.
 
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Jumping to Start

As an aside, to start the plane we jumped the starter rather than the battery.
The battery was installed so that the recommended (provided) charger was charging the battery and the Rotax charging system was actually feeding that charger.
Whenever I saw news shots of burning or exploding hover boards or phones, I think I subconsciously just assumed that those things happened to 'other' people.
Wake up call, to say the least.
But we both just ignored the fact that these things do not like to completely discharged, even if it IS our fault and we didn't want to trash a brand new (one hour old) $175 battery.
Lessons learned with no harm to anyone (except to the wallet).
 
Thanks for posting this info, but we would still like to know the brand, and did it have a battery management system built into the battery like EarthX?
 
bret said:
Thanks for posting this info, but we would still like to know the brand, and did it have a battery management system built into the battery like EarthX?
Click to expand...

Post 11 above. Sounds like it was an "Extreme" brand Lithium ION. No indication of BMS from a quick SOTW.
 
I searched, no, I did an extreme search for Extreme (including xtreme) batteries and found an extremely large number of offerings with a lot of extreme names. Maybe an extremely astute VAF member could narrow the field to definitively identify this battery model and manufacturer. It would be extremely helpful. Xtremely.

"new and improved"
 
Battery Brand

When I get back to my friend's hangar this weekend, I'll try to glean some brand information and/or part numbers from the blackened/burned case of the battery.
But it DID have a battery management system incorporated into the installation.
He's replacing it with an AGM sealed battery.
 
When people started using Lipo batteries (yes not exactly the same I know) in models there was a learning curve. People put crashed models in the trunk of their car and their car burned to the ground. Word got out via the internet and people started keeping buckets of sand at the flying field and at home and carrying their batteries in either steel ammo boxes or those portable fireproof home safes. Then came packs that were tapped for balancing circuits, smarter chargers, and just people being generally more careful. But I have a friend who had a major fire in his garage while charging and had he not been right there he could have lost his house.

So I would certainly consider a stainless and insulated battery box of some kind. Fire in a house or car or at a flying field is bad, but in an airplane at 2000 ft it is a whole different level of badness.

These batteries most likely can be dealt with by having over-voltage control, balancing and general battery management and protections on the charging circuit. But our homebuilts are so varied in the configuration of their electrical systems that it is really hard to be sure you have something robust. We won't do the testing for every scenario that a certified mfg will do, nor will we have the configuration control that they do. And look at what happened to Boeing with the 787 and they did tons of testing. Now the battery chemistry might be somewhat different than what Boeing had on the 787, but the overall concept is the same. This class of battery seems to be more sensitive to abuse and they seem to be much more liable to catch fire than an AGM battery. It seems like we are not yet there with the level of safety. The fires may be rare, and maybe they are usually the fault of the user, not the designer (I don't know) but when it happens it is real bad. We are all responsible for our own level of risk, so go in with your eyes wide open and a backup plan. AGMs still look real good to me. I'm sure we all could save that weight by more healthy means - like exercise and reducing carbs (guilty).
 
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There are many details not here to evaluate all the factors that lead up to this event but ANY lithium battery used with a Rotax 503 should not be used as they are not compatible due to the how crude the charging system are in these engines. To compensate for the design issues, Rotax uses a large capacity lead acid battery with this system (minimum of 16Ah) as a lead acid battery is much more tolerant to voltage irregularly. I would suspect the lithium battery used here was also severely undersized but I do not know that for a fact.

I also do not know any details about which particular battery manufacturer this is, but it is possible there were no warnings given about the use with this particular engine which is why I wanted to respond to this thread as there was warning signs prior to this event from the battery itself which will apply for any users of a lithium battery or lead acid batteries that need to be heeded.

First, any lithium iron phosphate battery that reads 10V needs to be evaluated before continued use as the odds of permanent damage to the cells at this level of discharge is very possible. What should have been done instead of jump starting the battery, is a slow amperage charge (around 2 amps) from the recommended charger from the battery manufacturer. If the battery did not charge on the charger, it would immediately alert you to a problem and to discontinue use. Never use a battery that will not accept a charge, no matter what the chemistry.

The second thing here is the fact the battery remained at a severely discharged state, and was used within a charging system that has poor voltage regulation. Do not do this with any battery, lead acid or lithium. Never try to use a battery that will not accept a charge.

All products have limitations and the continued use of a product that is defective can and will have a poor outcome. A quick example is continuing to fly your plane when you know that you have a gas leak, or you have bad tires for landing.

As EarthX was mentioned in this thread, I also want to point out that the EarthX aircraft specific batteries not only protect from the over discharge, over charge, short circuit, excessive cranking and cell balancing technology built in that is redundant, they also have an LED battery fault light indicator that alerts you with a solid or flashing light when you need to evaluate your battery as a possible problem exists. You must heed any warnings as they are there for a reason.
 
I understand the mistrust of lithium batteries in airplanes, and have shared this skepticism in the past. However its also interesting to reflect on how much energy is packed into your fuel tanks, and how dangerous it can be if not managed properly. By my calculation one gallon of gasoline contains roughly the same amount of energy (in joules) as about 250 batteries (assuming 12v and 12 a.h.). If a 12 a.h. lithium battery weighs 3 pounds, this means that you?d need 750 pounds of battery to equal 6 pounds of gas. Small wonder we don?t have practical electric planes yet!
 
I don't think that's a useful comparison because unless the gasoline is mixed at the right ratio with air, it won't have that energy capacity. You might say that a gallon of gasoline combined with roughly 1,200 cubic feet of sea level air, then it has that much energy.

If I understand it correctly.

Kind of like the difference between a jet engine and a rocket engine. One needs a lot of air and the other doesn't.

Dave
 
Don't get me wrong, I'm a fan of the (developing) lithium battery tech - but fuel tanks show a surprisingly low propensity toward bursting into flame than lithium batteries (so far).

No, it's not apples to apples - and that's the point - in the age of the Wright Brothers fuel tanks were much more likely to cause problems than they are today - and so were the engines. Technologies mature over time, it's the nature of the beast. Give this one some time to work out it's kinks and we may have something useful. Nobody is requiring you to install it if you don't want to - that's the great thing about Experimental category.
 
David Paule said:
I don't think that's a useful comparison because unless the gasoline is mixed at the right ratio with air, it won't have that energy capacity. You might say that a gallon of gasoline combined with roughly 1,200 cubic feet of sea level air, then it has that much energy.

If I understand it correctly.

Kind of like the difference between a jet engine and a rocket engine. One needs a lot of air and the other doesn't.

Dave
Click to expand...

I think you're correct assuming all of the energy has to be released at once (a fuel-air explosion). However I don't think this is the right comparison since the lithium battery didn't explode, it burned. You can certainly release all the energy in the gasoline if its allowed to burn more slowly.

My electric plane comparison wasn't quite right because only about 25% of the energy in gasoline can be converted into motion by an aircraft engine.
 
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airguy said:
Don't get me wrong, I'm a fan of the (developing) lithium battery tech - but fuel tanks show a surprisingly low propensity toward bursting into flame than lithium batteries (so far).
Click to expand...

I think anyone who has had a fuel tank rupture after a crash would strongly disagree with this statement (unfortunately many are unable). There's also been at least one RVer that I can recall who came to a tragic end due to an inflight fire.

I'm not 110% comfortable with lithium batteries myself yet, except of course the ones in my phone, watch, two laptops, RC airplane, etc... However I think my probability of being injured by a fuel tank is likely higher than being injured by a lithium battery. Hard to prove this of course since not many lithium batteries in service yet. I'll certainly watch mine carefully. I'm not that concerned however by reports of problems with batteries that are of a different design, that have been misused, or both.

airguy said:
No, it's not apples to apples - and that's the point - in the age of the Wright Brothers fuel tanks were much more likely to cause problems than they are today - and so were the engines. Technologies mature over time, it's the nature of the beast. Give this one some time to work out it's kinks and we may have something useful. Nobody is requiring you to install it if you don't want to - that's the great thing about Experimental category.
Click to expand...

Good point. But how will you know when the technology is "safe enough"? The Wright brothers had a 50% chance of dying in their creation; surely we're far beyond that point with lithium batteries. Lithium batteries in one form or another have been around for what, 50 years? They will never be 100% safe. Neither will gasoline, lead-acid batteries, or airplanes in general.

Good point as well concerning experimental aircraft. I have plenty of friends and acquaintances who think I'm taking an unreasonable risk every time I fly! The freedom this category provides is extraordinary.
 
Not for me

As holder of a patent concerning li ion batteries, they are not for me. I just dont see the advantage being great enough to offset the risk for a gas powered rv. Now if you are talking an all electric plane that would not get off the ground without a li ion battery, that is a different story. But i know of no RV that could not fly without li-ion. JMHO
 
Alan Carroll said:
I think you're correct assuming all of the energy has to be released at once (a fuel-air explosion). However I don't think this is the right comparison since the lithium battery didn't explode, it burned. You can certainly release all the energy in the gasoline if its allowed to burn more slowly....
Click to expand...

It takes the same amount of air to burn a gallon of gasoline regardless of the rate it burns. The air is the oxidizer and the gasoline is the fuel. Both are needed for combustion.

Dave
 
David Paule said:
It takes the same amount of air to burn a gallon of gasoline regardless of the rate it burns. The air is the oxidizer and the gasoline is the fuel. Both are needed for combustion.

Dave
Click to expand...

Dave,

We agree on that; I think I missed your point earlier. The gasoline poses no risk so long as it stays in the tank/fuel lines. My point is that sometimes it doesn't.
 
Always amuses me how some go to such great lengths to convince the entire group to conform to their level of risk tolerance, while they themselves fly in a plane that tens of thousands of certificated pilots wouldn't set foot. It's all personal preference, and thankfully, for a while yet, we in the US live in a country where the individual has the right to decide what level of risk is right for them. And further, someone's got to put the time on the new products so all the low risk people will feel comfortable using the new technology! ! Why are you trying to stop us?
 
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Confirmation bias.

https://en.wikipedia.org/wiki/Confirmation_bias


Low Pass said:
Always amuses me how some go to such great lengths to convince the entire group to conform to their level of risk tolerance, while they themselves fly in a plane that tens of thousands of certificated pilots wouldn't set foot. It's all personal preference, and thankfully, for a while yet, we in the US live in a country where the individual has the right to decide what level of risk is right for them. And further, someone's got to put the time on the new products so all the low risk people will feel comfortable using the new technology! ! Why are you trying to stop us?
Click to expand...
 
V111Pilot said:
Hmmmm. As I have earlier questioned L-ion battery safety, and was met with enthusiasm over EarthX (I own one) but I am still weary. Some say that because of their chemistry and protective circuitry they are safe.

Have a look at this though:

http://www.avidfoxflyers.com/index.php?/topic/2963-earth-x-battery-warning/

Thoughts?
Click to expand...

Read post #21 - The first paragraph clearly states that lithium batteries should not be used on a Rotax 503.

"There are many details not here to evaluate all the factors that lead up to this event but ANY lithium battery used with a Rotax 503 should not be used as they are not compatible due to the how crude the charging system are in these engines. To compensate for the design issues, Rotax uses a large capacity lead acid battery with this system (minimum of 16Ah) as a lead acid battery is much more tolerant to voltage irregularly. I would suspect the lithium battery used here was also severely undersized but I do not know that for a fact. "
 
Oh really . . . . .

F1R said:
Read post #21 - The first paragraph clearly states that lithium batteries should not be used on a Rotax 503.

"There are many details not here to evaluate all the factors that lead up to this event but ANY lithium battery used with a Rotax 503 should not be used as they are not compatible due to the how crude the charging system are in these engines. To compensate for the design issues, Rotax uses a large capacity lead acid battery with this system (minimum of 16Ah) as a lead acid battery is much more tolerant to voltage irregularly. I would suspect the lithium battery used here was also severely undersized but I do not know that for a fact. "
Click to expand...

Just where is this magic list of "approved" applications for EarthX - This clip is taken from their marketing brochure. I did not find any limitations or warnings in this document. It certainly implies ROTAX is approved. So, just what is a "bad" charging system, how long does a diode have to be bad in a good one to switch "smoke on" . This subject has not been adequately addressed - YET.

So which statement is clear??

EDIT: Searching EarthX website - it is clear that some applications are not compatible with a LiFeP battery of any brand. EarthX states this in several places. They also recommend that you contact them to discuss your system to see if any incompatibility exists. This is sound advice. I was stuck on the " approved" term and mistakenly so, as EarthX does NOT use that term in reference to experimental applications. I apologize for getting this off in the weeds with this particular issue.

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BillL said:
Just where is this magic list of "approved" applications for EarthX - This clip is taken from their marketing brochure. I did not find any limitations or warnings in this document. It certainly implies ROTAX is approved.
Click to expand...

Rotax makes a lot of different engines. The batteries in question may be approved with a 912iS (for example) but not on one of the two-stroke models. Approval for any given one of a manufacturer's products doesn't grant unlimited approval for all of that manufacturer's products.
 
rmartingt said:
Rotax makes a lot of different engines. The batteries in question may be approved with a 912iS (for example) but not on one of the two-stroke models. Approval for any given one of a manufacturer's products doesn't grant unlimited approval for all of that manufacturer's products.
Click to expand...

Yes, but EarthX talked about "approved" - I went back and looked at the website http://earthxbatteries.com/engine-charging-systems-use-lithium-batteries

This link addresses the AC content that is ok and not-ok. I would suggest that the marketing literature is misleading and worst, and just inaccurate at best.

Kudos for EarthX to have posted the waveform issues, now they can let us know about what happens with a failed diode on a 3 phase alternator.
 
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Clarification of marketing brochure

BillL said:
Just where is this magic list of "approved" applications for EarthX - This clip is taken from their marketing brochure. I did not find any limitations or warnings in this document. It certainly implies ROTAX is approved. So, just what is a "bad" charging system, how long does a diode have to be bad in a good one to switch "smoke on" . This subject has not been adequately addressed - YET.
Click to expand...


Dear BillL,

I am sorry the marketing brochure is unclear and this is not our intentions. It is impossible to have everything about a product listed in a small brochure.

We do list Rotax engines has approved our batteries but they have many, many engines that span years of production and the 503 is one that is not approved for use which we clearly state on our website in BOLD RED PRINT, also stated in the manual, and we also have a detailed Fact Sheet to outline why to clarify the reasons as we do try and provide information to our potential customers to help make an informed decision. http://earthxbatteries.com/engine-charging-systems-use-lithium-batteries


We also have Continental Motors that have approved our batteries for use and they have many, many, engines that span years of production including certified engines. Saying that Continental Motors approves our batteries does not mean you can use the experimental batteries with your certified engine as a bypass for FAA approval in a certified aircraft.

We also have many original equipment manufacturers (OEM's) that use the EarthX line in their experimental aircrafts but saying they approve the EarthX brand does not mean you can then put them in a certified aircraft from the same manufacturer.

The charging system of any aircraft is a very important component and no matter what manufacturer or part you use, it is very wise to research the application in depth before using it. This includes your alternator, regulator, and the battery, etc. You can always contact a manufacturer prior to purchase or use of their product to verify the application is correct for your system.

Hope this helps clarify things.
 
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The key item I don't understand is how the BMS failed to protect the battery.

I accept that the Rotax charging system is outside the parameters for what EarthX considers acceptable. I'd add that a runaway/overvoltage charging system on a Lycoming seems like it would be outside those parameters and would be one reason why the BMS is in place.

I have no dog in this discussion - I do not have or intend to purchase an EarthX battery for a variety of reasons - but find the engineering questions interesting.
 
ChiefPilot said:
The key item I don't understand is how the BMS failed to protect the battery.

I accept that the Rotax charging system is outside the parameters for what EarthX considers acceptable. I'd add that a runaway/overvoltage charging system on a Lycoming seems like it would be outside those parameters and would be one reason why the BMS is in place.

I have no dog in this discussion - I do not have or intend to purchase an EarthX battery for a variety of reasons - but find the engineering questions interesting.
Click to expand...

Thank you for the question as this illustrates perfectly why it is so important to educate yourself about using a product and it's applications.

If you are referring to this particular issue at the beginning of this thread, we have no idea what brand of battery, the spec's or any details about any type of built in protection, if any, with the battery that had an issue. But all products are built with limitations and that is why, especially in the battery world, there are application charts as one size battery does not fit all applications.

If you are referring to the thread where the EarthX battery was used in the Rotax 503 which caused a cell to rupture and the electrolyte came into contact with the plastic and caused a chemical reaction which made the plastic appeared melted, I can address that:

1- The battery used was 4 times smaller in capacity than the recommended lead acid battery for the engine by Rotax and also not one of the aircraft specific batteries that are recommended at EarthX for aircraft use. Using an undersized battery for any application causes extreme stress to the battery, whether it is lead acid or lithium. The reason for application charts is based on the ability and design of the limitations of a battery.

2- The user did not heed all warnings from EarthX's website to not use any lithium battery with this engine and charging system.

3- The electrical wiring on the plane was done incorrectly.

So your question is, why did the BMS not protect the battery even when all else failed? The BMS in this battery was designed for a motorcycle back in 2014 when this occurred. The rate or speed of voltage irregularities was too quick for the BMS to block and too erratic (which is why we warn not to use it). Add the amount of over stressing due to being such an undersized battery did not help.

Even with all the misuses (or abuses) here, the battery did not catch fire, did not "explode" nor did it cause smoke. This is what we would consider a catastrophic failure and a cell ruptured inside which released the electrolyte which once in contact with the plastic, will cause it to appear melted.


As a manufacturer, you have no control over what someone does with your product. The best you can do is try diligently to explain it's used and limitations. If you ever have questions about a product and it's use in your system, call the manufacturer and get clarifications.
 
ChiefPilot said:
The key item I don't understand is how the BMS failed to protect the battery.

I accept that the Rotax charging system is outside the parameters for what EarthX considers acceptable. I'd add that a runaway/overvoltage charging system on a Lycoming seems like it would be outside those parameters and would be one reason why the BMS is in place.

I have no dog in this discussion - I do not have or intend to purchase an EarthX battery for a variety of reasons - but find the engineering questions interesting.
Click to expand...

I'm not sure how the BMS would protect the battery except by disconnecting itself from the buss. That would then allow the voltage to go even higher possibly damaging expensive AV equipment. Having over voltage protection built into plane's electrical system maybe a better solution.
 
jj13 said:
I'm not sure how the BMS would protect the battery except by disconnecting itself from the buss. That would then allow the voltage to go even higher possibly damaging expensive AV equipment. Having over voltage protection built into plane's electrical system maybe a better solution.
Click to expand...

While I completely agree that OV protection is best built into the plane's electrical system for a variety of reasons, I thought that disconnecting the battery from the bus in such a case was one of the things the BMS was supposed to do.
 
jj13 said:
I'm not sure how the BMS would protect the battery except by disconnecting itself from the buss. That would then allow the voltage to go even higher possibly damaging expensive AV equipment. Having over voltage protection built into plane's electrical system maybe a better solution.
Click to expand...

That muddies the water. OV protection for installed equipment is a completely separate issue, and would apply no matter the battery chemistry.

To EarthX:
Saying that a solid state battery management system can't respond quickly enough to handle a noisy charging system, and blaming the charging system, just makes no sense to me, from an engineering perspective. If the company is uninterested in making the BMS capable of handling the transients, just say so & publish the excursions that it *can* tolerate. As others have pointed out, *any* charging system can have failure modes that will likely cause similar voltage/noise excursions to the Rotax. If the BMS isn't designed to handle those excursions, then the same problems can occur with a Lyc, Cont, etc, and the battery cannot be considered a 'drop in' replacement for a lead-acid battery, as your marketing implies, even if it doesn't state it explicitly.

Please don't misunderstand the seemingly negative posts you're seeing. I for one would love to have the weight savings, and want the product to be successful. But your operational limits and many statements you've made here over the last few months don't give me a warm & fuzzy feeling that you understand your own product. Another example is your limit to charging system size. I'd love to hear a rational explanation for this, since if flies in the face of any practical application I've ever heard of. Ex: a 12v 5w lamp doesn't care if it's powered from 8 AA cells, or a farm tractor battery capable of supplying 600 cold cranking amps. It just takes what it needs & leaves the rest. Why is your BMS any different?

Charlie
 
rv7charlie said:
That muddies the water. OV protection for installed equipment is a completely separate issue, and would apply no matter the battery chemistry.

To EarthX:
Saying that a solid state battery management system can't respond quickly enough to handle a noisy charging system, and blaming the charging system, just makes no sense to me, from an engineering perspective. If the company is uninterested in making the BMS capable of handling the transients, just say so & publish the excursions that it *can* tolerate. As others have pointed out, *any* charging system can have failure modes that will likely cause similar voltage/noise excursions to the Rotax. If the BMS isn't designed to handle those excursions, then the same problems can occur with a Lyc, Cont, etc, and the battery cannot be considered a 'drop in' replacement for a lead-acid battery, as your marketing implies, even if it doesn't state it explicitly.

Please don't misunderstand the seemingly negative posts you're seeing. I for one would love to have the weight savings, and want the product to be successful. But your operational limits and many statements you've made here over the last few months don't give me a warm & fuzzy feeling that you understand your own product. Another example is your limit to charging system size. I'd love to hear a rational explanation for this, since if flies in the face of any practical application I've ever heard of. Ex: a 12v 5w lamp doesn't care if it's powered from 8 AA cells, or a farm tractor battery capable of supplying 600 cold cranking amps. It just takes what it needs & leaves the rest. Why is your BMS any different?

Charlie
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There are pluses and minuses with any solution. Clearly there are some big pluses with LiFePO batteries, light weigh, lower internal resistance and maybe life span. There are minuses; high cost, cold weather use, over discharge and overcharging/voltage spikes intolerance. The BMS helps mitigate some of these disadvantages, but not all. I?m not sure technically how the BMS could protect the LiFePO cells and at the same time filter out the voltage spikes. To do that would require clamping down on the voltage spikes likely generating a lot of heat that would need to be dissipated. Where the lead battery with is weight and mass is better suited to filter and dissipate that heat. I would not want the BMS to open the connection to the cells to protect the battery allowing the voltage spikes to travel through the plane?s electrical system with no filtering effect. Not all planes have OV protection, but I do think you should have it when using a LiFePO battery for sure. I personally feel EarthX has developed a very good solution installed correctly and when used in the type of environments most of fly in.
 
Pylon Mount Battery- Jettisonable

DanH said:
Appear melted? Tell us more. The electrolyte will dissolve a plastic battery case? What is it?
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I can see it now, Dan's RV 8 with a jettison-able pylon mounted earth X that looks like a sidewinder or some low drag area rule tube like a T-38 wing tip tank:D
 
F1R said:
I can see it now, Dan's RV 8 with a jettison-able pylon mounted earth X that looks like a sidewinder or some low drag area rule tube like a T-38 wing tip tank:D
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Naaa. All I'll need is a VPX, an extra EFIS screen, and a battery management checklist so I'll know what to do when lights flash.

Sheesh. I have a light for battery management. Once a year I open the hellhole and shine a flashlight on the battery. Here's my checklist:

Is it still there? Yes__ No __

Ok, done for another year ;)
 
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