The issues surrounding lithium batteries.

[RFguy]

and people out there , watch out of USB chargers. they are notoriously RF noisy. they will produce carriers through the VHF aircraft band that drift around depending on their temperature.... If anyone wants advice on in aircraft EMI ,well, that is my professional game.....happy to comment / help

[spacesailor]

YES I noticed when using a phone charger next to my radio it makes a bad noise.

spacesailor

[Kyle Communications]

USB chargers most are crap..anything that is any good...like the ones that you can get from Belite and the mob that make those nice flush ipad mounts are really expensive...thats the reason they are expensive..they are quiet

[Kyle Communications]

Guardian avionics thats who it is

https://www.guardianavionics.com/Single-USB-Power-Supplies-FAA-Certified_c_85.html

 

The Belite being much cheaper

http://www.beliteaircraftstore.com/usb-c-a/

[RFguy]

just put some 0.01uF disc ceramics , minimal lead length. across the in and out voltage wires. the cheap-arse mfrs seem to omit them so the leads become the HF capacitors.

 

problem will (likely) go away.

 

and if you are really stuck, or if the position of the antenna is close to the cabin in a composite, some 43 type ferrite sleeves over the cable. I have plenty if anyone wants them to try I'll post them gratis.

Edited August 11, 2020 by RFguy

[Thruster88]

I am a industry user (non aviation) of batteries. Comms, remote sites, high temp environments.

The biggest industry problem is people confusing LiFePO4 (3.25 terminal voltage, 3.65 max) with "lithium poly and lithium ion' (3.7V terminal, 4.1 / 4.2V max) .

They have very different behaviours, they are very different batteries.

I would have a LiFePO4 battery in my plane any day. They are essentially unconditionally stable and safe. I would rather not have a Lead Acid because of the rather nasty failure modes. I would NOT permit a 'Lithium ion' in my plane. No way. Not ever.

pronounced - LiFePO4 "Life - poh" and Lithium Ion often referred as " lie-po" or "lie poly"

 

This might interest you. I am not 100% sure of the battery type involved

https://www.atsb.gov.au/publications/occurrence-briefs/2018/aviation/ab-2018-124/

[RFguy]

This might interest you. I am not 100% sure of the battery type involved

https://www.atsb.gov.au/publications/occurrence-briefs/2018/aviation/ab-2018-124/

Yeah I wrote to the ATSB and told them I thought their conclusion/ summary was wrong, and that Lithium battery chemistry varies, and that their understanding of these batteries needs to be improved, since stability varies across the variations. I pointed out to them that their blanket warnings were simplistic and outdated.

and it did it in a nice, not too public service threatening way...

 

My guess is from what I read that this was a LFP (LiFePO4) battery since, there are not any "lithium ion" batteries that have compatible voltage ranges with aircraft systems, and that it is actually quite hard to buy a "lithium ion' packaged suitably for this sort of work- it is all LFP. And indeed theATSB report stated it had a Deltran "Lithium-ion Phosphate" battery. ATSB do not understand their battery chemistry.

 

Someone else pulled this up in

https://vansairforce.com/community/showthread.php?p=1326970

 

post 24

 

In fact I cannot even find any facts that this is a LFP battery, just a Lead acid cell.

 

It would appear their understanding has lumped LiFePO4 (or LFP) in with remote control car, drone, phone batteries and all that rather touchy high energy density high volumetric efficiency battery tech (that varies enormously in quality) . There ARE good quality Cobalt electrode cells but they still have thermal runaway challenges much earlier than LFP. And of course further work is ongoing with improving the safety of cobalt electrode based batteries. The LFP are all phosphate eng electrodes.

Edited August 14, 2020 by RFguy

[Bruce Tuncks]

Roscoe, there is no need for you to change from the Odyssey. My SK has a legal max auw of 430 kg, so the 5kg weight saving from changing from the Odyssey to the LiFe was worthwhile. My old Odyssey is now doing great service in the farm buggy.

Unless you are an electronics nerd or hobbyist, and you have payload problems, I suggest you stick with what you have got.

Once I left the master on for a week and the Odyssey was dead flat . I thought it was ruined, but it charged up fine and is still going after more than ten years total time. You can't do that with a LiFe battery.

And thruster, the battery involved in that fire was a lithium ION. RFguy is quite correct about these when he said he would not put one of these in his plane. That mishap was worth knowing about, thanks for the info.

[RFguy]

do that with a LiFe battery.

And thruster, the battery involved in that fire was a lithium ION. RFguy is quite correct about these when he said he would not put one of these in his plane. That mishap was worth knowing about, thanks for the info.

Bruce just reread it carefully- ATSB put the battery into the "lithium Ion category" but was actually a LFP (LiFePO4) or lead acid. I not sure if it was LFP or PbSO since I cannot find specific mfr battery data on the Deltrin 330 battery.

[RFguy]

Vibration : Now, what I DO NOT KNOW, is the vibration induced failure modes of LFP batteries compared to PbSO4 . My understanding is that most PbSO batteries in aircraft are a sort or variation of an AGM . I have seen cell shorts even in those batteries, but only when they were mechanically damaged.

 

The jelly/mat structure of both AGM and LFP batteries means internals are well vibration damped. but this does not mean there are not material migration modes when exposed to specific vibration modes, and there would be many modes in an aircraft.

[Old Koreelah]

Bruce just reread it carefully- ATSB put the battery into the "lithium Ion category" but was actually a LFP (LiFePO4) or lead acid. I not sure if it was LFP or PbSO since I cannot find specific mfr battery data on the Deltrin 330 battery.

 

This contributor to the VANsairfirce site (link in Glen's post #. 57) says:

The report said the battery was a Deltran 330 Lithium-ion Phosphate battery. The Deltran 330 is not a lithium battery. It’s constructed with lead calcium alloy and absorbed glass mat technology. By the way, this isn’t even an aircraft battery: It’s for motorcycles, go-carts, and the like. http://products.batterytender.com/Ba...t-Battery.html

 

Bruce just reread it carefully- ATSB put the battery into the "lithium Ion category" but was actually a LFP (LiFePO4) or lead acid. I not sure if it was LFP or PbSO since I cannot find specific mfr battery data on the Deltrin 330 battery.

Crickey that's confusing; can anyone say definitively if the burnt J-170's battery was a LiFePO4 or not?

[Thruster88]

The report is also confusing, at one point it said the fire "began in the cockpit" so it could have been the jump pack.

[onetrack]

The Deltran 330 is most certainly a LiFePO4 battery. The person who stated it wasn't, and that it's a lead calcium alloy battery, is simply wrong.

 

https://www.cycleworld.com/2013/07/08/deltran-lifepo4-lithium-batteries/

[RFguy]

The Deltran 330 is most certainly a LiFePO4 battery. The person who stated it wasn't, and that it's a lead calcium alloy battery, is simply wrong.

 

https://www.cycleworld.com/2013/07/08/deltran-lifepo4-lithium-batteries/

 

confusion rains/reigns. I think that person saw the Deltran 330CCA- a 330A CCA rated Lead acid, of similar name.

 

Whatever the cause it is really hard to come to any conclusion since we do not have any solid forensic information about the crash. I dont think we have any fact traceable conclusion about the a crash except the aircraft had a LFP battery on board.

 

All the fires I have seen with LFP (LiFeSO4) or PbSO batteries have been because the battery fell over or moved and the terminals touched the chassis.... The wiring was fused but terminals were open and un protected.

Edited August 15, 2020 by RFguy

[onetrack]

There are about four main causes of battery problems creating a potential fire problem - overheating, a short circuit, incurring physical damage by being struck or penetrated by an object, and the battery coming loose in its cradle.

 

The last one is pretty easy to ensure it doesn't happen. Even in road vehicle situations, authorised inspection officers (police and others) check for battery security in its cradle. An aircraft is no different, you ensure battery hold-down security.

 

Being physically damaged by being struck or penetrated is largely eliminated by secure hold-down. But a battery in an aircraft could be struck or penetrated by a foreign object. The chances of that happening are probably too low to worry about.

 

Similarly, a short circuit is something that has a low likelihood of occurring if the installation is carried out with minimisation of short circuits in mind. A short circuit is nearly always as a result of unexpected battery movement, so revisit "battery security".

 

But overheating is a potential problem with any battery. Overheating comes from heavy battery loads or charging processes that are not correct for the battery. All LiFePO4 batteries are reliant on a reliable BMS to ensure correct charging and levels of current drawdown. As a result, the BMS is the most likely source of any LiFEPO4 battery failure, so this is the weak link in the chain.

 

Fortunately, LiFePO4 batteries have been proven to be difficult to ignite, and if overheated or damaged, they will merely smoulder heavily, and do not commence a frightening thermal runaway, with sheets of flame, as do other types of Li-Ion battery do. As a result, I have yet to see a fire or disastrous result from any LiFEPO4 battery "incident".

 

Note that the original Dreamliner Lithium battery fire problems were due to the use of LiCoO2 (Lithium Cobalt) batteries, which were the best available Lithium battery technology in 2007.

Since that time, LiFePO4 and LiMn2O4 (Lithium Manganate) have superseded earlier Lithium battery types, where battery fire safety is critical.

[Kenlsa]

Life was so much simpler when all we had to complain about was Lucas - "the prince of darkness"

Ken

[Bruce Tuncks]

Ken, here is an irrelevant story about Lucas. An ex-manager ( Lucas) topped our "mark up" stories with how Lucas charged $1400 for a european fuel pump which Lucas got for $70.

I think it was for a BMW but we couldn't get him to say more .

ANYWAY, my LiFe battery only starts the engine and is switched out of any circuit, including charging, well before takeoff. It is therefore no more likely to catch fire than it is switched off in the hangar, like it is right now.

As for battery management systems, I like onetrack's comments. Be careful to understand just how the bms works before buying. And, before buying, don't be fooled by " lead acid equivalent" stuff which I reckon is a rip-off idea.

But let's not be all too fearful. The rest of the world is going ahead with battery planes and cars and we will be left behind if we are too scared to move forward.

[Tasmag]

It was definitely a lifepo4 battery in the J170, I had a good look at the damage and I am off the opinion that the Reg caught fire, not the battery.

 

I believe the Reg overheated because the battery had failed and without the internal resistance of lead acid the alternator just kept producing more power until the Reg ignited.

 

This is supported by the findings that the fire started within 400mm of the battery, from memory.

 

Just my opinion though.

[RFguy]

It was definitely a lifepo4 battery in the J170, I had a good look at the damage and I am off the opinion that the Reg caught fire, not the battery.

 

I believe the Reg overheated because the battery had failed and without the internal resistance of lead acid the alternator just kept producing more power until the Reg ignited.

 

This is supported by the findings that the fire started within 400mm of the battery, from memory.

 

Just my opinion though.

mmmmmm rreally ?? naaaaa I dont buy it. caught fire? that would imply it was made of something combustible. A circuit PCB and some electronic components wont make much fire. maybe some smoke. Its already high temperature under the cowlings. The LIFEPO batteries wont fail like that, I have never seen a cell go short circuit, only high resistance. But if the battery was flat or for some reason discharged, the charging system may have been overloaded. But, the fuse should have blown between the regulator and the battery.

 

Is there a fuse between the alternator+regulator and battery ?

 

***

Now, what I have seen happen (automotive) was the diode pack in the alternator went short circuit.

 

The regulator passed the current from the battery back through the diode pack , hundreds of amps.

 

So the entire battery current capability would have been in the wiring and the alternator. which *might* melt the battery I dunno, the cabling in the pictures I have seen is just not that big.

 

If the regulator also had high current + and -, the same thing could happen with the reg.

 

Oh and just how hot is the battery getting where it is, does it see any radiant heat? Those heads are hot.

 

I'll have to get a look at a few Jabs so I am not talking out of my backside.

Edited August 16, 2020 by RFguy

[onetrack]

An alternator can produce enough AC current to turn it into a highly satisfactory welding power supply. If that high AC voltage got loose, I could sure imagine some serious fireworks.

[RFguy]

yeah true, but these are little alternators, comparively , and they are not going fast- they barely make output at 50% of running RPM.

 

Depending on what the alternator speed was, it might look like like a nice constant current source - IE a welder.

 

Get the arc started and you can set fire to anything that will burn

 

I would be thinking it takes a couple of failures to make this all happen- failed electric component, and unsuitable rating on a fuses.

 

The thing is , its all about the power . 40Amps x 12V = 480W. 480W in a small place can make fires.

 

Also, many large power semiconductors fail as short circuits. This is because they turn into silicon puddles !!

[RFguy]

I am going to add a bit more here. This is just from precautions in high power electronics.

 

If an arc gets going, it can burn or ignite almost anything. That's dangerous. If whatever it burns is not self extinguishing, that's bad also.

 

The inductive nature of the alternator output circuit might behave as a good welder. Remember simple stick welders are power supplies with inductors in series . It would depend on the alternator winding, mag circuit, all sorts of things.

 

This sort of problem is hard to solve with a fuse or circuit breaker. (This fact has been covered in other topics on these forums.)

Why ?

Because the 40 amps going into a battery is the normal. That current is turned into chemical energy. All is good.

Of course 40 amps going into an arc is not normal

 

But a fuse or CB cannot tell the difference .... 40 amps is 40 amps

 

The alternator behaves like a current limited device . So, there is some energy limit to the arc.

 

The battery current output is only likely limited by the wiring.

 

So, an arc with energy coming from the battery is more likely to blow a 50 amp fuse because the battery can supply 500 amps to blow it fast. It depends on the maximum electron density that can be got at the arc point, and the battery wiring size.

 

This problem of the fuse not knowing if there is a fault or not is sometimes mitigated with source and load gating.

I will make an example that suits this one: TWO current points are measured.

If the current measured leaving the alternator is NOT the same as the current measuring going into the battery, well then you have a problem .

 

So, care must be taken in design not to permit arc paths to sustain.

 

Lightning can do damage in electronics because the high voltage pulse permits an arc to establish, and then the supplying circuit goes on happily supplying current to the arc. ... Hence the need to meter the destination of the source of the energy to ensure it is going where it should.

[Markdun]

I am going to add a bit more here. This is just from precautions in high power electronics.

 

If an arc gets going, it can burn or ignite almost anything. That's dangerous. If whatever it burns is not self extinguishing, that's bad also.

 

The inductive nature of the alternator output circuit might behave as a good welder. Remember simple stick welders are power supplies with inductors in series . It would depend on the alternator winding, mag circuit, all sorts of things.

 

This sort of problem is hard to solve with a fuse or circuit breaker. (This fact has been covered in other topics on these forums.)

Why ?

Because the 40 amps going into a battery is the normal. That current is turned into chemical energy. All is good.

Of course 40 amps going into an arc is not normal

 

But a fuse or CB cannot tell the difference .... 40 amps is 40 amps

 

The alternator behaves like a current limited device . So, there is some energy limit to the arc.

 

The battery current output is only likely limited by the wiring.

 

So, an arc with energy coming from the battery is more likely to blow a 50 amp fuse because the battery can supply 500 amps to blow it fast. It depends on the maximum electron density that can be got at the arc point, and the battery wiring size.

 

This problem of the fuse not knowing if there is a fault or not is sometimes mitigated with source and load gating.

I will make an example that suits this one: TWO current points are measured.

If the current measured leaving the alternator is NOT the same as the current measuring going into the battery, well then you have a problem .

 

So, care must be taken in design not to permit arc paths to sustain.

 

Lightning can do damage in electronics because the high voltage pulse permits an arc to establish, and then the supplying circuit goes on happily supplying current to the arc. ... Hence the need to meter the destination of the source of the energy to ensure it is going where it should.

Seems like a lot of confusion here. I have lithium batteries in my planes for several years now. No problems. I do have Powermate voltage/current regulators, a 15A fuse in the AC side of the regulator, & 150A fuse at the battery terminal (like a motor vehicle). My lithium batteries are ‘ion’ as opposed to lithium metal, and ‘iron’ as in ferrous. They have their own BMS and are marketed as being drop in replacements for lead anchor batteries for motor bikes and race cars. They weigh nearly nothing. Both are mounted on the firewall on the engine side.

My experience is that they deliver exceptional current while maintaining voltage for starting the Jabiru donks. They turn the first few blades through compression very slowly, but then you have the engine whirring at over a 1000rpm. They really spin it up once the battery warms itself up a bit. On colder days it may take a bit more to get the battery warm.

The batteries can sit for months and still appear fully charged with over 13.2V. In my set up the batteries charge at the Powermate regulated rate of a bit over 8A after startup and it all settles down in a few minutes to 14.2V and 2A for my EFIS/EMS etc.

My only concern is whether the cranking power is a bit too much for the Jabiru flywheel.

As to fire risk, firstly, my understanding is that this comes mainly from lithium metal batteries. Dendrites off lithium metal grow across the anode andcathode to give you an internal short circuit. Second, some batteries come in flexible bags and damage to these bags can also cause internal shorts. Third, the BMS should prevent charging or discharging currents in excess of the batteries capacity. Fourthly, I use fuses in both the charging and discharging circuits, & the Power matE prevents the alternator doing a runaway current job... as well as the fuses. Fifthly, my batteries are mounted forward of the firewall.

Finally, I have had a Jabiru alternator do a complete meltdown in the air (blue smoke in cockpit) about 10 minutes after takeoff, just following a quick fuel and bladder stop after a 2.5 hour trip (so it’s not like the battery was deeply discharged). That set up had the standard Jabiru/Kubota tractor voltage regulator and a lead-acid battery. On landing we found the copper windings on the alternator had dropped molten copper onto the carb, & the reason the blue smoke cleared was the alternator went open circuit. I have noted that the Jabiru engine installation manual does not recommend a fuse in either the AC circuit from the alternator to the voltage reg. nor a bartery terminal fuse. On my view those fuses, whichcost a couple of dollars, ought to be considered essential. I was lucky; the molten copper could have started a fuel fire from the carb; or instead of the alternator burning out, I could have had an actual in cockpit fire from the battery wiring burning or the regulator which were mounted aft of the firewall and forward of the instrument panel..... and directly above the 67litre fibreglass fuel tank.

[Old Koreelah]

Very informative, Mark. Good to hear of another Powermate matched to Li battery setup. Sounds like it's working well, so that gives me more confidence in mine.

I installed my Powermate in a good stream of cooling air and the LiFePO4 battery behind the firewall.

I've also installed a fuse between alternator and battery, but haven't got one on the output side of the battery, but will soon.

[Old Koreelah]

...I have lithium batteries in my planes for several years now. No problems. I do have voltage/current regulators, a 15A fuse in the AC side of the regulator, & 150A fuse at the battery terminal (like a motor vehicle)...

Mark based on your post, I've been trying to locate the most suitable fuse for my battery (small, lightweight). My electrical mates think 150 A is overkill for my a J2.2. Are your Jabs 4s or 6s (and would that make any difference to the size of fuse needed?)

 

In trying to relocate this thread, I came across a related discussion a few years back with this interesting contribution from a well-respected source:

https://www.recreationalflying.com/threads/battery-isolator.23440/#post-264636