lithium batteries

[Bruce Tuncks]

I reckon that battery was illegal for sure in a VH plane, but it may also have been illegal in a 19 reg Jabiru. I think the article I had said that the guy had built the plane from a kit. The wife read the article and got angry with me for saying how he caught fire unnecessarily.

Mind you, the quality of the report was poor and there may be misleading bits there. It was obvious to me that the reporter knew nothing about batteries, for example.

[RFguy]

More likely to be something like wire through a firewall without suitable isolation relay/contactor etc I would think. I think most Jabiru's have a serious hazard in that department. 

[Bruce Tuncks]

please tell us more rf.

I think you mean that the wire could short at the firewall. Is this your point?

 

[sfGnome]

I had a battery wire short out to the firewall in a Mini many years ago. The car instantly filled with impenetrable smoke and I bailed quick smart. I’d hate to have that happen at altitude…

[kasper]

On 14/11/2021 at 9:07 AM, Bruce Tuncks said:

I reckon that battery was illegal for sure in a VH plane, but it may also have been illegal in a 19 reg Jabiru. I think the article I had said that the guy had built the plane from a kit. The wife read the article and got angry with me for saying how he caught fire unnecessarily.

Mind you, the quality of the report was poor and there may be misleading bits there. It was obvious to me that the reporter knew nothing about batteries, for example.

How could a battery be illegal on a 19- reg airframe??

 

The manufacturer of the engine cannot stop you using a battery - its not part of their engine (and you modify that anyway) - and I do not recall any Tech Manual areas that would mean RAAus have anything to say to you ... so how can it possibly be illegal?

[Markdun]

My guess that instead of blaming the battery, the more likely culprit is the absence of adequate circuit protection in many Jabiru powered aircraft, including factory made. How many have unfused wire cables from the battery going through the firewall to the circuit breakers and master switch on the panel?  No battery fuse!  How many have no fuse or circuit breaker in the AC circuit from the alternator to the voltage regulator?  And how many installations have yet to ditch the plastic Voltage regulator connector which has a pretty consistent burn/melt rate caused by corrosion and poorly fitted connections, not to mention that some lithium batteries and their BMS just weren’t designed to cope with the standard voltage regulator output.

 I’ve got lithium batteries in my Jabiru powered aeroplanes..... saves heaps of weight, cranks engines over really fast; don’t lose charge when not used regularly; and the battery is not wrecked if flattened. But i do have a 20A fuse in the alternator AC circuit; I do have a 150A (starter motor) and a 50A (12v bus) fuse on the battery terminal, and I have a voltage regulator that regulates voltage and current and doesn’t need a huge capacitor or lead acid anchor battery to temper the avionics killing voltage spikes produced by standard voltage regulator.

[Bruce Tuncks]

I have used LiFe batteries in my Jabiru for more than ten years and I agree they are much better. I only have a standard Jabiru voltage regulator which would damage the battery if left on. So I use a digital voltmeter in the panel and shut off the battery when it is back up to pre-start voltage. The battery is no more in the circuit then than it is sitting in the hangar.

The only 2  problems with this setup are that the master is OFF during flying and I have to remember to cut out the charger manually.

[Markdun]

Bruce, that’s all fine, but do you have unfused wires from the battery going through your firewall; is there a fuse in one of the wires (AC) from the alternator to the VR, or in the wire from your VR to your switch to turn charging off?  It’s not whether it works when everything is working but what happens when there is a failure.  I’m cautious because I’ve had an inflight ‘blue smoke’ cockpit in a Jab powered plane I was delivering caused by the standard VR outputting to much current caused by a failing lead acid anchor battery, the VR allowing the bus voltage to exceed 15.5V, and the fool in the pilot seat (me) toggling the charge switch every 5 minutes to keep the bus voltage between 11.5 and 14V.

  Glenn raised the issue with my setup in that the lithium batteries’ BMS will isolate or disconnect the battery if voltage drops below 11 volts, in which case my 12V bus would be powered by the VR with no battery and this could fry my avionics.  Worth thinking about.

[tillmanr]

The aircraft could be a VH experimental assembled from a kit and modified legally .

 I have heard that the battery was on the floor of the passenger side. Not sure if this is correct or myth.

[Bruce Tuncks]

Thanks Markdun.

I take your point and I will look at the plane soon and tell you.

[RFguy]

Again, I feel , based on my I think extensive professional experience with LIFEPO4 batteries , that all LIFEPO4 battery  fires are to blame on a wiring fault and the lack of a master master  isolation relay at the battery. 

[Markdun]

Glen, agree.  Potential higher currents (& reduced voltage drops) just more likely to show up wiring faults.  But wouldn’t an isolation relay just do two things: (a) enable the pilot to isolate the battery after the blue smoke emerges (a good thing to be able to do); and (b) prevent a runaway burn out, short when the plane is shut down, ie. no live wires going through the firewall or elsewhere for rodents to chew through etc (also good).  I don’t get how they would stop, say, a VR or stator windings in the alternator catching alight because a lithium battery has a lower resistance than a lead acid battery and may allow charging currents to exceed the capacity of the wiring, connectors or the VR and stator, or indeed a wire glowing red hot because it has shorted out going through the firewall.... with no fuse or circuit breaker protection at the battery?  
The lithium batteries we use are intended to be drop in replacements for lead-acid batteries in cars and motorbikes and have a BMS that is meant to handle the differences.  How many fires do they have in cars and bikes?

In my view, if someone wants to drop a lithium battery in their plane they should, in order of priority, do the following:  (a) eliminate wiring faults and review capability of the wiring to handle higher currents; (b) ensure adequate protection with fuses and/or circuit breakers at the battery terminal and in the charging circuit as an absolute minimum (applies equally to lead-acid batteries); (c) install a current limiting device in the charging circuit (either integrated in the VR or the various DC-DC lithium charging controllers now available for 4wds); and (d) install a cockpit controlled battery isolation device.  People with electronic ignition or EFI may want something a bit different too.

[Old Koreelah]

On 14/11/2021 at 10:40 PM, sfGnome said:

I had a battery wire short out to the firewall in a Mini many years ago. The car instantly filled with impenetrable smoke and I bailed quick smart. I’d hate to have that happen at altitude…

I once came across a mini on fire. Stopped, got out my extinguisher and rushed across to help. The owner shooed me away, saying “let it burn”.

 

Insurance?

[APenNameAndThatA]

12 minutes ago, Old Koreelah said:

I once came across a mini on fire. Stopped, got out my extinguisher and rushed across to help. The owner shooed me away, saying “let it burn”.

 

Insurance?

Fire extinguishers are expensive. 

[spacesailor]

Fire extinguisher,s are a waste !.

When used on Other people's property.

You,d be lucky to get a " thak you " after puting out a car fire, knowing it Will be trucked away & written off by the insurance  Company. ' let it burn ' is not such a bad thing when there,s no good at the end !.

I have lost two now, for others fires !.

spacesailor

[sfGnome]

2 hours ago, Old Koreelah said:

I once came across a mini on fire. Stopped, got out my extinguisher and rushed across to help. The owner shooed me away, saying “let it burn”.

 

Insurance?

Couldn’t have been me. I couldn’t afford insurance back then! 😝

[onetrack]

I'd only use my extinguisher on a fire where lives were in danger (people trapped in the vehicle). Otherwise, I'd let it burn. It only takes a small fire for anything to be declared a write-off today, anyway.

[Bruce Tuncks]

Once I was going to an aboriginal settlement out of Alice Springs with 2 tradies in a govt ute. Then smoke came from under the hood. One guy got the extinguisher out while the other guy lifted the hood on the signal from the extinguisher guy. Well the plunger came right out of that extinguisher, so we retired and waited under a gum tree.

Then the fire went out and the ute started ok.