SkyView Battery Overheat

I opened up my Electronics compartment to install ADS-B, return the Engine Monitoring module to Dynon for fix of the "known problem" of spiking EGT indications while transmitting, and to seal the compartment against possible water intrusion per the latest RV-12 Service Bulletin.

And guess what I discovered to my horror?! A partial melt-down of the SV back-up battery! This is another word for a lithium flare: ask any Boeing engineer! A definite safety-of-flight item. Although mine had not failed or fully burned, the damage was a clear indication of excessive heat.

Due to its installation within the electronics compartment, we cannot see, feel, or monitor this battery in any way. Nor could we reach it with a fire extinguisher.

Has anyone else had this problem? It should be of immediate concern to Vans, Dynon and any who take the RV-12 aloft.

Jim

Yikes! And Yikes again!

During the 787 Li Batt problems, my Boeing pals all asked if I had any Li batts on my airplane - I said three - the SV + 2 in the ELT. Those are right next to the fuel tank, and look identical to the batts on the Ethiopian 787 ELT that burned up at London-Heathrow. They have the same chemistry too.

I'm wondering if a VFR pilot really needs a SV backup power source.....

Then, there are all those iPads and such - me thinks they have Li batts as well.

Bob Bogash
N737G

Bob,

Yes, I agree. Now, even if Dynon replaces my SV battery, and I install it and press on my merry way, is it safe? Why did this happen? Will it happen again? I know there is much science and many parameters associated with lithium battery technology. For example, the charging rate cannot exceed 10% of the battery's amp rating. Has Dynon taken all this into consideration? Are there other RV-12's out there with over heated SV batteries? I mean, how often do we inspect the electronics compartment?

If you recall, the problem with the loose engine-mounting bolts was not addressed until quite a few builder/pilots, each discovering an anomoly he was reluctant to reveal, all "came out of the closet" and confessed they'd detected a serious safety item. I liken this battery problem to that, and suspect strongly that each of us should inspect his SV lithium battery, determine what caused this, and press for a manufacturer "fix" we can trust.

Jim

let it burn

Lipo fires are self oxidizing and cannot be extinguished. They have to burn out.

The Heathrow fire was caused by a pinched wire due to a poor install of a replacement battery.

The 787 lipos are now and were in containment cases. They can withstand a full blown meltdown and not jepordize flight safety. The new cases have better overboard venting to dump combustion sbyproducts.

The SV battery is much smaller but we all need to know what a runawy battery failure presents so we can engineer a proper isolation (if it hasn't already been done in the -12 case) to allow it to fail without acceptable loss of safety.

I wonder if Jim's battery failure was a worst case failure? It was so benign, it wasn't noticed at the time of failure. Or can the failure present itself more severely?

Any volunteers to force a failure in the SV battery and document it?

The D180 has the ability to display backup battery voltage. I wonder if that would be useful in detecting the failure before it turns catastrophic.

JRo, please report this on the Dynon Skyview Forum! I could do that via a link but it would be better coming from you.

Sky view battery

Had to remove top skin to check out radio problem. My backup battery looks fine but only 54 hrs on slsa. Battery sn 3395

Dynon recommends running the Skyview battery test once a year. Running this test more frequently might allow to detect a failure like the one mentioned without having to remove the avionic shelf cover. On the other hand repeated complete discharges of the battery will be creating stress that may result in earlier failure or limited lifetime for the battery. Dynon may want to provide guidelines on this matter in view of this recent discovery.

Another thought on this, I got a bad battery with mine, Dynon indicated if Irecall correctly that they had received a few bum batteries, they replaced mine under warranty, no more problems.

So just a quick post on this: We take failure reports of this kind extremely seriously. Jim's battery has been subjected to a full engineering tear-down inspection. His battery did not experience ANY electronic or heat-related failure of any kind. The short version is that a mounting fastener looks to have been torqued down tight enough onto the battery's plastic case to crack it. This caused cosmetic damage to the case (the case is not part of the functional pack). The battery pack inside was completely functional and undamaged. We'll have a more detailed post on this later.

Although Li-ion batteries have gotten a bad rep lately, there're extremely safe when they're built, charged, and managed properly (hence why there are billions of them in the world, in every device you carry on your body). We'll have more on what we do to in our battery and system design to produce an extremely safe and capable battery backup capability for SkyView shortly as well.

Michael Schofield
Marketing Manager
Dynon Avionics

JRo said:

And guess what I discovered to my horror?! A partial melt-down of the SV back-up battery! This is another word for a lithium flare: ask any Boeing engineer! A definite safety-of-flight item. Although mine had not failed or fully burned, the damage was a clear indication of excessive heat.

Click to expand...

A cracked battery case confused with a partial meltdown. Odd how reality and perception can be so different.

As I mentioned previously - here's a new article on our Preflight Briefing site that goes into the things we do on our battery and system design to mitigate possible failure modes in our backup solutions.

Best,

Mike