Lithium Battery Explosion

[Low Pass]

It's all about understanding the risks and judging accordingly. One thing that's imperative to me is having an over voltage alarm. Protective measures and fault tolerant systems are good, but I want the red blinking annunciator also. So I can intervene. One overvoltage occurrence in 14 yrs, 1600 hrs. Not frequent, but a reasonable concern.

Good info shared here!

[RVDan]

Ul 94 V0 is a flammability test standard, in general has nothing to do with batteries. Citing it is just saying that the plastic case won't significantly support flame and is self extinguishing after removal of the heat source.

[BillL]

Originally Posted by RVDan

Ul 94 V0 is a flammability test standard, in general has nothing to do with batteries. Citing it is just saying that the plastic case won't significantly support flame and is self extinguishing after removal of the heat source.

Thanks Dan. I am ignorant of actual aircraft validation standards. I am more familiar with development of validation tests based on FMEA and resulting field product warranty and reliability demands, not regulatory. I was fortunate enough to work for a large corp where we did all this for the ROI of developing better products faster. The clarification is appreciated.

[GEM930]

So I bought a Shorai battery a few months ago to replace my odyssey as I added a CS prop and was looking for some weight savings in the nose.... Now I'm thinking EarthX might have been a better option! Anyone have the model # for the EarthX replacment for the odyssey 680?

[dsteinfeld]

Hello everyone. I'm an inactive PP SEL, dreaming of building a -10 and so I've been lurking here for quite a while. With no building experience I haven't felt that I've had anything to contribute, but this thread is beginning to parallel a discussion over at the Cruiser's Forum, so I thought I'd offer a summary and a pointer. Think carefully before popping over there because that thread is over 3800 posts!

I have the following takeaways from that thread:

1) Any battery chemistry can be dangerous if misused. I had a sealed lead acid battery that bulged and got hot because I stuck it on an old-fashioned Sears charger overnight.

2) Lithium iron (in its various formulations) is arguably the safest of the rechargeable lithium chemistries to date but will be damaged by either overcharging or over discharging.

3) To mitigate (2), you must have a high voltage disconnect and should have a low voltage disconnect, but if you'd rather destroy or damage the battery because you need to keep drawing on it (alternator failure in IMC comes to mind) then leave off the low voltage disconnect. The high voltage disconnect is critical to avoid bulging, rupture, or a possible fire.

4) A battery monitoring system at the cell level rather than total pack voltage must drive the disconnects. You can charge at normal pack voltages and still overcharge (and damage) a single cell if the cells are way out of balance.

5) In deep-cycle service cells vary little in their voltages once an initial balance is done, and the consensus is that routine balancing is unnecessary. In the electric vehicle world things are different, and I suspect airplane use is somewhere in between. It all depends on charge/discharge rates, and how deeply you're willing to discharge.

6) Lithium iron looks to be a great up-and-coming technology, but it's not a lead-acid drop-in replacement--the entire charge/discharge system needs to be tailored to its different requirements. Those folks over at the Cruiser's Forum who've implemented LiFePO4 with thought and care are quite happy with the results.

Doug

[Bevan]

There is no "drop-in" replacement yet for EarthX as your PC680 battery box will need a slight enlargement (cut and weld). But as I recall, the closest spec electrically is the ETX36 series. See their web page comparison chart...

http://earthxmotorsports.com/product...ntal-aircraft/

Bevan

[Mike S]

Originally Posted by dsteinfeld

Hello everyone. I'm an inactive PP SEL, dreaming of building a -10 and so I've been lurking here for quite a while.


Doug

Doug, aboard the good ship VAF

[Mike H]

Originally Posted by dsteinfeld

Hello everyone. I'm an inactive PP SEL, dreaming of building a -10 and so I've been lurking here for quite a while. With no building experience I haven't felt that I've had anything to contribute, but this thread is beginning to parallel a discussion over at the Cruiser's Forum, so I thought I'd offer a summary and a pointer. Think carefully before popping over there because that thread is over 3800 posts!

I have the following takeaways from that thread:

1) Any battery chemistry can be dangerous if misused. I had a sealed lead acid battery that bulged and got hot because I stuck it on an old-fashioned Sears charger overnight.

2) Lithium iron (in its various formulations) is arguably the safest of the rechargeable lithium chemistries to date but will be damaged by either overcharging or over discharging.

3) To mitigate (2), you must have a high voltage disconnect and should have a low voltage disconnect, but if you'd rather destroy or damage the battery because you need to keep drawing on it (alternator failure in IMC comes to mind) then leave off the low voltage disconnect. The high voltage disconnect is critical to avoid bulging, rupture, or a possible fire.

4) A battery monitoring system at the cell level rather than total pack voltage must drive the disconnects. You can charge at normal pack voltages and still overcharge (and damage) a single cell if the cells are way out of balance.

5) In deep-cycle service cells vary little in their voltages once an initial balance is done, and the consensus is that routine balancing is unnecessary. In the electric vehicle world things are different, and I suspect airplane use is somewhere in between. It all depends on charge/discharge rates, and how deeply you're willing to discharge.

6) Lithium iron looks to be a great up-and-coming technology, but it's not a lead-acid drop-in replacement--the entire charge/discharge system needs to be tailored to its different requirements. Those folks over at the Cruiser's Forum who've implemented LiFePO4 with thought and care are quite happy with the results.

Doug

Doug, you are absolutely correct but you need to add one more item to your talking points. For use in aircraft any lithium chemistry battery should be mounted in a stainless steel enclosure which is sealed and vented overboard.

Than you for stating the facts. The data, testing and operational history already exist, you just have to actually look for it then leave your emotions out of the decision making process when making the decision to install lithium chemistry batteries in an aircraft.