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        Discussion For those who advocate against Lipos in sailplanes

#1 snakecrew Jan 16, 2013 07:31 PM

For those who advocate against Lipos in sailplanes
 
1 Attachment(s)
apparently 787's don't fair well either

#2 Twyl Jan 17, 2013 02:10 AM

Nor your Chevy Volt

http://www.zerohedge.com/sites/defau.../volt-fire.jpg

That said, supposedly size does matter and a larger lipo will be more difficult to keep stable.

-Jonathan

#3 Tailslide UK Jan 17, 2013 03:02 AM

Hat's off to the engineer though. The box looks like it contained it. Don't know anything about the event, so just going by the picture. I hope no one got hurt.

Tailslide

#4 Twyl Jan 17, 2013 03:06 AM

From what I heard, the potential dangers of Lipos was well in the minds of the designers and the FAA and numerous precautions were put into place to contain any such issue. Looks like whatever those precautions were, they did the job like you said.

-Jonathan

#5 Stehl Jan 17, 2013 03:16 AM

Wasn't it a Li-on battery?

#6 bjaffee Jan 17, 2013 03:21 AM

Is anyone running LiFe packs in gliders? I've heard they don't require a regulator, and they are not as prone to fire as LiPos.

#7 chris s Jan 17, 2013 06:26 AM

Boeing has Lithium iron batteries ( LiFe) in the B787. I think it has a set at the front for the cockpit etc and another set down the back for the APU.

I'm not a battery expert by any means but I am surprised such technology is being used in an aircraft if there is a risk of it catching fire and thus having to be contained. Normally in an aircraft the only thing you expect to burn is the fuel, not the battery.

I think most people who use Lipo`s know about the risks, and that the risk is real. It's hard to believe Boeing would risk their product just for the supposed benefit of a new battery type.

Anyway, hope Boeing get this plane ( not just the batteries ) sorted out asap. It doesn't look good for the moment, thats for sure.

C

#8 surfimp Jan 17, 2013 10:31 AM

Quote:

Originally Posted by chris s (Post 23840893)
Boeing has Lithium iron batteries ( LiFe) in the B787.

The articles I've read have indicated that the fires were caused by lithium ion batteries, not LiFePo ("lithium iron phosphate" aka "LiFe") chemistry... please cite a source that indicates otherwise?

As well as I understand it, lithium ion batteries were the first widely adopted of the lithium-based battery chemistries. This chemistry has mainstream use in everything from mobile phones to laptop computers to fullscale aircraft.

After lithium ion came lithium polymer, the ubiquitous "LiPo", which haven't been quite as widely adopted in mainstream use - although they have absolutely revolutionized the R/C hobby industry and have been the "magic bullet" that put electric power systems on par (and in many instances, vastly superior) to internal combustion power systems.

Most recent are the lithium iron phosphate batteries, known to us a "LiFePo" or "LiFe", which were initially created by A123 Systems and used in power tools. They definitely have a reputation for being safer to handle than lithium polymer and lithium ion batteries, not the least of which relates to the fact that the cells produced by A123 were designed with built-in safety measure to more safely deal with any thermal runaway issues which might occur. When first released, they were also capable of being safely charged and discharged at higher rates than comparable lipo cells, although modern lipos have caught up to and surpassed them in many regards. They also hold a charge for a very long time, and feature a very flat discharge curve. Besides not being offered in as many convenient form factors as NiMH batteries, they are basically as perfect of a receiver pack as we can ask for in model soaring.

Steve

#9 1000MPH Jan 17, 2013 11:03 AM

A quick search bring up this article...
http://www.greencarreports.com/news/...ic-cars-umm-no
"The cells in the 787, from Japanese company GS Yuasa, use a cobalt oxide (CoO2) chemistry, just as mobile-phone and laptop batteries do."

#10 GentlemanRider Jan 17, 2013 11:08 AM

I'm using a 2 cells Life on my Le Fishray. It's quite big but lightweight and has quite some capacity (1450mAh). That's enough to keep it in 'permanent storage mode': I charge it to 80% when I'm back from the slope and forget about it until I have time to fly again ;)

I have lots of NiMhs in my wings (permanently embedded in the foam), they require topping up before flying after some idle time and if I don't fly for let's say... 4 to 6 weeks I cycle them to avoid the chemistry from sleeping.

I have a 2 cell Lipo in the M60 with Corona HV servos (no BEC) but it's only 800 mAh so the storage level isn't safe to fly. I'm scared about leaving it fully charged because I've been told that LiPos don't like that. I charge it before flying, like the NiMhs, except it accepts a higher current.

IMHO a slightly oversized LiFe is the best so far. Goes without BEC wit almost all servos, doesn't require attention and the models are always ready for the last minute trip to the slope :D

#11 chris s Jan 17, 2013 11:21 AM

You are right about the battery Steve, its a Lithium-ion-polymer. Don't know what the abbreviation for that is.

#12 glasairIII Jan 17, 2013 08:32 PM

Years ago I saw the after effects of a nickel-cadmium battery thermal runaway. This was on a Cessna Citation. We found the battery remnants on the ground. We also found a square hole were in burnt it's way out the bottom of the plane:censored: At the time, this style of battery was fairly new to the industry. Now, it's used in all the commercial jets. Airbus, Boeing etc..... And I've haven't seen any issues, except dead battery's from being left on:)


Bottom line, Boeing will find the cause. And, I'd hazard a guess that they will temporarily go back to the tried and true nickel-cadmium. I'd also hazard a guess they went to the new technology for the same reason we do. Weight and capacity.

#13 bjaffee Jan 17, 2013 08:47 PM

Quote:

Originally Posted by chris s (Post 23843061)
You are right about the battery Steve, its a Lithium-ion-polymer. Don't know what the abbreviation for that is.

Isn't that just a LiPo? http://en.wikipedia.org/wiki/Lithium...olymer_battery

#14 1000MPH Jan 17, 2013 09:12 PM

I found this too...
http://www.s399157097.onlinehome.us/...s/LVP10-65.pdf

#15 O.G. Gamesta Jan 17, 2013 10:43 PM

People are for/against LiPo batteries for various reasons. It looks like many r/x and servo managers are upping the voltage requirement to accommodate the many folks who want to LiPo their planes. The advantages of a LiPo system are huge.

Where I live and fly, you risk burning down the whole of SoCal. During our current Santa Anna wind event, everything is so dry, even the bushes just crumble like dry hay. I've never run a battery down on a plane in one session as I usually bring a couple or more planes with me when I fly just to mix it up.


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