Why lio-ion, why not lipo in Boeings or planes?

g (0.36-0.95 MJ/kg)

/L (0.90-2.23 MJ/L)

W/kg

scharge versus capacity ratios.

why not lifepo4

afaikt they are comparable but much safer

-Lasse

On a sunny day (Sat, 23 Mar 2013 06:34:43 -0700 (PDT)) it happened " snipped-for-privacy@fonz.dk" wrote in :

Maybe because specific powr of 7.5 kW/kg is much higher for lipo? (versus 300 W/kg for LiFePO4)

w/o Download-manager

debug-versions

hth

- Michael Wieser

They should have done the Tesla thing, used a few thousand laptop batteries.

--

John Larkin Highland Technology Inc

Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

es.

.highlandtechnology.com  jlarkin at highlandtechnology dot com

With a few thousand of anything, the reliability calculations go all to hell.

ries.

ww.highlandtechnology.com jlarkin at highlandtechnology dot com

depends on what happens if one of them fails

-Lasse

Incwww.highlandtechnology.com  jlarkin at highlandtechnology dot com

So build in a lot of redundancy; it's almost inherent. That would be an advantage of using lots of production-quality cells.

Hello, as for RC "lipo" batteries, AFAIK these are Lithium cells wetted with liquid electolyte, and not solid polymer as the name suggests. These cells are optimized for lowest possible internal resistance and low weight, cycle life and safety are not a priority, and are not that good. I use them, but I dont know their real chemistry, the fact that they tend to burn like a torch (check youtube for RC lipo fires) suggests that probably they are the usual Lithium Cobalt Oxide, if I remember correctly the cobalt oxide tend to become unstable at temperatures around 200°C, giving away oxygen, so they burn happily with their oxigen source. Other chemistries (based on manganese, nichel, aluminium and mixes of these) are probably better, but the problem is still present. Their energy density is so high that it's easy for a failed cell to become very hot also if not fully charged.

AFAIK among the lithium chemistries lithium-phosphate is the safer one, but also lower energy density. Cycle life is good, and power density is not bad, check A123systems cells specs.

...snip...

One problem with complex things like planes is that the cycle time from design to production makes any fast-moving technology obsolete before it can be put into service.

On a sunny day (Sun, 24 Mar 2013 12:12:19 +1000) it happened Adrian Jansen wrote in :

That is true, but a bit modular design can make things better. Battery packs fit well in a modular design strategy.

Containment of the energy, plus disconnect and drop on overtemperature. would be good but not electronics desigh.

On a sunny day (Sun, 24 Mar 2013 22:44:32 -0500) it happened snipped-for-privacy@nospam.pobox.com (Will Janoschka) wrote in :

Not 100% sure what you want to express here, but they already completely redesigned that battery housing, adding considerable extra weight in the process. Seem a bit silly to me then NOT to look at alternatives like lipo that have a much higher energy per weight capacity (order of magnitude almost), and would require EXACTLY the same sort of 'explosion proof housing with venting' they have come up with now.,

Electronic design can never be seen separate from what it is used for, at least in my experience, I always had to study both subjects, Same with programming. So there is nothing new there. What could be not so new also is a blindfolded largely clueless management doing the ever so popular top down approach, and there is a 'dream'-liner. Joint strike fighter. NASA space projects. LOL

almost),

venting'

least in my experience,

As I read it, the original Lion battery was designed in to save 100 lbs of weight, compared to the commonly used ( and well tested ) NiCad system. After the repackaging to add better cell separation and strength, the pack now weighs 150 lbs heavier. Thats progress ?