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  #21  
Old 19-12-2014
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Si Coe Si Coe is offline
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The thing to remember is that we do rather abuse whatever cell tech we are using. Our demands in terms of peak discharge currents especially are far higher than most applications, and then we want rapid recharge too. Stuff like Tesla's spread big currents across many cells in parallel so the individual load is much less and weaker cells arent as stressed.
So if a cell tech IS dangerous we would spot it first, but at the same time we tend to pay more attention to our cells than in other applications where you can't easily spot the tell tale puffing.
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  #22  
Old 19-12-2014
SlowOne SlowOne is offline
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Quote:
Originally Posted by mattr View Post
Didn't realise tesla were still using 18650s, the rumour was that they'd switched.
But tesla is the one electric/hybrid we haven't opened the battery box up to have a look at!

Didn't the Boeing issue come down to the batteries simply not being up to the job?
Matt, my information comes from a 2011 American study into LiPo-related use and assessment and quotes Tesla as follows:

The Tesla Roadster battery pack is composed of approximately 6,800 18650-cells.

The Boeing issue is not clear. Just this month the NTSB has said the problem stems from poor work in the design and engineering of the cells and their related systems, but Boeing has cited problems in manufacture at the supplier, Yuasa. HTH
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  #23  
Old 20-12-2014
mattr mattr is offline
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Yeah, I found the safety bulletin on line. Reading between the lines it looks like they completely misread the manual for the LiPos!

Not surprising for Boeing, they've got form for that!
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  #24  
Old 20-12-2014
SlowOne SlowOne is offline
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What I thought worse was the criticism of the FAA for not having a proper certification procedure for those cells!

If the FAA apparently can't certify things properly and Boeing seemingly can't read instructions, how much better have we done in our sport where a bunch of amateurs have managed to do both with failure rates waaayyyy below the 787?!! That article is still a real bum piece of work...
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  #25  
Old 20-12-2014
mattr mattr is offline
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To be fair, aerospace as an industry is usually 10 years or more behind the cutting edge except in a very limited number of fields. Materials is mostly where the tech is. Composites and super alloys...... Giving them a Lipo is like giving a caveman a mobile phone......
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  #26  
Old 20-12-2014
SlowOne SlowOne is offline
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Originally Posted by mattr View Post
To be fair, aerospace as an industry is usually 10 years or more behind the cutting edge except in a very limited number of fields. Materials is mostly where the tech is. Composites and super alloys...... Giving them a Lipo is like giving a caveman a mobile phone......
Materials yes, but also manufacturing processes. Making the parts out of those latest materials pushes every manufacturing process you can think of to its limits. We are an inventive lot in aerospace; most people would not believe what can be achieved or what is required for an aerospace part, be it airframe or engine.

It always amuses me when things are advertised as CNC-machined - you can't buy a new machine tool worth using that doesn't have an CNC controller on it. As if being machined automatically was something new...!!

Way off topic now; I'll get me coat...
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  #27  
Old 20-12-2014
mattr mattr is offline
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I know, I spent several years designing gas turbines...... and most of the manufacturing isn't actually cutting edge, it's just being pushed a lot further than the poor buggers who thought it up in the first place were expecting!
With a few notable exceptions, where we had to invent new technology! Rather than nicking it.
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