[chbot] LiPo batteries

[Kay edgecumbe]

quote   If you over discharge them then they can lose capacity in a real hurry


at a chemistry lecture the clue to this was the statment

 

"when anion and cations combine in a solution they form an inert substance)"

 

not the same  but understands why discharging a lifepo4 battery below  a safe voltage they just die and cant be revived 
 

> Date: Fri, 17 May 2013 11:56:09 +1200
> To: chchrobotics at lists.linuxnut.co.nz
> From: markaren1 at xtra.co.nz
> Subject: Re: [chbot] LiPo batteries
> 
> How timely.
> 
> I am pretty sure that Li Ion and Li Po have similar issues:
> 
> Been given a small pile of Li Ion batteries, and 
> bought some http://www.ebay.com/itm/260841670123
> 
> Briefly, if you over charge them they do occasionally explode
> 
> If you over discharge them then they can lose capacity in a real hurry
> 
> There is a difference between 4.1V and 4.2V 
> cells, beware - this is absolute max terminal voltage.
> 
> The boards above have 5V in, 5V out and cell 
> protection, so the cell is taken out of circuit 
> of over-charge or over-discharge imminent. I do 
> plan to run one of these up carefully and see how they behave.
> 
> Li Ion can deliver large currents, so an in-line fuse is mandatory.
> 
> From Wikipedia
> Li Ion specific energy 100–265 Wh/kg
> Ni Mh specific energy 60–120 Wh/kg
> Ni Cd specific energy 40–60 Wh/kg
> 
> The good news is there is a lot in a lightweight package
> 
> The bad news is that there is a lot in a lightweight package
> 
> If treated with respect, they behave well -- these are not for the unwary.
> 
> In terms of burning your house down, you probably 
> already have lots of these units in your phone, laptop etc. already.
> 
> If you have concerns about safety, stick with 
> NiMh the older types have self discharge 
> problems, but I don't think they will blow up (a 
> function of internal resistance and available energy).
> 
> Mr Harris is one of (or The) resident expert, and 
> I await comments from him on this brain-dump.
> 
> -Mark
> 
> 
> At 11:17 a.m. 17/05/2013, you wrote:
> >How safe is it really to have LiPo batteries around the house?
> >
> >I was thinking of using some of the 1-cell hobbyking offerings as backup
> >for some microcontrollers. Then I read the reports of what these
> >batteries do to people, like burning the house down, but I don't fancy
> >having the chemical smoke of one of them's guts in the house either.
> >
> >What would people consider to be safe handling precautions in terms of
> >charger, charge location and storage? What about charging them
> >in-circuit?
> >
> >Thanks,
> >
> >Volker
> >
> >--
> >Volker Kuhlmann
> >http://volker.dnsalias.net/ Please do not CC list postings to me.
> >
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