Date: Fri, 23 Dec 2005 09:08:37 +0800
From: Raymond <[EMAIL PROTECTED]>
Subject: Re: [LIB] u100 battery life engineering problem
11.1V 2.2AH LiPoly batteries (3 cells) weighing about 120g can be readily
obtained that can pump 33 amps continuously without damage and without the
terminal voltage dropping significantly (internal resistance is in the
region of tens of milliohms per cell so we're talking drops of a volt or
two at 33 amps) ... and the pack itself is about 70x43x30mm in size. Any
decent hobby store will sell them to you (they're mainly used in electric
model planes, powered gliders and helis), in Australia you can get them
off-the-shelf for around $80-$90AUD.
I dunno about you but as far as I'm aware there aren't any NiMH cells or
any other battery technology for that matter (at least none that are
readily available) that can be formed into a pack that can approach that
sort of weight, size or internal resistance for that voltage or energy
capacity.
Besides, there has to be a reason why people from modellers to mobile phone
makers to laptop and PDA makers switched to LiIon/LiPoly despite the more
complex charging/discharging safeguard circuitry involved.
Which equations and graphed data do you refer to?
- Raymond
At 04:45 PM 22/12/2005 -0800, you wrote:
Date: Thu, 22 Dec 2005 16:44:30 -0800 (PST)
From: [EMAIL PROTECTED]
Subject: Re: [LIB] u100 battery life engineering problem
I've checked that out along with the equations and still don't get it.
first off they're equations are questionable when run up against the
graphed data. second when compared to the weight of the actual batteries I
have to carry when using li-poly as compared to the actual weight of ni-mh
cells the nimh cells are lighter. so what is this energy density stuff
anyway?
> Date: Thu, 22 Dec 2005 09:01:09 +1100
> From: Jonathan Paxman <[EMAIL PROTECTED]>
> Subject: Re: [LIB] u100 battery life engineering problem
>
> On 22/12/05, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
>> true, external temperatures affect li-poly but do not affect nicad/nimh
>> chemistries unless they are in the +120/-20 range. gotta wonder why the
>> industry uses an old technology like lithium when the nickel metal is so
>> much more superiour in every way.
>
> Two words: energy density.
>
> Jon
>
>
>
>
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