Re: [Gumstix-users] gumstix-users Digest, Vol 5, Issue 130

[<tim...@co...>]

You are right.  I reread the specs.  The mobos want >3.5 volts
The LiPos provide 4.2 - 3.0 volts with 3.5 volts 95% depleated.
What is the min voltage of the STUART board?

 -------------- Original message ----------------------
From: "Bruce Fortnam" <bfortnam@GlobalLocate.com>
> tim...@co... wrote:
> 
> >LiPo batts have a voltage range of 3.0 to 3.6 volts.  So you
> >would only get 50% usage from the battery as the gumstix
> >will stop working at 3.4 volts.
> 
> Hi Tim,
>  
> No battery has a straight-line discharge curve.  Li-Ion and Li-polymer both 
> start at 4.2 V when fully charged, drop quickly below 4 V, then decline very 
> slowly until they're about 90% depleted, at which point they drop off a cliff.  
> See the typical discharge curve at:
>  
> http://www.ibt-power.com/Battery_packs/Li_Polymer/Lithium_polymer_tech.html
>  
> With the battery shown, at room temperature, you will obtain over 95% of the 
> battery's capacity if you cut off at 3.4 V.  Note also that cutting off at 2.5 V 
> as some people are suggesting gains you almost nothing in terms of capacity.
>  
> At low temperatures, it's a different story: at -20 C, cutting off at 3.4 
> instead of 3.0 V will give up 20-30% of the capacity.
>  
> Regards,
> Bruce
>  
>